This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In early 2017 and 2023, California experienced two catastrophic and record-breaking floods that caused billions of dollars in damage, triggered mudslides and forced thousands of people to evacuate. Why this happened left scientists scratching their heads.
Both disasters struck during La Niña conditions, which normally bring drier-than-normal weather to California. Now, an international team of researchers thinks it may have the answer. Using detailed computer simulations, a team, led by Yongkang Xue at the University of California, Los Angeles, discovered that a key driver could have been a chain of atmospheric events that started with unusually warm weather on the Tibetan Plateau, thousands of miles away.
Their work is published in the journal Science Advances. Uncovering this previously unknown connection started with decades of real-world climate data. First, the researchers analyzed temperature data from the Tibetan Plateau and rainfall data from North America from 1984 to 2023.
They focused on the Tibetan Plateau because this vast, high-altitude region can influence weather patterns far beyond Asia. The data showed that when there is unusual heating over the Tibetan Plateau in early winter, heavier rains tend to fall over the western U.S. the following month. But this correlation was not the full picture.
To see whether the mountain heat was actually driving the weather, they ran two sets of computer simulations for both flood events. In the control set, they used standard weather data without adding the warm temperatures over Tibet. The simulations failed to produce the extreme rainfall seen in California.
But in the second set, the research team included the unusual heating. This time, the simulations produced about 56% of the above-normal rainfall in January 2017 and 38% of the above-normal rainfall in March 2023 in the affected regions. The simulations also helped explain how this long-distance connection works.
Extract — continue reading at the source.
