Using land surface model experiments to improve understanding of alteration of the global water cycle from human land cover and climate change

这项研究计划将利用陆面模拟实验和新的气候、蒸散和土地覆盖数据集相结合的方式，解决全球变化和水资源可获得性方面的紧迫科学问题。重点将放在定量解释土地复盖和气候变化如何相互作用来改变大陆上的蒸散和径流。我们星球上的淡水可获得性由大陆的水循环和储存速度决定。人类活动通过三个关键途径改变大陆水循环：直接取水、气候变化和土地覆盖变化。最近的研究表明，这三个主要因素对大陆径流的影响幅度相似；特别是气候变化和土地覆盖变化对年平均径流的影响幅度相似，但方向相反。这一新知识提出了一个关键的科学问题：在下个世纪，气候变化和土地覆盖变化将如何相互作用，改变地球上的水资源供应？土地覆盖和气候变化的影响将在哪里放大，它们的影响将在哪里抵消？在接下来的五年里，这项研究计划将专注于两个直接目标：1)为两个未来情景创建新的土地覆盖和气候数据集；2)利用全球陆地表面模式进行数值实验，控制以测试当前和未来情景中土地覆盖和气候变化的相对和综合影响。实现这些目标将减少关键水问题的不确定性，并提高我们应对气候变化的能力。

This research program will address pressing scientific questions in global change and water availability by using a combination of land surface modelling experiments and new climate, evapotranspiration, and land cover datasets. Emphasis will be placed on quantitative interpretation of how land cover and climate change interact to alter evapotranspiration and runoff on the continents. Freshwater availability on our planet is determined by continental rates of water cycling and storage. Human activity alters the continental water cycle through three key ways: direct water withdrawals, climate change, and land cover change. Recent advances show that these three dominating agents alter continental runoff by similar magnitudes; in particular, climate change and land cover change alter annual average runoff by similar magnitude, but in opposite directions. This new knowledge raises a critical scientific problem: over the next century, how will climate change and land cover change interact to alter water availability across the planet? Where will the effects of land cover and climate change be magnified, and where will their effects cancel out? Over the next five years, this research program will focus on two direct objectives: 1) create new datasets for land cover and climate for two future scenarios, and 2) conduct numerical experiments with a global land surface model, controlling to test relative and combined impacts of land cover and climate change in current and future scenarios. Achieving these objectives will reduce uncertainty in critical water issues and improve our ability to respond to climate change.