Thursday, 15 Nov 2018
News

The weather and climate behind the flaming hell that destroyed paradise

A firefighter takes cover as the wind burns as the campfire rages through paradise, fueled by strong winds in Butte County, California on November 8th. (Peter Dasilva / EPA-EFE / REX) the city of Paradise, Cali. Thursday in the form of smoke and flames engulfed the city which is now in ruins. Sparked just six hours earlier, the completely unconfined hell consumed about 20,000 acres exactly one day later. A second fire, dubbed the Woosley fire in southern California, has reached 8,000 acres since its inception on Thursday night. How do these types of forest fires grow so explosively? Lean rains, warm temperatures, strong winds and abundant fuel are to blame for the powder-burning conditions that fueled the flames. And in a rapidly changing environment characterized by rising temperatures, climate change is also playing a role. The California fire season usually begins in late spring, late May and early June. This lasts until the arrival of the winter rains, in November or December, when the "atmospheric rivers" carry tropical moisture into the otherwise arid region. But this fall, the hot, dry weather has persisted longer and the rains have not yet arrived, which is a trend that is likely to lengthen the wildfire season. "[T]The fact that things are still hot, windy and extremely dry is becoming more and more unusual as we approach mid-November, " tweeted Daniel Swain, climatologist at the University of California at Los Angeles. In an email, Swain said climate change had "shortened the rainy season at both ends and caused significant aridification. [drying] regional vegetation. When it's dry, Santa Ana, a seasonal breeze that can crescendo to become a complete storm, constitutes a serious hazard. Winds swirl around a semi-permanent high pressure ridge that sits every summer in northern Sierra Nevada, around Reno. Turning counter-clockwise, this system pushes the wind into the mountain range from west to coast. When the air goes down, it is compressed due to the increased weight of the atmosphere – and then warms up. But this "downstream" warmth dries the air and relative humidity percentages can reach single-digit values. It is this process that introduces a very dry air mass into the densely populated backbone of the Golden State. Thursday, the National Weather Service Office serving the San Francisco Bay Area Record record low levels of atmospheric moisture for the period of the year. These descending dry winds are often accompanied by winds of 100 km / h. When the Santa Ana winds arrive, any seemingly innocuous flame can quickly become deadly. The warming climate only makes the weather hotter and dryer – more sensitive to fire winds – more extreme. It intensifies a process called evapotranspiration in which plants release water into the air. The hotter the air, the more plants release water. These warmer temperatures result in dewatering of the vegetation, strewing the ground with vivid and brittle plant matter ready to fuel a fire. The soil also lacks moisture, providing little protection against the spread of fires. "[L]The ocal vegetation was at record drought levels for the time of year when the fire started, and that's partly why this event eventually became as serious as it was, "said Swain . California is warming up fast. Faster than many other states. The period from January to October is ranked as the fourth hottest ever recorded. The five hottest years ever recorded have all occurred in the last five years. The California climate change assessment predicts a daily average temperature increase of 5.6 to 8.8 degrees by 2100, well above the national average. Los Angeles, California has warmed by 3.2 degrees since the 1940s. Further north, the increase has been even more remarkable. As temperatures warmed, precipitation remained stable or decreased, causing additional drying of vegetation. With the onset of hot and dry conditions earlier and winter precipitation falling in shorter but more intense gusts, the terrain is ready for routine drought during the summer months. Last year, the US Department of Agriculture announced that a record 129 million trees – "mostly conifers" – died as a result of the drought. The agency cited an "increased threat of a forest fire" for 2018 in its December 2017 report, adding that 56% of its national budget was spent on firefighting efforts. With the approach of the 2018 fire season, experts already knew it would be a bad thing. "The total number of dead trees [surged to] a history of 8.9 million acres. But the last piece of the puzzle? Where we build Regardless of climate change, forest fires will inevitably require more structures if we continue to build and expand their goals. Experts refer to the urban-wildlife interface – WUI – the radius of about half a kilometer located on the outskirts of the community where forests and human beings "meet." According to an article published in the Proceedings of the National Academy of Sciences in March, there is a 41% increase in the number of homes built in the EUI between 1990 and 2010, totaling 43.4 million homes. This, explain the authors, could be a serious problem. "The problems with forest fires will not be alleviated if the recent trend of housing growth persists." Swain said the intrusion of wildfires in populated urban areas "was very rare in the past, but that it was occurring at an alarming frequency" change, leading the trend toward larger fires and more destructive in California.

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