Study Finds Drought Recoveries Taking Longer
调查表明干旱的恢复期增长了
Global patterns of drought recovery time, in months. The longest recovery times are depicted in shades of blue and pink, with the shortest recovery times in yellow. White areas indicate water, barren lands, or regions that did not experience a drought during the study period.
全球干旱恢复期一般在数月之间。最长的恢复期用蓝色和粉色的阴影表示，而最短的恢复期用黄色表示。白色代表水面、非耕地或在调查期间没有发生干旱的区域。
As global temperatures continue to rise, droughts are expected to become more frequent and severe in many regions during this century. A new study with NASA participation finds that land ecosystems took progressively longer to recover from droughts in the 20th century, and incomplete drought recovery may become the new normal in some areas, possibly leading to tree death and increased emissions of greenhouse gases.
在本世纪，由于全球温度的持续升高，许多地区干旱越来越频繁、严重。NASA参与的一次调查表明，20世纪的干旱造成土地生态系统的恢复期呈现不断增长的现象，而且干旱的不完全恢复成为许多地区的新常态。这将导致树木的死亡和温室气体排放的增长。
In results published Aug. 10 in the journal Nature, a research team led by Christopher Schwalm of Woods Hole Research Center, Falmouth, Massachusetts, and including a scientist from NASA's Jet Propulsion Laboratory, Pasadena, California, measured recovery time following droughts in various regions of the world. They used projections from climate models verified by observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra satellite and ground measurements. The researchers found that drought recovery was taking longer in all land areas. In two particularly vulnerable regions -- the tropics and northern high latitudes -- recovery took ever longer than in other regions.
8月10日出版的《自然》杂志刊载位于马萨诸塞州法尔茅斯Woods Hole研究中心由Christopher Schwalm领导和加州帕萨迪纳NASA喷气动力实验室的一位科学家参与的调查组观察了世界多地的干旱恢复时间。他们使用气候模型预测并由NASA地球卫星“中等分辨率图像分光辐射谱仪”观测和地面测量来验证，结果发现，在所有陆地区域内干旱的恢复期均有增长。在两个特别脆弱地区——热带和北部高海拔地区，恢复期比其他区域需要更长的时间。
Schwalm noted that in model projections that assumed no new restrictions on greenhouse gas emissions (the so-called business-as-usual scenario), "Time between drought events will likely become shorter than the time needed for land ecosystems to recover from them."
Schwalm注意到，模型预测在假设温室气体排放没有新规定的情况下（即所谓的一切照旧）时，“干旱间隔的时间比土地生态系统恢复所需的时间变得越来越短了”。
"Using the vantage point of space, we can see all of Earth's forests and other ecosystems getting hit repeatedly and increasingly by droughts," said study co-author Josh Fisher of JPL. "Some of these ecosystems recover, but, with increasing frequency, others do not. Data from our 'eyes' in space allow us to verify our simulations of past and current climate, which, in turn, helps us reduce uncertainties in projections of future climate."
“利用空间观测的优势，我们可以看到地球的森林和其他生态系统被干旱反复和越来越严酷的打击”，本次调查报告的共同撰写者约瑟夫. 费舍尔说道。“但是，这其中一些生态系统的恢复需要的时间越来越长，而有些则不会”。我们在太空的“眼睛”提供的数据，使得我们能够验证过去和现在的气象，并且帮助我们降低在预测未来气候中的不确定性。
The scientists argue that recovery time is a crucial metric for assessing the resilience of ecosystems, shaping the odds of crossing a tipping point after which trees begin to die. Shorter times between droughts, combined with longer drought recovery times, may lead to widespread tree death, decreasing the ability of land areas to absorb atmospheric carbon.
科学家们说恢复时间是评估生态系统快速恢复及调整不利因素临界点的关键标准。超过临界点树木就会开始死亡。干旱间隔时间的缩短，继之以干旱恢复期的增长，可能会导致大范围的树木死亡，降低陆地区域吸收大气二氧化碳的能力。
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