Explained: Climate sensitivity
This is the second part of an “Explained” on climate change. Part one dealt with radiative forcing.Climate sensitivity is the term used by the Intergovernmental Panel on Climate Change (IPCC) to express the relationship between the human-caused emissions that add to the Earth’s greenhouse effect — carbon dioxide and a variety of other greenhouse gases — and the temperature changes that will result from these emissions.Specifically, the term is defined as how much the average global surface temperature will increase if there is a doubling of greenhouse gases (expressed as carbon dioxide equivalents) in the air, once the planet has had a chance to settle into a new equilibrium after the increase occurs. In other words, it’s a direct measure of how the Earth’s climate will respond to that doubling.That value, according to the most recent IPCC report, is 3 degrees Celsius, with a range of uncertainty from 2 to...