Extreme wildfires are a significant cause of human death and biodiversity destruction within countries that encompass the Mediterranean Basin. Recent worrying trends in wildfire activity (i.e., occurrence and spread) suggest that wildfires are likely to be highly impacted by climate change. In order to facilitate appropriate risk mitigation, we must identify the main drivers of extreme wildfires and assess their spatio-temporal trends, with a view to understanding the impacts of global warming on fire activity. We analyse the monthly burnt area due to wildfires over a region encompassing most of Europe and the Mediterranean Basin from 2001 to 2020, and identify high fire activity during this period in Algeria, Italy and Portugal. We build an extreme quantile regression model with a high-dimensional predictor set describing meteorological conditions, land cover usage, and orography. To model the complex relationships between the predictor variables and wildfires, we use a hybrid statistical deep-learning framework that can disentangle the effects of vapour-pressure deficit (VPD), air temperature, and drought on wildfire activity. Our results highlight that whilst VPD, air temperature, and drought significantly affect wildfire occurrence, only VPD affects wildfire spread. To gain insights into the effect of climate trends on wildfires in the near future, we focus on August 2001 and perturb temperature according to its observed trends (median over Europe: +0.04K per year). We find that, on average over Europe, these trends lead to a relative increase of 17.1\% and 1.6\% in the expected frequency and severity, respectively, of wildfires in August 2001, with spatially non-uniform changes in both aspects.

翻译：极端野火是地中海盆地国家内造成人类死亡和生物多样性破坏的重要原因。近期野火活动（即发生与蔓延）令人担忧的趋势表明，气候变化对野火具有显著影响。为促进适当风险缓解措施的实施，我们必须识别极端野火的主要驱动因素并评估其时空趋势，以理解全球变暖对野火活动的影响。我们分析了2001至2020年间涵盖欧洲大部分地区及地中海盆地的月度野火烧毁面积，并确定了该时期内阿尔及利亚、意大利和葡萄牙的高野火活动。我们构建了一个极端分位数回归模型，其高维预测因子集描述了气象条件、土地利用类型和地形。为模拟预测因子与野火间的复杂关系，我们采用混合统计深度学习框架，能够解耦饱和水汽压差、气温和干旱对野火活动的影响。研究结果表明，饱和水汽压差、气温和干旱显著影响野火发生，但仅饱和水汽压差影响野火蔓延。为深入理解近期气候趋势对野火的影响，我们聚焦于2001年8月，并根据观测趋势（欧洲中位数：每年+0.04K）对气温进行扰动。研究发现，在欧洲范围内，这些趋势导致2001年8月野火预期发生频率和严重程度分别相对增加17.1%和1.6%，且两方面均呈现空间非均匀性变化。