全球水循環(huán)（包括植物蒸發(fā)蒸騰在內(nèi)）的加速,，被認(rèn)為是全球變暖對地球系統(tǒng)所產(chǎn)生影響的一個關(guān)鍵指標(biāo)。蒸發(fā)蒸騰指的是通過蒸發(fā)和植物呼吸的綜合作用從地球的地表向大氣層運動的水。Martin Jung及其同事利用一種由數(shù)據(jù)驅(qū)動的機器學(xué)習(xí)方法和一套基于過程的模型發(fā)現(xiàn),，在1982年和1997年間,，蒸發(fā)蒸騰隨全球變暖穩(wěn)步增加,。但從1998年以來,，這種增加趨勢平緩了下來，很可能是南半球（尤其是非洲和澳大利亞）土壤水分供應(yīng)的局限性所造成的一個結(jié)果,。
至于這是一種自然氣候變化的構(gòu)成部分、還是陸地蒸發(fā)蒸騰從長遠(yuǎn)來講將會更多受到供應(yīng)限制的一個氣候變化信號,，仍然有待觀察,。（生物谷Bioon.com）
生物谷推薦英文摘要：
Nature doi:10.1038/nature09396
Recent decline in the global land evapotranspiration trend due to limited moisture supply
Martin Jung,[email protected] Reichstein,[email protected] Ciais,Sonia I. Seneviratne,Justin Sheffield,Michael L. Goulden,Gordon Bonan,Alessandro Cescatti,Jiquan Chen,Richard de Jeu,A. Johannes Dolman,Werner Eugster,Dieter Gerten,Damiano Gianelle,Nadine Gobron,Jens Heinke,John Kimball,Beverly E. Law,Leonardo Montagnani,Qiaozhen Mu,Brigitte Mueller,Keith Oleson,Dario Papale,Andrew D. Richardson,Olivier Roupsard,Steve Running,Enrico Tomelleri,Nicolas Viovy,Ulrich Weber,Christopher Williams,Eric Wood,S?nke Zaehle& Ke Zhang
More than half of the solar energy absorbed by land surfaces is currently used to evaporate water1. Climate change is expected to intensify the hydrological cycle2 and to alter evapotranspiration, with implications for ecosystem services and feedback to regional and global climate. Evapotranspiration changes may already be under way, but direct observational constraints are lacking at the global scale. Until such evidence is available, changes in the water cycle on land—a key diagnostic criterion of the effects of climate change and variability—remain uncertain. Here we provide a data-driven estimate of global land evapotranspiration from 1982 to 2008, compiled using a global monitoring network3, meteorological and remote-sensing observations, and a machine-learning algorithm4. In addition, we have assessed evapotranspiration variations over the same time period using an ensemble of process-based land-surface models. Our results suggest that global annual evapotranspiration increased on average by 7.1?±?1.0?millimetres per year per decade from 1982 to 1997. After that, coincident with the last major El Ni?o event in 1998, the global evapotranspiration increase seems to have ceased until 2008. This change was driven primarily by moisture limitation in the Southern Hemisphere, particularly Africa and Australia. In these regions, microwave satellite observations indicate that soil moisture decreased from 1998 to 2008. Hence, increasing soil-moisture limitations on evapotranspiration largely explain the recent decline of the global land-evapotranspiration trend. Whether the changing behaviour of evapotranspiration is representative of natural climate variability or reflects a more permanent reorganization of the land water cycle is a key question for earth system science.
