News release

From: Springer Nature

Extreme global climate outcomes possible under moderate warming

Extreme climate hazards may occur under moderate 2 ºC warming at levels predicted for higher degrees of warming, a study in Nature finds. The research shows that severe drought, fire‑weather conditions and intense rainfall could threaten food production, forests and densely populated urban areas even exceeding the average projections typically associated with 3 ºC or 4 ºC of warming. The findings underscore the need for governments and institutions to prepare for plausible worst‑case scenarios, even under ’moderate’ levels of warming.

Climate assessments often rely on global and multimodel averages to communicate the most likely future climate. However, these averages do not capture how climate change affects specific systems, such as cities, forests or crop‑growing regions, and may mask large differences between individual climate models. This variability obscures the possibility that extreme rainfall, widespread drought, or dangerous fire‑weather conditions could arise under lower warming than projected. As warming approaches 1.5 ºC, understanding these credible worst‑case futures is essential for effective risk management and climate‑mitigation planning.

To provide a clearer picture of these risks, Emanuele Bevacqua and colleagues focus on climate hazards in some of the real‑world systems most vulnerable to change. They examine complete model simulations for specific climate‑sensitive areas; heavy rainfall in populated regions, drought across global breadbaskets, and fire‑weather conditions in forests. The authors find that individual climate models at 2 ºC project outcomes that are more extreme than the multimodel‑mean projections at 3 ºC or even 4 ºC. Under sector-specific analysis, heavy rainfall in populated areas could be projected to increase by 4–15%, with the worst‑case 2 ºC model exceeding the average outcome at 3 ºC. Additionally, 10 out of 42 models show drought conditions in major crop‑producing regions that surpass the average projections for 4 ºC, with drought frequency potentially rising by more than 50%.

These findings suggest that relying solely on multimodel averages could lead to the underestimating of the severity and timing of climate impacts across globally critical systems. As policymakers refine mitigation plans and organizations prepare for future climate risk, understanding and stress‑testing against these realistic worst‑case scenarios will be crucial.