How Much Fresh Water Exists in the World?

How much surface area do rivers and streams occupy on our planet? It’s a question we should have answered centuries ago and yet, the figure has just come to light and it happens to be 44% more that what was estimated. A team of scientists from the University of North Carolina at Chapel Hill and Texas A&M University used a combination of methods, including satellite imagery and field measurements, to carefully quantify the amount of fresh water moving on our planet. They found that it totals around 773,000 km2 (298,457 square miles). This information is important, not only because it allows us to better know our home and the amount of this vital liquid it holds, but also because it allows us to make more accurate calculations about the carbon cycle. According to the research, recently published in the journal Science, rivers accumulate greenhouse gases. It is essential to know how much land surface they occupy in order to estimate how much carbon dioxide passes from rivers and streams to our atmosphere each year. This study also makes available a large database, called Global River Widths, which contains nearly sixty million measurements of rivers around the world. This database will be used as a support for the next NASA mission, which will be focused specifically on measuring these bodies of water.

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