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181 Long-Term Predictions (Climate Simulation and Analysis)

Part 15. Global Hydrology

  1. Richard A Betts

Published Online: 15 APR 2006

DOI: 10.1002/0470848944.hsa188

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Betts, R. A. 2006. Long-Term Predictions (Climate Simulation and Analysis). Encyclopedia of Hydrological Sciences. 15:181.

Author Information

  1. Hadley Centre for Climate Prediction and Research, Exeter, UK

Publication History

  1. Published Online: 15 APR 2006


The global hydrological cycle is expected to change over the next century as a consequence of human perturbations to the Earth System. Human activities are modifying the composition of the atmosphere, in particular the concentrations of greenhouse gases such as CO2 and the concentrations of aerosols. This exerts a radiative forcing of the climate system, which already appears to be warming the global climate. These changes are predicted to increase in the future, and are expected to modify precipitation and evaporation regimes, and hence impact on hydrology, with streamflow increasing in some regions and decreasing in others. Furthermore, changes in atmospheric composition may also affect ecosystems directly, with plant physiological responses to CO2 increasing carbon storage, modifying biogeography, and decreasing evapotranspiration. This may have further effects on hydrology in addition to climate change. Human-induced changes in land cover, such as deforestation and afforestation, may also directly modify hydrology and climate by perturbing the surface water and energy budgets as well as by contributing to radiatively-forced climate change through changes in atmospheric composition. This article compares and contrasts the climatic, ecological, and hydrological changes predicted as a result of these three human perturbations to the Earth System, and discusses the key interactions between them.


  • Earth System modelling;
  • climate change;
  • land use;
  • plant physiology;
  • impacts;
  • hydrology;
  • terrestrial ecosystems;
  • deforestation;
  • evapotranspiration;
  • feedbacks