The distribution of fire on Earth has been monitored from space for several decades, yet the geography of global fire regimes has proven difficult to reproduce from interactions of climate, vegetation, terrain, land use and other human activities by empirical and process-based fire models. Here, we propose a simple, yet robust, model for the global distribution of fire potential based on fundamental biophysical constraints controlling fire activity in all biomes. In our ‘top-down’ approach we ignored the dynamics of individual fires and focus on capturing hydroclimatic constraints on the production and (seasonal) desiccation of fuels to predict the potential mean annual fractional burned area at 0.25 spatial resolution, here estimated by the 0.99 quantile of the observed mean annual fractional burned area () over the 1995-2016 period of the Global Fire Emissions Database (GFED4). We show that 80% of the global variation in can be explained from a combination of mean annual precipitation and potential evapotranspiration. The proposed hydroclimatic model reproduced observed 0.99 quantile fire activity levels equally well across all biomes and provided the first objective underpinning for the dichotomy of global fire regimes in two domains characterised by either fuel production limitations on fire or fuel dryness limitations on fire. A sharp transition between the two climate-fire domains was found to occur at a mean annual aridity index of 1.9 (1.940.02). Our model provides a simple but comprehensive basis for predicting fire potential under current and future climates, as well as an overarching framework for estimating effects of human activity via ignition regimes and manipulation of vegetation.

几十年来，人们一直在太空监测地球上的火势分布，但事实证明，全球火势的地理分布很难通过经验和基于过程的火模型从气候、植被、地形、土地利用和其他人类活动的相互作用中重现. 在这里，我们基于控制所有生物群落中火灾活动的基本生物物理约束，提出了一个简单而强大的火灾潜力全球分布模型。在我们的“自上而下”的方法中，我们忽略了个别火灾的动态，并专注于捕捉对燃料生产和（季节性）干燥的水文气候限制，以预测潜在的年均燃烧面积，空间分辨率为 0.25，这里估计为 0.99观测到的年均烧毁面积的分位数 () 1995-2016 年期间的全球火灾排放数据库 (GFED4)。我们表明 80% 的全球变化可以从年平均降水量和潜在蒸散量的组合来解释。拟议的水文气候模型在所有生物群落中同样很好地再现了观察到的 0.99 分位数火灾活动水平，并为两个领域的全球火灾状况的二分法提供了第一个目标基础，其特征是对火灾的燃料生产限制或对火灾的燃料干燥限制。发现两个气候火灾域之间的急剧转变发生在年平均干旱指数为 1.9 (1.940.02) 时。我们的模型为预测当前和未来气候下的火灾潜力提供了一个简单而全面的基础，并为通过点火机制和植被操纵来估计人类活动的影响提供了一个总体框架。