3546. Drought? This Is What Climate Change Looks like in the West

By Karyn Stockdale, Audubon.org, August 24, 2021 

Living back East for a few years, I missed the expansive bright blue skies of the Rockies. Now that I’ve returned to the West, I’m remembering the smoky haze that fills the sky. I’m remembering how the smell of summer has turned into the smell of smoke from wildfires. How the ash from fires hundreds of miles away sometimes coats your car and porch furniture. But it’s getting worse.

I’m used to the seasonality of streams—the spring runoff that slows to a trickle with hot summer days. My kids would wait for the monsoon storms to bring back the water flowing to our arroyo. But it was shocking to see how low the rivers and streams got so early this year. Recently, some southwestern states have seen abundant monsoonal rainfall, with some intense flooding. But in Utah, Nevada, California, and parts of the Northwest, the dryness and record-setting heat waves have intensified large wildfires. The combination of drought and heatwaves are pushing birds to their limits, leading to lethal dehydration.

Welcome drought.

There's a lot to unpack in that word. Decades of drought in the West seems to be hitting a tipping point, garnering national attention. More and more, people are recognizing this isn’t just a drought. This isn’t temporary.

It’s fires, it’s decreasing water supplies, it’s air quality issues, it’s high temperatures, and unpredictable weather. It’s an era of extremes.

This summer has turned into the worst water year for many farmers and ranchers, for wildlife managers, for businesses and communities concerned about their water supplies. We urgently need to adapt and better prepare for constant drought and for extremes to become more common. As my colleague said recently, “This is climate change stealing your water.”

Climate change is increasingly impacting all of us—threatening the health of millions of birds, our food supplies and economies, our air quality, and the water security for all of us. It’s starting to affect our way of life.

And this affects birds. The future of several bird species, including some protected by the Endangered Species Act, is tied to the health of rivers and lakes. We’ve already lost too many wetlands and riparian habitats across the West and birds are pushed to congregate in high concentrations in the last places left with water. You might recall the death of 40,000 ducks from avian botulism last year due to overcrowded conditions with limited water and habitat left at the Lower Klamath National Wildlife Refuge.  

How bad is this drought? 2021 is shaping up to be the driest year in the last century.

Everywhere in the West we see signs of the ongoing megadrought. Here are a few indicators that we are concerned about at Audubon:

• Lake Mead, the largest reservoir on the Colorado River (and in the country), has officially reached its lowest water level in history—and it’s expected to continue dropping.
   
• Great Salt Lake reached its lowest lake level ever recorded, and will continue to drop this year, maybe even by a foot more.
   
• Years of reduced inflows, along with drought and a warming climate, continue to shrink the Salton Sea in California, impacting the health of surrounding communities and the available habitat and food sources for migratory birds.
   
• Our last remaining wetlands in California’s Central Valley—essential Pacific Flyway habitat for waterfowl—are expected to receive only about 57% of their water supply.
   
• In rural Arizona, unlimited groundwater pumping (80% of the state has no groundwater management!) is causing wells to go dry and further stressing flows in rivers and streams.
   
• The Klamath River Basin’s drought is testing everything:  There's not enough water to meet all the demands from farmers, tribes, and wildlife, including endangered fish.
   
• The Southwest’s other major river basin—the Rio Grande—is also historically dry.

At Great Salt Lake, the 17 named islands that usually exist on the lake, where nesting birds are protected from predators, are now peninsulas. In this “Year of the Shorebird” as designated by Utah’s Governor, the decreased water coming into the shrinking lake is affecting the whole ecosystem with potentially hemispheric implications. Great Salt Lake and its surrounding wetlands create vital habitat in the Western Hemisphere for millions of breeding and migrating shorebirds including more than 56% of the global population of American Avocets and nearly 30% of the global population of Wilson’s Phalaropes. If nothing is done to reverse course, Great Salt Lake risks suffering the fate of other large, saline lakes around the world, the loss of which invariably triggers dramatic harm to communities, local business, and human health.

In the West, we are used to competing demands for scarce water for farms, cities and rural communities, hydropower, recreation, and the environment (typically last in consideration) which can lead to conflict. Audubon’s Western Water team continues to push for all of us to face these risks and plan for water shortages with a changing climate in mind.

I keep thinking of that folk song “It Ain’t Gonna Rain No More” from my childhood. My extended family lived through the Dust Bowl in Texas and Oklahoma and went into dryland ranching. This year doesn’t feel like business as usual—it feels like the cusp of another Dust Bowl.

New approaches are needed to adapt to, respond to, and mitigate the compounding and extreme risks of climate change to communities, economies, ecosystems, and the water resources that support them.

This is why Audubon is working in state capitals and in Washington, D.C. to advocate for sensible policies and funding that benefit birds and communities alike. We have worked to ensure that the needs of birds and habitat aren’t carved out of policy decisions and water management.

Audubon is also working to secure water to enhance habitats where water is most needed. Working with partners, we continue to enable and secure water flows in rivers in places like Colorado, New Mexico, Utah, California, and Arizona. And through our science, we are improving our understanding of the long-term health of priority places for birds and how we might better manage the limited water availability into the future. 

With drought conditions persisting now into a third decade and climate change increasingly impacting water supplies and habitat in the West, we urgently need inclusive and equitable long-lasting water solutions for climate resilience. Please join us in advocating for policies, funding, and on-the-ground actions that result in sustainable change.

3524. Consequences of the Drought in California: Rattlesnakes Everywhere

By Gabriel Cannon, The Guardian, June 26, 2021

Wildlife vets have reported big changes in the numbers of abandoned babies or injured animals brought into their centers and sightings – especially of bears. Photograph: Noah Berger/EPA

Len Ramirez stalked through the dried landscape, scanning the ground ahead searching for movement. Called out to an estate in Napa Valley, the owner of Ramirez Rattlesnake Removal company was finishing up his last job of another busy day wrangling, removing and relocating snakes from homes across northern California. He’d found three in just this yard, including one nestled roughly 1,000 yards from the pool.

Rattlesnakes are everywhere these days, he says – on front porches, in potted plants, and under children’s play equipment. “I am busier than I have ever been. Complaints are coming in from all over the state.”

Ramirez believes the drought may be partly to blame. He opened his business in 1985, and has seen spikes before. And while he doesn’t think the rattlesnake population is necessarily growing, snakes are increasingly finding their way into urban environments in search of refuge from the rising temperatures and relief from the drying landscape.

And it’s not just snakes.

California and other states across the south-west are in the grips of a historic drought. The conditions have produced consequences that extend beyond the risks of a decreased water supply and worsening wildfires. And as urban development creeps further into once-wild areas, the drought has also increased negative interactions between people, animals and pests – who are all trying to adapt.

“Rattlesnakes are becoming more common in the places where we live, work and play,” Ramirez says. After opening his business in 1985, he’s become a go-to source for removal and public education about the snakes, speaking to the media and producing safety videos for California’s office of emergency services. He clears snakes from properties and public areas and relocates them to uninhabited areas.

‘Rattlesnakes are becoming more common in the places where we live, work and play’ Photograph: David McNew/Getty Images

Ramirez worked through California’s last drought – which stretched from the end of 2011 to 2019 – and saw similar patterns. But now it’s gotten worse, mostly because he says, “there is so much development taking place, and that’s going to displace wildlife, including rattlesnakes”.

Ramirez says he’s had jobs when he has had to remove more than 60 snakes at a time. “I always remind parents to be a good scout before your kids go out to play,” he says.

As essential water sources start to run dry, other wild animals have also been spotted searching the suburbs for water, sustenance and reprieve from the intensifying conditions. Wildlife veterinarians have reported the numbers of abandoned babies or injured animals brought into their centers and animal sightings – especially of bears who are venturing deeper into urban areas – are surging.

“The bear population is expanding its range, so bears are showing up in areas where they’ve never seen before,” Rebecca Barboza, a wildlife biologist who studies the trend for the California department of fish and wildlife, told ABC News this month.

Smaller animals and insects are also coming closer in search of water – and some have the ability to cause a lot more damage. Song birds carrying the West Nile virus, which can cause a deadly and debilitating neurological disease, are increasingly showing up in back yards.

“Because there’s limited water in the environment and everything is dry, the birds go looking for water and refuge,” says Cameron Webb, a medical entomologist and senior investigator with the Centre for Infectious Diseases and Microbiology – Public Health who studies the mosquitoes that transmit the disease. “You get this combination of factors that means not only are conditions suitable for mosquitoes, but also the birds that carry the virus are more likely to be in higher concentration closer to where people live.”

Surprisingly, disease-carrying mosquitoes, which most people associate with wet times rather than dry, thrive in cities during times of drought when waters recede and grow still. Webb explains that human-made structures like pipes, pits and ponds are prime spots for stagnant water to become a breeding ground for the insects. “Fish and other animals that live in these systems die and the mosquitoes have free rein”.

In California, public health officials have already warned residents of an increase in virus activity and scientists believe the threat of transmissions of West Nile will increase with climate change, especially in coastal areas of California.

Less perilous pests may also pose more problems during drought conditions. Ants, cockroaches and rodents and other visitors also need water to survive and human homes are typically where they go to find it when it’s absent in outdoor environments.

“Drought conditions not only mean that a pest’s water supply dries up, but natural food sources can also be harder to find as well,” Mike Bentley, an entomologist for the National Pest Management Association, says. “Drought often drives pests into homes or other structures in search of these resources to survive”.

Not only does the drought mean an increase in unwanted houseguests, but it’s changing the behavior of critters themselves. They are “incredible at adapting to change”, he says. “This can mean rodents nesting in wall voids versus underground burrows and feeding from garbage bags rather than fallen fruits and seeds. Or, ants moving into potted plants to nest and feeding on last night’s leftovers.”

3351. 'Megadrought' Emerging in the Western US Might Be Worse Than Any in 1,200 Years

By Doyle Rice, USA Today, April 17, 2020

Fueled in part by human-caused climate change, a “megadrought” appears to be emerging in the western U.S., a study published Thursday suggests.

In fact, the nearly-20-year drought is almost as bad or worse than any in the past 1,200 years, scientists say. 

Megadroughts – defined as intense droughts that last for decades or longer – once plagued the Desert Southwest. Thanks to global warming, an especially fierce one appears to be coming back:

"We now have enough observations of current drought and tree-ring records of past drought to say that we're on the same trajectory as the worst prehistoric droughts," said study lead author A. Park Williams, a bioclimatologist at Columbia University, in a statement. This is “a drought bigger than what modern society has seen." 

Scientists say that about half of this historic drought can be blamed on man-made global warming. Some of the impacts today include shrinking reservoirs and worsening wildfire seasons.

Since temperatures are projected to keep rising, it is likely the drought will continue for the near future or fade briefly only to return, researchers say. 

The study covers an area stretching across nine U.S. states from Oregon and Montana down through California, New Mexico and part of northern Mexico.

Daniel Swain, a UCLA climate scientist who wasn’t part of the study, called the research important because it provides evidence “that human-caused climate change transformed what might have otherwise been a moderate long-term drought into a severe event comparable to the ‘megadroughts’ of centuries past.”

Williams said the region could stay dry for centuries. "That's not my prediction right now, but it's possible." 

Naturally occurring western megadroughts have taken place many times before. In fact, most of the USA's droughts of the past century, even the 1930s Dust Bowl that forced migrations of Oklahomans and others from the Plains, "were exceeded in severity and duration multiple times by droughts during the preceding 2,000 years," the National Climate Assessment said.

The difference now, of course, is the western USA is home to more than 70 million people who weren't here for the previous medieval megadroughts. The implications are far more daunting.

University of Michigan environment dean Jonathan Overpeck, who studies southwestern climate and was not part of the study, calls this drought “the first observed multidecadal megadrought in recorded U.S. history.”

To identify past droughts, scientists studied thousands of tree rings to find out how much – or little – rain fell hundreds of years ago. Scientists used historical data in combination with several computer model simulations to reach their conclusions. 

One additional worrisome fact from the study was that the 20th century was the wettest century in the entire 1,200-year record. It was during that time that the population boomed in the western U.S., and that has continued.

"The 20th century gave us an overly optimistic view of how much water is potentially available," said study co-author Benjamin Cook, a NASA climate scientist, in a statement.

"It goes to show that studies like this are not just about ancient history," he said. "They're about problems that are already here."

The study was published Thursday in the peer-reviewed journal Science.

2207. Global Scarcity of Fresh Water Worse Than Thought, Study Finds

By Andrea Germanos, Common Dreams, February 12, 2016

2011 drought in the Horn of Africa

A new analysis reveals that global water scarcity is a far greater problem than previously thought, affecting 4 billion people—two-thirds of the world's population—and will be "one of the most difficult and important challenges of this century."

Previous analyses looked at water scarcity at an annual scale, and had found that water scarcity affected between 1.7 and 3.1 billion people. The new study, published Friday in the journal Science Advances, assessed water scarcity on a monthly basis, more fully capturing the specific times of year when it could be an issue.

"Water scarcity has become a global problem affecting us all," stated study co-author Arjen Hoekstra, a professor of water management at the University of Twente in the Netherlands.

The study found that almost half of the 4 billion affected by severe water scarcity for a month or more are in India and China. Millions of others affected live in Bangladesh, Nigeria, Pakistan, and Mexico.

The United States is far from immune to the problem, with 130 million people affected by water scarcity for at least one month a year, mostly in the states of Texas, California, and Florida. And among the rivers the study notes that are fully or nearly depleted before reaching their end is the Colorado River in the West.

There are also half a billion people who face severe water scarcity year round, the analysis found.

From study:

Direct victims of the overconsumption of water resources are the users themselves, who increasingly suffer from water shortages during droughts, resulting in reduced harvests and loss of income for farmers, threatening the livelihoods of whole communities. Businesses depending on water in their operations or supply chain also face increasing risks of water shortages. Other effects include biodiversity losses, low flows hampering navigation, land subsidence, and salinization of soils and groundwater resources.

The study concludes that "[m]eeting humanity’s increasing demand for freshwater and protecting ecosystems at the same time. . . will be one of the most difficult and important challenges of this century."

The new publication follows a pair of NASA studies led by researchers from the University of California Irvine that showed that the impacts of global warming along with growing demand has caused the world's water supply to drop to dangerous levels.

"The water table is dropping all over the world," Jay Famiglietti, senior water scientist at NASA’s Jet Propulsion Laboratory, said at the time. "There's not an infinite supply of water."

"We need to get our heads together on how we manage groundwater," Famiglietti added, "because we’re running out of it."

2185. The Debate on Cuba’s Farm Crisis: Pessimists vs. Optimists

By Erasmo Caldazilla, Havana Times, February 2, 2016

Regions in Cuba suffer from climate change induced drought

Cuban agriculture is going through one of its recurrent crisis. What is the cause this time around?

One sector sees speculation and a lack of regulations as the root of the problem, while others claim just the opposite: regulations and State intervention is what Cuba has too much of.

What should be regulated and what should we liberalized in Cuba’s economy and agricultural sector today? I’m not entirely sure. The only thing I know is that all extremes have already been tried somewhere and that they are bad.

That said, I am fascinated by how our deep-thinking analysts have assumed it’s possible – and would be splendid – to squeeze more out of the countryside in order to accelerate agricultural production. You can find people as different as Machado Ventura (No. 2 in the Communist Party), from the high echelons of the Party bureaucracy, and reform-minded economists Juan Triana and Armando Nova, espousing this view. There is of course no shortage of passionate defenders of full capitalist liberalization.

I ended a previous post with two questions: “is this really our best option or is there a better one?” No one who commented on my post paid any attention to these queries.

I am of the opinion that it is not the only option available and it is quite possibly not the best. I explain why below.

Climate Change

Cienfuegos during a rainy season.

I have a relative who’s a farmer. Not long ago, he told us how delighted he was with the top-notch field of beans he had managed to sow thanks to the unusual heat and rains this time of the year. The day before yesterday, we found out the unusual downpours of recent days had destroyed his crop and enthusiasm.

Agro-meteorologists and the FAO have been saying it for years: agricultural productivity, stability and revenues will fall. These are not predictions for a hundred years from now, they describe a process that’s already underway.

Last year was one of the hottest on record. Cuba’s average temperature has risen gradually. Currently, it is 0.9 degrees Celsius above the historical mean (and low temperatures have risen much more). This may not seem like a lot, but it’s actually a huge increase.

The sea level has risen at an average of 1.4 millimeters every year, contributing to the much-feared salinization processes, which already affect 10% of the country’s land. Draughts have become chronic towards the country’s east. Eleven out of Cuba’s 14 provinces show signs of desertification. It does rain, but so intensely and tempestuously that ends up ruining crops. The sugarcane harvest is behind schedule because of the rains that unexpectedly fell during the dry season.

Taken from the blog of Gail Tverberg

Energy

The other issue absent from the debate surrounding the agricultural crisis is that of energy. Capitalism – and then the revolution – sought to establish “modern” agriculture in Cuba, which requires as much oil as it does water. Black gold consumption, however, has been declining in Cuba since the end of the last decade, and not precisely because we are becoming efficient. Since 2013, the government has not published any statistics on this, a sign that things are getting even worse. Most countries in the region (including ours) have already surpassed their extraction peak and will be plunged into a serious economic, political and social crisis at some point in time.

Soils

Tourism ads sell Cuba as a tropical island with exuberant flora and fauna. Nothing could be further from the truth. Our soils evince a degree of erosion that’s so high that this has been considered the country’s chief environmental problem since 1997.

The following data offer a sense of the magnitude of the disaster:

• 65% of cultivable lands have potential yields below 50%.
• More than 70% of farming lands report poor (and decreasing) concentrations of organic matter. The once fertile plains surrounding the capital (which feeds nearly one third of the country’s population) is seriously affected by this problem. A century ago, it reported a high 8% of organic matter. Today, its fertility is below 3%. In the country’s east, the situation is not much different and is aggravated by draughts and desertification.
• The agro-productive potential of Cuba’s mountains can be classified as anywhere from middle to low.
• 60% of cultivable lands suffer from acidity, high salinity, high sodium levels, compactness, poor drainage and other ills that affect their fertility.

With such alarming signs everywhere, one cannot help but ask: will Cuba be capable of the steep increase in agricultural production we need to satisfy growing demand and to lower prices?

Environmentalists, agro-meteorologists and risk analysts who have studied our country’s energy situation don’t think that’s too likely. But a team of high-ranking economists, State officials and the fans of liberal reforms see absolutely no problem. If Vietnam could do it, why can’t we?

Notes:

• The data on the state of Cuban soils were taken from a report prepared by Geocuba and from several articles written by environmentalist Eudel Cepero.
• Since 1997, Cuba’s Environmental agency has regarded soil degradation as the country’s most pressing environmental issue.

2018. Middletown, California, Is Razed by Wildfire

By Ian Lovett and Ashely Southall, The New York Times, September 13, 2015

LOS ANGELES — The fire moved fast, faster than even veteran firefighters had seen. As it ripped down a hill toward Middletown, two hours north of San Francisco, some residents hardly had time to dress before they fled.

“We were surrounded by fire,” said Maddie Ross, 25, a student at Santa Rosa Junior College who fled with her grandparents on Saturday from their home in nearby Hidden Valley Lake.

They did not even have time to put their shoes on. “It looked like hell everywhere,” Ms. Ross said. “It was terrifying, truly terrifying. I’ve never been in a situation like that. We all felt like the world was coming to an end.”

By Sunday afternoon, up to 1,000 homes and commercial structures had been burned by the so-called Valley fire. They were the latest casualties of the worst drought in California’s recorded history, which has left hillsides thick with dry brush and made wildfires more common than ever.

But even in the midst of a fire season that threatens to be the longest and most destructive the American West has endured, the Valley fire stood out for just how fast it devoured the communities in Lake County.

The fire had grown to 50,000 acres by Sunday afternoon, and half of Middletown was in ashes, said Scott McLean, a battalion chief for the California Department of Forestry and Fire Protection, known as Cal Fire. Gov. Jerry Brown declared a state of emergency in Lake and Napa Counties on Sunday.

“I’m standing in the middle of a bombed-out town,” Mr. McLean said. “I’m on a block of burned-down structures. There’s the frame of a mobile home — that’s all that’s left. The cars are burned-out hulks. The trees look like skeletons. There’s a porch swing, a bathtub. I’m seeing the remnants of somebody’s life.”

He added: “This year is different. The fires don’t need that wind, but unfortunately this fire had that wind component, and it was extremely dynamic.”

Dry conditions from the drought, high temperatures and gusty winds were contributing to “explosive” conditions, said Daniel Berlant, a spokesman for Cal Fire.

Since January, firefighters in California have responded to nearly 6,800 wildfires burning 545,000 acres, Mr. Berlant said. Cal Fire handled 5,000 of the wildfires, over 1,500 more than average, he said. The fires handled by Cal Fire this year have burned more than 150,000 acres, compared with 80,000 per year on average.

Across the state, Cal Fire was fighting 13 fires, including a large blaze in Amador and Calaveras Counties, where the governor declared a state of emergency on Friday.

The United States Forest Service, meanwhile, was also battling a handful of fires that had engulfed more than 250,000 acres of national forests from the Oregon border to an area east of Fresno.

Efforts to get ahead of the Valley fire have so far failed, as its embers continue to jump past firefighters and move to new areas, where they have to form a new containment line.

“It doesn’t necessarily matter how many firefighters we put on it — the fire just jumps right over us,” Mr. Berlant said.

The Valley fire began on Cobb Mountain on Saturday, but was soon funneled down by 20-mile-an-hour winds toward Middletown and the surrounding communities. In only a few hours, half the town was destroyed.

The Ross family was in such a hurry that it left behind family photos and medication for Ms. Ross’s grandparents. Only the family’s dogs were taken along.

“The police just said, ‘Run!’ ” Ms. Ross said.

It took the family an hour to get out of Hidden Valley Lake because the roads were packed with hundreds of people trying to get out, she said. Others, in their haste, abandoned their cars on the road.

The Ross family fled west to Ukiah, where it was staying at the Discovery Inn. The hotel was full of Hidden Valley Lake residents, who fled in trucks packed with supplies, pets and small livestock, Ms. Ross said. The area is full of horse farms, and many of the animals were left behind.

Other owners managed to take their horses with them to an American Red Cross shelter at the Napa Valley fairgrounds in Calistoga. About 600 people had taken refuge there on Sunday, and many of them were “thunderstruck,” said Gary Kraus, a former fire chief who is a Calistoga city councilman.

“There’s a sense of disbelief,” he said. “It will be an absolute miracle if we don’t start hearing about fatalities up there. You get heart attacks, accidents in cars, because this fire came through so quick.”

The fire threatened to scorch the California wine industry at harvest time. Nearly half the nation’s wineries are in California, concentrated in the Napa Valley and Sonoma County. Harvest season begins in late summer and many wineries see an uptick in traffic.

Many of the workers who help keep Napa Valley’s famous wineries running live in the section of Lake County that was hit by the wildfire, said Michael Dunsford, the vice mayor of Calistoga, who owns a restaurant in town. The chef at his restaurant believed his house was gone, as did the manager of a restaurant down the street. With the road back to Middletown closed, neither of them had been able to check.

“Lake County is the more affordable place to live,” Mr. Dunsford said, “so that’s where a lot of the employees for the wineries and the restaurants and hotels go. They’re the ones who are now being hit hardest and losing their homes.”

2016. Extreme Weather and Food Shocks

By Tim Benton and Rob Bailey, The New York Times, September 8, 2015

Recent events highlight concerns about the risks to global food security posed by changing patterns of extreme weather affecting the world’s “breadbasket” regions such as the American Midwest, South America’s southern cone, the Black Sea and the Yangtze River valley. In 2012, the worst drought to hit the U.S. Midwest in half a century sent international maize and soybean prices to record levels. In 2011, wheat prices nearly doubled after an unprecedented heat wave devastated the Russian harvest. The global food price crisis of 2007-8 had its roots in a run of poor harvests in previous years.

Global food security largely depends on the production of a few “mega-crops” in the breadbasket regions: maize, wheat, rice and soybeans. On the whole, the system works well. International trade provides a global market for these specialized production centers, reducing the cost of food for billions of people by allowing agriculture to flourish where it can be most efficient. Trade also allows countries to meet unforeseen production shortfalls through imports, as Britain did in the summer of 2013 after floods spoiled the winter wheat harvest. But when extreme weather ruins the harvest in a breadbasket region, that’s not just a problem in the country affected, it’s a problem for all importing countries.

Of course the risk to the world’s food security doesn’t arise simply from bouts of bad weather. Weather’s impact can be compounded by the actions of governments and markets. Governments can make things much worse when, for example, they try to shore up domestic food supplies by banning or limiting agricultural exports, further pushing up international prices. The 2007-8 crisis saw over 30 governments impose export restrictions in a spiral of rising prices and collapsing market confidence; the 2011 wheat spike was amplified when Russia turned off exports.

Likewise it is becoming clear that severe weather shocks rippling through the food system can ignite wider instability. During the 2007-8 crisis, protests erupted in 61 countries and turned violent in 23. In the wake of the Russian heat wave, the price of bread was one of several grievances behind the Arab Spring. Once shocks to the food system spill over into other areas, they can cascade through economic and political systems with sometimes devastating consequences.

Amid these pressures, the global food system is coming under increasing strain, as highlighted in a recent report that we wrote in conjunction with other British and American experts for the U.K.-led Global Food Security program. Rising incomes and changing dietary preferences mean demand for food is growing faster than cereal yields. Water scarcity and soil depletion present challenges for agriculture, which faces sharper competition for resources from urbanization and energy production. A precarious supply-and-demand balance means the system is easily unbalanced.

The stability of the global food system faces risks from the increasingly frequent extreme weather that is being driven by climate change. For example, in the United States there were more than four times more weather events causing damage in excess of $1 billion (in 2011 prices) in 2007-11 than in 1980-85. Drought is a particularly powerful driver of global food shocks. Two episodes stand out: in 1988-9, when maize and soybean were seriously affected in the U.S. Midwest, and in 2002-3, when rice and wheat were hit in Eastern Europe and Western Asia.

Were these two events to happen in the same year — a multiple breadbasket failure — it would result in the loss of between 5 and 10 percent of the production of these major crops, more than enough to supply the basic calorie needs of the United States for a year. Until recently, such a calamity would have been expected every 100 to 200 years, but this number is shrinking rapidly due to climate change. An initial analysis of recent data suggests that the risk of a 1-in-100-year event during the second half of the last century is likely to increase to 1-in-30 years by 2040 — and perhaps even 1-in-15 years in the decades after 2050.

A multiple failure in the world’s breadbaskets in the same year is, in our view, a plausible worst-case scenario for today. In fact, by the end of the century such an event may occur every few years unless we reduce emissions overall, and we change what we grow, and how we grow it, to adapt to the changing climate. Such a crisis would almost certainly be compounded by export restrictions, panic buying and hoarding, driving food prices to new heights.

This would be particularly serious for the food-importing countries of the developing world, especially in Sub-Saharan Africa. The shock would come at the economic level, in the form of inflation, balance-of-payment difficulties and budgetary pressures, and it would strike at the human level in increasing poverty; in the developed economies, consumers would feel the pinch as grocery prices climbed. Of even more concern, however, would be the spread of the crisis from food markets to political systems in the world’s geopolitical hotspots; fragile countries could be destabilized, especially the major grain importers of the Middle East and North Africa.

Given these predictions and warnings, what needs to be done?

Agriculture must of course be adapted to a dramatically changing climate: We need to reverse declines in yield growth. This requires significantly more research and development investment to increase maximum attainable yields and to expand agricultural extension services. Additional investment is needed to reduce the environmental impact of farming and to bolster its ability to withstand climate change.

In addition, vulnerable countries can shore up their food security through policy measures to insulate their populations from market shocks. Such efforts include holding strategic stocks, raising national production to reduce import dependency and improve self-sufficiency, and “buying forward” to lock in future import prices.

The greatest challenge will be to make the global food system far more resilient. Rules limiting the use of export barriers will become vital if a functional trading system is to be maintained. Biofuel policies will also need to be reformed by making mandates flexible, so that biofuel use falls when food prices rise, or by limiting the use of staple food crops in biofuel production when food demand outstrips supply.

Recent multilateral efforts to improve the quality and availability of key market data, such as food stock levels, can help governments anticipate crises and avoid panic. But improved climate and economic modeling is needed to understand the risks and assess how best to manage them. Armed with this knowledge, governments, international organizations and businesses could engage in contingency planning, set up early-warning systems, and coordinate the management of strategic stocks.

International food shocks exacerbated by extreme weather events can affect millions of people in countries around the world. Taking smart and practical steps to ease the impact of our changing climate on our food supplies is vital if we are to ride out the droughts and storms that will impact our food prices.

Tim Benton is the academic director of the Global Security Program and a professor of population ecology at the University of Leeds. Rob Bailey is the research director for Energy, Environment and Resources at Chatham House.

2003. Hotter Planet Fuels Drought, Scientists Find

By Justin Gillis, The New York Times, August 20, 2015

Global warming caused by human emissions has most likely intensified the drought in California by 15 to 20 percent, scientists said on Thursday, warning that future dry spells in the state are almost certain to be worse than this one as the world continues to heat up.

Even though the findings suggest that the drought is primarily a consequence of natural climate variability, the scientists added that the likelihood of any drought becoming acute is rising because of climate change. The odds of California suffering droughts at the far end of the scale, like the current one that began in 2012, have roughly doubled over the past century, they said.

“This would be a drought no matter what,” said A. Park Williams, a climate scientist at the Lamont-Doherty Earth Observatory of Columbia University and the lead author of a paper published by the journal Geophysical Research Letters. “It would be a fairly bad drought no matter what. But it’s definitely made worse by global warming.”

The National Oceanic and Atmospheric Administration also reported Thursday that global temperatures in July had been the hottest for any month since record-keeping began in 1880, and that the first seven months of 2015 had also been the hottest such period ever. Heat waves on several continents this summer have killed thousands of people.

The paper on the California drought echoes a growing body of research that has cited the effects of human emissions, but scientists not involved in the work described it as more thorough than any previous effort because it analyzed nearly every possible combination of data on temperature, rainfall, wind speed and other factors that could be influencing the severity of the drought. The research, said David B. Lobell, a Stanford University climate scientist, is “probably the best I’ve seen on this question.”

The paper provides new scientific support for political leaders, including President Obama and Gov. Jerry Brown of California, who have cited human emissions and the resulting global warming as a factor in the drought. As he races around his battered state, from massive forest fires to parched farms, Mr. Brown has been trying to cajole the Republican presidential candidates into explaining what they would do about climate change.

“To say you’re going to ignore that there’s a huge risk here, the way we’re filling the atmosphere with heat-trapping gases, is folly, ignorance and totally irresponsible,” Mr. Brown said Thursday in a telephone interview. “And virtually the entire Republican Party in Congress is saying exactly that. It’s inexplicable.”

Several Republican presidential candidates, including Senator Lindsey Graham of South Carolina and Gov. John R. Kasich of Ohio, do acknowledge that climate change poses risks, but they are skeptical of the way Mr. Obama has gone about trying to limit emissions, with a plan expected to force the shutdown of many coal-fired power plants.

Chris Schrimpf, a spokesman for Mr. Kasich, said Thursday that political leaders confronting questions about climate change “can’t stick their heads in the sand and pretend it isn’t happening. Instead we need to be about the business of taking action, but action that doesn’t throw the economy and jobs out the window at the same time.”

However, many of the leading Republican candidates are openly skeptical of climate science and play down the risks. In response to a letter from Mr. Brown asking about their plans, several of the candidates retorted last week that California should be building more dams to store water for future droughts. Senator Ted Cruz of Texas said that “alarmists” about global warming were trying to gain “more power over the economy and our lives.”

A report this week by researchers at the University of California, Davis, projected that the drought would cost the California economy some $2.7 billion this year. Much of that pain is being felt in the state’s huge farming industry, which has been forced to idle a half-million acres and has seen valuable crops like almond trees and grape vines die.

As climate scientists analyze the origins of the drought, they have been tackling two related questions: What caused the dearth of rain and snow that began in 2012? And, regardless of the cause, how have the effects been influenced by global warming?

The immediate reason for the drought is clear enough: For more than three years, a persistent ridge of high pressure in the western Pacific Ocean has blocked storms from reaching California in the winter, when the state typically gets most of its moisture. That pattern closely resembles past California droughts.

Some scientists have argued that the ocean and atmospheric factors that produced the ridge have become somewhat more likely because of global warming, but others have disputed that, and the matter remains unresolved.

On the question of the effects, scientists have been much clearer. Rising temperatures dry the soil faster and cause more rapid evaporation from streams and reservoirs, so they did not need any research to tell them that the drought was probably worse because of the warming trend over the past century. The challenge has been to quantify how much worse.

The group led by Dr. Williams concluded that human-caused climate change was responsible for between 8 and 27 percent of the deficit in soil moisture that California experienced from 2012 to 2014.

But, in an interview, Dr. Williams said the low number was derived from a method that did not take account of the way global warming had sped up since the 1970s. That led him and his colleagues to conclude that climate change was most likely responsible for about 15 to 20 percent of the moisture deficit.

Since 1895, California has warmed by a little more than 2 degrees Fahrenheit. That increase sounds small, but as an average over an entire state in all seasons, scientists say, it is a large number. The warmer air can hold more water vapor, and the result is that however much rain or snow falls in a given year, the atmosphere will draw it out of the soil more aggressively.

“It really is quite simple,” said Richard Seager, a senior climate scientist at Lamont and a co-author on the Williams paper. “When the atmosphere is as warm as it is, the air is capable of holding far more water. So more of the precipitation that falls on the ground is evaporated, and less is in the soil, and less gets into streams.”

Dr. Williams calculated that the air over California can absorb about 8.5 trillion more gallons of water in a typical year than would have been the case in the cooler atmosphere at the end of the 19th century. The air does not always manage to soak up that much, however, because evaporation slows as the soils dry out.

How much more California will warm depends on how high global emissions of greenhouse gases are allowed to go, but scientists say efforts to control the problem have been so ineffective that they cannot rule out another 5 or 6 degrees of warming over the state in this century, a level that could turn even modest rainfall deficits into record-shattering droughts.

For politicians like Mr. Obama and Mr. Brown, the emerging question is whether Americans will awaken to the risks and demand stronger action before emissions reach such catastrophic levels.

“I don’t think climate change is anywhere near the issue that it’s going to be, but the concern is rising in the public mind,” Mr. Brown said Thursday. “The facts can’t be concealed forever.”