Devastating megadrought spreading across the world

(Bloomberg) — Severe drought conditions have helped fuel Los Angeles’ wildfires. But a new study released Thursday in the journal Nature comes with a warning: Climate change is making devastating, multiyear “megadroughts” even worse around the world.

Drought is relative – for example, a drought in normally rainy Seattle may register as an unusually wet period in a dry climate like Phoenix, Arizona. But they can disrupt ecosystems, sometimes in dangerous ways.

“This is what we are seeing in California right now,” said Dirk Nicolas Karger, a senior researcher at the Swiss federal institute WSL and a paper author. “Over time, vegetation dries up, and we have increased the frequency of fires, and houses burn down. In other areas, we will have agricultural failures.”

The fires in California are being caused by only eight months of low rainfall. While climate change is contributing to more erratic rainfall in the western US, the new paper takes a global view of past years’ drought. The researchers were inspired to do this when Karger and co-author Francesca Peliciotti spent time in Chile, which is in the midst of a drought that began in 2010.

“The consequences were devastating, from ecosystems to agriculture,” said Pellicciotti, a professor at the Institute of Science and Technology Austria. The drought has caused intermittent water shortages, including in the country’s capital, Santiago, as well as disrupted mining, a major part of Chile’s economy. In 2021 and 2022, London-based Chilean multinational Antofagasta said it was forced to cut production due to drought. In September, Google said it was halting plans to build a large data center due to water problems.

To find out how many other places might have experienced similar megadroughts, the researchers looked at rainfall and vegetation data. They also looked at spatial data to see how much area the drought affected.

They found that in the last 40 years, severe drought has occurred on every continent except Antarctica. Mongolia, southeastern Australia and the western US were among the areas with the highest density of severe multi-year drought events. However, the longest drought in their research occurred in the eastern Congo Basin which lasted for a decade. It covered 576,924 square miles (1,494,226 km²), an area nearly twice the size of Texas.

The researchers also found that the areas experiencing multi-year drought are increasing due to climate change.

“The extent to which these dry areas are increasing per year is roughly equivalent to the size of Switzerland,” said Liangzhi Chen, a postdoctoral researcher at the Swiss Federal Institute WSL and lead author of the study.

As megadroughts expand their reach, so does the damage they are capable of causing. Droughts drive five times more people to flee than floods worldwide. According to a World Bank analysis, dry weather is responsible for an average decline in gross domestic product of more than half a percent in low- and middle-income countries. And as the climate warms, the problem is likely to get worse.

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