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

该研究项目将结合陆地表面模拟实验和新的气候、蒸散发和土地覆盖数据集，解决全球变化和水资源供应方面的紧迫科学问题。重点将放在定量解释土地覆盖和气候变化如何相互作用，以改变大陆上的蒸散和径流。地球上的淡水可用性是由大陆的水循环和储水量决定的。人类活动通过三种关键方式改变了大陆水循环：直接取水、气候变化和土地覆盖变化。最近的进展表明，这三种主要因素对大陆径流的影响程度相似；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，从而改变整个地球的水资源供应？哪里的土地覆盖和气候变化的影响会被放大，哪里的影响会被抵消？未来5年，该研究项目将重点关注两个直接目标：1)创建两种未来情景下的土地覆盖和气候新数据集；2)利用全球陆地表面模式进行数值试验，控制测试当前和未来情景下土地覆盖和气候变化的相对影响和综合影响。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.