There is mounting concern that global wildfire activity is shifting in frequency, intensity, and seasonality in response to climate change. Fuel moisture provides a powerful means of detecting changing fire potential. Here, we use global burned area, weather reanalysis data, and the Canadian fire weather index system to calculate fuel moisture trends for multiscale biogeographic regions across a gradient in vegetation productivity. We quantify the proportion of days in the local fire season between 1979 and 2019, where fuel moisture content is below a critical threshold indicating extreme fire potential. We then associate fuel moisture trends over that period to vegetation productivity and comment on its implications for projected anthropogenic climate change. Overall, there is a strong drying trend across realms, biomes, and the productivity gradient. Even where a wetting trend is observed, this often indicates a trend toward increasing fire activity due to an expected increase in fuel production. The detected trends across the productivity gradient lead us to conclude global fire activity will increase with anthropogenic climate change.

中文翻译：

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由于气候驱动的燃料水分下降，全球野火风险增加

人们越来越担心全球野火活动的频率、强度和季节性因气候变化而发生变化。燃料水分提供了检测变化的火势的有力手段。在这里，我们使用全球燃烧面积、天气再分析数据和加拿大火灾天气指数系统来计算跨植被生产力梯度的多尺度生物地理区域的燃料水分趋势。我们量化了 1979 年至 2019 年间当地火灾季节的天数比例，其中燃料水分含量低于表明极端火灾可能性的临界阈值。然后，我们将那个时期的燃料水分趋势与植被生产力联系起来，并评论其对预计的人为气候变化的影响。总体而言，跨领域、生物群落、和生产力梯度。即使在观察到润湿趋势的情况下，这通常也表明由于燃料产量的预期增加而导致火灾活动增加的趋势。通过生产力梯度检测到的趋势使我们得出结论，全球火灾活动将随着人为气候变化而增加。