Heat, Floods, Fires: Jet Stream Is Key Link In Climate Disasters

Deadly weather as far apart as China, Germany and the U.S. reveal the devastating impact of a swinging jet stream. Heat, Floods, Fires: Jet Stream Is Key Link In Climate Disasters

Devastating floods destroyed towns in Germany and Belgium. A ruthless heat wave broiled the Western U.S. and Canada. Heavy rains paralyzed a Chinese industrial hub home to 10 million people. These recent weather phenomena are being intensified by the changing climate.

But the link between these far-flung extremes goes beyond warming global temperatures. All of these events are touched by jet streams, strong and narrow bands of westerly winds blowing above the Earth’s surface. The currents are generated when cold air from the poles clashes against hot air from the tropics, creating storms and other phenomena such as rain and drought.

“Jet streams are the weather—they create it and they steer it,” said Jennifer Francis, a senior scientist at the Woodwell Climate Research Center. “Sometimes the jet stream takes on a very convoluted pattern. When we see it taking big swings north and big dips southward we know we’re going to see some unusual weather conditions.”
Jet Streams

Fast-Moving Belts Of Wind Take Wavy, Meandering Paths Around The Planet

Meteorologists worry whenever those swings and dips form omega-shaped curves that look like waves. When that happens, warm air travels further north and cold air penetrates further south. The result is a succession of unusually hot and cold weather systems along the same latitude. Under these conditions, winds often weaken and dangerous weather can remain stuck in the same place for days or weeks at a time—rather than just a few hours or a day—leading to prolonged rains and heat waves.

“It’s just like when waves in the ocean get to a beach, overturn and break,” said Tess Parker, a research fellow at the ARC Centre for Excellence for Climate Extremes at Monash University in Melbourne. “That can happen in the atmosphere as well, and if that happens you tend to catch a high- or low-pressure system that will become stationary.”

That’s what sunk parts of Germany into floods earlier this month, as a low pressure system became pinned above the country’s western region. Heavy rains soaked the terrain for the first two days, followed by a few hours of even more intense precipitation that caused rivers to overflow. Water and mudslides overran houses and roads, killing more than 170 people and leaving hundreds missing. Heavy rains also swamped parts of Luxembourg, Belgium and the Netherlands.

Of course the events in Germany had to do with the position of the jet stream,” said Johannes Quaas, a meteorologist and a professor at Leipzig University. At the same time, he said, there’s evidence that the atmosphere can hold 7% more moisture for every degree of Earth’s warming. Global average temperatures are already about 1.2º Celsius above pre-industrial levels.

“We were immensely shocked,” said Stefan Heydt, a spokesperson for the German armed forces in the state of North Rhine-Westphalia, which suffered severe damage in the recent floods. His home state, Rhineland-Palatinate, was also badly affected. Heydt said a cousin still lives there and now has to drive 60 kilometers for electricity.

“Whole existences were destroyed from one moment to the next,” Heydt said.

The economic fallout from the floods in Europe is still unfolding, and it’s already clear that a wide range of sectors will feel the blow. Germany halted operations at an open-cast lignite mine run by RWE AG, curbing output at the connected Weisweiler power station.

Most of the company’s hydroelectric dams in the west of the country and one power station in the Netherlands also stopped operating.

When movements in the jet stream, which was first documented by U.S. bombers flying to missions to Japan in World War II, coincide with climate-driven extremes—heat, drought, intense rainfall—the consequences can be catastrophic.

That may be what happened in China this week. A record rainstorm brought a year’s worth of precipitation in three days to Zhengzhou, the world’s biggest manufacturing base for iPhones and a major hub in central China for food production. At least 33 people died and as many as 380,000 had to be evacuated.

Scientists at the China Meteorological Administration attributed the storm to strong and sustained high-pressure blocks that, along with Typhoon In-fa approaching from the southeast, pushed water vapor in from the sea. That dense air hit the mountains surrounding Henan, the province where Zhengzhou lies, converged and then shot upwards, where it cooled to form the destructive rains.

The situation in the atmosphere may have been brought on by jet stream weakening, “but it will require additional analysis to confirm,” said Michael Mann, an atmospheric science professor at Pennsylvania State University. “What is certainly true is that a slower summer jet stream, which is a robust prediction of a warming climate, allows these systems to persist in the same location for longer periods of time, contributing to many of these record rainfall totals we’re seeing in Europe and Eurasia,” he said.

The question for scientists is to what extent climate change affected those disturbances in the jet stream. It takes time to do that kind of analysis. A rapid attribution study of the Europe floods has already begun, led by the German weather service, with results expected by mid-August.

The heat waves that struck western U.S. and Canada in late June were so unprecedented that researchers were able to conclude by early July that climate change had made them at least 150 times more likely. A high-pressure system, typically linked to hot and dry weather, was made worse by the fact that the land below it was extremely dry.

Usually moisture on the ground absorbs much of the sun’s heat and cools the air when it evaporates. But the extreme drought over the northwestern part of North America meant temperatures could only go up, building a bubble of warm air in the atmosphere. Since then, a second heat wave has hit the region, with wildfires now burning across the U.S. West and parts of Canada.

The extreme heat has helped propel natural gas futures and power prices as millions of people crank up air conditioners. Droughts are forcing almond growers to pull out trees in California. On the High Plains of North America, grasshoppers are thriving and chomping on already diminished fields of grass and wheat. With food inflation soaring amid disruptions from the Covid-19 outbreak, the weather could keep prices for crops and meat elevated in the months ahead.

Meanwhile western and central Russia were cold, even as heat and wildfires hit eastern Siberia. And as Germany and Belgium experienced heavy rains, high temperatures prompted the U.K. Met Office to issue its first-ever extreme heat warning. “The jet is sneaking around these weather systems that come one after another, linking weather in different regions,” said Tim Woollings, a professor of physical climate science at the University of Oxford.

Most scientists agree that climate change is making events driven by the jet stream worse, but there’s debate over how much global warming is directly impacting the currents. Researchers have already connected the jet stream to several natural disasters over the last two years.

Scientists have determined, for example, that a high-pressure system stuck over eastern Siberia caused heat that would have been almost impossible without climate change. In Australia, a two-year drought coupled with a high-pressure system over the state of New South Wales led to multi-decade temperature records in 2020 and fueled the country’s worst-ever fire season.

Francis, from the Woodwell Climate Research Center, studies how warming in the Arctic is influencing weather elsewhere on the planet. She thinks one consequence is a weakening of the jet stream. As the Arctic warms faster than areas farther south, the temperature difference gets smaller, weakening the winds, making its path curvier and extreme events over one area more persistent.

“We’re somewhere between hypothesis and theory at this point,” Francis said. “There’s a lot of supporting evidence, because it’s such a complicated atmosphere, it’s really hard to determine very clearly what’s making any one weather event more extreme.”

Other researchers don’t draw such a clear connection, but see signs of other climate-driven changes. There’s good evidence that the jet streams are getting closer to the poles, according to Woollings. That shift is displacing storms further to the north in the Northern hemisphere and to the south in the Southern hemisphere, and helps explain the multi-year drought that southern Australia and central Chile are currently experiencing.

Today, researchers are focusing their efforts on predicting swings in the jet stream. It’s a complex task, and much of the research has focused on the Northern Hemisphere. Impacts in the south, particularly in South America and the southern tip of Africa, are less well understood because there’s less research and raw data from that part of the world.

Some extreme weather may have nothing to do with the jet stream at all. Temperatures in Brazil’s coffee-growing regions fell below 0°C for hours on Tuesday, damaging bean crops and orange groves. The frost is dealing growers a second blow after a severe drought driven by La Nina weather patterns left fields parched and depleted water reservoirs needed for irrigation.

Still, understanding the jet stream is becoming more pressing as warming temperatures drive more frequent extreme weather events. “We need to think more about the way weather systems will change with the changing climate, rather than just how the climate will change,” said Parker from Monash University. “This division between climate and the weather is, to a large extent, an artificial one.”

The World’s Biggest Governments Are Still Propping Up Fossil Fuels

Subsidies are falling, but polluters are still getting plenty of public support.

The International Energy Agency published a hopeful finding last month on global subsidies for fossil fuel consumption, showing a fall of more than 40% in 2020 — following a drop of more than 30% in 2019.

That does not, however, mean that countries have reduced their support for fossil fuel industries.

Two things helped lower these subsidies: a sharp drop in consumption during the pandemic, and a significant drop in prices. The full breadth of government support, however, covers a lot more than lowering the price tags consumers see. It also includes investment by state-owned companies, budgetary transfers, tax breaks, and concessional grants and loans from public financial institutions.

In a new report to the Net Zero Asset Owner Alliance, my colleagues at BloombergNEF have added up fossil fuel support from the G-20 governments. Their work shows that support to state-owned energy companies — often their countries’ sole energy supplier — constitutes 45% of total fossil fuel subsidies, while consumer subsidies are a little over 21%.

The total amount of that support, too, is worth noting. In the five years from 2015 to 2019, G-20 governments provided $3.3 trillion of direct support to coal, oil and gas, and fossil fuel-fired power generation. That number has been pretty stubborn over the years, falling from a high of $706 billion in 2015 to a low of $636 billion in 2019 — a change of only about 10%.

Stubbornly High

G-20 Governments’ Support For Coal, Oil And Gas, And Fossil-Fueled Power

Those amounts don’t track particularly well to the underlying cost of energy. Over that same five years, the spot price of Brent crude swung from less than $30 a barrel to nearly $90. This lack of alignment indicates that the connection between near-term energy prices and long-term support for energy is loose at best.

That’s not to say there’s been no progress at all in reducing support for fossil fuels in the G-20. Saudi Arabia, for instance, has cut its total support for fossil fuels by half since 2015 — but still provides nearly three times as much per capita as any other government.

Fully half of those governments have supported fossil fuels less since 2015 — but then again, the law of averages means that at least some of the remaining half have raised theirs. Both Canada and the U.S. raised their subsidies significantly on a percentage basis, but Canada provides almost 10 times the per capita support to its industry as the U.S., almost all of which is public finance for oil and gas producers and utilities.

Argentina, meanwhile, is the second-highest supporter per capita, even despite declining consumer subsidies, with state-owned companies receiving more than 80% of support.

Government backing for consumer energy prices is important. Artificially low electricity prices provide little incentive for conserving electricity. Artificially low road fuel costs give little incentive for vehicle-owners to switch from internal combustion engines to electric models.

Support at the business level, however, could be even more significant for the long-term prospects of decarbonization. Government funding capacity may not be strictly limited, but it’s also not infinite, and funds devoted to supporting an incumbent fossil fuel industry are by definition not able to fund energy transition.

Just as importantly, government support has the potential to lock in assets — and the behaviors that go with them — for decades. Those include assets and behaviors related not just to the consumption of fossil fuels, but also to the production and distribution of same, not to mention the politics that go along with them.

Government action also creates future unfunded liabilities in the form of potential bills for clean-up and environmental mediation.

Finally, governments may be creating future stranded assets, projects that for either policy or economic reasons could soon be permanently out of the money.

If we want to achieve a net-zero energy system by mid-century, companies and governments will need to invest anywhere from $92 trillion to $173 trillion in the next three decades, according to BNEF’s latest New Energy Outlook. Doing so will be difficult, but not impossible. Every dollar supporting any path other than zero net carbon dioxide emissions by 2050, however, makes net zero all the more difficult in the meantime.

Updated: 9-8-2021

Amid Western Blazes, Prescribed Fire Is Keeping Some Forests Resilient

Islands of green trees near Lake Tahoe survived the fast-moving flames of the Caldor Fire, thanks in part to earlier controlled burns and other treatments, officials say.

With more than 217,000 acres burned as of September 8, the Caldor Fire southwest of Lake Tahoe has left swaths of the Sierra Nevada severely devastated. More than 900 structures have been destroyed, including virtually the entire town of Grizzly Flats.

But within the fire’s massive footprint stand patches of green, living trees. One looks like a finger poking into the eastern edge of the fire, along Caples Creek and around Caples Lake. That expanse of vitality overlaps extensively with an 8,800-acre area that had been treated in 2019 with prescribed burning, a tactic practitioners say can make fire-adapted forests less susceptible to catastrophic blazes, and limiting the threat they pose to people.

By setting smaller, controlled fires, forest managers can help eliminate the brush, branches and thickets of young trees that can supercharge fast-moving blazes, while leaving larger, older trees alive. After a century of fire suppression policies, much of California’s conifer woodlands are thickly overgrown, making them vulnerable to runaway megafires, especially in the midst of a severe drought.

In the Caldor Fire, now 50% contained, officials are spotlighting the role that prescribed burning and other fuel-reducing tactics likely played in slowing its spread. After weeks of intense firefighting and a weekend of obliging weather, the risk to the area’s largest community, the city of South Lake Tahoe, has subsided, with thousands of residents now returning home after evacuation orders were downgraded.

“The hard work that the Forest Service has done to pull out those fuels and basically clean up the forest in that area made stops that have absolutely helped,” said Parker Wilbourn, a public information officer at the Sacramento Metro Fire District assigned to the Caldor incident.

There are other factors, namely the thousands of firefighters who have worked grueling shifts to beat back flames with bulldozers, helicopters, and hand crews. It will be months before the Caldor Fire’s behavior is fully analyzed, and adjacent communities are not fully out of danger. But many foresters are looking at the trajectory of the blaze thus far with a hint of optimism about what forest management techniques can achieve.

In the Caples Lake area, the 2019 prescribed burn achieved its goal of clearing out ground fuel that present the biggest fire risk, said Duane Nelson, a now-retired district ranger who oversaw parts of that project. “It was on a large enough footprint that it now seems to be changing the behavior of the 15th largest fire in the history of the state,” he said.

Other burned sections of forest are currently in “beautiful” condition, said Dana Walsh, a public information officer at the U.S. Forest Service. That includes expanses near Grizzly Flats, Sly Park, Mormon Emigrant Trail, the Silver Fork American River, and along Highway 50 that had fuel reduction treatments, such as tree thinning and mulching, in recent years. With the help of that earlier work, the Caldor Fire has left some of these areas healthier than before, by paring back undergrowth.

“There are broad patches that this fire has burned through in a way that’s been beneficial,” Walsh said. “The fire is leaving these places intact and doing better to run through than avoid it.”

But handling fire as a tool instead of a foe is a contentious topic in these tinder-dry woods. The 2019 Caples area burn turned into a wildfire when it escaped the control of its managers, burning hundreds of additional acres and drawing criticism. Since August, a national moratorium on managed fire — where crews allow certain wildfires to burn for the benefit of the ecosystem — as well as stringent new limits on prescribed fire have been in effect.

In a letter, Forest Service Chief Randy Moore stated that all resources would focus on suppression until western wildfire activity abated. “We are in a ‘triage mode’ where our primary focus must be on fires that threaten communities and infrastructure,” Moore wrote.

More than 40 scientists signed a letter protesting that policy and asking for it to be reconsidered. “Even if temporary, these directives will significantly limit options for resource managers in a time when increasing the pace and scale of forest restoration and fuel reduction is of critical importance,” they wrote.

The controversy over controlled burns is unlikely to let up after this record-breaking fire season. While Indigenous people have stewarded forest growth with fire for millennia, the practice has been slow to gain traction among government agencies, particularly in the ignition-prone U.S. West, where putting out blazes as fast as possible in order to protect homes and commercial buildings has long been the goal.

“This is a problem where we need every tool in the toolbox.”

The ferocity and scale of this summer’s wildfires suggest the limits of the suppression approach as climate change brings hotter, drier, and less predictable conditions. North of the Tahoe area, the Dixie Fire is the single largest fire in California history, burning more than 900,000 acres since it started on July 14. Dozens of others are scorching the West, spreading dangerous levels of smoke and haze around the region.

Yet the spots of green in the Caldor Fire’s footprint aren’t the only ones on the landscape. The Bootleg Fire, which engulfed more than 413,000 acres in southern Oregon, reportedly moved around two nature preserves where Klamath tribal members recently helped lead prescribed burns.

Experts say these islands of resilience support the case for more intensive forest management, including the use of mechanical tools such as chainsaws to thin younger trees where possible, as well as prescribed fire, which can clean up brush and ground cover at a much larger scale. Earlier controlled burns can also make it safer for fire crews to deploy tactics such as backburning, where a smaller fire is set to keep a larger active wildfire at bay.

More funding, staffing, and political will is critical for scaling up forest treatments and the positive effects they can have, said Ryan Tompkins, a forest and natural resources advisor at University of California Cooperative Extension who signed the letter of concern about the Forest Service’s new limits on wildfire management.

“This is a problem where we need every tool in the toolbox,” he said. “And we need to be doing it at maximum capacity.”