Increasing wildfires threaten progress on halting deforestation in Brazilian Amazonia.
Increasing wildfires threaten progress on halting deforestation in Brazilian Amazonia.
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不断增加的野火威胁着巴西亚马逊流域阻止森林砍伐的进展。
DOI：
10.1038/s41559-023-02233-3
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发表时间：
2023
影响因子：
16.8
通讯作者：
De Oliveira G
中科院分区：
文献类型：
--
作者：
De Oliveira G
可持续地管理亚马逊地区对于减缓全球气候变化和保护该地区的生物和文化多样性至关重要。在2010年代承诺减少退化之后，过去5年土地转换和森林砍伐回到历史高水平，严重破坏了这些目标。这种土地转换——主要是伐木、采矿和放牧的结果——已经产生了跨尺度的社会、经济和环境负担。令人鼓舞的是，在巴西现任联邦政府的领导下，对亚马逊的保护出现了复苏的迹象。但随着森林砍伐的减少，一个新的威胁正在上升：不受控制的火灾。巴西国家空间研究所（INPE）的TerraBrasilis网站提供了关于亚马逊和塞拉多生物群落的森林砍伐、森林覆盖变化和活跃火灾的交互式数据地图。例如，报告显示，2023年森林砍伐率已经下降——1月至7月的森林砍伐警报比2022年同期下降了42%。此外，威胁生态系统和土著社区（特别是在雅诺马米地区）的主要非法采矿活动正在受到限制。自卢拉总统于2023年1月掌舵以来，巴西政府实施了政策和执法行动，其中最引人注目的是恢复了“合法亚马逊地区预防和控制森林砍伐行动计划”（PPCDAm）。然而，这种减少的直接原因尚不清楚。一些分析人士认为，在前总统博尔索纳罗（Bolsonaro）政府时期形成的对非法砍伐森林不受惩罚的感觉，已经被对制裁的恐惧所取代，这一点从恢复PPCDAm就可以看出。另一些人则认为，森林砍伐的罪魁祸首正在评估新的政治格局。尽管有迹象表明森林砍伐有所减少，但亚马逊地区仍面临着野火的肆虐。尽管历史上罕见，但气候变化下的干旱和热浪——加上主要由农业企业驱动的森林砍伐和破碎化——使火灾成为亚马逊地区退化和森林损失的主要原因。2023年6月，亚马逊地区的活火数量达到3075起，是自2007年6月以来的最高水平，2007年6月有3519起火灾（参考文献4）。2023年上半年的火灾总数为8344起，比2022年前六个月的7533起火灾高出10.76%（参考文献4）。此前火灾数量的飙升（包括2022年8月和9月创纪录的非干旱年份的火灾）与不受控制的森林砍伐有关，森林砍伐是火灾的主要来源，也是燃烧面积的有力预测指标。在森林砍伐减少的背景下，今年火灾数量高企且不断攀升，突显了森林火灾与森林砍伐的脱钩；事实上，TerraBrasilis的数据显示，2023年1月至6月期间，只有19%的火灾与最近的森林砍伐有关（低于2022年的39%）。2023年厄尔尼诺现象Niño导致的更热更干燥的气候条件已经影响到亚马逊的部分地区，并可能增加火灾，这与之前的厄尔尼诺现象Niños 7一致。额外的压力可能会影响火灾数量，包括前总统博尔索纳罗（bolsonaro）领导下环境法律执行不力导致的森林砍伐热潮的滞后效应——近年来被机械砍伐的一些森林地区现在才变得干燥到可以燃烧。最后，土地所有者可能会在旱季提前烧掉牧场，因为他们预计会发生火灾……
Sustainably managing the Amazon region is essential to mitigating global climate change and to preserving the biological and cultural diversity of the region. After promising reductions in degradation in the 2010s, a return to historically high levels of land conversion and deforestation during the past 5 years has severely undermined these goals. This land conversion—primarily the result of logging, mining and ranching—has generated social, economic and environmental burdens across scales 1. Encouragingly, signs of recovery towards Amazon protection are appearing under Brazil’s current federal administration. But amid the drop in deforestation, a new threat is on the rise: uncontrolled fires. The TerraBrasilis website of the Brazilian National Institute for Space Research (INPE) provides interactive maps of data on deforestation, forest-cover change and active fires across the Amazon and the Cerrado biomes 2. It shows, for example, that 2023 has already seen falling deforestation rates—deforestation alerts were 42% lower between January and July than in the same period of 2022. Additionally, major illegal mining operations that threaten the ecosystem and Indigenous communities (particularly in Yanomami territory) are being curtailed 3. This decrease in deforestation follows policy and enforcement actions carried out under the Brazilian government since President Lula took the helm in January 2023, most notably the reinstatement of the ‘Action Plan for Preventing and Controlling Deforestation in the Legal Amazon’(PPCDAm). However, the proximate causes of this decrease remain unclear. Some analysts suggest that a sense of impunity for illegal deforestation that developed under former president Bolsonaro’s administration has been replaced with a fear of sanction—signalled by the reinstatement of the PPCDAm. Others believe the slowdown represents a hiatus in which actors who are responsible for deforestation are assessing the new political landscape. Despite promising signs of reduced deforestation, Amazonia faces surging wildfire. Although rare historically, drought and heat waves under climate change—combined with deforestation and fragmentation driven largely by agribusiness—have transformed fire into a leading cause of degradation and forest loss in Amazonia 1. In June 2023, the number of active fires in the Amazon reached 3,075, the highest for this month since June 2007, which had 3,519 fires (ref. 4). Total fire counts for the first half of 2023 were 8,344, 10.76% higher than the 7,533 fires during the first six months of 2022 (ref. 4). Previous spikes in fire counts (including the record-breaking fires for a non-drought year in August and September of 2022) were associated with uncontrolled deforestation 5, a primary source of fire and a strong predictor of burned area. This year’s high and climbing fire counts in the context of reduced deforestation highlight a decoupling of forest fires from deforestation; indeed, TerraBrasilis data show that only 19% of the fires were related to recent deforestation during January–June 2023 (down from 39% in 2022).Hotter and drier climate conditions resulting from the 2023 El Niño are already affecting portions of the Amazon 6 and may be increasing fires, consistent with previous El Niños 7. Additional pressures may be affecting fire counts, including the lag effect of the deforestation boom associated with weakened enforcement of environmental laws under former president Bolsonaro—some areas of forest that were mechanically slashed in recent years are only now becoming dry enough to burn. Finally, landholders may be burning pastures earlier in the dry season 8 in anticipation of a fire …