Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest
Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest
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DOI：
10.1073/pnas.0804619106
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发表时间：
2009-12-08
影响因子：
11.1
通讯作者：
Meir, Patrick
中科院分区：
文献类型：
--
作者：
Malhi, Yadvinder;Aragao, Luiz E. O. C.;Meir, Patrick
我们研究了21世纪气候变化可能导致亚马逊雨林大规模“枯死”或退化的可能性。我们采用了一个新的框架来评估热带森林的降雨制度，并由此推断出目前森林生存能力的降水边界。然后，我们研究了19个全球气候模型（GCM）在这种情况下的气候模拟，发现大多数倾向于低估目前的降雨量。大气环流模式对亚马逊河流域未来气候变化的预测也有很大差异。我们试图考虑到在20世纪世纪的GCM模拟和观测到的降雨制度之间的差异。我们的分析表明，旱季水分胁迫可能会增加E。亚马逊河流域的气候在世纪逐渐变暖，但该地区的气候更适合季节性森林，而不是热带稀树草原。这些季节性森林可能对季节性干旱有抵抗力，但很可能面临因气温升高而加剧的缺水问题，并容易发生火灾，而目前在亚马逊河流域的大部分地区，火灾在自然界是罕见的。与森林砍伐、伐木和破碎化有关的火灾蔓延可能成为核化点，触发这些季节性森林过渡到以火灾为主的低生物量森林。相反，故意限制森林砍伐和火灾可能是一种有效的干预措施，以保持亚马逊森林在面对21世纪气候变化时的复原力。这种干预可能足以导航E。亚马逊远离一个可能的“临界点”，超过这个临界点，大片的雨林将变得不可持续。
We examine the evidence for the possibility that 21st-century climate change may cause a large-scale "dieback'' or degradation of Amazonian rainforest. We employ a new framework for evaluating the rainfall regime of tropical forests and from this deduce precipitation-based boundaries for current forest viability. We then examine climate simulations by 19 global climate models (GCMs) in this context and find that most tend to underestimate current rainfall. GCMs also vary greatly in their projections of future climate change in Amazonia. We attempt to take into account the differences between GCM-simulated and observed rainfall regimes in the 20th century. Our analysis suggests that dry-season water stress is likely to increase in E. Amazonia over the 21st century, but the region tends toward a climate more appropriate to seasonal forest than to savanna. These seasonal forests may be resilient to seasonal drought but are likely to face intensified water stress caused by higher temperatures and to be vulnerable to fires, which are at present naturally rare in much of Amazonia. The spread of fire ignition associated with advancing deforestation, logging, and fragmentation may act as nucleation points that trigger the transition of these seasonal forests into fire-dominated, low biomass forests. Conversely, deliberate limitation of deforestation and fire may be an effective intervention to maintain Amazonian forest resilience in the face of imposed 21st-century climate change. Such intervention may be enough to navigate E. Amazonia away from a possible "tipping point,'' beyond which extensive rainforest would become unsustainable.