New Study Suggests Earth Has Almost 45 Percent More Rivers Than Once Thought

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A new study published by a team of researchers from the University of North Carolina and based on data from a NASA satellite suggests that our planet might have much more rivers and streams than originally believed.

According to the study, which was published this week in the journal Science, Earth is covered by almost 300,000 square miles (773,000 square kilometers) of rivers and streams, or about 44 percent higher than what was previously estimated. This, the researchers warned, is an important figure considering how man-made pollution results in the exchange of greenhouses gases between rivers and the atmosphere.

Speaking to Gizmodo, University of Minnesota Duluth limnologist and biogeochemist John Downing, who was not involved in the study, explained that rivers and streams, contrary to previous belief that they merely delivered carbon to the ocean, were found to be leaking methane, carbon dioxide, and other similar greenhouse gases into the atmosphere slightly more than a decade ago. He believes that the greater amount of river coverage could be a sign that projections of greenhouse gas emissions might be too modest considering the potential gas emissions given off whenever water supplies are contaminated by waste.

“Here’s another reason not to spoil water. If you pollute it, you spoil fishing and swimming, but you also spoil the atmosphere,” said Downing, who had previously published his own study estimating global river and stream coverage.

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For their research, hydrologists George Allen and Tamlin Pavelsky of the University of North Carolina in Chapel Hill gathered data from a NASA Landsat satellite and studied thousands of images, crunching them through a software program designed by Pavelsky. This resulted in 58 million river measurements, which they took into account when coming up with an estimate for the level of river and stream coverage on Earth.

Gizmodo added that the researchers’ methodologies also included the recruitment of a “small army of undergraduates” who made sure that Pavelsky’s software was not picking up any false positives, such as roads, and not making any errors in its analysis.

All in all, Downing commented that Allen and Pavelsky’s study yielded some “exciting” results and covered a vast number of data points, with the North Carolina researchers coming up with numbers that were within 15 percent of his previous figures.

“They put in a massive amount of effort and confirmed the numbers we already had that were created from basic physical principles.”

While it was a considerable finding that the researchers discovered that Earth might have close to 45 percent more river and stream coverage than believed, they also found that rivers in specific didn’t cover as much in “human-developed areas.” The researchers have yet to back up their hypothesis with additional research, but they believe that this is because humans are using the water for agricultural purposes, or for draining swamps, among other tasks.