Groundwater depletion and water storage in reservoirs have led to a significant rise in global-mean sea level between 1961 and 2003, indicates a study published online this week in Nature Geoscience. These estimated contributions - which result from changes in human terrestrial water storage - are larger than those of previous assessments, and could help explain the magnitude of observed sea-level rise.
Yadu Pokhrel and colleagues used an integrated model of terrestrial water flows and stocks outside the ice sheets of Greenland and Antarctica to estimate the contribution of human activities on land to sea-level rise. They find that unsustainable use of groundwater comprises the largest contribution of such activities to the rise. In their model, groundwater consumption, together with reservoir operation, climate-driven changes in terrestrial water storage and the loss of water from closed basins like the Aral Sea, have contributed about 42% of the observed sea-level rise between 1961 and 2003.