Lethal Heating: 12/13/21

13/12/2021

(USA NBC) EXPLAINER: Was Tornado Outbreak Related To Climate Change?

NBC - Suman Naishadham | Seth Borenstein

These types of severe storms in December are not incredibly unusual, but the intensity and length of Friday night's tornadoes likely put them into a record breaking category

1min 19sec

The calendar said December but the warm moist air screamed of springtime. Add an eastbound storm front guided by a La Nina weather pattern into that mismatch and it spawned tornadoes that killed dozens over five U.S. states.

Tornadoes in December are unusual, but not unheard of. But the ferocity and path length of Friday night's tornadoes likely put them in a category of their own, meteorologists say.

One of the twisters — if it is confirmed to have been just one — likely broke a nearly 100-year-old record for how long a tornado stayed on the ground in a path of destruction, experts said.

“One word: remarkable; unbelievable would be another,” said Northern Illinois University meteorology professor Victor Gensini. “It was really a late spring type of setup in in the middle of December.”

Warm weather was a crucial ingredient in this tornado outbreak, but whether climate change is a factor is not quite as clear, meteorologists say.

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Arkansas Dec 11

Edwardsville Weather Dec 11

Scientists say figuring out how climate change is affecting the frequency of tornadoes is complicated and their understanding is still evolving. But they do say the atmospheric conditions that give rise to such outbreaks are intensifying in the winter as the planet warms.

And tornado alley is shifting farther east away from the Kansas-Oklahoma area and into states where Friday's killers hit. Here's a look at what's known about Friday's tornado outbreak and the role of climate change in such weather events.

What Causes A Tornado?

Tornadoes are whirling, vertical air columns that form from thunderstorms and stretch to the ground. They travel with ferocious speed and lay waste to everything in their path.

Thunderstorms occur when denser, drier cold air is pushed over warmer, humid air, conditions scientists call atmospheric instability. As that happens, an updraft is created when the warm air rises. When winds vary in speed or direction at different altitudes — a condition known as wind shear — the updraft will start to spin.

These changes in winds produce the spin necessary for a tornado. For especially strong tornadoes, changes are needed in both the wind’s speed and direction.

“When considerable variation in wind is found over the lowest few thousand feet of the atmosphere, tornado-producing ‘supercell thunderstorms’ are possible,” said Paul Markowski, professor of meteorology at Pennsylvania State University. “That’s what we had yesterday.”

There's usually a lot of wind shear in the winter because of the big difference in temperature and air pressure between the equator and the Arctic, Gensini said.

But usually, there's not a lot of instability in the winter that's needed for tornadoes because the air isn't as warm and humid, Gensini said. This time there was.

What Conditions Led To Storms Of This Scale?

A few factors, which meteorologists will continue to study.

Spring-like temperatures across much of the Midwest and South in December helped bring the warm, moist air that helped form thunderstorms.

Some of this is due to La Nina, which generally brings warmer than normal winter temperatures to the Southern U.S. But scientists also expect atypical, warm weather in the winter to become more common as the planet warms.

“The worst-case scenario happened. Warm air in the cold season, middle of the night,” said John Gordon, a National Weather Service meteorologist in Louisville, Kentucky.

Once the storm formed, exceptionally strong wind shear appears to have prevented the tornadoes from dissipating, experts say. Tornadoes are thought to die off when thunderstorm updrafts lose energy.

Tornadoes typically lose energy in a matter of minutes, but in this case it was hours, Gensini said. That’s partly the reason for the exceptionally long path of Friday's storm, going more than 200 miles or so, he said.

The record was 219 miles and was set by a tornado that struck four states in 1925. Gensini thinks this one will surpass it once meteorologists finish analyzing it.

“In order to get a really long path length, you have to have a really fast moving storm. This storm was moving well over 50 miles (80 kilometers) per hour for a majority of its life,” Gensini said. That's not the speed of the winds, but of the overall storm movement.

“You’re talking about highway-speed storm motions,” Gensini said.

How Related Is Climate Change To Tornado Outbreaks?

It’s complicated. Scientists are still trying to sort out the many conflicting factors about whether human-caused climate change is making tornadoes more common — or even more intense.

About 1,200 twisters hit the U.S. each year — though that figure can vary — according to the NOAA National Severe Storms Laboratory. No other country sees as many.

Attributing a specific storm like Friday's to the effects of climate change remains very challenging.

Less than 10% of severe thunderstorms produce tornadoes, which makes drawing conclusions about climate change and the processes leading up to them tricky, said Harold Brooks, a tornado scientist at the National Severe Storms Laboratory.

Scientists have observed changes taking place to the basic ingredients of a thunderstorm, however, as the planet warms. Gensini says in the aggregate, extreme storms are “becoming more common because we have a lot warmer air masses in the cool season that can support these types of severe weather outbreaks.”

Climate Change is Making Extreme Weather More Extreme 6min 28sec

The U.S. is likely to see more tornadoes occur in the winter, Brooks said, as national temperatures rise above the long-term average. Fewer events will take place in the summer, he said.

Furtado of the University of Oklahoma said tornado alley, a term used to describe where many twisters hit the U.S., has shifted eastward into the Mississippi River Valley. That shift is because of increases in temperature, moisture and shear.

“Bottom line: The people in the Mississippi River Valley and Ohio River Valley are becoming increasingly vulnerable to more tornadic activity with time,” he said.

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(USA Washington Post) A Warming World Could Add More Fuel To Tornadoes, Scientists Say

Washington Post - Michael Birnbaum | Brady Dennis | Jason Samenow

While the link between global warming and disasters like wildfires and flooding are more definitive, experts say, warmer temperatures could intensify cool-season thunderstorms and tornadoes in the future.

BOWLING GREEN, KY - DECEMBER 11: A damaged apartment complex in Bowling Green, Kentucky, on Saturday, Dec. 11, 2021. One or more tornados tore through Bowling Green in the early morning. One or more tornados tore through Bowling Green in the early morning. (Austin Anthony/For The Washington Post)

In the wake of deadly storms that ravaged parts of the South and the Midwest this weekend, scientists had a warning: While the exact link between climate change and tornadoes remains uncertain, higher temperatures could add fuel to these violent disasters.

Article Audio 6min

As rescuers searched Saturday amid the rubble of violent tornadoes that barreled through multiple states, killed scores of people, and leveled homes and businesses, climate scientists said people around the world needed to brace for more frequent and intense weather-driven catastrophes.

“A lot of people are waking up today and seeing this damage and saying, ‘Is this the new normal?’ ” said Victor Gensini, a meteorology professor at Northern Illinois University, adding that key questions still remain when it comes to tornadoes because so many factors come into play. “It’ll be some time before we can say for certain what kind of role climate change played in an event like yesterday.”

Still, he said the warm December air mass in much of the country and La Niña conditions created ideal conditions for a turbulent event. Thunderstorms — the raw material for tornadoes — happen when there is warm, moist air close to the ground and cooler, drier air above, creating a path for humidity to travel upward.

The tornadic thunderstorm carved a 250-mile path of destruction through northeast Arkansas, southeast Missouri, northwest Tennessee and western Kentucky, hurling debris into the sky for more than three straight hours. At times, the wreckage reached an altitude of 30,000 feet. As the twister blasted through Mayfield, Ky., it sheared entire homes off their foundations, indicating its top-tier intensity.

Whether or not scientists can pin down a link between this week’s horrific storms and climate change, Gensini said there’s no doubt that the tornadoes will go down as “one of the most devastating long-track tornadoes” in U.S. history — probably the worst since the Tri-State Tornado of 1925, which tore across three states over several hours and killed hundreds of people.

Meteorologists at the National Weather Service are surveying damage to determine whether this week’s storm was a single tornado or several. If it was a single tornado traveling on the ground without interruption for 250 miles, it will rank as the longest tornado track in U.S. history and the first to cross through four states.

As the death toll is expected to swell, it will become the deadliest December tornado outbreak on record and potentially among the most deadly in any month. Until Friday night, the deadliest December outbreak occurred on Dec. 5, 1953, which killed 38 people in Vicksburg, Miss.

Temperatures in the zone ravaged by tornadoes rose into the 70s to near 80 degrees Friday afternoon, providing the conditions for severe thunderstorms to develop that night. Dozens of record highs were set that day in the states hardest hit by the storms: In Memphis, temperatures soared to 79 degrees, breaking a 103-year-old record.

In a warming world, Gensini said: “It’s absolutely fair to say that the atmospheric environments will be more supportive for cool-season tornado events.”

But Gensini and other climate and weather experts noted that tornadoes are among the most difficult events to link definitively to global warming, partly because they are relatively small and short-lived events compared with the wildfires, heat waves and other climate disasters.

How tornadoes that ripped through 6 states became so deadly 1min 45sec

“Tornadoes are, unfortunately, one of the extreme events where we have the least confidence in our ability to attribute or understand the impact of climate change on specific events,” said Zeke Hausfather, a climate scientist who directs climate and energy programs at the Breakthrough Institute, a climate research center based in Oakland, Calif. “There is not much evidence to date that the number of strong tornadoes is different today than it was over much of the past century.”

The most recent National Climate Assessment, assembled by experts at numerous federal agencies, underscored this dynamic in 2018.

“Observed and projected future increases in certain types of extreme weather, such as heavy rainfall and extreme heat, can be directly linked to a warmer world,” the authors wrote. “Other types of extreme weather, such as tornadoes, hail, and thunderstorms, are also exhibiting changes that may be related to climate change, but scientific understanding is not yet detailed enough to confidently project the direction and magnitude of future change.”

The report went on to say tornado activity in the United States has become “more variable” in recent decades, with a decrease in the number of days per year that saw tornadoes but an increase in the number of tornadoes on these days.

Harold Brooks, a senior research scientist at the National Oceanic and Atmospheric Administration’s Severe Storms Laboratory, said extreme tornadoes are becoming “clumpier” over time, meaning they have become more concentrated in day-long bursts. He said it wasn’t clear whether there was a connection to climate change.

And warmer Decembers will probably lead to more December thunderstorms.

“Studies suggest that the frequency and intensity of severe thunderstorms in the U.S. could increase as climate changes, particularly over the U.S. Midwest and Southern Great Plains during spring,” Hausfather said.

The additional factors required to transform a thunderstorm into a tornado — among them, a change in wind speeds at different altitudes, with more intense winds up above — are so complex that scientists have a hard time drawing a straight line between warming temperatures and more frequent tornadoes. In fact, the number of intense tornadoes in the United States “hasn’t changed back into the fifties,” Brooks said, around 500 a year.

There may be some evidence that wintertime tornadoes are becoming more frequent, Brooks said. But the tornadoes are rare enough — and hard enough to measure and classify — that it is difficult to achieve statistical confidence.

What is unequivocal, Gensini said, is that the steady warming of the planet is making a broad array of extreme weather disasters more likely and more intense.

“When you look at these things in the aggregate, it becomes pretty clear that changes are happening,” he said. “There are definitely shifts in the probability of these things happening.”

That includes longer severe weather seasons and more instability in the atmosphere during “shoulder” seasons when such disasters historically would have been less common, he said. It also could include more variability than in the past — some years could be very intense and marked by multiple catastrophes, while others could prove mild when it comes to severe weather.

That is in line with the findings of a major report the U.N. Intergovernmental Panel on Climate Change released this summer, which found that as humans have continued to pump planet-warming gases into the atmosphere, weather-related disasters are growing more extreme and affecting every region of the world.

While the report didn’t draw a conclusion about the relationship between tornadoes and climate change, it noted that the frequency and intensity of extreme precipitation in the United States was increasing.

One thing that’s different now: More people and more “things” lie in the paths of future tornadoes and other extreme weather events.

“As populations continue to grow, as cities get larger, as we continue to have more things — this is what you get,” Gensini said. “I know for certain there will be more disaster as our human footprint continues to grow.”

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(AU NYT) First Fires, Then Floods: Climate Extremes Batter Australia

New York Times - Damien Cave | Photographs and Video by Matthew Abbott

Many of the same areas that suffered through horrific bush fires in 2019 and 2020 are now dealing with prodigious rainfall that could leave some people stranded for weeks.

WEE WAA, Australia — Two years ago, the fields outside Christina Southwell’s family home near the cotton capital of Australia looked like a dusty, brown desert as drought-fueled wildfires burned to the north and south.

Last week, after record-breaking rains, muddy floodwaters surrounded her, along with the stench of rotting crops. She had been trapped for days with just her cat, and still didn’t know when the sludge would recede.

“It seems to take for bloody ever to go away,” she said, watching a boat carry food into the town of Wee Waa. “All it leaves behind is this stink, and it’s just going to get worse.”

Life on the land has always been hard in Australia, but the past few years have delivered one extreme after another, demanding new levels of resilience and pointing to the rising costs of a warming planet. For many Australians, moderate weather — a pleasant summer, a year without a state of emergency — increasingly feels like a luxury.

The Black Summer bush fires of 2019 and 2020 were the worst in Australia’s recorded history. This year, many of the same areas that suffered through those epic blazes endured the wettest, coldest November since at least 1900. Hundreds of people, across several states, have been forced to evacuate. Many more, like Ms. Southwell, are stranded on floodplain islands with no way to leave except by boat or helicopter, possibly until after Christmas.

Christina Southwell in her garden shed in Wee Waa, Australia, where floodwaters have surrounded her house.

Hundreds of people, across several states, have been forced to evacuate. Many more are stranded on floodplain islands with no way to leave except by boat or by helicopter.

undreds of people, across several states, have been forced to evacuate. Many more are stranded on floodplain islands with no way to leave except by boat or by helicopter.

Bryce Guest, a helicopter pilot in Narrabri, flying over farms in the region.

And with a second year of the weather phenomenon known as La Niña in full swing, meteorologists are predicting even more flooding for Australia’s east coast, adding to the stress from the pandemic, not to mention from a recent rural mouse plague of biblical proportions.

“It feels constant,” said Brett Dickinson, 58, a wheat farmer who lives not far from Ms. Southwell in northwest New South Wales, about a six-hour drive from Sydney. “We’re constantly battling all the elements — and the animals too.”

There’s a tendency to think of such extremes as “natural disasters” or “acts of God” that come and go with news reports. But Australia’s nightmares of nature ebb and flow. Its droughts and floods, though weather opposites, are driven by the same forces — some of them timeless, others newer and caused by humans.

Andy Pitman, director of the ARC Center of Excellence for Climate Extremes at the University of New South Wales, said the ups and downs of weather had been severe for millenniums on the Australian landmass, which is as large as the continental United States and surrounded by powerful climate-driving oceans, from the tropical South Pacific to the colder Southern Ocean off Antarctica.

New York Times

As a consequence, the El Niño and La Niña patterns tend to hit Australia harder than they do other places, with harsh droughts that end with major floods. Some scientists even suggest that the way marsupials reproduce, with the ability to put active pregnancies on pause, shows that the El Niño-La Niña cycle has been around long enough for flora and fauna to adapt.

Australia has been hit with harsh droughts that end with major floods, a phenomenon caused by the El Niño and La Niña patterns and intensified by climate change.

On top of that already-intense variability, Professor Pitman said, are now two additional complicating factors: “climate change and human decisions around building things.”

Both make fires and floods more damaging.

“A small change in climate coupled with a small change in landscapes can have a large impact on flood characteristics,” Professor Pitman said.

The results are already visible in government budgets. The cost of climate disasters in Australia has more than doubled since the 1970s.

Ron Campbell, the mayor of Narrabri Shire, which includes Wee Waa, said his area was still waiting for government payments to offset damage from past catastrophes. He wondered when governments would stop paying for infrastructure repairs after every emergency.

“The costs are just enormous, not just here but at all the other places in similar circumstances,” he said.

Volunteers and locals transporting food and supplies in Wee Waa.

A sandbag station in Narrabri. The area is still waiting for government payments to offset damage from past catastrophes.

Boxes full of supplies are stacked in front of photos of previous floods, at the State Emergency Service headquarters in Narrabri.

More viscerally, the impact of a “supercharged climate” is drawn on the land itself. Across the vast tracts of farmland and small towns between Melbourne and Sydney where much of the country’s food, cattle, wine — and coal — are produced, the effects of fire, drought and flood coexist.

Even in areas that did not burst into flames, the heat waves and lack of rainfall that preceded the bush fires killed as much as 60 percent of the trees in some places. Cattle farmers culled so much of their herds during the drought that beef prices have risen more than 50 percent as they rush to restock paddocks nourished (nearly to death) by heavy rain.

Bryce Guest, a helicopter pilot in Narrabri, once watched the dust bowls grow from above. Then came “just a monstrous amount of rain,” he said, and new kind of job: flights to mechanical pumps pushing water from fields to irrigation dams in a last-ditch effort to preserve crops that had been heading for a record harvest.

On one recent flight, he pointed to mountains of stored grain — worth six figures, at least — that were ruined by the rains, with heavy equipment trapped and rusting next to it. Further inland, a home surrounded by levees had become a small island accessible only by boat or copter.

“Australia is all about water — everything revolves around it,” he said. “Where you put your home, your stock. Everything.”

Stacks of stored grain damaged by flooding.

The flood plains in what is known as the Murray-Darling basin stretch out for hundreds of miles, not unlike the land at the mouth of the Mississippi River. The territory is so flat that towns can be cut off with roads flooded by less than an inch of additional rain.

That happened a few weeks ago in Bedgerabong, a few hundred miles south of Narrabri. On a recent afternoon, a couple of teachers were being driven out of town in a hulking fire truck — equipment for one disaster often serves another. Across a flooded road behind them, three other teachers had decided to camp out so they could provide some consistency for children who had already been kept out of school for months by pandemic lockdowns.

Paul Faulkner, 55, the principal of the school (total enrollment: 42), said that many parents craved social connection for their children. The Red Cross has sent in booklets for those struggling with stress and anxiety.

“Covid has kept everyone from their families,” he said. “This just isolates them even more.”

He admitted that there were a few things they did not discuss; Santa, for one. The town is expected to be cut off until after the holidays as the waters that rose with surging rains over a few days take weeks to drain and fade.

Children in the area have been kept out of school for months, first by pandemic lockdowns and now by the floods.

A flock of sheep on a small patch of land surrounded by floodwaters. Cattle farmers, too, have been affected by the drought and the heavy rain.

The view from Ms. Southwell’s kitchen out onto her flooded yard.

In Wee Waa, where the water has started to recede, supplies and people flowed in and out last week by helicopter and in a small boat piloted by volunteers.

Still, there were shortages everywhere — mostly of people. In a community of around 2,000 people, half of the teachers at the local public school couldn’t make it to work.

At the town’s only pharmacy, Tien On, the owner, struggled with a short-handed staff to keep up with requests. He was especially concerned about delayed drug deliveries by helicopter for patients with mental health medications.

Ms. Southwell, 69, was better prepared than most. She spent 25 years volunteering with emergency services and has been teaching first aid for decades. After a quick trip into Wee Waa by boat, she returned to her home with groceries and patience, checking a shed for the stray cats she feeds and discovering that only one of her chickens appeared to have drowned.

She said she wasn’t sure how much climate change could be blamed for the floods; her father had put their house on higher stilts because they knew the waters would rise on occasion.

All she knew was that more extreme weather and severe challenges to the community would be coming their way.

“The worst part of it is the waiting,” she said. “And the cleanup.”

Destroyed crops on flooded farmland between Narrabri and Wee Waa.

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