Wednesday, January 19

Heat, Drought and Fire: How Weather Hazards Combine for a Catastrophic “Perfect Storm” | Climate crisis in the American West

NorthThe Dixie Fire in Northern California this weekend became the largest fire incident the state has ever recorded, a mammoth that swept through mountain towns, produced flames that shot 200 feet into the air and burned nearby. of 490,000 acres.

“It’s the perfect storm,” says Rick Carhart, public information officer for the California Department of Forestry and Fire Protection (Cal Fire), adding that the difficult and steep terrain, parched vegetation, and hot, dry weather had united to fuel the conflagration that has sent flames 200 feet into the sky.

And, he says, the Dixie fire was just one of a series of large fires that have affected the area in recent years. “It has been a giant devastating fire after a giant devastating fire.”

Investigators are concerned that the record for the Dixie fire will not stand for long. The parched landscapes and rising temperatures that set the stage for bigger fires this year aren’t anomalies, they’re trends. And conditions are going to get worse.

Trifecta of a climate crisis

Drought, extreme heat, and destructive hells are devastating in their own right, but together they cause calamities. The combination increases its effects and makes each individual condition intensify. Scientists say they are see the trifecta more often in the west and that climate collapse is the main culprit.

“This is what climate scientists have been warning about for years,” says Park Williams, a hydroclimatologist at the University of California, Los Angeles.

Drought and fires have always been part of the climate in the western US, but the increased heat, which scientists say is directly attributable to human-caused climate change, has had a devastating impact. “These things amplify each other,” Williams says, adding that the effects increase exponentially.

Weather conditions do not act alone, and fire and water policies play a role in increasing risks and also in determining the outcome. Most fires are still started by people. The expansion of communities into forested and fire-prone areas adds new dimensions that complicate containment efforts when flames increase. But what is happening in the environment has made fires much more difficult to fight.

That’s why new discs not only highlight old ones, they erase them. In 2020, the 4.2 million acres that burned in California were nearly triple the previous record. This year, the fires have burned more than three times more land than at this point in 2020, according to Cal Fire.

“And there’s really no end in sight to the ability for that kind of thing to happen again,” says Williams.

A vicious cycle of heat and drought

Heat affects drought in several ways. Higher temperatures cause precipitation to fall as rain instead of snow. Falling snow melts much faster, leaving less to drip into streams, rivers, and reservoirs. People, plants and animals depend on the snow cover to power water systems and, with less availability, the landscape and anything that lives in it or outside it will feel the stress.

Heat also removes moisture from the landscape. The hotter it is, the more water plants and animals need to regulate themselves, and that further increases water scarcity. What complicates all this is that the relationship works in the other direction as well: drought conditions increase heat.

“Heat is both a response to drought and also a driver of drought,” says Andrew Hoell, a meteorologist in the physical sciences laboratory of the National Oceanic and Atmospheric Administration. Dry soils radiate and reflect energy from the sun that would otherwise be used for evaporation. That raises surface temperatures even more.

“Just like we get cold when we get out of a pool, the ground cools when the water evaporates,” says Hoell. “When the soils are dry, when it is hot, there is not as much water available to evaporate. That means the earth doesn’t get cold. “

This is why Hoell calls climate change a “threat multiplier.” As the region gets warmer and drier, the risk of tiny sparks quickly turning into huge, erratic wildfires increases.

Fires add another dimension to the threat

New research also suggests that wildfires themselves will increase drought and heat, adding a new dimension to the catastrophic cycle. The researchers are discuss hypothesesHoell explains that the smoke and aerosols released into the atmosphere by wildfires can alter weather patterns. There are already studies showing that forest fires influence the formation of clouds in the sky and could decrease precipitation.

Gould Fickardt, 71, left, and Woody Hovland, 70, of Greenville, sit with their dogs, Prime, right, and Sheva, left, outside a home where they are staying after losing their own homes to the Dixie fire.
Gould Fickardt, 71, left, and Woody Hovland, 70, of Greenville, sit with their dogs, Prime, right, and Sheva, left, outside a home where they are staying after losing their own homes to the Dixie fire. Photograph: Mel Melcon / Los Angeles Times / Rex / Shutterstock

“It is very dynamic and very complicated, but that is where we are going as a scientific community: we are trying to figure out how forest fires feed back into drought,” he said.

Researchers are also investigating how the shrunken canopies of forest decimated by fires expose the blanket of snow that was once shaded by the sun.

Although more research is needed to better understand these complex relationships, the scientific record is clear that increased heat will lead to increased extreme events.

“Global surface temperature will continue to rise until at least mid-century in all emission scenarios considered,” according to the Intergovernmental Panel on Climate Change in its sixth report, released Monday, which went on to detail and list the expected increase in both the frequency and intensity of hot extremes, ecological droughts, and reductions in Arctic sea ice, snow cover, and permafrost, along with other catastrophic conditions.

“In all future scenarios and levels of global warming, temperatures and extremely high temperatures are expected to continue to rise,” the report on North and Central America said, attributing the increase to “human influence.”

Models show that extreme heat waves are expected to occur more frequently, with greater intensity, and over larger areas of land in just the next three decades. “Historically, we’ve had four to six extreme heat events in a given year,” said Steve Ostoja, director of the USDA California Climate Center. “By 2050, we expect that number to be between 25 and 30 events. That is a big difference. That basically means it’s going to be so hot all the time. “

There is no time to lose

The trends are already being felt. Currently, about half of the contiguous The United States is in a drought, according to federal agencies. The entire state of California is experiencing drought conditions, with more than 88% of the state in the “extreme drought” category, as determined by the US Drought Monitor. Meanwhile, dozens of weather stations in the West documented the warmest months of June and July on record, as extreme heat waves increased temperatures across the region.

Ecosystems under stress have already become more vulnerable. Disasters have taxed trees, which are being ravaged by diseases and pests. Studies show approximately 150 million trees died in the last period of drought and billions of creatures that lived along the coasts died during this summer’s heat waves.

Climate scientists say there is still time to make big changes and there is a chance that the worst effects of climate change can be avoided. But there is no time to lose.

In the west, forest fires, drought and heat are already wreaking havoc. Williams, the UCLA climate scientist, says there are clear indications that places like California won’t look the way they do now for much longer. The landscape becomes more arid and, as it becomes drier and hotter, there will be more fires. That will lead to fewer forests and more grasslands, scrublands, and deserts.

“Fire has been around for hundreds of millions of years and is a fundamental part of the Earth system,” he said. But the fires of the future will do much more than clear brush. “Now the fires that we are seeing are completely eliminating giant patches of forest,” he added, explaining that many tree species had not evolved to repopulate the giant gaps quickly.

“It could take hundreds of years for the ponderosa or Jeffrey pine, which we see a lot in the Sierra Nevada, to really re-occupy giant patches of forest,” he said. “At that time, the climate could be totally inappropriate for those species anyway.”

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