Is it possible and what are the consequences of exceeding a given global mean temperature threshold and then bringing warming back down again? Although a limited and temporary climate overshoot is better than reaching a peak temperature and staying there, some of its impacts may be irreversible and could push ecosystems towards dangerous tipping points.
In the coming decade global mean temperatures are almost certainly going to exceed the “well below 1.5 degrees Celsius” goal set out in the Paris Agreement.
In April 2022 the IPCC stated that it is “almost inevitable” that we will temporarily exceed the 1.5 degrees Celsius temperature threshold and the UN’s World Meteorological Organization recently stated in its annual report that there is a “50:50 chance of global temperature temporarily reaching 1.5°C threshold in the next five years.”
However, most scientists also agree that some of this excess warming can be reversed if CO2 emissions are brought to net zero.
This temporary rise and subsequent cooling of temperatures is known as climate overshoot and the extent and degree to which we overshoot will have a significant impact on the world of tomorrow.
“The difference between the peak global mean temperature and where we manage to come back down to is generally referred to as climate overshoot,” explains climate change researcher Zebedee Nicholls, who recently co-authored a paper on the impact of current Paris Agreement pledges on global temperatures.