Mankind is moving buckets and buckets of water from land to the ocean.

Sometimes science moves slowly and sometimes quickly. This is an instance of quick.

A couple of weeks ago TheGreenGrok covered a paper by Tajdarul Syed of the University of California, Irvine, et al who used hydrologic data to estimate the rates at which water flowed from the continents to the sea. They found that the rate rose over the study period from 1994 to 2006 and that the strongest component of that increase was an increase in evaporation over the ocean. The authors noted that such trends, if they continue into the future, would be evidence of an intensification of the hydrologic cycle, in which increased evaporation over the ocean leads to increased precipitation over the continents and subsequently more river discharge into the ocean.

While I had some reservations about the study — recognizing, as the authors did, that the time period wasn’t sufficiently long enough to draw conclusions about changes in the hydrologic cycle, and finding there were uncertainties in the numbers they derived — I generally saw the paper as but another confirmation of the fact that our climate is changing. (To be clear, the findings of Syed et al were and are in no way central to the climate change issue but in line with it.)

But a new piece of the puzzle has been added with a report just out in the journal Geophysical Research Letters by Yoshihide Wada of Utrecht University in the Netherlands and colleagues. And that new piece calls into question the conclusions of Syed et al.

The Wada et al paper is about groundwater, but before we get to the specifics, a little background.