Not exceeding 1.5 degrees is almost impossible: how to reduce overshooting?

All IPCC scenarios expect exceeding 1.5 degrees even temporarily

If the probability of exceeding 1.5 degrees is now higher than 50%, what are the plausible scenarios that allow us to reduce the overshooting time, that is, the period in which the global temperature exceeds this threshold? This is the question from a study by the US Department of Energy and the Pacific Northwest National Laboratory published in Nature Climate Change.

The priority is not to waste time. Rapid action, even if insufficient to avoid exceeding 1.5 degrees, still reduces the time of overshooting and therefore also the power of the impact of climate change on our societies. “Moving fast means reaching commitments to zero emissions sooner, decarbonizing faster and achieving more ambitious emission targets,” the authors say. “Every small contribution is useful, and a combination of all these elements is needed. But our results show that the most important thing is to do it soon. On the contrary, do it now“.

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The result is based on the 28 different scenarios built in the study, where mitigation paths are explored with varying levels of ambition starting from the state of climate promises at the end of the COP26 in Glasgow. In slightly more ambitious scenarios, the authors define the limited amount of warming when countries accelerate decarbonization and anticipate the dates of their commitments to zero emissions. The key is to increase short-term ambition, which will result in a rapid reduction of carbon dioxide emissions from all sectors of the energy system, immediately and until 2030.

If you follow the current trajectory by adding a minimum decarbonization rate of 2% per year, for example, climate neutrality will not be achieved during this century. In the most ambitious scenarios, however, it is assumed that the decarbonization rate is 8% per year and that the net-zero horizon is anticipated in 10 years. In this way, climate neutrality could be achieved in 2057.