Groundwater depletion and other human-induced changes in terrestrial water storage were responsible for almost half of the increase in global sea level observed between 1961 and 2003.

Thermal expansion of the oceans, the melting of polar ice and changes in terrestrial water reservoirs all contribute to rising sea levels. To single out the impact of changes in land-based water use on sea level, Yadu Pokhrel at the University of Tokyo and his colleagues ran a simulation of global terrestrial water stocks and flows, accounting for human activities such as irrigation (pictured), which often uses groundwater, and dam-building.

The model suggests that about 42% of the almost eight-centimetre rise in sea level observed over the study period has resulted from changes in terrestrial water storage, particularly groundwater use. This human contribution could explain the discrepancy between observed and expected sea levels, the authors say.


Nature Geosci. (2012)

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