Rivers and Streams Release More Greenhouse Gases than Lakes

Carbon dioxide is on the rise in our atmosphere. Now, scientists have discovered a bit more about this gas. It turns out that rivers and streams release carbon dioxide at a rate five times greater than the world's lakes and reservoirs combined. This finding flies in the face of the common belief that the opposite is true.

"Identifying the sources and amounts of carbon dioxide released from continental water sources has been a gap in understanding the carbon cycle," said Hans Durr, one of the researchers, in a news release. "Our findings show just how much carbon dioxide inland waters release and identified that rivers and streams are the main source not lakes and reservoirs, as previously thought."

In order to find out a little bit more about the release of carbon dioxide from bodies of water, the researchers used a modeling tool called Coastal Segmentation and related Catchments (COSCAT). This tool put data of water bodies into a global context. The model itself is a global database of water bodies, or catchments, that connect to the oceans. This land-ocean water connection is important for the movement of nutrients, greenhouse gases and metals in water systems.

"This study is an example of how much new knowledge can be gained by bringing together different tools, techniques and ideas from hundreds of scientists to tackle a global issue," said Durr in a news release. "More integrated, international collaborations like this are needed."

So what did they find? It turns out that the rate at which lakes and reservoirs release carbon dioxide, or evasion rate, was lower than previous estimates. The rate from rivers and streams, in contrast, was three times higher. It was even greater in smaller, fast-moving streams. In fact, the scientists found that the global carbon dioxide evasion rate from rivers and streams was 1.8 billion tons of carbon per year. That's compared with .32 billion tons from lakes and reservoirs.

The findings reveal a bit more about the flow of carbon dioxide in these bodies of water. More specifically, the new research could help inform future climate models that tracks the release of carbon dioxide.

The findings are published in the journal Nature.