A major new study of the relationship between carbon dioxide and global warming lowers the odds on worst-case climate change scenarios while also ruling out the most optimistic estimates nations have been counting on as they attempt to implement the Paris agreement.
A group of 25 leading scientists now conclude that catastrophic warming is almost inevitable if emissions continue at their current rate, even if there’s less reason to anticipate a totally uninhabitable Earth in coming centuries.
The research, published Wednesday in the journal Reviews of Geophysics, narrows the answer to a question that’s as old as climate science itself: How much would the planet warm if humanity doubled the amount of carbon dioxide in the atmosphere? That number, known as "equilibrium climate sensitivity,” is typically expressed as a range. The scientists behind this new study have narrowed the climate-sensitivity window to between 2.6 and 3.9 degrees Celsius.