Posts Tagged: change
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
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.
/h3>Franco: Deciphering Soil Macrobiome and Ecosystem Responses to Global Change
It promises to be an outstanding seminar. André Custodio Franco, assistant professor, Indiana University, Bloomington, will speak on...
What's up with soil and global change? Andre Franco of Indiana University will speak on "Deciphering the Soil Macrobiome: Belowground Communities Driving Ecosystem Responses to Global Change" at 4:10 p.m., Monday, Nov. 18 in 122 Briggs Hall. It also will be on Zoom and then archived. (Photo by Kathy Keatley Garvey)
White House Summit explores impact of extreme heat, ways to adapt
UC ANR Small Farms Network supports small-scale and underserved farmers impacted by extreme heat
Ruth Dahlquist-Willard, interim director for the UC Sustainable Agriculture Research and Education Program, joined more than 100 participants from across the country at the first-ever White House Summit on Extreme Heat. Community representatives and practitioners met with federal agency representatives and Biden Administration officials to discuss successful locally tailored, community-driven practices to adapt to extreme heat as well as available federal resources.
According to the National Oceanic and Atmospheric Administration or NOAA, summer 2024 was California's warmest summer on record. As California's climate is changing, episodes of extreme heat are becoming more common, leading to substantial health, economic and ecosystem impacts.
In the agricultural sector, extreme heat events can cause heat illness in farmworkers, crop losses and changes in pest pressure. California crop losses due to drought, wildfire and heat were estimated at $239 million in 2023.
Disaster relief funds are available to help growers recover from lost production due to extreme heat. Since 2021, the UC ANR Small Farms Network has connected small-scale farmers with over $5.8 million in direct-to-producer relief funds for losses related to drought, flooding and other extreme weather events.
To further support small-scale farmers in adapting to the changing climate, Dahlquist-Willard and the Small Farms Network are evaluating how the extreme heat of summer 2024 impacted farmers. Farmers reported anecdotal observations that included:
- Shifting work hours to cooler parts of the day
- Closing farm stands and farmers markets due to extreme heat
- Crops ripening more quickly than expected, impacting harvesting and packing schedules
- Poor fruit set due to extremely high temperatures
The team is working to determine what damage symptoms on small-acreage California specialty crops can be attributed to extreme heat based on scientific literature and assessments from UC ANR colleagues. Understanding the impact of extreme heat on the farming community can help inform research and policy, ultimately equipping farmers with strategies to adapt to extreme heat events.
“It was inspiring to meet with leaders from around the nation who are working to support communities impacted by extreme heat and learn about the creative solutions they are implementing,” said Dahlquist-Willard. “The challenges faced by these communities make it all the more important to continue to work against climate change by reducing greenhouse gas emissions, as well as to develop new methods and resources to mitigate the effects of extreme heat and other climate impacts.”
The Extreme Heat Summit highlighted the Biden-Harris Administration's investments in climate reliance and put forth an Extreme Heat Call to Action calling upon public and private sectors to prepare for future extreme heat events. Communities and governments interested in participating are asked to use all available tools to protect people from extreme heat. Approaches and tools which could be used to protect people and resources from extreme heat are highlighted in the U.S. Climate Resilience Toolkit and the National Heat Strategy. Submissions for the Call to Action will be accepted through Nov. 1, 2024.
Further reading:
Heat Illness Prevention, UC Davis Western Center for Agricultural Health and Safety
Pathak et al., 2018. Climate Change Trends and Impacts on California Agriculture: A Detailed Review
UC's New Climate Action Goals: Frequently Asked Questions
Bumble Bees: Feeling Impact of Climate Change
We remember the reaction of Robbin Thorp (1933-2019), UC Davis distinguished emeritus professor of entomology and an international...
UC Davis research shows that rising temperatures are particularly alarming to some bumble bee species, including the Western bumble bee, Bombus occidentalis. This one was located on Aug. 15, 2012 in the Mt. Shasta area. (Photo by Kathy Keatley Garvey)
UC Davis researchers found that one of "the winners" in their climate change study is the yellow-faced bumble bee, Bombus vosnesenskii, shown here heading for a California golden poppy. (Photo by Kathy Keatley Garvey)
A male bumble bee, Bombus bifarius, nectaring on coastal goldfield, Lasthenia minor, at Bodega Bay. A UC Davis study shows that the rising temperatures are particularly alarming to a number of species, including this one. (Photo by Kathy Keatley Garvey)
Webinars explore role of trees in climate change resilience, May 14-16
A free webinar series titled “Trees to the Rescue: Solutions for Climate Change” will be held on May 14-16, from 4 p.m. to 5:30 p.m. each day. The webinars are sponsored by the University of California Thelma Hansen Fund.
“The webinars aim to increase our understanding of the role of trees in mitigating and adapting to climate change, how to plant the right trees and keep them healthy in urban environments, and the challenges of increasing the number of trees at the local level,” said Annemiek Schilder, director of Hansen Agricultural Research and Extension Center, who is organizing the series. Hansen REC is operated by UC Agriculture and Natural Resources.
Participants will discuss some of the challenges and pitfalls of reforestation, urban greening and tree equity. They will also provide diverse perspectives on tree planting and maintenance efforts and policy at the local level.
“Anyone interested in learning about the importance of trees in urban environments and climate resilience, as well as tree retention in the landscape should join us,” she said.
The agenda for each 90-minute webinar is listed below. To register, visit https://bit.ly/HansenTreesWebinar.
Tuesday, May 14: Trees as a Tool for Climate Change Mitigation and Resilience
4 p.m. Welcome—Annemiek Schilder, Director of Hansen Agricultural Research and Extension Center
4:05 p.m. Opening Remarks—Matt LaVere, Ventura County Supervisor District 1
4:10 p.m. Improving Outcomes of Tree Growing and Forest Restoration Efforts—Karen Holl, Professor of Environmental Studies, UC Santa Cruz
4:50 p.m. Climate Resilience through Urban Greening—Edith de Guzman, UC Cooperative Extension Specialist, Water Equity and Adaptation Policy, UCLA
5:30 p.m. Closing—Annemiek Schilder
Wednesday, May 15: Optimizing Tree Survival in a Changing Climate
4 p.m. Welcome—Emma Volk, Production Horticulture Advisor, UCCE Ventura and Santa Barbara counties
4:05 p.m. Cooling Urban Heat Islands with Climate-Resilient Trees—Janet Hartin, Environmental Horticulture Advisor, UCCE Los Angeles and San Bernardino counties
4:30 p.m. Keeping Trees Healthy from Sapling to Maturity—James Downer, Environmental Horticulture and Plant Pathology Advisor Emeritus, UCCE Ventura County
5:05 p.m. Dealing with the Inevitable Threat of Exotic and Invasive Pests—John Kabashima, Environmental Horticulture Advisor Emeritus, UCCE Orange County
5:30 p.m. Closing—Emma Volk
Thursday, May 16: Tree Advocacy and Planning at the Local Level
4 p.m. Welcome—Julie Clark, Natural Resources Community Education Specialist, UCCE Ventura County
4:05 p.m. Native Tree Restoration with Partners and the Public—Joey Algiers, Restoration Ecologist, Santa Monica Mountains National Recreation Area
4:30 p.m. Panel Discussion (Joey Algiers, moderator):
- Joey Algiers, Santa Monica Mountains National Recreation Area
- Mireille Vargas, County of Ventura Sustainability Division
- Mikaela Randolph, Green Schoolyards America
- Jan Scow, Registered Consulting Arborist, Ojai Valley
- Max Young, Ventura Regional Fire Safe Council
5:30 p.m. Closing—Julie Clark