Global sea levels rose by an average of 0.07 inches per year from 1961-2003, according to data from tide gauges.
A team led by Yadu Pokhrel of the University of Tokyo now says that the trillions of gallons of water pumped out of underground aquifers, rivers and lakes for human use is making its way to the ocean through rivers and soil evaporation.
Writing in the journal Nature Geoscience, the researchers say that a combination of the unsustainable groundwater use and loss of water from closed bodies of water, like the disappearing Aral Sea, have contributed to about 42 percent of the observed rises in sea levels.
The rises would have been even higher had not manmade reservoirs held back vast amounts of stored water on land.
Rising tides have until now been primarily blamed on melting glaciers and thermal expansion of the oceans due to warming.
“In the long run, I would still be more concerned about the impact of climate change, but this work shows that even if we stabilize the climate, we might still get sea level rise due to how we use water,” sea level expert Robert Nicholls, of the University of Southampton, told The Guardian.