New Delhi, March 26 Extreme climate hazards, such as severe droughts and intense rainfall that are usually linked with 3 degrees Celsius or 4 degrees Celsius global warming, could occur even under a moderate warming of 2 degrees Celsius, threatening food production, forests, and densely populated urban areas, a study has found.
While the Paris Agreement sets a target of limiting global warming to 1.5 degrees Celsius, current climate policies of countries are estimated to put the world on track to achieve 2.3 degrees Celsius to 2.5 degrees Celsius warming.
Researchers evaluated climate models, including those forming the basis of reports from the Intergovernmental Panel on Climate Change (IPCC), and identified projections showing the worst-case and best-case scenarios for a specific context, such as "droughts in major global agricultural regions".
"At 2 degrees Celsius, 10 of the 42 (climate) models examined produce a drought increase that is considerably above the model average at 4 degrees Celsius of warming," said lead author Emanuele Bevacqua, a climate researcher at the Helmholtz Centre for Environmental Research-UFZ in Germany.
Therefore, the risk of droughts in globally important growing regions is much higher than would be expected from an analysis of model averages, the researchers said.
The findings, published in the journal Nature, underscore the need for governments and institutions to prepare for plausible worst-case scenarios, even under "moderate" levels of warming, they said.
The researchers said that until now, worst-case "extreme global climate outcomes" have typically been described using the average results of many climate models at high levels of global warming (3 or 4 degrees Celsius).
However, this approach does not account for the fact that even at moderate levels of global warming, individual climate projections for certain regions can be very severe, they said.
Therefore, the team adopted a new approach where they identified sector-specific drivers of climate impact such as precipitation extremes and droughts as well as regions where vulnerable sectors are located – heavy rainfall in densely populated regions, droughts in major global agricultural regions, and fire-conducive weather in forests.
This makes it possible to examine climate changes in locations where they are particularly relevant for specific global risks, the researchers said.
The authors show that "extreme global climate outcomes may occur even under moderate 2 degrees Celsius warming for several sectors."
"For droughts in global key breadbasket regions, precipitation extremes over highly populated areas and fire weather extremes across forests, global climatic impact-drivers at 2 degrees Celsius of global warming may turn out to be much more extreme than model-averaged projections at 3 degrees Celsius or 4 degrees Celsius warming," they said.
Responsible risk assessment should therefore look beyond the most likely ranges projected by climate models and consider extreme outcomes with possible severe societal or environmental consequences, Bevacqua said.
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, the researchers said.