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首页> 美国卫生研究院文献>Proceedings of the National Academy of Sciences of the United States of America >From the Cover: Medieval warming initiated exceptionally large wildfire outbreaks in the Rocky Mountains
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From the Cover: Medieval warming initiated exceptionally large wildfire outbreaks in the Rocky Mountains

机译：从封面开始：中世纪变暖在落基山脉引发了特大火灾

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Many of the largest wildfires in US history burned in recent decades, and climate change explains much of the increase in area burned. The frequency of extreme wildfire weather will increase with continued warming, but many uncertainties still exist about future fire regimes, including how the risk of large fires will persist as vegetation changes. Past fire-climate relationships provide an opportunity to constrain the related uncertainties, and reveal widespread burning across large regions of western North America during past warm intervals. Whether such episodes also burned large portions of individual landscapes has been difficult to determine, however, because uncertainties with the ages of past fires and limited spatial resolution often prohibit specific estimates of past area burned. Accounting for these challenges in a subalpine landscape in Colorado, we estimated century-scale fire synchroneity across 12 lake-sediment charcoal records spanning the past 2,000 y. The percentage of sites burned only deviated from the historic range of variability during the Medieval Climate Anomaly (MCA) between 1,200 and 850 y B.P., when temperatures were similar to recent decades. Between 1,130 and 1,030 y B.P., 83% (median estimate) of our sites burned when temperatures increased ∼0.5 °C relative to the preceding centuries. Lake-based fire rotation during the MCA decreased to an estimated 120 y, representing a 260% higher rate of burning than during the period of dendroecological sampling (360 to −60 y B.P.). Increased burning, however, did not persist throughout the MCA. Burning declined abruptly before temperatures cooled, indicating possible fuel limitations to continued burning.
机译：近几十年来，美国历史上许多最大的野火都在燃烧，而气候变化是造成燃烧面积增加的主要原因。极端野火天气的频率将随着持续变暖而增加，但是未来的火灾情况仍存在许多不确定性，包括随着植被的变化，大火的风险将如何持续。过去的火灾-气候关系提供了一个机会来限制相关的不确定性，并揭示了过去温暖间隔期间北美西部大片地区的广泛燃烧。但是，由于这些事件是否也烧毁了单个景观的大部分，因此很难确定，因为过去火灾的年代不确定性和有限的空间分辨率通常会阻止对过去燃烧面积的具体估计。考虑到科罗拉多州亚高山景观中的这些挑战，我们估计了过去2,000 y跨12个湖沉积的木炭记录的百年尺度火灾同步性。在中世纪气候异常（MCA）介于1200和850 y.B.P.之间，当时的温度与最近几十年相似，被烧毁场所的百分比仅偏离了历史上的可变性范围。在1,130到1,030 y B.P.之间，当温度相对于前几个世纪上升约0.5°C时，我们的站点有83％（中值估计）被烧毁。 MCA期间基于湖的火势旋转估计减少至120年，比树状生态采样期间（360至-60年B.P.）高出260％。但是，在整个MCA上燃烧不增加。在温度降低之前，燃烧突然下降，这表明继续燃烧可能会限制燃料。

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