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Floods, droughts, then fires: Hydroclimate whiplash is speeding up globally
New research links intensifying wet and dry swings to the atmosphere's sponge-like ability to drop and absorb water
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Key takeaways
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Los Angeles is burning, and accelerating hydroclimate whiplash is the key climate connection.
After years of severe drought, dozens of atmospheric rivers deluged California with record-breaking precipitation in the winter of 2022-23, burying mountain towns in snow, flooding valleys with rain and snow melt, and setting off hundreds of landslides.
Following a second extremely wet winter in southern parts of the state, resulting in abundant grass and brush, 2024 brought a record-hot summer and now a record-dry start to the 2025 rainy season, along with tinder-dry vegetation that has since burned in a series of damaging wildfires.
This is just the most recent example of the kind of “hydroclimate whiplash” – rapid swings between intensely wet and dangerously dry weather – that is increasing worldwide, according to a paper published Jan. 9 in Nature Reviews.
“The evidence shows that hydroclimate whiplash has already increased due to global warming, and further warming will bring about even larger increases,” said lead author Daniel Swain, a climate scientist with UC Agriculture and Natural Resources and UCLA. “This whiplash sequence in California has increased fire risk twofold: 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 weather records show hydroclimate whiplash has swelled globally by 31% to 66% since the mid-20th century, the international team of climate researchers found – even more than climate models suggest should have happened. Climate change means the rate of increase is speeding up. The same potentially conservative climate models project that the whiplash will more than double if global temperatures rise 3 degrees Celsius above pre-industrial levels. The world is already poised to blast past the Paris Agreement's targeted limit of 1.5 C. The researchers synthesized hundreds of previous scientific papers for the review, layering their own analysis on top.
Anthropogenic climate change is the culprit behind the accelerating whiplash, and a key driver is the “expanding atmospheric sponge” – the growing ability of the atmosphere to evaporate, absorb and release 7% more water for every degree Celsius the planet warms, researchers said.
“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.”
The global consequences of hydroclimate whiplash include not only floods and droughts, but the heightened danger of whipsawing between the two, including the bloom-and-burn cycle of overwatered then overdried brush, and landslides on oversaturated hillsides where recent fires removed plants with roots to knit the soil and slurp up rainfall. Every fraction of a degree of warming speeds the growing destructive power of the transitions, Swain said.
Many previous studies of climate whiplash have only considered the precipitation side of the equation, and not the growing evaporative demand. The thirstier atmosphere pulls more water out of plants and soil, exacerbating drought conditions beyond simple lack of rainfall.
“The expanding atmospheric sponge effect may offer a unifying explanation for some of the most visible, visceral impacts of climate change that recently seem to have accelerated,” Swain said. “The planet is warming at an essentially linear pace, but in the last 5 or 10 years there has been much discussion around accelerating climate impacts. This increase in hydroclimate whiplash, via the exponentially expanding atmospheric sponge, offers a potentially compelling explanation.”
That acceleration, and the anticipated increase in boom-and-bust water cycles, has important implications for water management.
“We can't look at just extreme rainfall or extreme droughts alone, because we have to safely manage these increasingly enormous influxes of water, while also preparing for progressively drier interludes,” Swain said. “That's why ‘co-management' is an important paradigm. It leads you to more holistic conclusions about which interventions and solutions are most appropriate, compared to considering drought and flood risk in isolation.”
In many regions, traditional management designs include shunting flood waters to flow quickly into the ocean, or slower solutions like allowing rain to percolate into the water table. However, taken alone, each option leaves cities vulnerable to the other side of climate whiplash, the researchers noted.
“Hydroclimate in California is reliably unreliable,” said co-author John Abatzoglou, a UC Merced climate scientist. “However, 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 floodwater management to ensure future water security in an increasingly variable hydroclimate.”
Hydroclimate whiplash is projected to increase most across northern Africa, the Middle East, South Asia, northern Eurasia, the tropical Pacific and the tropical Atlantic, but most other regions will also feel the shift.
“Increasing hydroclimate whiplash may turn out to be one of the more universal global changes on a warming Earth,” Swain said.
In California this week, although winds are fanning the extreme fires, it's the whiplash-driven lack of rain that suspended Southern California in fire season.
“There's not really much evidence that climate change has increased or decreased the magnitude or likelihood of the wind events themselves in Southern California,” Swain said. “But 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.”
Under a high warming scenario, California will see an increase in both the wettest and driest years and seasons by later this century.
“The less warming there is, the less of an increase in hydroclimate whiplash we're going to see,” Swain said. “So anything that would reduce the amount of warming from climate change will directly slow or reduce the increase in whiplash. Yet we are currently still on a path to experience between 2 degrees and 3 degrees Celsius of global warming this century — so substantial further increases in whiplash are likely in our future, and we really need to be accounting for this in risk assessments and adaptation activities.”
The research was supported with funding from The Nature Conservancy of California and the Swiss National Science Foundation.
Bohart Museum Welcomes You to Next Open House
You can meet the scientists, examine the collections, look through microscopes, hold walking sticks, and participate in a family arts-and-crafts...
UC Davis entomology major Kaitai Liu chats with budding entomologist Eden Jett of Berkeley as she holds a walking stick. (Photo by Kathy Keatley Garvey)
My Lazarus Plant
As gardeners, we know that we have failures and sadly wind up sometimes killing a plant we love. Such was the case with my Begonia rex. It lived for several years outdoors in a spot that had indirect light. At first, it thrived, but then it began to deteriorate. I moved to Fairfield and placed my plant inside next to the window, where it got indirect light, but sadly, it just deteriorated from there. Finally, I called it quits, cut the plant down to soil level, and left it like that for a time. As it turns out, I could not help myself and kept watering the soil in the hope that something might happen. After all, what was the harm other than wasting a little water? This went on for months until one day to my surprise and delight, just like magic the plant began to show signs of life. I kept on watering and fertilizing and wound up with a plant that looks like this in its new permanent home![1]
Begonia rex, commonly known as King Begonia or Painted-Leaf begonia, is a species of flowering perennial plant in the family Begoniaceace. It was found in southeast China and was then introduced to Bangladesh, Cuba, and Hispaniola (the most populous island in the West Indies.) It is the parent to over 500 cultivars, with many cultivars earning the Royal Horticultural Society's Award of Garden Merit. Fortunately, the care and maintenance for all cultivars are the same! As I discovered through trial and error, Begonia rex thrives in bright, indirect light[2] since the leaves will burn in excessive direct sunlight. It prefers to be planted in well-draining soil, thriving in a mixture of clay, sand, and loam. It also responds well to a mixture of potting soil mixed with peat moss and perlite. Drainage, drainage, drainage! Keep in mind that you can detect a potting mix that is too heavy if the water pools on the soil surface.
Rex begonia does best at 50% humidity. If you do not have a humidifier, put the plant on a shallow tray filled with pebbles and fill it with water up to the top of the pebbles, making sure the water does not touch the bottom of the pot. Some varieties of begonia go dormant in winter, requiring reduced watering until spring when new growth returns. The tricks to watering are to ensure the top two inches of soil are always moist while ensuring your plant is not sitting in excessive water. One of the most common plant disease Begonias are susceptible to is root rot which comes from overwatering. In fact, for beginner gardeners, overwatering your plants is the number one mistake we make! Another helpful tip for watering any of your plants is to let the water sit in a container for 24 hours before using which will allow for the contaminants to evaporate causing less stress for your plants.[3] It also allows for your water to be room temperature, which most plants prefer.
King begonias are known for their large, variegated leaves. My begonia has leaves up to nine inches long and five inches wide, and interestingly enough, the leaves were even larger the second time around, which demonstrates the benefits of hard (aggressive) pruning. Finally, Rex Begonias need a steady supply of nutrients to flourish. They prefer a balanced fertilizer (the macro ingredients, N-P-K) nitrogen, phosphorus, and potassium all have the same number as 10-10-10. Organic fertilizers such as compost or worm casting offer slow-release fertilization and will improve soil quality over time.[4]
I have so enjoyed my begonia because of its vivid colors, it is hearty nature and its ease of care. So much so I am designating a corner of a room just for them! Just like Lazarus of Bethany, my plant miraculously came back to life, but this time with much more vigor![5]
[1] Website Garden Guides
[2] Wikipedia- Begonia rex
[3] Website- plantophiles.com
[4] Website- livetoplant.com
[5] Picture of plant, top right was taken by the author of her own plant!
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CORRECTED Sheep Shearing Flyer 25
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