Mid-latitude freshwater availability reduced by projected vegetation responses to climate change
Mid-latitude freshwater availability reduced by projected vegetation responses to climate change
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DOI：
10.1038/s41561-019-0480-x
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发表时间：
2019-12-01
影响因子：
18.3
通讯作者：
Williams, A. Park
中科院分区：
文献类型：
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作者：
Mankin, Justin S.;Seager, Richard;Williams, A. Park
在大气二氧化碳浓度增加的情况下，植物通过影响地表对蒸散的阻力，预计将产生更多的全球规模径流。最近使用耦合模型相互比较项目第5阶段的地球系统模型进行的研究表面上重申了这一结果，进一步表明植物将改善其他使用干旱指标的研究预测的水资源可用性的严重减少。在这里，我们通过分析高二氧化碳浓度和变暖下多个地球系统模型中降水分配到植物，径流和储存的变化来使这种叙述复杂化。我们表明，预计的植物响应直接减少了北美，欧洲和亚洲大片地区未来的径流，因为大量冠层水需求随着额外的植被生长和更长更温暖的生长季节而增加。尽管地表对蒸散和植被总水分利用效率的阻力增加，即使在降水增加或不变的地区，这些径流量也会下降。我们证明，限制大的不确定性，在多模式集成与区域尺度观测的蒸散分割加强了这些结果。我们的结论是，陆地植被在塑造未来的区域淡水供应方面发挥着巨大而尚未解决的作用，这将不会普遍改善未来变暖驱动的地表干燥。
Plants are expected to generate more global-scale runoff under increasing atmospheric carbon dioxide concentrations through their influence on surface resistance to evapotranspiration. Recent studies using Earth System Models from phase 5 of the Coupled Model Intercomparison Project ostensibly reaffirm this result, further suggesting that plants will ameliorate the dire reductions in water availability projected by other studies that use aridity metrics. Here we complicate this narrative by analysing the change in precipitation partitioning to plants, runoff and storage in multiple Earth system models under both high carbon dioxide concentrations and warming. We show that projected plant responses directly reduce future runoff across vast swaths of North America, Europe and Asia because bulk canopy water demands increase with additional vegetation growth and longer and warmer growing seasons. These runoff declines occur despite increased surface resistance to evapotranspiration and vegetation total water use efficiency, even in regions with increasing or unchanging precipitation. We demonstrate that constraining the large uncertainty in the multimodel ensemble with regional-scale observations of evapotranspiration partitioning strengthens these results. We conclude that terrestrial vegetation plays a large and unresolved role in shaping future regional freshwater availability, one that will not ubiquitously ameliorate future warming-driven surface drying.