A new study finds that most communities will face excessive rainfall and excessive heat under climate change

Earth’s land masses have a greater chance of becoming wetter than dryer as temperatures rise. In a new study, researchers found that rainfall coinciding with extreme temperatures will become more frequent, intense and widespread under climate change than under dry, hot conditions.

When hot, humid conditions hit, heat waves first dry out the soil and reduce its ability to absorb water. Subsequent rainfall has difficulty penetrating the soil and instead extends along the surface, contributing to floods, landslides and crop failure.

“These complex extreme climate events have attracted significant attention in recent decades because of their disproportionate pressure on agriculture, industry and ecosystem sectors – much more than individual extreme events alone,” said Haijiang Wu, a researcher at Northwest A&F University of China and lead author. the study. The research was published in Earth’s future.

The team used a series of climate models to project complex extreme weather events by the end of the century if carbon dioxide emissions continue to rise.

They found that while some areas of the world will become drier as temperatures rise — such as southern Africa, the Amazon and parts of Europe — many regions, including the eastern United States, eastern and southern Asia, Australia and central Africa, will receive more rainfall. . Wet and hot extremes will also cover a larger area and be more intense than dry and hot extremes.

In the future, hot and wet extremes will become more likely because the atmosphere’s ability to retain moisture increases by 6% to 7% for every 1°C rise in temperature. As the Earth warms, the warmer atmosphere will contain more water vapor, which means more water will be available to fall as rain.

The regions most likely to be severely affected by extreme wet and hot weather events host many densely populated areas that are already vulnerable to geological hazards, such as landslides and mudflows, and produce many of the world’s crops. Increased heavy rainfall and heat waves could cause more landslides that threaten local infrastructure, while flooding and extreme heat could destroy crops.

Many parts of the world are already experiencing extreme heat events. In Western Europe, weather conditions led to deadly floods in 2021. That summer, record high temperatures dried out the soil. Shortly after, heavy rain fell on the surface of the dry soil and caused massive landslides and flash floods that swept away entire homes, killing more than 200 people.

The increase in extreme weather events, such as European flood conditions in 2021, creates a need for climate adaptation approaches that take hot, humid conditions into account.

“Given the fact that the risk of combined wet and warm extremes in a warm climate is greater than that of combined dry and warm extremes, these combined wet and warm extremes should be included in risk management strategies,” Wu said.

While heatwaves and torrential rains can be dangerous on their own, their combined effects can be even more devastating.

“If we ignore the threat of complex and hot extreme weather events and fail to provide adequate early warning, the impacts on water, food and energy security will be unimaginable,” Wu said.