Rapid swings between extreme wet and dry weather known as hydroclimate whiplash are accelerating globally due to climate change, with further escalation expected as temperatures rise, according to a study led by UCLA climate scientist Daniel Swain.
The study, published in Nature Reviews, highlights the role of the “expanding atmospheric sponge,” a phenomenon where the atmosphere absorbs, evaporates, and releases 7% more water for every degree Celsius of global warming. This process intensifies the swings between droughts and floods, posing new challenges for water and disaster management.
California offers a vivid illustration of hydroclimate whiplash. Following years of drought, the state experienced record-breaking precipitation during the winters of 2022-23, triggering floods, snowbursts, and landslides. By 2024, a scorching summer combined with a record-dry rainy season left vegetation tinder-dry, fueling destructive wildfires.
“This sequence has doubled fire risk,” Swain explained, noting that abundant vegetation from wet winters becomes highly flammable during subsequent dry periods.
The study found that hydroclimate whiplash has increased globally by 31% to 66% since the mid-20th century faster than climate models predicted. If global temperatures rise 3°C above pre-industrial levels, the frequency and intensity of such swings are expected to more than double.
The “expanding atmospheric sponge” effect intensifies the severity of both droughts and floods. As the atmosphere becomes “thirstier” with warming, it draws more moisture from plants and soil, exacerbating drought conditions even in the absence of reduced rainfall.
“The atmosphere’s capacity to hold water grows exponentially, much like compound interest,” Swain said. This leads to amplified transitions between extremes, from catastrophic flooding to prolonged droughts.
Implications for Water Management
The findings underscore the need for holistic water management strategies that address both extremes simultaneously. Traditional approaches such as quickly diverting floodwaters to the ocean leave cities vulnerable to subsequent droughts.
“Co-management of extreme rainfall and droughts is essential,” Swain noted. This includes solutions like replenishing groundwater during wet periods and designing infrastructure to manage extreme water surpluses and deficits effectively.
Hydroclimate whiplash is expected to escalate most in regions like northern Africa, the Middle East, South Asia, and the tropical Pacific, though impacts will be felt worldwide.
In California, warming scenarios suggest both the wettest and driest seasons will become more extreme by the end of the century.
“The less warming we allow, the less severe hydroclimate whiplash will be,” Swain emphasized. While global temperatures are on track to rise by 2-3°C this century, mitigating warming could reduce the pace and severity of these dangerous climate shifts.
For regions like California, adapting to this new climate reality is urgent. The increasing overlap of dry vegetation and wind-driven fire seasons, compounded by whiplash events, demands immediate attention in disaster risk planning and infrastructure adaptation.