"Hydroclimate whiplash" is wreaking havoc across the U.S.

California has become a vivid example of a global phenomenon known as “hydroclimate whiplash,” which involves sudden and dramatic swings between extreme wet and dry conditions. 

These abrupt shifts are increasingly destabilizing ecosystems and communities, as shown in a new study published in Nature Reviews Earth and Environment. 

The research highlights how climate change is intensifying these weather patterns and their associated risks, from destructive wildfires to devastating floods.

A state in constant flux

The winters of 2022-23 and 2023-24 brought California unprecedented precipitation, fueled by dozens of atmospheric rivers. 

Mountain towns were buried under snow, valleys were inundated with rain and snowmelt, and landslides occurred across the state. 

However, these deluges were followed by record summer heat and a drought-ridden start to the 2025 rainy season. The resulting dry vegetation has provided ample fuel for a series of wildfires.

“This whiplash sequence in California has increased fire risk twofold,” explained lead author Daniel Swain, a climate scientist at the University of California, Los Angeles (UCLA) and UC Agriculture and Natural Resources. 

“First, by greatly increasing the growth of flammable grass and brush in the months leading up to fire season, and then by drying it out to exceptionally high levels with the extreme dryness and warmth that followed.”

Global trends in climate whiplash

California’s situation mirrors a global trend. The study found that hydroclimate whiplash has increased worldwide by 31% to 66% since the mid-20th century – outpacing predictions made by climate models. 

The trend is accelerating due to human-driven climate change, with projections suggesting that whiplash events could more than double if global temperatures rise by three degrees Celsius above pre-industrial levels.

A key driver of this intensification is the “expanding atmospheric sponge,” a phenomenon in which a warmer atmosphere absorbs and releases more water. 

For every degree Celsius of warming, the atmosphere’s capacity to hold moisture increases by 7%, compounding the severity of both droughts and floods.

“The problem is that the sponge grows exponentially, like compound interest in a bank,” Swain said. “The rate of expansion increases with each fraction of a degree of warming.”

Beyond rainfall: The role of evaporation

While many studies focus solely on precipitation patterns, this research emphasizes the role of increasing “evaporative demand.” 

A warming atmosphere pulls more moisture from plants and soil, exacerbating drought conditions even when rainfall does not decrease.

“The expanding atmospheric sponge effect may offer a unifying explanation for some of the most visible, visceral impacts of climate change,” Swain noted. 

This includes the rapid transitions between floods and droughts, landslides triggered by oversaturated soil, and cycles of vegetation growth and fire.

Challenges for water management

The intensifying hydroclimate whiplash poses significant challenges for water resource management. 

California’s traditional strategies, such as diverting flood waters to the ocean, need to be balanced with measures to retain water for prolonged dry spells. Swain emphasized the importance of a “co-management” approach that considers drought and flood risks together.

John Abatzoglou, a UC Merced climate scientist and co-author of the study, highlighted the strain on California’s infrastructure: 

“Hydroclimate in California is reliably unreliable. Swings like we saw a couple years ago, going from one of the driest three-year periods in a century to the once-in-a-lifetime spring 2023 snowpack, both tested our water-infrastructure systems and furthered conversations about flood water management to ensure future water security in an increasingly variable hydroclimate.”

Global phenomenon of climate whiplash 

While California offers a stark example, hydroclimate whiplash is a global issue.

Regions such as northern Africa, South Asia, and the tropical Pacific are projected to experience the most dramatic increases, but almost every region will face growing risks.

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

Southern California: Fire season’s extended grip

Southern California’s wildfire risks have been amplified by the lack of rain and the dry vegetation left behind by previous wet seasons. 

While seasonal winds, such as the Santa Anas, play a role in spreading fires, Swain noted that “climate change is increasing the overlap between extremely dry vegetation conditions later in the season and the occurrence of these wind events.” 

“This, ultimately, is the key climate change connection to Southern California wildfires.”

Slowing the intensification of climate whiplash

The study highlights the urgent need to reduce global warming to slow the intensification of hydroclimate whiplash. 

“The less warming there is, the less of an increase in hydroclimate whiplash we’re going to see,” Swain said.  However, with the planet on track for two to three degrees Celsius of warming this century, substantial increases in variability are likely.

Adapting to these changes will require rethinking water management, infrastructure, and conservation strategies. By addressing both ends of the water spectrum – flood and drought – policymakers and communities can better prepare for the challenges of a warming world.

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