Global floods, droughts are getting worse with warming

According to a study published Monday in the journal Nature Water, the intensity of extreme droughts and rainfall has increased “dramatically” over the past 20 years. These are not just severe weather events, they are leading to extreme conditions Crop failureDamage to infrastructure, even humanitarian crises and conflicts.

The big picture on water comes from data from a pair of satellites known as GRACE, or the Gravity Recovery and Climate Experiment, which were used to measure changes in Earth’s water storage — on land, including groundwater, and the sum of all water, surface water, ice and snow.

“It’s incredible that we can now monitor continental water pulses from space,” said Park Williams, a bioclimatologist at the University of California, Los Angeles who was not involved in the research.

“I have a feeling when future generations look back and try to determine when humanity began to understand the planet as a whole, this will be one of the highlighted studies,” he said.

Researchers say the data confirms that both the frequency and intensity of rainfall and drought are increasing Burning fossil fuels and other human activities that emit greenhouse gases.

“I was surprised by how well global warming was correlated with global average temperature,” said Matthew Rodel, study author and deputy director of Earth Sciences for Hydrosphere, Biosphere, and Geophysics at NASA Goddard Space Flight Center.

The strong link between these climate extremes and rising global average temperatures means continued global warming will mean more droughts and rainstorms that are worse by many measures — more frequent, more intense, longer and larger.

Researchers looked at 1,056 events from 2002-2021 using a novel algorithm that detects when land is much wetter or drier than normal.

It shows sub-Saharan Africa receiving the heaviest rainfall, at least through December 2021, the end of the data. Precipitation extremes occurred in central and eastern North America from 2018–2021 and in Australia from 2011–2012.

The story continues

The most severe drought was a record-breaking one in northeastern South America in 2015–2016; An event in the Cerrado region of Brazil that began in 2019 and continues; and the ongoing drought in the American Southwest that has caused dangerously low water levels in the two largest US reservoirs, Lake Mead and Lake Powell. Although the rainfall is heavy this year, it is less.

Drought events exceed rainfall events by 10%. Their geographical spread and how long they lasted were similar.

A warmer atmosphere increases the rate of water evaporation during dry periods. It holds more water vapor, which fuels heavy precipitation events.

The study notes that infrastructure such as airports and sewage treatment plants that were designed to withstand once-in-100-year events are becoming more challenged as these extremes occur more frequently and with greater intensity.

“Looking into the future, in terms of water resource management and flood control, we should anticipate that the wet edges will be wetter and the dry edges will be drier,” said Richard Seeger, a climate scientist at the Lamont Doherty Earth Observatory. at Columbia University, who was not involved in the research.

Seeger said it’s a mistake to assume future wet and dry extremes can be handled in the same way as in the past because “everything is going to expand on both ends of the dry-wet spectrum.”

According to the US National Integrated Drought Information System, 20% of annual economic losses from extreme weather events in the US are from floods and droughts.

A sharp swing between extreme drought and unprecedented flooding, called “weather whiplash,” is becoming common in some regions.

Water stress is expected to significantly affect poor, disenfranchised communities as well as ecosystems that are underfunded and exploited.

For example, the United Nations says Somalia is experiencing its longest and most severe drought, an event that has killed millions of livestock and caused widespread hunger. Venezuela, a country that has experienced years of political and economic crisis, resorted to nationwide power cuts in April 2016 as a result of drought conditions affecting the water levels of the Guri Dam.

For solutions, using floodwater to replenish depleted aquifers and improving the health of agricultural soil so it can better absorb water and store more carbon are some of the methods that could improve water resilience in a warming world, the study said.

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