Weather Whiplash: The Increasingly Dangerous Trend of Rapid Weather Changes
It’s supposed to be the rainy season in Southern California, but the last time Los Angeles measured more than a tenth-inch of rain was eight months ago, after the city logged one of the soggiest periods in its recorded history. Since then, bone-dry conditions have set the stage for the catastrophic wildfires now descending upon the metropolis from multiple directions.
This quick cycling between very wet and very dry periods — one example of what scientists have come to call “weather whiplash” — creates prime conditions for wildfires. The rain encourages an abundance of brush and grass, and once all that vegetation dries out, it only takes a spark and a gust of wind to fuel a deadly fire. That’s what happened in Los Angeles County this week when a fierce windstorm fueled the Palisades and Eaton fires, which as of Wednesday night had killed at least five people, destroyed more than 2,000 buildings, and forced tens of thousands of people to evacuate their homes.
The kind of weather whiplash that fueled the fires is only becoming more common, and not just in the United States. A new analysis in the peer-reviewed academic journal Nature Reviews Earth & Environment has found that rapid shifts between heavy rain and drought (and vice versa) are becoming more intense — and the trend is unfolding faster than climate models have projected. Across the world’s land area, weather whiplash within three-month periods has increased by 31 to 66 percent since the mid-20th century, according to the research. That means that most places around the world find themselves getting both wetter and drier in quick succession, a dangerous combination that can lead to landslides, crop losses, and even the spread of diseases.
“The volatility of wet and dry extremes is this sort of emerging signature of climate change,” said Daniel Swain, a co-author of the paper and a climate scientist at the University of California, Los Angeles. “This year, unfortunately, I couldn’t have asked for a better poster child for this process than Southern California.”
Swain, along with researchers across the United States and in Switzerland, analyzed a flurry of recent research on what they refer to as “hydroclimate volatility” and developed a way to measure how it might get worse in the future. They found that the swings between very wet and very dry weather are rising exponentially for each passing fraction of a degree the globe warms.
“I do think this is a big part of the reason why it feels like climate change has accelerated,” Swain said.
To understand why wet and dry periods are becoming more extreme, it can help to think of the atmosphere as a kitchen sponge that’s becoming more and more absorbent as it warms. When you wring out this more powerful sponge, it sends down heavier rains than before. On the other hand, when the sponge dries out, it has even more capacity to suck up moisture from the soil and plants below, parching the landscape and turning it into tinder. The paper’s authors coin a new phrase for this phenomenon: the “expanding atmospheric sponge effect.” Jim Stagge, who runs the Hydrologic Extremes Research Laboratory at The Ohio State University and was not involved in the new research, called it “a clever analogy” and said the paper’s evidence was generally convincing.
The volatile swings between wet and dry patterns aren’t unfolding uniformly across the world. The Mediterranean, for example, is getting less rain on average, whereas the eastern United States is getting distinctly wetter, according to Swain. While the expanding atmospheric sponge effect is happening everywhere, changes in regional weather patterns are either countering some of its effects or else amplifying them. The regions experiencing the biggest whiplash include a broad swath of land from northern Africa through the Arabian Peninsula and into South Asia, as well as high latitudes in Canada and Eurasia, the research found.
Adapting to a future that’s both wetter and drier presents a unique social challenge. For instance, it would be easy to get tunnel vision and focus on preparing for water scarcity, only to accidentally make a town more vulnerable to flooding in the process, Swain pointed out. Flexibility is key to successful interventions, according to the new paper. As climate change continues to alter weather patterns around the world, it is crucial to explore innovative solutions to mitigate its impact. One approach gaining traction is the expansion of natural floodplains and the removal of impermeable pavement from cities. These strategies not only help reduce the risk of flooding by allowing the soil to absorb more rainfall but also provide a way to store water underground for future use.
By expanding natural floodplains, we can create more space for excess water to be absorbed by the soil instead of causing destructive floods. This approach mimics the natural ecosystem’s ability to absorb and retain water, reducing the strain on existing drainage systems and infrastructure. Additionally, restoring floodplains can also enhance biodiversity and create valuable green spaces in urban areas.
Removing impermeable pavement from cities is another effective way to combat flooding and replenish groundwater supplies. Impermeable surfaces like concrete and asphalt prevent rainwater from seeping into the ground, leading to increased runoff and flooding. By replacing these surfaces with permeable materials like porous pavement or green infrastructure, we can allow water to infiltrate the soil and recharge aquifers.
Furthermore, storing water underground through these methods can help address water scarcity issues in drought-prone regions. By capturing and storing excess rainfall in underground reservoirs, we can ensure a sustainable water supply for agriculture, industry, and municipal use. This approach not only reduces the reliance on surface water sources but also helps to mitigate the impacts of droughts and water shortages.
While extreme weather events are becoming more common, it is essential to consider the changing patterns of moderate weather as well. As the study highlights, light rain is becoming less frequent in many regions, leading to more intense rainfall events. By implementing nature-based solutions like expanding floodplains and removing impermeable pavement, we can better adapt to these shifting weather patterns and build resilience against future climate challenges.
In conclusion, embracing innovative approaches to water management, such as expanding natural floodplains and promoting groundwater recharge, can help mitigate the impacts of climate change and create more sustainable urban environments. By working with nature rather than against it, we can enhance our resilience to extreme weather events and ensure a more secure water supply for future generations.
