AmeriFlux Contributes New Insights into Evapotranspiration
Large scale changes in the Earth’s water cycle have been hypothesized to result from global warming. DOE-funded investigators and DOE’s AmeriFlux network report in Nature evidence of systematic changes in global land evapotranspiration, although the authors are not able to assign causality to the changes. Using a combination of long-term observational (including data from numerous AmeriFlux sites), meteorological and remote sensing records, combined with model results, the authors identify a systematic increase in global land evapotranspiration from 1982 to 1997. From 1998 to 2008, this trend appears to have declined or leveled off. The authors suggest that soil moisture limitations, particularly in the southern hemisphere are responsible for the change. If this continues over the long-term, it may indicate that climate-driven changes in terrestrial hydrological cycles exist and that there are limits to the ability of these cycles to respond to changing climate.
Jung, M., M. Reichstein, P. Ciais, S. Seneviratne, J. Sheffield, M. Goulden, G. Bonan, A. Cescatti, J. Chen, R. de Jeu, A. J. Dolman, W. Eugster, D. Gerten, D. Gianelle, N. Gobron, J. Heinke, J. Kimball, B. Law, L. Montagnani, Q. Mu, B. Mueller, K. Oleson, D. Papale, A. Richardson, O. Roupsard, S. Running, E. Tomelleri, N. Viovy, U. Weber, C. Williams, E. Wood, S. Zaehle, and K. Zhang. 2010. “Recent Decline in the Global Land Evapotranspiration Trend Due to Limited Moisture Supply,” Nature 467, 951–954. DOI: 10.1038/nature09396.