Abstract. Climate change is increasing the frequency and intensity of wildfires globally, with significant impacts on society and the environment. However, our understanding of the global distribution of extreme fires remains skewed, primarily influenced by media coverage and regional research concentration. This inaugural State of Wildfires report systematically analyses fire activity worldwide, identifying extreme events from the March 2023–February 2024 fire season. We assess the causes, predictability, and attribution of these events to climate change and land use, and forecast future risks under different climate scenarios. During the 2023–24 fire season, 3.9 million km² burned globally, slightly below the average of previous seasons, but fire carbon (C) emissions were 16 % above average, totaling 2.4 Pg C. This was driven by record emissions in Canadian boreal forests (over 9 times the average) and dampened by reduced activity in African savannahs. Notable events included record-breaking wildfire extent and emissions in Canada, the largest recorded wildfire in the European Union (Greece), drought-driven fires in western Amazonia and northern parts of South America, and deadly fires in Hawai’i (100 deaths) and Chile (131 deaths). Over 232,000 people were evacuated in Canada alone, highlighting the severity of human impact. Our analyses revealed that multiple drivers were needed to cause areas of extreme fire activity. In Canada and Greece a combination of high fire weather and an abundance of dry fuels increased the probability of fires by 4.5-fold and 1.9–4.1-fold, respectively, whereas fuel load and direct human suppression often modulated areas with anomalous burned area. The fire season in Canada was predictable three months in advance based on the fire weather index, whereas events in Greece and Amazonia had shorter predictability horizons. Formal attribution analyses indicated that the probability of extreme events has increased significantly due to anthropogenic climate change, with a 2.9–3.6-fold increase in likelihood of high fire weather in Canada and a 20.0–28.5-fold increase in Amazonia. By the end of the century, events of similar magnitude are projected to occur 2.22–9.58 times more frequently in Canada under high emission scenarios. Without mitigation, regions like Western Amazonia could see up to a 2.9-fold increase in extreme fire events. For the 2024–25 fire season, seasonal forecasts highlight moderate positive anomalies in fire weather for parts of western Canada and South America, but no clear signal for extreme anomalies is present in the forecast. This report represents our first annual effort to catalogue extreme wildfire events, explain their occurrence, and predict future risks. By consolidating state-of-the-art wildfire science and delivering key insights relevant to policymakers, disaster management services, firefighting agencies, and land managers, we aim to enhance society’s resilience to wildfires and promote advances in preparedness, mitigation, and adaptation.

中文翻译：

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2023–24 年野火状况


摘要。气候变化正在增加全球野火的频率和强度，对社会和环境产生重大影响。然而，我们对极端火灾全球分布的理解仍然存在偏差，这主要受到媒体报道和区域研究集中度的影响。这份首份《野火状况》报告系统分析了全球火灾活动，确定了 2023 年 3 月至 2024 年 2 月火灾季节的极端事件。我们评估这些事件的原因、可预测性以及气候变化和土地利用的归因，并预测不同气候情景下的未来风险。在 2023-24 火灾季节，全球燃烧了 390 万平方公里 ² ，略低于前几个季节的平均水平，但火灾碳 (C) 排放量比平均水平高出 16%，总计 2.4 Pg C。加拿大北方森林创纪录的排放量（超过平均水平的 9 倍）以及非洲大草原活动减少的影响。值得注意的事件包括加拿大创纪录的野火范围和排放量、欧盟（希腊）有记录的最大野火、亚马逊西部和南美洲北部地区干旱引发的火灾以及夏威夷致命火灾（100 人死亡）和智利（131 人死亡）。仅在加拿大就有超过 232,000 人被疏散，凸显了人类影响的严重性。我们的分析表明，需要多个驱动因素才能引发极端火灾活动。在加拿大和希腊，高火灾天气和大量干燥燃料的结合使火灾发生的概率分别增加了 4.5 倍和 1.9-4.1 倍，而燃料负载和直接人类压制往往会调节异常燃烧面积的区域。 根据火灾天气指数，加拿大的火灾季节可以提前三个月预测，而希腊和亚马逊地区的火灾季节可预测范围较短。正式归因分析表明，由于人为气候变化，极端事件的可能性显着增加，加拿大发生高火灾天气的可能性增加了 2.9-3.6 倍，亚马逊流域增加了 20.0-28.5 倍。到本世纪末，在高排放情景下，加拿大发生类似规模事件的频率预计将增加 2.22-9.58 倍。如果不采取缓解措施，亚马逊西部地区等地区的极端火灾事件可能会增加 2.9 倍。对于 2024-25 年火灾季节，季节性预报强调加拿大西部和南美洲部分地区的火灾天气出现中度正异常，但预报中没有出现极端异常的明确信号。这份报告是我们首次对极端野火事件进行分类、解释其发生并预测未来风险的年度工作。通过整合最先进的野火科学并提供与政策制定者、灾害管理服务、消防机构和土地管理者相关的关键见解，我们的目标是增强社会对野火的抵御能力，并促进备灾、减灾和适应方面的进步。