Abstract Fire is a fundamental Earth system process and the primary ecosystem disturbance on the global scale. It affects carbon and water cycles through changing terrestrial ecosystems, and at the same time, is regulated by weather and climate, vegetation characteristics, and, importantly, human ignitions and suppression (i.e., the direct human effect on fire). Here, we utilize the Community Land Model version 4.5 (CLM4.5) to quantify the impacts of changes in human ignition and suppression on fire dynamics and associated carbon and water cycles. We find that the impact is to significantly reduce the 20th century global burned area by a century average of 38 Mha/yr and by 103 Mha/yr at the end of the century. Land carbon gain is weakened by 17% over the 20th century, mainly due to increased human deforestation fires and associated escape fires (i.e., degradation fires) in the tropical humid forests, even though the decrease in burned area in many other regions due to human fire suppression acts to increase land carbon gain. The direct human effect on fire weakens the upward trend in global runoff throughout the century by 6% and enhances the upward trend in global evapotranspiration since ~ 1945 by 7%. In addition, the above impacts in densely populated, highly developed (if population density > 0.1 person/km2), or moderately populated and developed regions are of opposite sign to those in other regions. Our study suggests that particular attention should be paid to human deforestation and degradation fires in the tropical humid forests when reconstructing and projecting fire carbon emissions and net atmosphere-land carbon exchange and estimating resultant impacts of direct human effect on fire.

中文翻译：

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人类对 20 世纪火灾动态的影响以及对全球碳和水轨迹的影响

摘要 火是地球系统的基本过程，是全球范围内主要的生态系统扰动。它通过改变陆地生态系统影响碳和水循环，同时受天气和气候、植被特征以及重要的是人类点火和抑制（即人类对火灾的直接影响）的调节。在这里，我们利用社区土地模型版本 4.5 (CLM4.5) 来量化人类点火和抑制变化对火灾动力学和相关碳和水循环的影响。我们发现，其影响是将 20 世纪全球燃烧面积显着减少，本世纪末平均减少 38 兆公顷/年，减少 103 兆公顷/年。在 20 世纪，土地碳增加减少了 17%，主要是由于人类砍伐森林的火灾和相关的逃生火灾增加（即。例如，热带潮湿森林中的退化火灾），尽管由于人类灭火导致许多其他地区的燃烧面积减少会增加土地碳增加。人类对火灾的直接影响使整个世纪全球径流的上升趋势减弱了 6%，并使自 1945 年以来全球蒸散量的上升趋势增强了 7%。此外，在人口稠密、高度发达（如果人口密度>0.1 人/km2）或中等人口和发达地区，上述影响与其他地区相反。