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

该研究计划将通过结合陆地表面模拟实验和新的气候，蒸散和土地覆盖数据集来解决全球变化和水资源可用性方面的紧迫科学问题。 重点将放在对土地覆盖和气候变化如何相互作用以改变各大陆的蒸散和径流的定量解释上。我们星球上的淡水供应量取决于大陆的水循环和储存速度。人类活动通过三种主要方式改变大陆水循环：直接取水、气候变化和土地覆盖变化。 最近的进展表明，这三个主要代理人改变大陆径流相似的幅度，特别是，气候变化和土地覆盖变化改变年平均径流相似的幅度，但在相反的方向。这一新知识提出了一个关键的科学问题：在下一个世纪，气候变化和土地覆盖变化将如何相互作用，改变整个地球的水资源供应？土地覆盖和气候变化的影响在哪里会被放大，它们的影响在哪里会被抵消？在接下来的五年里，该研究计划将专注于两个直接目标：1）为两种未来情景创建新的土地覆盖和气候数据集，2）使用全球陆面模型进行数值实验，控制测试土地覆盖和气候变化在当前和未来情景中的相对和综合影响。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.