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Climate change could leave Californians with "weather whiplash"



But the same factors make California susceptible to climate change, and the weather conditions that permeate the area lead to dramatic variations between drought and flooding, a kind of "weather whiplash".

These climate extremes have a significant impact on society, and swift swinging from one extreme to the other makes mitigation and adaptation much more difficult.

"In a place like California, we really need to think about both risks." [drought and flood] at the same time, "said Daniel Swain, a climate scientist at the University of California, Los Angeles and principal author of the study.

Unfortunately, many of the risk management practices currently being used in California, such as storing water in large reservoirs, are put to use during drought years. "We will be held accountable in very wet years when we need so much space in reservoirs to maintain flood control," Swain said.

A dramatic example of this has recently been written: The Worst Drought in History (by 201
0 to 2016) was directly involved in massive floods from the end of 2016 until the beginning of 2017. It culminated in the disaster at the Oroville Dam, which forced 250,000 people to leave their homes.

The study used an ensemble of computer modeling simulations, known as the Community Earth System Model Large Ensemble, and analyzed how the future Never climate change in response to persistent greenhouse gas emissions.

The researchers tested whether it could simulate California's historical rainfall and reproduce known weather patterns that lead to drought and flooding.

This gives the scientists confidence in the projections that result from running the model in different scenarios.

What they found was that, although precipitation will generally not change much, the variability between rainfall and fall will vary significantly.

"If you only look for shifts in average rainfall, you miss all the major changes in the character of the rainfall," Swain said.

  A house in Montecito, California, flooded by a mudslide in January.

The study highlights the rapid changes in climate variability that are more likely in a warming world, rather than focusing on longer-term threats.

"This is a very important step in the climate community," said Jason Furtado, assistant professor of meteorology at the University of Oklahoma, who reviewed the study but was not part of the research.

"We recognize that the effects of climate change are not only on long time scales, but are also present in short-term, high-impact weather events," said Furtado.

Still wet, dry and & # 39; weather whiplash & # 39;

Extreme It is expected that the wet years we experienced in California over the past two years will be 2.5 times more likely by the end of this century.

These types of seasons cause major infrastructure problems for the state, with frequent mudslides and damage to dams and dykes such as in Oroville. Currently, they occur about once every 25 years, but this rate will rise to more than one in 10 years by 2100.

The newspaper also found a significant increase in the number of dry years, a trend that has already been observed. 19659002] Extremely dry years (events of 100 years) that occurred in the years 1976-77 and 2013-14 will occur by 80% to 140% more frequently at the end of this century.

Although both of these findings are important on their own, the data yielded an even more interesting result: a frequent wild swing from an extremely dry to an extremely humid year, which the authors termed "precipitating whiplash" [19659002] These abrupt transitions were observed in the future at 50% to 100% more, with the most frequent fluctuations in Southern California.

Weather whiplash from wet to dry can cause explosive firing conditions, as increased vegetation from above-average rainfall years is parched during a very dry year. Regular Santa Ana winds are needed to fuel the flames, and the result is devastating forest fires.

On the other hand, when extremely wet seasons are extremely dry, deadly mudslides can be the result. Only last year in Montecito, heavy rains caused a mudslide in the blaze of the last forest fires, killing 20 people.

One trillion dollar disaster crops up

In addition to more extreme annual rainfall totals, the study examined how much rainfall occurred in shorter (40 day) periods, coinciding with the time of the California Great Flood of 1862 coincides.

"The Great Flood of 1862 was an extraordinary meteorological and hydrological event with no precedent in modern California," Swain said.

  Oroville Lake, the emergency overflow and damaged spillway on February 13, 2017.

[19659006Swaindescribedtheeventas"arelentlessforty-dayseriesof'atmosphericriverstorms'thatbroughtanalmostunimaginableamountofrainfalltotheentirestate"

Rain a total of 30 to 40 inches near the coast, with more than 100 inches on the western slopes of the Sierra Nevada. Much of the Central Valley has been converted into a vast inland sea over 250 miles in length, and according to Swain, now home to millions of people in the Sacramento Valley, the coastal Bay Area and Los Angeles / Orange Counties have sunk.

Although California has been fortunate enough to avoid repetition, its time could be short.

Prolonged storm episodes of the magnitude of the 1862 event will occur fivefold by the end of this century.

  A storm episode of the magnitude of the Great Flood of 1862 will be five times more common by 2100.

To put it in a nutshell, California's major urban centers, including San Francisco and Los Angeles, are "more likely to experience at least one of these catastrophic events between 2018 and 2060 Study says:

The US Geological Survey has examined exactly this scenario that is happening in modern times and calls it "the other big thing" in terms of the ubiquitous threat of another big earthquake in the state.

What a Another historic flood disaster would likely overwhelm California's flood control infrastructure, and the economic burden would be a trillion dollars – almost three times what most models estimate for a major Southern California earthquake.

CNN's Judson Jones contributed to this report.


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