United StatesDepartment of                Effects of Climatic Variability andAgricultureForest Service                    ...
The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of multiple use management of theNa...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870AbstractVose, James M.; Peterson, David L.; Patel-Weynand, Toral, eds. 2012. Effects o...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870Executive Summary                                                discusses interrelate...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870Managing Risk and Adapting to                                     direct exposure to t...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870•	 The potential for increased wildfire hazard, longer              Projections of cha...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870Contents1	    Chapter 1: Introduction	     David L. Peterson and James M. Vose4	    Li...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870107	 Interactions Between Trees and Climate in Urban Environments108	 Effects of Clima...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870197	 Ecological Disturbances and Extreme Events197	 Coordination With Other Assessment...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870United States was caused by “global-change type drought.”          often focuses on ex...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870Literature Cited                                                Karl, T.R.; Melillo, J...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-8706
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870more dramatic effects, because temperatures are expected         variability at an ind...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
GENERAL TECHNICAL REPORT PNW-GTR-870Figure 2.1—Multimodel mean annual differences in temperature between the three future ...
Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sec...
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector
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Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector

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This U.S. Forest Service report examines the likely effects of climate change on the nation's forests during the 21st century.

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Transcript of "Effects of Climate Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector"

  1. 1. United StatesDepartment of Effects of Climatic Variability andAgricultureForest Service Change on Forest Ecosystems:Pacific NorthwestResearch Station A Comprehensive ScienceGeneral Technical Synthesis for the U.S. ForestReportPNW-GTR-870 SectorDecember 2012 REDE PA RT TU MENT OF AGRI C U L
  2. 2. The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of multiple use management of theNation’s forest resources for sustained yields of wood, water, forage, wildlife, and recreation. Through forestry research, coop-eration with the States and private forest owners, and management of the national forests and national grasslands, it strives—as directed by Congress—to provide increasingly greater service to a growing Nation.The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color,national origin, sex, religion, age, disability, sexual orientation, marital status, family status, status as a parent (in educationand training programs and activities), because all or part of an individual’s income is derived from any public assistance pro-gram, or retaliation. (Not all prohibited bases apply to all programs or activities).If you require this information in alternative format (Braille, large print, audiotape, etc.), contact the USDA’s TARGET Center at(202) 720-2600 (Voice or TDD).If you require information about this program, activity, or facility in a language other than English, contact the agency office re-sponsible for the program or activity, or any USDA office.To file a complaint alleging discrimination, write USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W.,Washington, D.C. 20250-9410, or call toll free, (866) 632-9992 (Voice). TDD users can contact USDA through local relay orthe Federal relay at (800) 877-8339 (TDD) or (866) 377-8642 (relay voice users). You may use USDA Program DiscriminationComplaint Forms AD-3027 or AD-3027s (Spanish) which can be found at: http://www.ascr.usda.gov/complaint_filing_cust.htmlor upon request from a local Forest Service office. USDA is an equal opportunity provider and employer.EditorsJames M. Vose is a research ecologist, U.S. Department of Agriculture, Forest Service, Southern Research Station,Center for Integrated Forest Science and Synthesis at North Carolina State University, Department of Forestry andEnvironmental Resources, Campus Box 8008, Raleigh, NC 27695; David L. Peterson is a research biological scientist, U.S.Department of Agriculture, Forest Service, Pacific Northwest Research Station, Pacific Wildland Fire Sciences Laboratory,400 N 34th Street, Suite 201, Seattle, WA 98103; Toral Patel-Weynand is a national coordinator for bioclimatology, U.S.Department of Agriculture, Forest Service, Research and Development, 1601 N Kent Street, RPC 4, Arlington, VA 22209.
  3. 3. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest SectorEffects of Climatic Variability and Change onForest Ecosystems:A Comprehensive Science Synthesis for theU.S. Forest SectorJames M. Vose, David L. Peterson, and Toral Patel-Weynand, EditorsPublished by:U.S. Department of AgriculturePacific Northwest Research StationForest ServicePortland, OregonGeneral Technical Report PNW-GTR-870December 2012 i
  4. 4. GENERAL TECHNICAL REPORT PNW-GTR-870AbstractVose, James M.; Peterson, David L.; Patel-Weynand, Toral, eds. 2012. Effects of climatic variability and change on forest ecosystems: a comprehensive science synthesis for the U.S. forest sector. Gen. Tech. Rep. PNW-GTR-870. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 265 p.This report is a scientific assessment of the current condition and likely future condition of forest resources in the UnitedStates relative to climatic variability and change. It serves as the U.S. Forest Service forest sector technical report for theNational Climate Assessment and includes descriptions of key regional issues and examples of a risk-based framework for as-sessing climate-change effects. By the end of the 21st century, forest ecosystems in the United States will differ from those of today as a result of chang-ing climate. Although increases in temperature, changes in precipitation, higher atmospheric concentrations of carbon dioxide(CO2), and higher nitrogen (N) deposition may change ecosystem structure and function, the most rapidly visible and mostsignificant short-term effects on forest ecosystems will be caused by altered disturbance regimes. For example, wildfires,insect infestations, pulses of erosion and flooding, and drought-induced tree mortality are all expected to increase during the21st century. These direct and indirect climate-change effects are likely to cause losses of ecosystem services in some areas,but may also improve and expand ecosystem services in others. Some areas may be particularly vulnerable because currentinfrastructure and resource production are based on past climate and steady-state conditions. The ability of communitieswith resource-based economies to adapt to climate change is linked to their direct exposure to these changes, as well as tothe social and institutional structures present in each environment. Human communities that have diverse economies and areresilient to change today will also be prepared for future climatic stresses. Significant progress has been made in developing scientific principles and tools for adapting to climate change throughscience-management partnerships focused on education, assessment of vulnerability of natural resources, and development ofadaptation strategies and tactics. In addition, climate change has motivated increased use of bioenergy and carbon (C) seques-tration policy options as mitigation strategies, emphasizing the effects of climate change-human interactions on forests, aswell as the role of forests in mitigating climate change. Forest growth and afforestation in the United States currently accountfor a net gain in C storage and offset approximately 13 percent of the Nation’s fossil fuel CO2 production. Climate changemitigation through forest C management focuses on (1) land use change to increase forest area (afforestation) and avoiddeforestation, (2) C management in existing forests, and (3) use of wood as biomass energy, in place of fossil fuel or in woodproducts for C storage and in place of other building materials. Although climate change is an important issue for manage-ment and policy, the interaction of changes in biophysical environments (e.g., climate, disturbance, and invasive species) andhuman responses to those changes (management and policy) will ultimately determine outcomes for ecosystem services andpeople. Although uncertainty exists about the magnitude and timing of climate-change effects on forest ecosystems, sufficientscientific information is available to begin taking action now. Building on practices compatible with adapting to climatechange provides a good starting point for land managers who may want to begin the adaptation process. Establishing a foun-dation for managing forest ecosystems in the context of climate change as soon as possible will ensure that a broad range ofoptions will be available for managing forest resources sustainably. Keywords: Adaptation, carbon, climate change, climate-change effects, climate-smart management, ecological distur-bance, forest ecosystems, mitigation, National Climate Assessment.ii
  5. 5. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest SectorAcknowledgments English EquivalentsThe editors express their profound thanks to the many When you know: Multiply by: To find:authors who contributed excellent material to this report Millimeters (mm) 0.0394 Inchesunder a tight deadline. We also thank the following technical Centimeters (cm) .394 Inchesreviewers who provided insightful comments and sugges- Meters (m) 3.28 Feettions on earlier drafts, thus improving the quality of the Kilometers (km) .621 Milesfinal publication: Craig Allen, Dan Binkley, Barry Bol- Hectares (ha) 2.47 Acreslenbacher, Paul Bolstad, Marilyn Buford, Catherine Dowd, Square meters (m2) 10.76 Square feetDaniel Fagre, Bruce Goines, Margaret Griep, Sue Hagle, Square kilometers (km ) 2 .386 Square milesEdie Sonne Hall, Jeffrey Hicke, Randy Johnson, Evan Megagrams (Mg) 1 TonsMercer, David Meriwether, James Morrison, Charles Sams, Teragrams (Tg) 1,102,311.31 TonsAmy Snover, and David Theobald. Ellen Eberhardt assisted Degrees Celsius (C) 1.8 °C + 32 Degrees Fahrenheitwith formatting the report and tracking many details of theeditorial process. Patricia Loesche carefully edited the entirereport and provided many helpful suggestions on writingquality. Robert Norheim created and revised several maps.Participants in the Forest Sector stakeholders workshop inAtlanta, Georgia, in July 2011 provided helpful input onthe overall content of the report, owing in large part to theskillful facilitation and workshop design provided by NancyWalters. Financial support for the editors and for publicationwas provided by the U.S. Forest Service Southern ResearchStation (James M. Vose), Pacific Northwest Research Station(David L. Peterson), and national research and developmentstaff (Toral Patel-Weynand). iii
  6. 6. GENERAL TECHNICAL REPORT PNW-GTR-870Executive Summary discusses interrelated aspects of biophysical and socioeco- nomic phenomena in forested ecosystems that may beThe forest sector technical report is a sector-wide scien- affected by climatic variability and change, followed bytific assessment of the current condition and likely future these chapters:condition of forest resources in the United States relative toclimatic variability and change. The assessment provides • Effects of Climatic Variability and Changetechnical input to the National Climate Assessment (NCA) • Climate Change, Human Communities, and Forestsand serves as a framework for managing forest resources in in Rural, Urban, and Wildland-Urban Interfacethe United States. The report provides technical input to the Environments2013 NCA developed by the U.S. Global Change Research • Adaptation and MitigationProgram (USGCRP). • Improving Scientific Knowledge The Global Change Research Act of 1990 requires the • Future Assessment ActivitiesUSGCRP to produce the NCA for the President and the Con- • Conclusionsgress every four years, analyzing the effects of global change It is difficult to conclude whether recently observedon multiple sectors and regions in the United States. The trends or changes in ecological phenomena are the result ofUSGCRP is responsible for preparing the report based on human-caused climate change, climatic variability, or othertechnical information provided by public agencies and non- factors. Regardless of the cause, forest ecosystems in thegovernmental organizations. The NCA evaluates the effects United States at the end of the 21st century will differ fromof global change on agriculture, forests, energy production those of today as a result of changing climate. Below weand use, land and water resources, transportation, human discuss the most important issues that have emerged fromhealth and welfare, human social systems, and biological di- the report, including a brief summary of regional issues.versity, projecting major trends forward for up to 100 years. In addition, the USGCRP is tasked with providing a co- Effects of Climate Change onordinated strategy and implementation plan for assessing the Ecosystem Structure, Function,effects of a changing climate on the Nation. This strategy is and Servicesbeing developed to provide support to the NCA and establish A gradual increase in temperature will alter the growinga mechanism for an ongoing assessment capability beyond environment of many tree species throughout the Unitedthe 2013 report. States, reducing the growth of some species (especially in The forest sector technical report is the key technical dry forests) and increasing the growth of others (especiallyinput to the NCA forest sector chapter. To provide national in high-elevation forests). Mortality may increase in olderstakeholder input to the forest sector technical report, a forests stressed by low soil moisture, and regenerationworkshop was held in Atlanta, Georgia, on July 12–14, may decrease for species affected by low soil moisture and2011, to solicit input from public, private, and tribal forest competition with other species during the seedling stage.stakeholders, nongovernmental organizations, academics, Most models preject that species habitat will move upwardprofessional organizations, private corporations, and federal in elevation and northward in latitude and will be reduced inagencies. These stakeholder suggestions helped to frame current habitats at lower elevations and lower latitudes. Newthe subject matter content and management options in the climatic conditions may “move” faster in some locationsreport, ensuring relevance for decisionmakers and resource than tree species can disperse, creating uncertainty about themanagers. future vegetation composition of these new habitats. The forest sector technical report builds on the portion The high genetic diversity of most tree species confersof the 2009 NCA that discussed forest ecosystems and tolerance of a broad range of environmental conditions,incorporates new findings from scientific and management including temperature variation. Therefore, in many spe-perspectives. The introduction provides an overview and cies, tree growth and regeneration may be affected moreiv
  7. 7. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sectorby extreme weather events and climatic conditions than by services in others (e.g., increased growth of high-elevationgradual changes in temperature or precipitation. Longer dry trees, longer duration of trail access in high-snow regions).seasons and multiyear droughts will often become triggers Some areas may be particularly vulnerable because currentfor multiple stressors and disturbances (e.g., fire, insects, infrastructure and resource production are based on pastinvasive species, and combinations thereof). These pulses climate and the assumption of steady-state natural resourceof biophysical disturbance will change the structure and conditions. Any change in forest ecosystems that affectsfunction of ecosystems across millions of hectares over a water resources will typically result in a significant loss ofshort period of time, focusing pressure on the regeneration ecosystem services.stage of forest ecosystems. Increased atmospheric carbondioxide (CO2) and nitrogen deposition will potentially alter Effects of Disturbance Regimesphysiological function and productivity of forest ecosystems, The most rapidly visible and significant short-term effectswith considerable variation in response among species and on forest ecosystems will be caused by altered disturbanceregions. regimes, often occurring with increased frequency and se- The effects of climate change on water resources will verity. Interacting disturbances will have the biggest effectsdiffer by forest ecosystem and local climatic conditions, as on ecosystem responses, simultaneously altering speciesmediated by local management actions. Higher temperature composition, structure, and function. The type and mag-during the past few decades has already decreased snow nitude of disturbances will differ regionally and will posecover depth, duration, and extent, a trend that will probably significant challenges for resource managers to mitigate andcontinue with further warming. Decreased snow cover will reduce damage to resource values:exacerbate soil moisture deficit in some forests, which may • Wildfire will increase throughout the United States,decrease tree vigor and increase susceptibility of forests to causing at least a doubling of area burned by the mid-21stinsects and pathogens. As climatic extremes increase and century.forest ecosystems change, water produced from forest lands • Insect infestations, such as the current advance of barkmay become more variable and of lower quality. beetles in forests throughout the Western United States Forest growth and afforestation in the United States cur- and Canada, will expand, often affecting more land arearently account for a net gain in carbon (C) storage, offsetting per year than wildfire.approximately 13 percent of the Nation’s fossil fuel CO2 • Invasive species will likely become more widespread,production. During the next few decades, Eastern forest especially in areas subject to increased disturbance andecosystems are expected to continue to sequester C through in dry forest ecosystems.favorable response to elevated CO2 and higher tempera- • Increased flooding, erosion, and movement of sedimentture, although retention of C will depend on maintaining into streams will be caused by (1) higher precipitationor increasing total forest area. Western forest ecosystems intensity in some regions (e.g., Southern United States),may begin to emit C if wildfire area and insect disturbance (2) higher rain:snow ratios in mountainous regionsincrease as expected. (western mountains), and (3) higher area burned (western Future changes in forest ecosystems will occur on both dry forests). These increases will be highly variable inpublic and private lands and will challenge our ability to space and time, affecting decisions about management ofprovide ecosystem services desired by society, especially roads and other infrastructure, as well as access for usersas human populations continue to grow and demands for of forest land.ecosystem services increase. Climate change effects in • Increased drought will exacerbate stress complexes thatforests are likely to cause losses of ecosystem services in include insects, fire, and invasive species, leading tosome areas (e.g., timber production, water supply, recre- higher tree mortality, slow regeneration in some species,ational skiing), but they may improve and expand ecosystem and altered species assemblages. v
  8. 8. GENERAL TECHNICAL REPORT PNW-GTR-870Managing Risk and Adapting to direct exposure to these changes, as well as to the social andClimate Change institutional structures present in each environment. Human communities that have diverse economies and are resilient toA risk-management framework for natural resources identi- change today will also be better prepared for future climaticfies risks and quantifies the magnitude and likelihood of stresses, especially if they implement adaptation strategiesenvironmental and other effects. Although risk management soon. Federal agencies have made significant progress in de-frameworks have been used (often informally) in natural veloping scientifically based principles and tools for adapt-resource management for many years, it is a new approach ing to climate change. These tools and techniques are readilyfor projecting climate change effects, and some time may be available in recent materials that can be supplied to public,needed for scientists and resource managers to feel comfort- private, and tribal land owners and managers for their use inable with this approach. Risk assessment for climate change forest management.must be specific to a particular region and time period, and itneeds to be modified by an estimate of the confidence in the Regional Effects of Climaticprojections being made. Variability and Change Ecosystem services derived from forests are producedin (1) rural areas, where human population densities are The report incorporates a regional perspective and highlightslow and forest cover dominates; (2) urban settings, where key issues for the forest sector in the NCA regions.trees may exist in low densities but provide high value for Alaskadirect ecosystem services; and (3) transition zones betweenrural and urban settings (wildland-urban interface [WUI]). • Alaskan forests are regionally and globally significant,Climate change will alter ecosystem services, perceptions and changes in disturbance regimes will directly affectof value, and decisions regarding land uses. Outcomes for the global climate system through greenhouse gaspeople will be determined by the interaction between chang- emissions and altered surface energy budgets.es in biophysical environments (e.g., climate, disturbance, • Climate-related changes in Alaskan forests have societaland invasive species) and human responses to those changes consequences, because some forests are in proximity to(management and policy). In recent years, C sequestration (urban and rural) communities and provide a diversity ofpolicy options and increased use of bioenergy emphasize ecosystem services.both climate change-human interactions on forests and the • In interior Alaska, the most important effects of climaterole of forests in mitigating climate change. change are permafrost thawing and changes in fire Land use shifts in rural areas under climate change regimes.could involve conversion of forests to agricultural uses, • South-central Alaska will be sensitive to climate changedepending on market conditions. Climate change is expected because of its confluence of human population growthto alter productivity (local scale) and prices (market scale). and changing disturbance regimes (insects, wildfire,The extent of WUI areas and urban areas are projected to invasive species).increase, often at the expense of rural forests. Higher tem- • In southeast Alaska, climatic warming will affect forestperature coupled with population growth will increase the ecosystems primarily through effects on precipitationextent and value of urban trees for mitigating climate change (i.e., snow versus rain).effects, but these two factors may also increase the difficultyof keeping trees healthy in urban environments. Hawaii and the Pacific Territories The ability of communities with resource-based • Pacific islands are vulnerable to climate change becauseeconomies to adapt to climate change is linked to their of (1) the diversity of climate-related stressors; (2) low financial, technological, and human resource capacitiesvi
  9. 9. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector to adapt to or mitigate projected effects; and (3) diverse • A combination of higher temperature and dense, low- and often more pressing concerns affecting island vigor stands have increased vulnerability to bark beetles communities. and other insects, and mortality is currently high in some• Island societies and cultures based on traditional dry forests. knowledge and institutions have provided resilience to these communities during past stressful periods. Southwest Contributing to resilience are locally based ownerships • Disturbance processes facilitated by climatic extremes, and management, subsistence economies, tight linkages primarily multiyear droughts, will dominate the effects between landowners and government, and opportunities of climatic variability and change on both short- and for migration. long-term forest dynamics.• The direct effects of changing climate on forests will • Although diebacks in species other than pinyon pine be significant and strongly dependent on interactions (Pinus edulis Engelm.) are not widespread, large fires with disturbances, especially novel fire regimes that are and insect outbreaks appear to be increasing in frequency expanding into new areas because of flammable invasive and spatial extent throughout the Southwest. species. • Increased disturbance from fire and insects, combined• For low-lying islands, enhanced storm activity and with lower forest productivity at most lower elevation severity and sea level rise will cause the relocation locations, will result in lower C storage in most forest of entire communities, with the first climate refugees ecosystems. The fire-insect stress complex may keep already having to relocate from homelands in the region. many low-elevation forests in younger age classes in For high islands, higher temperature, expanded cover perpetuity. of invasive species, and higher fire frequency and • Increased fire followed by high precipitation (in winter severity will affect ground-water recharge, downstream in California, in early summer in much of the rest of agriculture, urban development, and tourism. the Southwest) may result in increased erosion and downstream sediment delivery.Northwest• Based on projections of distribution of tree species and Great Plains forest biomes, widespread changes in the distribution • Trees occur along streams, on planted woodlots, as and abundance of dominant forest species are expected, isolated forests such as the Black Hills of South Dakota, although the results of modeling studies differ. Forest and near the biogeographic contact with the Rocky cover will change faster via disturbance and subsequent Mountains and Eastern deciduous forests, providing regeneration responses, rather than through slow significant value in riparian areas, at higher elevations, adjustment to gradual warming. and within agroforestry systems.• Climate is projected to become unfavorable for Douglas- • Tree species in mountainous regions are expected to fir (Pseudotsuga menziesii (Mirb.) Franco) over 32 gradually become redistributed to higher elevations, with percent of its current range in Washington, and up to 85 disturbances mediating rapid change in some locations. percent of the range of some pine species may be outside • Climate-driven changes in hydrology are expected to the current climatically suitable range. reduce the abundance of dominant, native, early-• Area burned and biomass consumed by wildfire will successional tree species and increase herbaceous, greatly increase, leading to changes in ecosystem drought-tolerant, late-successional woody species structure and function, resource values in the WUI, and (including nonnative species), leading to reduced habitat expenditures for fire suppression and fuels management. quality for riparian fauna. vii
  10. 10. GENERAL TECHNICAL REPORT PNW-GTR-870• The potential for increased wildfire hazard, longer Projections of change in suitable habitat indicate that, of droughts, insect outbreaks, and fungal pathogens, the 84 most common species, 23 to 33 will lose suitable individually and in combination, could significantly habitat under low- and high-emission scenarios, 48 to 50 reduce forest cover and vigor. Reduced tree distribution will gain habitat, and 1 to 10 will experience no change. will likely have a negative effect on agricultural systems, • Warmer temperature will increase rates of microbial given the important role of shelterbelts and windbreaks decomposition, N mineralization, nitrification, and in reducing soil erosion. denitrification, resulting in higher short-term availability of calcium, magnesium, and N for forest growth, as wellMidwest as elevated losses of these nutrients to surface waters.• Northern and boreal tree species at the southern edge • Migratory bird species that require forest habitat are of their current range will decrease in abundance and arriving earlier and breeding later in response to recent extent as their current habitat becomes less suitable (and warming, with consequences for the annual production moves northward) and reestablishment in a warmer of young and their survival. Many bird species have climate becomes more difficult. Some forested wetlands already expanded their ranges northward. may also disappear as the climate warms. Some oak and hickory species tolerant of low soil moisture may Southeast become more abundant. • Red spruce (Picea rubens Sarg.) and eastern hemlock• Increased drought and fire occurrence are expected (Tsuga canadensis [L.] Carrière), already declining to have rapid and extensive effects on the structure in some areas, are projected to be extirpated from the and function of forest ecosystems. Oak decline and southeast by 2100 as a result of the combined stresses of invasive species are expected to become more common, warming, air pollution, and insects. contributing to stress complexes that include nearly two • The majority of the Nation’s pulp and timber supply is centuries of land use activities. produced in the southeast, but if temperature continues• Increased disturbance will tend to fragment forest to increase and precipitation becomes more variable, landscapes that are already highly fragmented in terms conditions for pine growth may begin to deteriorate. of species, structure, and ownerships. This will reduce Even if regional forest productivity remains high, the habitat connectivity and corridors for species movement. center of forest productivity could shift northward• The large amount of private land and fine-scale into North Carolina and Virginia, causing significant fragmentation of forest landscapes will make it economic and social impacts. challenging to implement climate change adaptation. • Increasing demand for water from a rapidly growing Outreach to private land owners will be necessary to urban population, combined with increased drought ensure that climate preparedness is effective. frequency could result in water shortages in some areas of the Southeast.Northeast • Warmer temperature may increase decomposition of• Stress complexes are especially important in northeastern soil organic matter and emissions of CO2, reducing the forests, where climate interacts with nitrogen (N) deposi- potential for C sequestration. tion, tropospheric ozone, land use, habitat fragmentation, • Increased fire hazard and insect outbreaks will provide invasive species, insects, pathogens, and fire. significant challenges for sustainable management of• A warmer climate will cause a major reduction of forests for timber and other uses, but may also motivate spruce-fir forest, moderate reduction of maple-birch- restoration of fire-tolerant longleaf pine (Pinus palustris beech forest, and expansion of oak-dominated forest. Mill.) forests.viii
  11. 11. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest SectorAn Imperative for Action and ownership boundaries by developing, sharing, and implementing effective adaptation approaches. This will beClimate change will generally reduce ecosystem services accomplished by (1) embracing education on climate sciencebecause most human enterprises are based on past climatic for resource professionals and the general public; (2) ensur-environments and the assumption of static natural resource ing accountability and infusing climate change into organi-conditions. Increased forest disturbance will, at least tem- zational efforts (e.g., management plans and projects); (3)porarily, reduce productivity, timber value, and C storage, implementing an all-lands approach through collaborationand, in some cases, will increase surface runoff and ero- across administrative, political, and ownership boundaries;sion. Changes in forest ecosystems that affect hydrology and (4) streamlining planning processes and establishingand water supply will typically result in a significant loss of projects on the ground. The twofold challenge of adaptingresource value. Scientific principles and tools for adapting to climate change and managing C in the broader contextto these climate change effects focus on education, vulner- of sustainable forest management will require creativity byability assessment of natural resources, and development of future generations of forest resource managers. In the shortadaptation strategies and tactics. The hallmark of successful term, management strategies that are relatively inexpensive,adaptation efforts in the United States has been science- have few institutional barriers, and produce timely resultsmanagement partnerships that work collaboratively within can be rapidly implemented. For adaptation, examplespublic agencies and externally with various stakeholders. include reducing nonclimatic stressors in forests (e.g., non-Several recent case studies of adaptation for national forests native pathogens), implementing fuel reduction, and reduc-and national parks are now available and can be emulated by ing stand densities. For C management, examples includeother land management organizations. reducing deforestation, increasing afforestation, reducing Although uncertainty exists about the magnitude and wildfire severity, increasing tree growth, and increasing usetiming of climate change effects on forest ecosystems, suf- of wood-based bioenergy. Specific strategies and actionsficient scientific information is available to begin taking will differ by location, inherent forest productivity, and localaction now. Managing simultaneously for C and for on-the- management objectives.ground implementation of adaptation plans is challenging Coordinating adaptation and C management will helpin both public and private sectors; however, implementation optimize implementation across specific landscapes. Forcan be increased through effective exchange of information example, fuel reduction treatments can reduce wildfireand success stories. Land managers are already using “cli- severity in dry forests (adaptation) and provide material formate-smart” practices, such as thinning and fuel treatments local bioenergy use (C management). In the near term, wethat reduce fire hazard, reduce intertree competition, and in- anticipate that federal agencies will continue to lead the de-crease resilience in a warmer climate. Building on practices velopment of science-management partnerships and collab-compatible with adapting to climate change provides a good orative approaches to climate-smart management, althoughstarting point for land managers who may want to begin the (static) legal, regulatory, and institutional constraints willadaptation process. Establishing a framework for managing continue to deter timely responses to (dynamic) climate-forest ecosystems in the context of climate change as soon as caused changes in forest ecosystems. Successful adaptationpossible will ensure that a broad range of options is available strategies and C management will likely accelerate acrossfor managing forest resources sustainably. large landscapes as community-based partnerships integrate We are optimistic that a proactive forest sector will climate change-related concerns into sustainable stewardshipmake the necessary investments to work across institutional of natural resources. ix
  12. 12. GENERAL TECHNICAL REPORT PNW-GTR-870Contents1 Chapter 1: Introduction David L. Peterson and James M. Vose4 Literature Cited7 Chapter 2: Effects of Climatic Variability and Change Michael G. Ryan and James M. Vose7 Introduction8 Projected Changes in Future Climate8 Scenarios for Projecting Future Climate9 Temperature Projections15 Sea Level Rise16 Key Findings16 Key Information Needs16 Effects of Climate Change on Disturbance Regimes16 Fire18 Key Findings18 Key Information Needs18 Insects and Pathogens18 General Concepts21 Climate and Biotic Disturbances27 Impacts and Interactions With Other Disturbances28 Future Vulnerabilities and Opportunities28 Key Findings28 Key Information Needs28 Invasive Plants32 Interactions Between Climate Change and Plant Invasion32 Temperature, Precipitation, and Carbon Dioxide33 Disturbance and Resource Availability34 Key Findings34 Key Information Needs34 Erosion, Landslides, and Precipitation Variability35 Erosion and Landslides36 Drought and Water Supply36 Key Findings36 Key Information Needs36 Disturbance Interactions36 Thresholds38 Stress Complexes: From Conceptual to Quantitative Models40 Uncertainties42 Key Findingsx
  13. 13. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector42 Key Information Needs42 Effects of Climate Change on Forest Processes42 Carbon and Nutrient Cycling43 Response of Forest Carbon Cycling Processes to Increased Temperature, Changes in Precipitation,  Increased Carbon Dioxide, Nitrogen Deposition, and Tropospheric Ozone46 Effects on Nutrient Cycling46 Key Findings47 Key Information Needs47 Forest Hydrological Processes47 Forest Evapotranspiration and Streamflow47 Elevated Atmospheric Carbon Dioxide48 Warmer Temperatures and Drought48 Changing Species Composition49 Snowmelt50 Soil Infiltration, Ground Water Recharge, and Lateral Redistribution50 Carbon and Water Tradeoffs50 Key Findings50 Key Information Needs50 Forest Tree Species Distributions51 Species Distribution Models52 Process Models52 Demography Studies57 Dispersal and Migration Models57 Assisted Migration58 Key Findings58 Key Information Needs58 Effects of Altered Forest Processes and Functions on Ecosystem Services61 Conclusions63 Literature Cited97 Chapter 3: Climate Change, Human Communities, and Forests in Rural, Urban, and Wildland-Urban Interface Environments David N. Wear and Linda A. Joyce97 Introduction97 Socioeconomic Context: Ownership, Values, and Institutions98 Forest Ownership Patterns in the United States101 Economic Contributions of Forests103 Policy Context of Forest Management in Response to Climate Change105 Interactions Among Forests, Land Use Change, and Climate Change105 Interactions Among Forests, Agricultural Land Use, and Climate Change in Rural Environments xi
  14. 14. GENERAL TECHNICAL REPORT PNW-GTR-870107 Interactions Between Trees and Climate in Urban Environments108 Effects of Climate Change on Urban Trees108 Effects of Urban Trees on Climate Change109 Interactions Between Climate Change and the Wildland-Urban Interface110 Disturbances in the Wildland-Urban Interface111 Multiple Stressors on Wildlands in the Interface112 Social Interactions With Forests Under Climate Change112 Natural Resource-Based Communities114 Tribal Forests116 Social Vulnerability and Climate Change117 Conclusions119 Literature Cited125 Chapter 4: Adaptation and Mitigation Constance I. Millar, Kenneth E. Skog, Duncan C. McKinley, Richard A. Birdsey, Christopher W. Swanston, Sarah J. Hines, Christopher W. Woodall, Elizabeth D. Reinhardt, David L. Peterson, and James M. Vose125 Strategies for Adapting to Climate Change125 Principles for Forest Climate Adaptation125 Successful Climate Adaptation Planning and Implementation125 Education and Training126 Science-Management Partnerships126 Risk and Uncertainty127 Toolkit Approach127 No-Regrets Decisionmaking127 Flexibility and Adaptive Learning127 Mixed-Models Approach128 Integration With Other Priorities and Demands of Forest Management128 Placing Adaptation in Context128 Biogeography and Bioclimate128 Scale130 Institutional and Regulatory Contexts130 Adaptation Strategies and Implementation130 Overview of Forest Adaptation Strategies134 Tools and Resources for Adaptation and Implementation134 Web Sites135 Tools136 Institutional Responses136 President’s Directive136 U.S. Forest Service137 U.S. Department of the Interior (DOI)xii
  15. 15. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector140 Regional Integrated Sciences and Assessment (RISA)142 State and Local Institutions142 Western Governors’ Association (WGA)142 Minnesota State Climate Response143 North Carolina State Climate Response143 State University and Academic Response144 Industrial Forestry144 Native American Tribes and Nations145 Nongovernmental Organizations146 Ski Industry146 Examples of Regional and National Responses146 Western United States147 Southern United States148 Northern United States151 National Example151 Challenges and Opportunities151 Assessing Adaptation Response152 Existing Constraints154 Vision for the Future156 Path to the Vision156 Carbon Management157 Status and Trends in Forest-Related Carbon160 Monitoring and Evaluating Effects of Carbon Management164 Carbon Mitigation Strategies167 In Situ Forest Carbon Management169 Ex Situ Forest Carbon Management172 Mitigation Strategies: Markets, Regulations, Taxes, and Incentives175 The Role of Public Lands in Mitigation176 Managing Forests in Response to Climate Change179 Literature Cited193 Chapter 5: Improving Scientific Knowledge James M. Vose and David L. Peterson195 Chapter 6: Future Assessment Activities Toral Patel-Weynand195 Introduction196 Regional Issues196 Developing a Risk-Based Framework196 Social Issues197 Management Options xiii
  16. 16. GENERAL TECHNICAL REPORT PNW-GTR-870197 Ecological Disturbances and Extreme Events197 Coordination With Other Assessment Activities198 Effects on Tribal Lands198 Carbon Estimation199 Conclusions199 Literature Cited201 Chapter 7: Conclusions David L. Peterson and James M. Vose201 Introduction201 Forest Disturbance202 Forest Processes203 Species Distributions203 Risk and Social Context204 Preparing for Climate Change205 Appendix 1: Regional Summaries205 Alaska210 Hawaii and U.S.-Affiliated Pacific Islands215 Northwest219 Southwest223 Great Plains227 Midwest231 Northeast238 Southeast243 Appendix 2: Risk-Based Framework and Risk Case Studies243 Risk-based Framework for Evaluating Changes in Response Thresholds and Vulnerabilities Dennis S. Ojima, Louis R. Iverson, and Brent L. Sohngen246 Risk Case Study: A Framework for Assessing Climate Change Risks to Forest Carbon Stocks Christopher W. Woodall and Grant M. Domke249 Risk Assessment for Wildfire in the Western United States David L. Peterson and Jeremy S. Littell253 Risk Assessment for Forested Habitats in Northern Wisconsin Louis R. Iverson, Stephen N. Matthews, Anantha Prasad, Matthew P. Peters, and Gary W. Yohe256 Risk Assessment for Two Bird Species in Northern Wisconsin Megan M. Friggens and Stephen N. Matthews259 Appendix 3: Western Mountain Initiative Synthesis259 Response of Western Mountain Ecosystems to Climatic Variability and Change: A Synthesis From the Western Mountain Initiative Crystal L. Raymondxiv
  17. 17. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest SectorChapter 1IntroductionDavid L. Peterson and James M. Vose1Projected changes in climate (temperature and precipita-tion means and extreme events), increased atmosphericcarbon dioxide (CO2), and increased nitrogen deposition arelikely to affect U.S. forests throughout this century. Effectswill be both direct (e.g., effects of elevated CO2 on forestgrowth and water use) and indirect (e.g., altered disturbanceregimes), and will differ temporally and spatially across theUnited States. Some of these effects may already be occur-ring. For example, large insect outbreaks and large wildfiresduring the past decade (Bentz et al. 2009, Turetsky et al.2010) are a wake-up call about the potential effects of a rap-idly changing climate on forest ecosystems. Individually andin combination, these two major disturbance phenomena arereshaping some forest landscapes and may be causing long-term, possibly permanent changes in forest structure, func-tion, and species composition (Hicke et al. 2012, McKenzieet al. 2004). Combined with other stressors, such as invasivespecies and air pollution (McKenzie et al. 2009), and a Archer 2008) provides a foundation and point of departurelegacy of fire exclusion and other land management activi- for this document. We focus on the latest observations of ef-ties, maintaining resilience and restoring forest ecosystems fects of climatic variability and change in forest ecosystems,in the face of climate change will be a major challenge for supported by scientific literature, with emphasis on issuesthe 21st century and beyond (Peterson et al. 2011). and solutions relevant for sustainable management of forest In this document, we provide a scientific assessment of resources.the current condition and likely future condition of forest It is difficult to conclude whether recently observedresources in the United States relative to climatic variability trends or changes in ecological phenomena are the resultand change. This assessment, which is conducted periodi- of human-caused climate change or climatic variability.cally by the U.S. Global Change Research Program as a Regardless of the cause, we emphasize the response of forestcomponent of a broader assessment of the effects of climate resources to climatic patterns observed over the past fewchange on natural resources (U.S. Global Change Research decades because they are similar to climatic phenomenaProgram 2012), is scheduled to be completed in 2013. The expected for the rest of the 21st century. Compared to mostmost recent assessment of the forest sector (Ryan and of the 20th century, these more recent patterns are associated with periods of warmer temperature throughout the United1 David L. Peterson is a research biological scientist, U.S. Depart- States, and to multiyear droughts (low soil moisture) inment of Agriculture, Forest Service, Pacific Northwest ResearchStation, Pacific Wildland Fire Sciences Laboratory, 400 N 34th arid and semiarid regions of the Western United States andStreet, Suite 201, Seattle, WA 98103; James M. Vose is a research many areas of the Eastern United States (Karl et al. 2009).ecologist, U.S. Department of Agriculture, Forest Service, SouthernResearch Station, Center for Integrated Forest Science and Synthesis For example, Breshears et al. (2005) concluded that diebackat North Carolina State University, Department of Forestry and of pinyon pine (Pinus edulis Engelm.) in the SouthwesternEnvironmental Resources, Campus Box 8008, Raleigh, NC 27695. 1
  18. 18. GENERAL TECHNICAL REPORT PNW-GTR-870United States was caused by “global-change type drought.” often focuses on extreme events and ecological disturbance,If extended drought will indeed be more common in the because these phenomena usually produce faster, larger,future, then it is reasonable to infer that this type of dieback and more persistent changes than does a gradual increase inwill also be more common. “Global-change type” climatic temperature.phenomena provide a reasonable context for projecting the Although the short-term effects of the El Niño-Southerneffects of climate change on forest ecosystems. Oscillation on natural resources have been well documented, In this document, we develop inferences from small- the effects of dominant modes of climatic variability (Atlan-scale experiments (e.g., soil warming or CO2 enrichment tic Monthly Oscillation, Pacific Decadal Oscillation, Pacificstudies) and time series of natural resource data when avail- North American pattern) provide a better understandingable, while recognizing the challenges and uncertainties about the potential effects of climate change, because peri-of scaling small-scale and site-specific studies in time and ods of warmer (and cooler) and drier (and wetter) conditionsspace (Peterson and Parker 1998). We also use the results of are experienced over two to three decades at a time. For ex-simulation modeling to project the effects of climate change ample, in some areas of the Western United States, the warmon species distribution and abundance, ecosystem processes, phase of the Pacific Decadal Oscillation is associated withecological disturbance, and carbon dynamics. The results more area burned by wildfire than in the cool phase (Hesslof both empirical (statistical) and process-based (mecha- et al. 2004, Schoennagel et al. 2007). Studies of longer termnistic) models are presented, and we emphasize that these modes of climatic variability thus provide a window into theresults are projections (proposed or calculated), rather than nature of a permanently warmer climate, including quanti-predictions (forecast or foretold about the future). Trends tative relationships among temperature, precipitation, andestablished by empirical data, combined with results from area burned, on which projections of the effects of differentrobust modeling, are a good combination on which to base climatic conditions can be based.inferences about climate change effects (e.g., Araújo et al. Forests that experience frequent disturbance often have2005). In this document, climate change effects are rarely characteristics that enhance their capacity to survive distur-projected beyond 2100, the limit for most current global cli- bance events (resistance) or facilitate recovery after distur-mate models and emission scenarios (Solomon et al. 2007). bance (resilience) (Millar et al. 2007). Despite this inherentWe have high confidence in projections through the mid-21st capacity, current thinking suggests that the rapid pace andcentury, beyond which agreement among global climate magnitude of climate change will exceed the resistance andmodels diverges. resilience capacity of many forests, and novel ecosystems Forest ecosystems are inherently resilient to variability without historical analogs will develop (Hobbs et al. 2009,in climate at time scales ranging from daily to millennial. Williams and Jackson 2007). A significant challenge forFor example, forest species distribution and abundance have resource managers is to identify areas where forests are mostshifted over long time scales by responding individually to vulnerable to change (i.e., have low resistance and resil-variability in temperature, precipitation (Brubaker 1986), ience) and where the effects of change on critical ecosystemand climatic influences on wildfire and other disturbance services will be greatest. Among the most obvious locationsregimes (Prichard et al. 2009, Whitlock et al. 2008). Gradual for vulnerable forest ecosystems (and species) are thosechanges in mean climate or atmospheric environment near the limits of their biophysical requirements (Parmesanproduce gradual changes in ecosystems. However, a rapid and Yohe 2003). However, the complexities of fragmentedincrease in temperature will increase the number of extreme landscapes and multiple co-occurring stressors are likelyclimatic periods (e.g., extended droughts), leading to more to change response thresholds in many forest ecosystemsfrequent and intense ecological disturbances, which in turn (Fagre et al. 2009), with outcomes that may be unpredict-lead to rapid change in the composition and dynamics of able and unprecedented (Anderson et al. 2009, Scheffer etforests (McKenzie et al. 2009). Therefore, this assessment al. 2009). Under these conditions, traditional approaches2
  19. 19. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sectorto forest management that focus on historical conditions or range of ecosystem dynamics. Risk is generally associatedprotection of rare species or communities are likely to fail. with the likelihood of exposure or effects at specific pointsManagement approaches that instead anticipate and respond in time, combined with the magnitude of the consequenceto change by guiding development and adaptation of forest of a particular biophysical change (Mastrandrea et al. 2010,ecosystem structures and functions will be needed to sustain Yohe and Oppenheimer 2011). Risk is inherently associateddesired ecosystem services and values across large land- with human judgments and ranking (e.g., high, medium,scapes and multiple decades (Millar et al. 2007, Seastedt et low) and human values related to ecosystem services andal. 2008). In this document, we discuss new management perceptions (good vs. bad). When clearly articulated, inapproaches along with specific tools and case studies. either qualitative or quantitative terms, uncertainty and riskUncertainty and risk are frequently discussed in this docu- are useful concepts for natural resource managers, decision-ment, as mandated by general guidance for the National makers, and policymakers (Spittlehouse and Stewart 2003).Climate Assessment. Important sources of uncertainty Incorporating risk into discussions of climate change effectsinclude short time series of climatological and forest effects is relatively new for the forest resources community, but wedata, limited spatial extent of many types of measurements, are optimistic that doing so will improve our ability to applylack of understanding of complex ecological processes, and climate change science to the management of forest ecosys-simulation models that cannot accurately represent a wide tems, including the development of adaptation options. 3
  20. 20. GENERAL TECHNICAL REPORT PNW-GTR-870Literature Cited Karl, T.R.; Melillo, J.M.; Peterson, T.C., eds. 2009. Glob- al climate change impacts in the United States: a state ofAnderson, T.; Carstensen, J.; Hernández-García, E.; knowledge report from the U.S. Global Change Research Duarte, C.M. 2009. Ecological thresholds and regime Program. New York: Cambridge University Press. 192 p. shifts: approaches to identification. Trends in Ecology and Evolution. 24: 49–57. Mastrandrea, M.D.; Field, C.B.; Stocker, T.F. [et al.]. 2010. Guidance note for lead authors of the Intergovern-Araújo, M.B.; Whittaker, R.J.; Ladle, R.J.; Erhard, M. mental Panel on Climate Change 5th assessment report on 2005. Reducing uncertainty in projections of extinction consistent treatment of uncertainties. http://www.ipcc.ch/ risk from climate change. Global Ecology and Biogeogra- pdf/supporting-material/uncertainty-guidance-note.pdf. phy. 14: 529–538. (20 January 2012).Bentz, B.; Allen, C.D.; Ayres, M. [et al.]. 2009. Beetle McKenzie, D.; Gedalof, Z.; Peterson, D.L.; Mote, P. 2004. outbreaks in western North America: causes and conse- Climatic change, wildfire, and conservation. Conserva- quences. Salt Lake City, UT: University of Utah Press. tion Biology. 18: 890–902. 44 p. McKenzie, D.; Peterson, D.L.; Littell, J.J. 2009. GlobalBreshears, D.D.; Cobb, N.S.; Rich, P.M. [et al.]. 2005. warming and stress complexes in forests of western North Regional vegetation die-off in response to global-change America. In: Bytnerowicz, A.; Arbaugh, M.J.; Riebau, type drought. Proceedings of the National Academy of A.R.; Andersen, C., eds. Wildland fires and air pollution. Sciences USA. 102: 15144–15148. The Hague, Netherlands: Elsevier Publishers: 317–337.Brubaker, L.B. 1986. Responses of tree populations to Millar, C.I.; Stephenson, N.L.; Stephens, S.L. 2007. climatic change. Plant Ecology. 67: 119–130. Climate change and forests of the future: managing inFagre, D.B.; Charles, C.W.; Allen, C.D. [et al.]. 2009. the face of uncertainty. Ecological Applications. 17: Thresholds of climate change in ecosystems: final report, 2145–2151. synthesis, and assessment product 4.2. U.S. Climate Parmesan, C.; Yohe, G. 2003. A globally coherent finger- Change Science Program and the Subcommittee on print of climate change impacts across natural systems. Global Change Research. Reston, VA: U.S. Department Nature. 421: 37–42. of the Interior, Geological Survey. 70 p. Peterson, D.L.; Halofsky, J.E.; Johnson, M.C. 2011. Man-Hessl, A.E.; McKenzie, D.; Schellhaas, R. 2004. Drought aging and adapting to changing fire regimes in a warmer and Pacific Decadal Oscillation linked to fire occurrence climate. In: McKenzie, D.; Miller, C.; Falk, D., eds. The in the inland Pacific Northwest. Ecological Applications. landscape ecology of fire. New York: Springer: 249–267. 14: 425–442. Chapter 10.Hicke, J.A.; Allen, C.D.; Desai, A.R. [et al.]. 2012. Effects Peterson, D.L.; Parker, V.T., eds. 1998. Ecological scale: of biotic disturbances on forest carbon cycling in the theory and applications. New York: Columbia University United States and Canada. Global Change Biology. 18: Press. 615 p. 7–34. Prichard, S.J.; Oswald, W.W.; Gedalof, Z.; Peterson,Hobbs, R.J.; Higgs, E.; Harris, J.A. 2009. Novel eco- D.L. 2009. Holocene fire and vegetation dynamics in a systems: implications for conservation and restoration. montane forest, North Cascade Range, Washington, USA. Trends in Ecology and Evolution. 24: 599–605. Quaternary Research. 72: 57–67.4
  21. 21. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest SectorRyan, M.G.; Archer, S.R. 2008. Land resources: forests Spittlehouse, D.L.; Stewart, R.B. 2003. Adaptation to and arid lands. In: Backlund, P.; Janetos, A.; Hatfield, J. climate change in forest management. BC Journal of [et al.], eds. The effects of climate change on agriculture, Ecosystems and Management. 4: 1–11. land resources, water resources, and biodiversity in the Turetsky, M.R.; Kane, E.S.; Harden, J.W. [et al.]. 2010. United States. A report by the U.S. Climate Change Sci- Recent acceleration of biomass burning and carbon losses ence Program and the Subcommittee on Global Change in Alaskan forests and peatlands. Nature Geoscience. 4: Research. Washington, DC: U.S. Environmental Protec- 27–31. tion Agency: 75–120. Chapter 3. U.S. Global Change Research Program. 2012. The na-Scheffer, M.; Bascompte, J.; Brock, W.A. [et al.]. 2009. tional climate assessment. http://www.globalchange.gov/ Early-warning signals for critical transitions. Nature. 461: what-we-do/assessment. (20 January 2012). 53–59. Whitlock, C.; Marlon, J.; Briles, C. [et al.]. 2008. Long-Schoennagel, T.; Veblen, T.T.; Kulakowski, D.; Holz, A. term relations among fire, fuel, and climate in the north- 2007. Multidecadal climate variability and climate inter- western US based on lake-sediment studies. International actions affect subalpine fire occurrence, western Colorado Journal of Wildland Fire. 17: 72–83. (USA). Ecology. 88: 2891–2902. Williams, J.W.; Jackson, S.T. 2007. Novel climates, no-Seastedt, T.R.; Hobbs, R.J.; Suding, K.N. 2008. Man- analog communities, and ecological surprises. Frontiers agement of novel ecosystems: are novel approaches in Ecology and the Environment. 5: 475–482. required? Frontiers in Ecology and the Environment. 6: 547–553. Yohe, G.; Oppenheimer, M. 2011. Evaluation, characteriza- tion, and communication of uncertainty by the Intergov-Solomon, S.; Quin, D.; Manning, M. [et al.], eds. 2007. ernmental Panel on Climate Change—an introductory Climate change 2007: the physical science basis. Con- essay. Climatic Change. 108: 629–639. tribution of working group I to the fourth assessment report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom: Cambridge University Press. 996 p. 5
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  23. 23. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest SectorChapter 2Effects of Climatic Variability and ChangeMichael G. Ryan and James M. Vose1ContributorsMatthew P. Ayres, Lawrence E. Band, Chelcy R. Ford, Paul J. Hanson, Jeffrey A. Hicke, Louis R. Iverson, BeckyK. Kerns, Steven L. Klein, Jeremy S. Littell, Charles H. Luce, Don McKenzie, David N. Wear, and Aaron S. Weed2Introduction climate, elevated atmospheric carbon dioxide (CO2) concen- trations, and nitrogen deposition, deepening our understand-Climate profoundly shapes forests. Forest species com- ing since the publication of the last forest sector assessmentposition, productivity, availability of goods and services, (Ryan et al. 2008). We have many new examples of howdisturbance regimes, and location on the landscape are all changes in climate over the period 1971–2000 have affectedregulated by climate. Much research attention has focused on forest ecosystems, including long-term monitoring data onthe problem of projecting the response of forests to changing forest change, multifactor experiments that document the potential interactions between temperature and elevated1 Michael G. Ryan is a research forest ecologist, U.S. Departmentof Agriculture, Forest Service, Rocky Mountain Research Station, CO2, and new modeling approaches that project the effect240 W Prospect Road, Fort Collins, CO 80526; James M. Vose is a of projected changes in climate on forest ecosystems, theirresearch ecologist, U.S. Department of Agriculture, Forest Service,Southern Research Station, Center for Integrated Forest Science goods and services, and their disturbance regimes. Climateand Synthesis at North Carolina State University, Department of projections are being done on a finer spatial scale, and globalForestry and Environmental Resources, Campus Box 8008, Raleigh,NC 27695. climate models include more detail and feedbacks with ter-2 Matthew P. Ayres is a professor of biological sciences, Dartmouth restrial processes. Downscaled estimates from these modelsCollege, Hanover, NH 03755; Lawrence E. Band is a professor ofgeography, University of North Carolina at Chapel Hill, Campus are more readily available and have been used for moreBox 3220, Chapel Hill, NC 27559; Chelcy R. Ford is a research regional and local assessments. Despite the large amountecologist, U.S. Department of Agriculture, Forest Service, SouthernResearch Station, Coweeta Hydrologic Laboratory, 3160 Coweeta of new research, this new information has not substantiallyLab Road, Otto, NC 28763; Paul J. Hanson is a group leader, altered the primary projections made in the last assess-Oak Ridge National Laboratory, Environmental Sciences Division,Ecosystem and Plant Services Group, Bethel Valley Road, Building ment (Ryan et al. 2008). In this assessment, we have added1062, Oak Ridge, TN 37831; Jeffrey A. Hicke is an assistant pro- more detail about the effects covered in the last assessmentfessor, University of Idaho, Moscow, ID 83844; Louis R. Iversonis a landscape ecologist, U.S. Department of Agriculture, Forest (especially altered disturbance regimes and potential effectsService, Northern Research Station, 359 Main Road, Delaware, OH43015; Becky K. Kerns is a research ecologist, U.S. Department on hydrologic processes), provided more information aboutof Agriculture, Forest Service, Pacific Northwest Research Station, regional effects, and covered additional topics.3200 SW Jefferson Way, Corvallis, OR 97331; Steven L. Klein isa research forester, U.S. Environmental Protection Agency, Western Climate change, higher CO2 concentrations, and in-Ecology Division, 200 SW 35th Street, Corvallis, OR 97333; Jeremy creased nitrogen (N) deposition have already significantlyS. Littell is a research ecologist, U.S. Department of the Interior,Geological Survey, Alaska Climate Science Center, 4210 Univer- affected the Nation’s forests. These effects are projected tosity Drive, Anchorage, AK 99508; Charles H. Luce is a research get even larger in the future as the climate warms throughouthydrologist, U.S. Department of Agriculture, Forest Service, RockyMountain Research Station, Boise Aquatic Sciences Lab, 322 East this century and moves further from the historical climate.Front Street, Suite 401, Boise, ID 83702; Don McKenzie is a Although projecting the response of forest ecosystems tobiological scientist, U.S. Department of Agriculture, Forest Service,Pacific Northwest Research Station, Pacific Wildland Fire Sci- global change is difficult and complex, we have a highences Laboratory, 400 N 34th Street, Suite 201, Seattle, WA 98103;David N. Wear is a research forest economist, U.S. Department degree of confidence in many of the projections made forof Agriculture, Forest Service, Southern Research Station, Center larger scales and for the next few decades. Our confidencefor Integrated Forest Science and Synthesis at North Carolina StateUniversity, Department of Forestry and Environmental Resources, comes from the observed changes that have occurred inCampus Box 8008, Raleigh, NC 27695; Aaron S. Weed is a post- response to the relatively small changes in climate over thedoctoral fellow, Dartmouth College, Department of BiologicalSciences, Hanover, NH 03755. past 30 years. Predicted future climate will likely bring even 7
  24. 24. GENERAL TECHNICAL REPORT PNW-GTR-870more dramatic effects, because temperatures are expected variability at an individual location begin to emerge. Forto be 2.5 to 5.3 °C warmer than in 1971 to 2000, and large example, in the Western United States, the annual areaeffects have been seen with less than 1 °C warming over burned by fire has increased and snowmelt has occurred ear-the past 30 years. For example, snowpack is melting earlier lier as temperatures have warmed. However, projecting howin the spring, forest fires are becoming larger, bark beetles fire or snowmelt will be affected at the local or forest-standare moving higher in elevation and attacking species that scale is much more subject to contingencies and local factorswere climatically protected in the past, bark beetle and other that were not assessed in developing regional relationships,insect outbreaks have become larger and more frequent with- making the projections very uncertain at smaller spatialout very cold winters to stop them, and drought has killed scales.trees in the drier regions of tree species’ ranges. For many Predictions for the long term are also uncertain. Projec-factors, the aggregate ecosystem response over large areas tions of future climate differ among both the global climateis well understood, perhaps even better understood than the models used and the different emission scenarios. For eco-projections of future climate, which differ from model to systems, longer time periods allow more time for contingen-model, are less certain about precipitation than temperature, cies and unanticipated factors to shape the future, addingand have less certain regional and local projections. additional uncertainty. Sometimes, we do not know enough about the science In this chapter, we review studies that were eitherto make good projections. For example, how do increased published after the last forest assessment (Ryan et al. 2008)temperature and drought interact to affect tree mortal- or not previously covered. We summarize the state-of-ity? Will mature trees respond to elevated CO2? For these knowledge on projected changes in future climate. Next, weproblems, further research will improve our projections. In discuss the potential effects of climate change on disturbanceaddition, many outcomes rely on complex interactions and regimes and forest processes and their interactions. Finally,contingencies, making projections difficult, highly uncertain, connections between biophysical responses and socioeco-or sometimes, impossible. Some of the projected climates nomic responses are discussed in the context of ecosystemwill be novel, with no historical analog and hence, we services.have limited experience or data on how ecosystems mightrespond. Trees are long-lived organisms and individuals of Projected Changes in Future Climatesome species may remain in place long after an altered cli- Scenarios for Projecting Future Climatemate would favor the establishment of different species. This Projected changes in future climate are based on outputis because seeds for replacement species may not move into from 15 global climate models (GCMs) (box 2.1). All modelan altered environment, so the best-adapted species to the runs used future scenarios of economic growth, populationnew climate may not be available. The interaction of climate growth, and greenhouse gas emissions scenarios that wereand disturbance will substantially alter forest ecosystems. intended to represent the high (A2) and low (B1) ends ofAs a result, species and forest ecosystem processes may not future emissions. A2 describes a world with continuous highhave time to adapt to a rapidly changing climate, and mul- population growth, slow economic development, slow tech-tiple disturbance and stressor interactions will make it even nological change, and independently operating, self-reliantmore difficult to understand and project responses to climate nations. B1 describes an environmentally friendly worldchange. with an emphasis on global solutions to economic, social, Predicting outcomes for a particular location is very un- and environmental stability; a global population that peakscertain, because in general, projections of future climate and in mid-century and then declines, and with rapid changesecosystem response for a given area are very uncertain. Over in the economy toward a service and information economy,a very large area, patterns that are obscured by interannual reductions in material intensity, and the introduction of clean and resource-efficient technologies. For models of effects,8
  25. 25. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sectorsome additional scenarios and GCMs were used in this whereas other areas, especially in the Southwest, now re-report and are noted where appropriate. ceive less (Backlund et al. 2008). Trends in temperature and precipitation from weatherstations show that the United States has warmed over the Temperature Projectionspast 100 years, but the trends differ by region (Backlund et Average annual air temperatures across the continentalal. 2008). The southeastern United States has cooled slightly United States are likely to steadily increase over the next(<0.7 °C), and Alaska has warmed the most (~4.5 °C); other century under the two emission scenarios (fig. 2.1). Com-Northern and Western U.S. regions also show a warming pared to 1971 through 2000, average annual air temperaturetrend (~1.5 °C). Much of the Eastern and Southern United will likely increase from 0.8 to 1.9 °C by 2050, from 1.4 toStates now receives more precipitation than 100 years ago, 3.1 °C by 2070, and from 2.5 to 5.3 °C by 2099. The range Box 2.1—Global climate models and emission scenarios Most of the climate projections used to describe future climatic conditions in this report are based on model ensembles, that is, syntheses of the output of various global climate models (GCMs).3 The report includes output from four specific GCMs, as summarized below: CCSM2 (Community Climate System Model, version 2)—U.S. National Center for Atmospheric Research (http://www.CESM.NCAR.edu). CSIRO Mk3—Australian Commonwealth Scientific Industrial Research Organisation (Gordon et al. 2002). Hadley (versions 1 to 3)—United Kingdom Hadley Center (Burke et al. 2006). PCM (Parallel Climate Model)—U.S. National Center for Atmospheric Research (Washington et al. 2000). This report also uses terminology that refers to standard greenhouse gas (GHG) emission scenarios as described by the Intergovernmental Panel on Climate Change (IPCC). Emission scenarios cited in the report are described below, in which A scenarios have higher GHG emissions and higher projected temperature increases than B scenarios. A2—A2 scenarios represent a more divided world, characterized by independently operating, self-reliant na- tions; continuously increasing population, and regionally oriented economic development. A1F1—A1 scenarios represent a more integrated world, characterized by rapid economic growth, a global population that reaches 9 billion in 2050 and then gradually declines, quick spread of new and efficient technolo- gies, a world in which income and way of life converge between regions, and extensive social and cultural interac- tions worldwide. A1F1 emphasizes the use of fossil fuels. A1B—Same as A1F1, except it emphasizes a balance of energy sources. B1—B1 scenarios represent a more integrated, ecologically friendly world, characterized by rapid economic growth as in A1, but with rapid changes toward a service and information economy, population rising to 9 billion in 2050 and then declining as in A1, reductions in material intensity and the introduction of clean and resource ef- ficient technologies, and an emphasis on global solutions to economic, social, and environmental instability. B2—B2 scenarios represent a more divided but more ecologically friendly world, characterized by continuous- ly increasing population but at a slower rate than in A2; emphasis on local rather than global solutions to economic, social, and environmental instability; intermediate levels of economic development; and less rapid and more frag- mented technological change than in A1 and B1. The forthcoming Fifth IPCC Assessment, scheduled for publication in 2014, will use representative concentration path- ways (RCP) rather than the emission scenarios that were used in the Fourth Assessment (Solomon et al. 2007). The RCPs are four GHG concentrations (not emissions), named after a possible range of radiative forcing (increased irradiance caused by GHGs) values at the Earth’s surface in the year 2100: RCP2.6, RCP4.5, RCP6, and RCP8.5, which represent 2.6, 4.5, 6.0, and 8.5 W·m-2, respectively (Moss et al. 2008). Current radiative forcing is approximately 1.6 W·m-2, which is equivalent to a global-scale warming effect of 800 terawatts. 3 Kunkel, K.E.; Stevens, L.E.; Sun, L. [et al.]. [N.d.]. Climate of the contiguous United States. Tech. Memo. National Oceanographic and Atmospheric Administration. On file with: North Carolina State University, 151 Patton Avenue, Asheville, NC 28801. 9
  26. 26. GENERAL TECHNICAL REPORT PNW-GTR-870Figure 2.1—Multimodel mean annual differences in temperature between the three future periods compared to 1971 to 2000, from15 global climate models using two greenhouse gas emission scenarios (A2 and B1). The A2 scenario is for higher greenhouse gasemissions than for B1 (see text). For most interior states, models project a 1.4 to 1.9 °C temperature increase, rising to 2.5 to 3.6 °Cfor 2051 to 2071, and to > 4.2 °C for 2071 to 2099, depending on the emission scenario. (Kunkel, K.E.; Stevens, L.E.; Sun, L. [et al.].[N.d.]. Climate of the contiguous United States. Manuscript in preparation. On file with: NOAA’s National Climate Data Center, 151Patton Avenue, Asheville, NC 28801.)10
  27. 27. Effects of Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sectorof these estimated temperatures is bounded by the B1 and °C) and spring seasons (1.4 to 2.5 °C). Winter season showsA2 emission scenarios. Within each scenario, the magnitude the most pronounced warming across the United States, withof increase depends on both latitude and proximity to coastal little change across the South and increases up to 3.6 °C inareas. Greater warming is projected in more northern and the North. During the summer, greater warming is projectedinterior locations. For example, the largest temperature in- for more interior locations (up to 3.6 °C warming across thecreases are projected for the upper Midwest, and the smallest central United States from Kentucky to Nevada).temperature increases are projected for peninsular Florida. In addition to overall warming over the next century,Seasonally, these two constraints on the magnitude of warm- both the number of days when maximum temperaturesing are also apparent. For the higher emission scenario, the exceed 35 °C and when heat waves occur (defined as theleast amount of warming is expected for autumn (1.9 to 3.1 number of consecutive days with maximum temperaturesFigure 2.2—Spatial distribution of the mean change in the annual number of days with a maximumtemperature above 35 °C (A), and in the annual number of consecutive days with a maximum tem-perature greater than 35 °C (B) between 1971 to 2000 and 2041 to 2070. Models project that much ofthe Southeastern and Southwestern United States will experience more days with maximum tempera-ture exceeding 35 °C, and longer runs of those days. Results are for the high (A2) emission scenarioonly, from the North American Regional Climate Change Assessment Program multimodel means (n= 9 GCMs). (Kunkel, K.E; Stevens, L.E.; Sun, L. [et al.]. [N.d.]. Climate of the contiguous UnitedStates. Manuscript in preparation. On file with: NOAA’s National Climate Data Center, 151 PattonAvenue, Asheville, NC 28801.) 11

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