There is growing recognition that climate change will significantly impact global migration patterns in the coming decades. While estimates of current climate migrants vary, research agrees that climate migration is increasing and climate risks will accelerate this trend further. This chapter provides context on current migration trends, the impacts of climate change on these patterns, and informs the climate migration modeling and analysis in this report. It overviews the scale of internal migration currently, its underlying causes and impacts, and how expected climate trends may change the pace and impacts of climate migration in the future.

1. 17Understanding the Climate Change–Migration Nexus
17Understanding the Climate Change–Migration NexusChapter 2There is growing
realization among researchers, policy makers, and the wider public that the impacts of
climate change will have a large effect on global migration patterns in the coming decades.
Although there is no consensus on the current number of climate migrants, most research
recognizes that the rate of climate migration is increasing and that growing climate risks in
the coming decades will accelerate this trend. This chapter presents the state of play of
migration trends, with a focus on the impacts of climate change on these patterns, and
provides context for the modeling approach and the analysis done in this report.Migration
has important impacts on people, places, and development. It can enhance adaptive capacity
under certain conditions, but it can also destroy livelihoods if not adequately planned for
and managed (McLeman 2016). A rich body of literature describes the conditions and
complexities underlying migration (including climate change-induced) and the impacts of
climate migration (albeit to a lesser degree). Research on climate migration first emerged in
the 1980s. Output rose to about 10 peer-reviewed publications a year in the 1990s and to
more than 100 a year since 2008, including at least 447 empirical case studies, mostly on
Africa, the Asia-Pacific region, and the American continent (Ionesco, Mokhnacheva, and
Gemenne 2016).5 The work carried out for this report builds on previous work.This chapter
overviews the scale of current internal migration, underlying causes, and its impacts.6
Overlaying this information with expected climate trends, the chapter aims to draw
attention to the change in the pace of climate migration and its future impacts. This context
informs the modeling approach in Chapter 3, and the interpretation and narrative of the
results in the subsequent chapters.5. Ionesco, Mokhnacheva, and Gemenne (2016) draw on
studies recorded in the Climig Database by the Institute of Geography University of
Neuchâtel, Switzerland (https://www.unine.ch/geographie/climig_database), which
includes research in several languages.6. The chapter also draws on background papers
commissioned for this report, including McLeman (2016) and Hunter (2016).Understanding
the Climate Change–Migration Nexus