Fires in the wildland-urban interface (WUI) are an important issue globally. To understand the change of WUI, we develop a 9 km worldwide unified wildland-urban interface database for 2001–2020 with Random Forest models and satellite data. We find that WUI has been increasing in all populated continents from 2001 to 2020 and the global relative increase is 24%, with the largest relative increase (∼59%) over Africa. Global total fire counts decrease by 10% from 2005 to 2020, whereas the WUI fraction of fire counts increases by 23%. The global total burned area decreases by 22% from 2005 to 2020, whereas the WUI fraction of burned area increases by 35%. These are mainly due to the expansion of WUI area. On all the populated continents, the WUI fractions of fire counts are higher than the WUI fractions of burned area, implying that WUI fires tend to have smaller sizes than wildland fires. We also project future WUI changes for the years 2030 and 2040, together with the projection of future fire burned area under different shared socioeconomic pathways (SSP) scenarios in the Community Earth System Model version 2 (CESM2). The projected global WUI fraction (excluding Antarctica and the oceans) is 5.9% in 2040 compared to 4.8% in 2020. The global WUI fraction of burned area is projected to increase from now to 2040 under most scenarios analyzed in this study, unless the WUI area stays at the 2020 level together with the projected burned area under SSP4-4.5. This study is a first step to understanding the changes of WUI fires at the global scale and demonstrates a growing importance of WUI fires. The global multi-year WUI and WUI fire datasets developed in this study can facilitate future work quantifying the impacts of WUI fires on air quality and climate.

中文翻译：

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荒地-城市界面 (WUI) 和 WUI 火灾的全球扩张：来自多年全球统一数据库 (WUWUI) 的见解

荒地与城市交界处（WUI）的火灾是全球性的一个重要问题。为了了解WUI的变化，我们利用随机森林模型和卫星数据开发了2001-2020年9公里全球统一荒地-城市界面数据库。我们发现，从 2001 年到 2020 年，所有人口稠密大陆的 WUI 都在增加，全球相对增幅为 24%，其中非洲相对增幅最大（~59%）。从 2005 年到 2020 年，全球火灾总数减少了 10%，而 WUI 火灾数比例增加了 23%。 2005 年至 2020 年，全球总烧毁面积减少了 22%，而 WUI 烧毁面积比例则增加了 35%。这主要是由于WUI面积的扩大。在所有人口稠密的大陆上，火灾数量的 WUI 分数高于烧毁面积的 WUI 分数，这意味着 WUI 火灾的规模往往小于荒地火灾。我们还预测了 2030 年和 2040 年未来 WUI 的变化，以及社区地球系统模型版本 2 (CESM2) 中不同共享社会经济路径 (SSP) 情景下未来火灾烧毁面积的预测。预计 2040 年全球 WUI 比例（不包括南极洲和海洋）为 5.9%，而 2020 年为 4.8%。在本研究分析的大多数情景下，全球 WUI 比例预计从现在到 2040 年将增加，除非 WUI面积以及 SSP4-4.5 下预计烧毁面积保持在 2020 年水平。这项研究是了解全球范围内 WUI 火灾变化的第一步，并表明 WUI 火灾的重要性日益增加。本研究中开发的全球多年 WUI 和 WUI 火灾数据集可以促进未来量化 WUI 火灾对空气质量和气候影响的工作。