West LA Times

Hydroclimate whiplash, characterized by rapid transitions between wet and dry weather, is intensifying globally due to climate change. A team led by UCLA's Daniel Swain has reported that this phenomenon will likely increase as the planet continues to warm. The study highlights the "expanding atmospheric sponge," which describes the atmosphere's capacity to evaporate, absorb, and release 7% more water for each degree Celsius of warming.

The research underscores the necessity of co-managing extreme rainfall and droughts rather than treating them separately. This approach aims to develop effective interventions and solutions for these growing challenges.

In California, recent events illustrate hydroclimate whiplash. After a severe drought period, California experienced heavy precipitation during the winter of 2022-23, leading to flooding and landslides. This was followed by a hot summer in 2024 and a record-dry start to 2025, resulting in wildfires fueled by dry vegetation.

"The evidence shows that hydroclimate whiplash has already increased due to global warming," said Daniel Swain. He noted that this sequence in California has doubled fire risk by increasing flammable vegetation growth before drying it out with subsequent heat and dryness.

Global data indicates that hydroclimate whiplash has risen by 31% to 66% since the mid-20th century, surpassing previous climate model predictions. If global temperatures rise by 3 degrees Celsius above pre-industrial levels, the phenomenon could more than double.

Swain emphasized the role of anthropogenic climate change in this acceleration: "The problem is that the sponge grows exponentially." He added that every fraction of a degree of warming increases destructive transitions' power.

The implications extend beyond floods and droughts; they include increased risks like landslides on oversaturated hillsides after fires have removed stabilizing vegetation. Traditional water management strategies may be inadequate under these conditions.

Co-author John Abatzoglou from UC Merced highlighted California's unreliable hydroclimate: "Swings like we saw a couple years ago...tested our water-infrastructure systems."

Hydroclimate whiplash is expected to increase most significantly across northern Africa, the Middle East, South Asia, northern Eurasia, and tropical regions but will affect other areas too.

"Increasing hydroclimate whiplash may turn out to be one of the more universal global changes on a warming Earth," Swain stated.

In Southern California, while winds contribute to wildfires' spread, it's primarily the lack of rain driven by whiplash that's prolonging fire season. Swain noted no substantial evidence linking climate change directly with wind event frequency or intensity but stressed its role in creating conditions conducive to fires through dry vegetation overlap with wind events.

Under high warming scenarios, California might see an increase in both its wettest and driest periods later this century. Swain concluded: "Anything that would reduce...warming from climate change will directly slow or reduce...whiplash."

This research received support from The Nature Conservancy of California and the Swiss National Science Foundation.