Study reveals link between Tibetan Plateau heat and record rain in California

The discovery could transform winter forecasting and explains why severe floods hit the US west coast when dry weather was expected

In the winters of 2016-2017 and 2022-2023, record-breaking rain swept across the US state and surrounding areas, causing billions of dollars in damage and several deaths during years when drier weather was expected in the region.

A study led by researchers from the University of California, Los Angeles (UCLA) found that these rain events happened shortly after periods of unusually high land surface temperatures on the Tibetan Plateau in early winter.

The record rain caused “extraordinary damage and severe societal impacts”, according to the paper published in the peer-reviewed journal Science Advances on Wednesday.

Rainfall in the winter of 2016-2017 effectively ended California’s five-year drought, with property damage reaching around US$2 billion. Heavy precipitation in the winter of 2022-2023 brought severe flooding, killing several people and causing around US$4.6 billion in damage.