1.5

Exceeding 1.5°C temporarily, and just fust for one month, does not mean the Paris Agreement goal of staying under 1.5°C is lost, as September is generally the hottest month on Earth. However, a temporary rise above 1.5° is likely to trigger some irreversible tipping points.

Current policies and actions make it very likely, at least temporarily, to overshoot the Paris climate targets of 1.5–<2.0 °C above pre-industrial levels. If this global warming range is exceeded, potential tipping elements such as the Greenland Ice Sheet and Amazon rainforest may be at increasing risk of crossing critical thresholds. This raises the question of how much this risk is amplified by increasing overshoot magnitude and duration. …Our model analysis reveals that temporary overshoots can increase tipping risks by up to 72% compared with non-overshoot scenarios, even when the long-term equilibrium temperature stabilizes within the Paris range. 

– Wunderling et el, Global warming overshoots increase risks of climate tipping cascades in a network model, Nature Climate Change 13,  22 December 2022.