A first of its kind study has revealed that freshwater is flowing into Earth’s oceans in greater quantities every year, all as a result of more frequent and extreme storms caused by global warming.
The study, published this week in the journal Proceedings of the National Academy of Sciences, shows that 18 percent more water is being fed into the world’s oceans from rivers and melting polar ice sheets in 2006 than was in 1994, with an average rise of 1.5 percent.
“That might not sound like much – 1.5 percent a year – but after a few decades, it’s huge,” said Jay Famiglietti, from the University of California – Irvine and the principal investigator on the study.
What’s the Problem with more Rain?
And though freshwater is essential to humans and our planet’s ecosystems, the rain that is falling is falling in all the wrong places and for all the wrong reasons.
“In general, more water is good,” Famiglietti said. “But here’s the problem: Not everybody is getting more rainfall, and those who are may not need it. What we’re seeing is exactly what the Intergovernmental Panel on Climate Change predicted – that precipitation is increasing in the tropics and the Arctic Circle with heavier, more punishing storms. Meanwhile, hundreds of millions of people live in semiarid regions, and those are drying up.”
Again and Again and Again
In short, the evaporation and precipitation cycle that is so familiar to us is accelerating to a point where it is contributing significantly to the rise in monsoons and hurricanes across the globe. Hotter weather above the oceans causes freshwater to be evaporated at an accelerated speed, which causes heavier clouds to unleash more powerful storms over land, sending all that freshwater back into the ocean.
And the cycle begins again.
“Many scientists and models have suggested that if the water cycle is intensifying because of climate change, then we should be seeing increasing river flow. Unfortunately, there is no global discharge measurement network, so we have not been able to tell,” wrote Famiglietti and lead author Tajdarul Syed of the Indian School of Mines, formerly of UCI.
“This paper uses satellite records of sea level rise, precipitation and evaporation to put together a unique 13-year record – the longest and first of its kind. The trends were all the same: increased evaporation from the ocean that led to increased precipitation on land and more flow back into the ocean.”
The study continues, employing NASA and other world-scale satellites to observe the total water volume each month flowing from the continents into the oceans.
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