Droughts are among the greatest dangers linked to climate change. They threaten food security and access to essential goods such as drinking water. They cause enormous economic damage in developed countries, and migration and deaths in less fortunate areas of the planet. Scientists have long warned that they will become increasingly frequent due to global warming, but a new study just published in the pages of Nature indicates that the situation could turn out to be even worse than expected.
The study was born to try to reduce the uncertainties present in the forecasts of the main climate models, which currently prevent the best calibration of adaptation strategies in many regions of the planet. With more precise forecasts, according to the authors of the study – an international team of experts in climatology and adaptation to climate change – it would be possible to minimize the environmental, social and economic impact of drought waves. And for this reason, they tried to obtain more precise estimates.
First, the researchers analyzed the most widely used climate models to identify potential sources of error and uncertainty that make their results conflicting, focusing on the two most likely and worrying scenarios: the high-emissions scenario – or “business as usual” – in which there will be no appreciable reductions in greenhouse gas emissions over the next few decades, and the moderate-emissions scenario, in which emissions will continue to increase until they peak around 2040, and then finally begin to decline.
Drought even 10 days longer than expected
Having identified the weak points of the models, they then calibrated the results using the historical series of the longest drought periods in each area of the planet between 1998 and 2018. And they then repeated the simulations, demonstrating – according to them – that the models used to date have always underestimated the risks that drought will pose in the coming decades. The models calibrated by the researchers, in fact, predict drought periods that are on average 42-44 percent longer than the uncalibrated models.
In concrete terms, between 2080 and 2100, the models calibrated by the researchers indicate annual droughts that will be about 10 days longer than previously predicted. And in some areas, such as North America, southern Africa and Madagascar, it could be even worse, with droughts lasting twice as long as those predicted by the uncalibrated models. In other areas, such as Central and Eastern Asia, the duration of droughts is instead expected to decrease, which, according to the authors of the study, probably indicates an increase in extreme precipitation and floods.