What is Climate Sensitivity?

Written By Teacher: Liz Ransom

As a High School Spanish teacher and student newspaper advisor, Liz has taught for over 20 years and has served as World Languages Department Chair and K-6 summer camp activities leader. She has worked in Ohio, Maine, New Jersey, Maryland, and Chile.

Students concerned about the climate crisis will inevitably encounter the term “climate sensitivity” used by climate scientists in the context of explaining their predictions if we don’t take climate action.  This topic can feel overwhelming, but teachers can inspire their students with innovative ways people across the planet are working to solve the climate crisis with these resources from Project Drawdown.  In addition, teachers can empower students to debunk misinformation about climate change with this journalism lesson. 

Written By: MIT Environmental Solutions Initiative

The MIT Climate Change Engagement Program, a part of MIT Climate HQ, provides the public with nonpartisan, easy-to-understand, and scientifically-grounded information on climate change and its solutions.

Climate sensitivity is a term used by the Intergovernmental Panel on Climate Change (IPCC) to describe to what extent rising levels of greenhouse gases affect the Earth’s temperature. Specifically, it describes how much warmer the planet will get if the amount of greenhouse gases in the atmosphere doubles.

Although scientists don’t know exactly what Earth’s climate sensitivity is, it’s a useful concept for thinking about the range of risks we face from climate change: from slower and more manageable consequences if our climate sensitivity is low, to faster and more dire changes if it’s high. According to the most recent IPCC report, our climate sensitivity is very likely somewhere between 2 and 5 ℃ (between 3.6 and 9 ℉). 

Feedback Effects

If that range sounds pretty wide, that’s because there are many factors that can speed up or slow down the rise in atmospheric temperatures. The main ones are clouds, sea ice, and water vapor. Scientists call these factors “feedback effects,” and they can make predicting the planet’s future climate more complicated.

Climate scientists agree that with no feedback effects at all, our climate sensitivity would be just 1 ℃. Many controversies in climate science hinge on just how strong the various feedbacks are, and whether scientists have accounted for all of them. Clouds are a good example. Clouds can warm or cool the planet, depending on how high they are and the size of their water droplets. Overall, most scientists expect changes in clouds to mostly warm the planet, but some say it’s hard to know.