![]() “The fire weather changes driven by declining Arctic sea ice during the past four decades are of similar magnitude to other leading modes of climate variability, such as the El Niño-Southern Oscillation, that also influence fire weather in the western US.” He tells Carbon Brief that the impact of melting sea ice on US wildfires is comparable to that of other, better known drivers: Dr Hailong Wang, an Earth scientist at the Pacific Northwest National Laboratory, is an author on the study. The plot shows that when sea ice concentrations are low, the fire favourable circulation index and fire weather index are generally high. Red shading indicates years with low sea ice concentration while blue shading indicates periods with high sea ice concentration. Plot showing changes in sea ice concentration (SIC, blue), fire weather index (FFWI, red) and fire-favourable circulation index (Z500i, yellow) over 1979-2015. Note that the y-axis for SIC is inverted, with low sea ice concentration at the top of the scale and high sea ice concentration at the bottom. It shows changes in sea ice concentration (blue), a fire weather index (red) a fire-favourable circulation index (yellow) over 1979-2020, where red shading indicates low sea ice concentration and blue sharing indicates high sea ice concentration. The plot below highlights the link between low sea ice concentration and fire-favourable weather. These results are bad news, as sea ice is expected to continue its downward spiral because our emissions of heat-trapping, ice-melting gases show no signs of abating.” “Diminishing sea ice favours hotter, drier conditions in western states that set the stage for fierce wildfires, such as those scorching the region during recent years. She summarises the teleconnection and tells Carbon Brief why it is significant in a warming climate: While these two impacts may seem unrelated, a new study – using a range of observations, sensitivity tests and targeted model runs – suggests that they are linked through a pattern of large-scale atmospheric pressure and circulation changes called a “teleconnection”.ĭr Jennifer Francis is the acting deputy director at the Woodwell Climate research centre and was not involved in the research. California’s August Complex fire, which consumed more than 1m acres alone, became the first-ever giga-fire in 2020.” Last year, Arizona saw the most acres burned in its history. Eight of the top 20 fires in Oregon occurred in that time frame too. “More than half of the 20 largest fires in California history burned in just the last four years. Meanwhile, a recent Guardian article says: A 2018 Carbon Brief factcheck found that “most of the area burned today is in the western US, where drier conditions tend to allow for large, quickly-spreading wildfires”. Meanwhile, hotter and drier weather is driving wildfires to tear through parts of the US with increasing intensity and frequency. Over the past 15 years, scientists have recorded the 15 lowest Arctic sea ice extents in the satellite record, while September of this year marked the lowest level of “multi-year” Arctic sea ice on record. The Arctic is warming more than twice as fast (pdf) as the global average, driving rapid sea ice loss. ![]() The impacts of climate change are diverse, affecting different parts of the world in different ways. Meanwhile, a separate study published in Nature Climate Change finds that extreme wildfire activity has increased globally over 1979-2020 – mainly driven by decreasing humidity and increasing temperatures.Īs the climate warms and fire weather becomes “more extreme”, there may be “more catastrophic fires” stretching across larger regions, the authors warn. ![]() They add that this mechanism may strengthen over the coming decades as the Arctic melts further, making the western US “even more susceptible to destructive fire hazards”. This tends to bring hotter and drier conditions in the western US over the following autumn, resulting in more frequent and intense fires in the region, the authors find. The study, published in Nature Communications, finds that low Arctic sea ice levels during July to October have knock-on impacts in the atmosphere that push the jet stream northwards. Arctic sea ice melt has driven an increase in “fire-favourable weather” across the western US over the past four decades, according to new research.
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