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195 Acceleration of the Global Hydrologic Cycle

Part 17. Climate Change

  1. John Roads1,
  2. Robert Oglesby2,
  3. Forrest Hoffman3,
  4. Franklin Robertson2

Published Online: 15 APR 2006

DOI: 10.1002/0470848944.hsa204

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Roads, J., Oglesby, R., Hoffman, F. and Robertson, F. 2006. Acceleration of the Global Hydrologic Cycle. Encyclopedia of Hydrological Sciences. 17:195.

Author Information

  1. 1

    Scripps Institution of Oceanography, UCSD La Jolla, CA, US

  2. 2

    NASA/Marshall Space Flight Center, Huntsville, AL, US

  3. 3

    Oak Ridge National Laboratory, Oak Ridge, TN, US

Publication History

  1. Published Online: 15 APR 2006

Abstract

The global hydrologic cycle, which can be conceptually described as evaporation of water vapor from the ocean, transport of water vapor by atmospheric winds to land regions, condensation, and precipitation of atmospheric water back to the surface, and subsequent transport, by streams, of this water back to the ocean, may intensify or accelerate in the future, as the planet warms owing to an increasing greenhouse resulting from increasing emissions of anthropogenic gases. As in many previous studies, increased hydrologic fluxes are found in a 100-year integration of the NCAR Coupled Climate System Model when forced with increasing CO2 levels. That is, as the earth warms, the evaporation increases, which not only increases the precipitation rate, but also the subsequent moisture convergence to land regions. However, if this increase in the cycling rate by various processes is measured with respect to the changing atmospheric and surface water reservoirs, then the atmospheric hydrologic cycle may appear to be actually deaccelerating since the atmospheric reservoir in this model is influenced more by the temperature changes than the actual transformation processes are. By contrast the land surface water reservoirs are less affected and thus there does appear to be an accelerated land surface hydrologic cycle, especially at high latitudes, and a coupled land-atmosphere acceleration, at least over land regions. There are also important regional differences.

Keywords:

  • hydrologic cycle;
  • climate change