Direct human influence of irrigation on atmospheric water vapour and climate

Abstract Human activity increases the atmospheric water vapour content in an indirect way through climate feedbacks. We conclude here that human activity also has a direct influence on the water vapour concentration through irrigation. In idealised simulations we estimate a global mean radiative forcing in the range of 0.03 to +0.1 Wm–2 due to the increase in water vapour from irrigation. However, because the water cycle is embodied in the climate system, irrigation has a more complex influence on climate. We also simulate a change in the temperature vertical profile and a large surface cooling of up to 0.8 K over irrigated land areas. This is of opposite sign than expected from the radiative forcing alone, and this questions the applicability of the radiative forcing concept for such a climatic perturbation. Further, this study shows stronger links than previously recognised between climate change and freshwater scarcity which are environmental issues of paramount importance for the twenty first century.

[1]  Petra Döll,et al.  A digital global map of irrigated areas. , 2000 .

[2]  Comparing estimates of actual evapotranspiration from satellites, hydrological models, and field data : a case study from Western Turkey , 2000 .

[3]  K. Trenberth,et al.  Earth's annual global mean energy budget , 1997 .

[4]  Z. Jianping,et al.  Climate change and causes in the Yuanmou dry-hot valley of Yunnan, China , 2002 .

[5]  Stuart Rojstaczer,et al.  Irrigation-Induced Rainfall and the Great Plains , 2001 .

[6]  Babita Pal,et al.  The Effect of Irrigation on Premonsoon Season Precipitation over South West Bengal, India , 1995 .

[7]  Leon D. Rotstayn,et al.  Indirect Aerosol Forcing, Quasi Forcing, and Climate Response , 2001 .

[8]  Radhika Vidanage De Silva,et al.  World water demand and supply, 1990 to 2025: scenarios and issues , 1998 .

[9]  D. D. Vries,et al.  THE INFLUENCE OF IRRIGATION ON THE ENERGY BALANCE AND THE CLIMATE NEAR THE GROUND , 1959 .

[10]  Petra Döll,et al.  Global modeling of irrigation water requirements , 2002 .

[11]  B. V. Leer,et al.  Towards the Ultimate Conservative Difference Scheme , 1997 .

[12]  V. Ramanathan,et al.  Reduction of tropical cloudiness by soot , 2000, Science.

[13]  O. Boucher,et al.  A satellite view of aerosols in the climate system , 2002, Nature.

[14]  J. Hansen,et al.  Radiative forcing and climate response , 1997 .

[15]  Moti Segal,et al.  On the Potential Impact of Irrigated Areas in North America on Summer Rainfall Caused by Large-Scale Systems , 1998 .

[16]  R. Mahmood,et al.  Impact of Irrigation on Midsummer Surface Fluxes and Temperature under Dry Synoptic Conditions: A Regional Atmospheric Model Study of the U.S. High Plains , 2003 .

[17]  R. Betts,et al.  The influence of land-use change and landscape dynamics on the climate system: relevance to climate-change policy beyond the radiative effect of greenhouse gases , 2002, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[18]  Alan Robock,et al.  Global cooling after the eruption of Mount Pinatubo: a test of climate feedback by water vapor. , 2002, Science.

[19]  J. Penner,et al.  Aviation and the Global Atmosphere , 1999 .

[20]  G. Myhre,et al.  Role of spatial and temporal variations in the computation of radiative forcing and GWP , 1997 .

[21]  Olivier Boucher,et al.  History of sulfate aerosol radiative forcings , 2002 .

[22]  P. Milly,et al.  Sensitivity of the Global Water Cycle to the Water-Holding Capacity of Land , 1994 .

[23]  Frédéric Hourdin,et al.  The Use of Finite-Volume Methods for Atmospheric Advection of Trace Species. Part I: Test of Various Formulations in a General Circulation Model , 1999 .

[24]  M. Tiedtke.  A Comprehensive Mass Flux Scheme for Cumulus Parameterization in Large-Scale Models , 1989 .

[25]  B. V. Leer,et al.  Towards the ultimate conservative difference scheme. IV. A new approach to numerical convection , 1977 .

[26]  Koen De Ridder,et al.  Land Surface-Induced Regional Climate Change in Southern Israel , 1998 .

[27]  David Molden,et al.  Accounting for water use and productivity , 1997 .

[28]  H. Treut,et al.  Sulfate Aerosol Indirect Effect and CO2 Greenhouse Forcing: EquilibriumResponse of the LMD GCM and Associated Cloud Feedbacks , 1998 .

[29]  Petra Döll,et al.  Impact of Climate Change and Variability on Irrigation Requirements: A Global Perspective , 2002 .

[30]  T. Zhou,et al.  Simulation of the east asian summer monsoon using a variable resolution atmospheric GCM , 2002 .

[31]  Paul T. Schickedanz,et al.  The Effect of Irrigation on Warm Season Precipitation in the Southern Great Plains. , 1984 .

[32]  D. Gaffen,et al.  Climatology and Trends of U.S. Surface Humidity and Temperature , 1999 .

[33]  G. Müller,et al.  The Scientific Basis , 1995 .