1120. Overconfidence in Climate Overshoot

Global efforts to reduce greenhouse emissions remain insufficient to meet the temperature targets of the Paris Agreement. For this reason, discussions are being held on the assumption of so-called overshoot pathways, which temporarily exceed the target global warming limit before returning the temperature to safer levels. 

A paper published in the journal Nature said there is no guarantee that temperature decline will be achieved after an overshoot, and it called for short-term, rapid emissions reductions to reduce climate risks.

If we can achieve a reduction in global temperatures, we can limit long-term climate risks, such as sea level rise and changes in the cryosphere, compared to simply stabilizing warming. But even if we could reverse global warming decades from now, it might not be very useful for adaptation planning today. Strong Earth system feedbacks could prevent the reversal of temperature rises, resulting in short-term and sustained warming.

To avoid high risks, hundreds of gigatons of carbon dioxide removal are required. However, from a technical, economic, and sustainability perspective, there is a limit to what can be achieved by large-scale carbon removal deployments. Therefore, there is no guarantee that a temperature drop after an overshoot will be achievable within the deadlines of the currently expected time scale. There is no effective alternative to reducing climate risks other than short-term, rapid emissions reductions.

Reference
Carl-Friedrich Schleussner, Overconfidence in climate overshoot, Nature (2024). https://www.nature.com/articles/s41586-024-08020-9

Contributor: IIYAMA Miyuki, Information Program