Technical note: Low meteorological influence found in 2019 Amazonia fires
Technical note: Low meteorological influence found in 2019 Amazonia fires
复制标题
DOI：
10.5194/bg-18-787-2021
复制
发表时间：
2021-02-04
期刊：
影响因子：
4.9
通讯作者：
Dong, Ning
中科院分区：
文献类型：
--
作者：
Kelley, Douglas, I;Burton, Chantelle;Dong, Ning
亚马逊火灾在2019年火灾季节早期突然增加，成为全球头条新闻。虽然有大量推测认为火灾是由人为点火或人为引起的景观变化引起的，但也有人认为气象条件可能发挥了作用。在这里，我们提出两个问题：2019年亚马逊地区发生的火灾在历史记录中是前所未有的吗？气象条件是否导致了燃烧加剧？为了回答这个问题，我们利用最近开发的建模框架，优化了一个简单的火灾模型对燃烧面积的观测，其输出被描述为概率密度。这使我们能够测试2019年火灾季节仅因气象条件而发生的概率。观察结果表明，在亚马逊地区已经有大量森林砍伐活动的地区，被烧毁的面积高于往年。总体而言，自我们的观测记录开始以来，11%的地区记录了最高的早期（6月至8月）烧毁面积，巴西中部森林砍伐弧的地区在8月份记录了有史以来最高的月度烧毁面积。然而，大面积森林砍伐地区以外的地区显示出比历史平均水平更少的烧毁面积，优化模型显示，这种低烧毁面积将扩展到亚马逊东部的大部分地区，包括巴西的森林砍伐中心弧，2019年火灾发生率很高。我们发现，有9%的可能性，观察到的8月火灾是由气象条件单独，下降到6%-7%沿着巴西中部各州的农业湿润森林界面和8%，在巴拉圭和玻利维亚干燥森林。我们的研究结果表明，土地利用、覆盖或管理的变化可能是2019年火灾季节早期烧毁面积大幅增加的驱动因素，特别是在巴西。9月份森林砍伐弧中的烧毁面积有14%-26%的可能性是由气象条件造成的，这可能与南美政府火灾相关政策的转变相吻合。
The sudden increase in Amazon fires early in the 2019 fire season made global headlines. While it has been heavily speculated that the fires were caused by deliberate human ignitions or human-induced landscape changes, there have also been suggestions that meteorological conditions could have played a role. Here, we ask two questions: were the 2019 fires in the Amazon unprecedented in the historical record, and did the meteorological conditions contribute to the increased burning? To answer this, we take advantage of a recently developed modelling framework which optimises a simple fire model against observations of burnt area and whose outputs are described as probability densities. This allowed us to test the probability of the 2019 fire season occurring due to meteorological conditions alone. The observations show that the burnt area was higher than in previous years in regions where there is already substantial deforestation activity in the Amazon. Overall, 11 % of the area recorded the highest early season (June-August) burnt area since the start of our observational record, with areas in Brazil's central arc of deforestation recording the highest ever monthly burnt area in August. However, areas outside of the regions of widespread deforestation show less burnt area than the historical average, and the optimised model shows that this low burnt area would have extended over much of the eastern Amazon region, including in Brazil's central arc of deforestation with high fire occurrence in 2019. We show that there is a 9 % likelihood of the observed August fires being caused by meteorological conditions alone, decreasing to 6 %-7 % along the agricultural-humid forest interface in Brazil's central states and 8 % in Paraguay and Bolivia dry forests. Our results suggest that changes in land use, cover or management are the likely drivers of the substantial increase in the 2019 early fire season burnt area, especially in Brazil. Burnt area for September in the arc of deforestation had a 14 %-26 % probability of being caused by meteorological conditions, potentially coinciding with a shift in fire-related policy from South American governments.