Abrupt change is a hallmark of the climate record. It has happened in the past, and is already happening in some systems now.
Abrupt climate change—large shifts in climate that take place within decades or even years—is the topic of increasing scientific research because of the potential for such changes to happen faster than society or ecosystems could adapt. A new report from the National Research Council evaluates the potential for abrupt changes in the ocean, atmosphere, ecosystems, and high latitude regions to help decision makers and communities make informed decisions about how to prepare for sudden changes. The report calls for an early warning system to help society better anticipate abrupt changes.
This poster, presented at the American Geophysical Union (AGU) meeting in Dec. 2013, outlines what's happening already and what's not thought to be an immediate danger, and calls for an early warning system. See more at http://instaar.colorado.edu/explore-our-science/activities/abrupt-climate-change/