Global sea level has been rising over the past half century. Thermal expansion of oceans, melting of glaciers and loss of the ice masses in Greenland and Antarctica are commonly considered as the largest contributors. Changes in terrestrial water storage are also likely to affect sea level, but comprehensive and reliable estimates of this contribution, particularly through human water use, are scarce.

Yadu N. Pokhrel, University of Tokyo, Japan, and colleagues estimated sea-level change in response to human impacts on terrestrial water storage. They used an integrated model that simulates global terrestrial water stocks and flows (exclusive to Greenland and Antarctica) and especially accounts for human activities such as reservoir operation and irrigation. They find that unsustainable use of groundwater represents the largest contribution, because groundwater does not flow back into its original systems, but into the sea after usage.

Together unsustainable use of groundwater, artificial reservoir water impoundment, climate-driven changes in terrestrial water storage, and the loss of water from closed basins have contributed to a sea-level rise of about 0.77 mm yr⁻¹ between 1961 and 2003, about 42 % of the observed sea-level rise.

• Model estimates of sea-level change due to anthropogenic impacts on terrestrial water storage,
  Yadu N. Pokhrel, Naota Hanasaki, Pat J-F. Yeh, Tomohito J. Yamada, Shinjiro Kanae, Taikan Oki,
  Nature Geosci. 2012.
  DOI: 10.1038/ngeo1476