In a first-of-its-kind study, scientists have been able to use NASA satellites to measure the volume of water flowing from continents into the oceans, and they’ve found something remarkable. Turns out 18% more water flowed into the oceans from rivers and ice sheets in 2006 than did in 1994.
That’s an observable fact. What it means, on the other hand, is complicated. Here are your FAQs.
Why haven’t we drowned?
Well, first of all, it’s not just the ocean influx that has increased; ocean evaporation has also increased. What we appear to be seeing is an acceleration of the water cycle (evaporation, precipitation, evaporation, etc.) that we all learned about in elementary school.
An accelerated water cyle? Is that necessarily a bad thing?
For many communities, the acceleration of the water cycle could be dangerous. A faster moving water cycle translates into thicker clouds and nastier storms. Monsoon season could do more damage than before. “Meanwhile, hundreds of millions of people live in semiarid regions,” said study author Jay Famiglietti, of UC Irvine, “and those are drying up.”
You’re going to tell me this has to do with that global warming thing I’ve been hearing about, aren’t you?
Well, probably. The data certainly fits the predictions made by the UN’s Intergovernmental Panel of Climate Change, which told us to expect increased rainfall in the tropics and Arctic Circle, with more dangerous storms. So it certainly fits climate change models. Imputing the cause to climate change is a larger project. And in fact, 13 years of data really isn’t enough to draw robust long-term trends, since there can be a lot of fluctuation in climate phenomena over a period that short. The researchers plan to study the matter further.
So what’s the bottom line here?
Scientists have used satellite records in an important new way, directly observing a phenomenon rather than simply modeling it on computers. More study is needed to get a firmer read on this apparent acceleration of the water cycle. But the technique is here to stay: “What we’ve shown here is that we now have the tools to see global climate change as it occurs,” said NASA’s Josh Willis, “not just the warming, but changes in the hydrological cycle as well.”