National Geographic, December 2023
Thirty-five years after NASA scientist James Hansen testified before the United States Congress about the specter of climate change, Earth is on pace to experience 2.7°Celsius (4.9 degrees Fahrenheit) of warming by 2100. And while there is little consensus among nations about how and how fast to reduce the carbon emissions that are responsible for that warming, there is near universal consensus that this temperature increase would be disastrous.
For that reason, the 196 signatories to the Paris Agreement, signed in 2015, committed to keeping the mean rise in global temperatures below 2° C (3.6° F) above pre-industrial levels and preferably limit any increase to 1.5° C (2.7° F). Participants in the 28th United Nations Climate Change Conference (COP 28), taking place in Dubai November 30-December 12, will be expected to update their progress on meeting those goals.
Given that the globe is already about 1.2 °C (2.2° F) warmer than it was before the Industrial Revolution, that target may seem, depending on your level of optimism, either highly ambitious or perfectly within reach. But what exactly does this goal save us from, and how was it selected in the first place?
