Why is a few degrees of warming such a big deal when it comes to climate change?
A stark United Nations report issued in 2018 calls on governments to try to keep any further global warming well below 1.5 Celsius. The scientists who authored it concede that there is “no documented historic precedent” for such a rapid transformation of the global economy, but say the world faces myriad crises as early as 2040 — including food shortages, extreme weather, wildfires, and a mass die-off of coral reefs — unless greenhouse gas emissions are sharply cut.
But we’re only talking about a few degrees of warming. Why is that such a big deal?
Richard Alley, a professor of geosciences at Penn State University, explains why the world is more sensitive to climate change than we like to think: