Standard Article

Detectable Trends in Hydroclimatical Variables During the Twentieth Century

Part 17. Climate Change

  1. Zbigniew W Kundzewicz1,2

Published Online: 15 SEP 2008

DOI: 10.1002/0470848944.hsa205

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Kundzewicz, Z. W. 2008. Detectable Trends in Hydroclimatical Variables During the Twentieth Century. Encyclopedia of Hydrological Sciences. 17.

Author Information

  1. 1

    Polish Academy of Sciences, Research Centre for Agricultural and Forest Environment, Poznan, Poland

  2. 2

    Potsdam Institute for Climate Impact Research, Potsdam, Germany

Publication History

  1. Published Online: 15 SEP 2008


The twentieth century was a period of considerable climatic and nonclimatic change. The atmospheric concentration of greenhouse gases increased significantly, due to increased burning of fossil fuels and land-use changes that reduce carbon sequestration. The long carbon dioxide record from Mauna Loa illustrates the man-caused enhancement of the “greenhouse effect”, which resulted in an increase in global temperature of 0.74 °C over the last 100 years. In the Northern Hemisphere, the temperature increase during the twentieth century is likely to have been greater than for any other century in the last 1000 years. This has affected hydrological processes. Patterns of precipitation change are more spatially and temporally variable, but some regional regularities can be detected. The river runoff process, which is the most important for freshwater management, has not shown general, nor coherent, changes globally, because river runoff is an integrator of many climatic and nonclimatic factors. In a number of places, nonclimatic drivers can be demonstrated to have had a considerable influence on hydrological records.


  • change detection;
  • trend;
  • hypothesis testing;
  • hydrology;
  • climatology;
  • hydroclimatology