氣候「鞭打」與洛杉磯肆虐的大火有關

In Southern California, wildfires are raging, and scientists have linked these fires to climate change. They explain that climate change has made the grasses and shrubs in the area more susceptible to burning. In recent years, the weather has fluctuated rapidly between dry and wet conditions, leading to an abundance of dry vegetation that is ready to catch fire. California experienced a long drought, followed by two years of heavy rainfall in 2022 and 2023. However, this was followed by a return to very dry conditions in the autumn and winter of 2024. According to scientists, climate change has increased what they refer to as 'whiplash' weather patterns globally by 31 to 66 percent since the mid-20th century. The wildfires have spread across parts of Los Angeles, resulting in at least five fatalities, the destruction of hundreds of buildings, and evacuation orders for over 179,000 residents. Daniel Swain, a lead author from UCLA, stated, 'This whiplash sequence in California has increased fire risk twofold. ' He explained that the rapid growth of flammable grass and brush in the months leading up to fire season, followed by extreme dryness and warmth, has created a perfect storm for wildfires. Researchers have found that with every degree of warming, the atmosphere can evaporate, absorb, and release 7 percent more water. This phenomenon, referred to as an 'expanding atmospheric sponge,' not only leads to flooding during wet periods but also extracts additional moisture from plants and soils during dry spells. Other researchers have emphasized that the volatility of precipitation and evaporation plays a significant role in driving both floods and fires. Professor Sir Brian Hoskins, Chair of the Grantham Institute for Climate Change at Imperial College London, remarked, 'It's clear from the devastation caused by the current wildfires in LA that rapid changes in the volatility of precipitation and evaporation can have a large impact. ' He also noted that climate models may underestimate the changes observed so far, but even those models suggest a doubling of volatility for a global temperature increase of 3 degrees Celsius, which is becoming increasingly likely. The new study adds to the growing body of evidence that a warmer climate has altered the conditions that contribute to the wildfires currently affecting Los Angeles. Much of the Western United States, including California, experienced a prolonged drought that ended just two years ago. The subsequent wet conditions led to the rapid growth of shrubs, grasses, and trees, which serve as fuel for fires. However, last summer was extremely hot, followed by a dry autumn and winter with minimal rainfall. Downtown Los Angeles has received only 0. 16 inches of rain since October, which is over four inches below average. Researchers believe that a warming world is creating conditions that are favorable for wildfires, including low humidity levels. These 'fire weather' days are increasing in many regions, with climate change intensifying these conditions and extending the fire season in various parts of the world. In California, the situation is exacerbated by the terrain, with fires burning more intensely and spreading rapidly in steep areas. This region is also characterized by naturally fire-prone shrub vegetation. Professor Stefan Doerr, Director of the Centre for Wildfire Research at Swansea University, stated, 'While fires are common and natural in this region, California has seen some of the most significant increases in the length and extremity of the fire weather season globally in recent decades, driven largely by climate change. ' However, he cautioned that it is too early to determine the extent to which climate change has made these specific fires more severe, and further detailed analysis will be necessary.