Waterloo’s model key to globalizing carbon dioxide water study

Monday, December 9, 2013

A fast-flowing river in France.Researchers from world-class institutions in Belgium, Canada, Finland, France, Germany and the United States teamed up to determine the amount of carbon dioxide lakes, streams, rivers and other bodies of water hold as well as how much is transferred to the atmosphere. They found rivers and streams emitted five times more carbon dioxide than lakes and reservoirs, and twice as much as previously reported.

Figuring out how much carbon dioxide inland water bodies contribute to the global carbon cycle is a difficult task. Researchers pulled together data from a variety of sources, including satellite data, census data on lakes and rivers, and experimental data on gas-transfer rates for freshwater to measure the amount of carbon dioxide release. 

But a modelling tool called COSCAT (Coastal Segmentation and related Catchments) developed by University of Waterloo scientist Hans Dürr was used to scale up the findings to the global level.

Co-author Hans Dürr is a Research Assistant Professor for the Ecohydrology Research Group in the Faculty of Science. Dürr is also a member of the University of Waterloo’s Water Institute.

The model is a global database of water bodies, or catchments, that connect to oceans. This land–ocean water connection is important for the movement of nutrients, greenhouse gases and metals in water systems.

Overall, the researchers found that the global carbon dioxide evasion rate from rivers and streams was 1.8 billion tons of carbon per year compared with the 0.32 billion tons from lakes and reservoirs. Together, the global rate from inland waters is about 2.1 billion tons per year.

“This study is an excellent example of how new knowledge can be gained by bringing together different tools, techniques and ideas from hundreds of scientists to tackle a global issue,” said Dürr. “More efforts like this are needed.”

The researchers found that the carbon dioxide evasion rate from lakes and reservoirs was lower than previous estimates, but that the rate from rivers and streams was three times higher. The carbon dioxide contribution was the greatest in smaller streams where turbulence levels are high. River hotspots included Southeast Asia, the Amazon, Europe Central America, Southeast Alaska and selected regions of Africa and South America.

This study provides new insights into how rivers and streams affect the global carbon cycle but emphasizes that additional research is needed to determine the carbon dioxide evasion rate for inland waters in the northern hemisphere. Regions in higher latitudes are predicted to experience faster than average temperature increases.

This research was partly funded by the Canada Excellence Research Chair in Ecohydrology, held by Prof. Philippe Van Cappellen.

Science in the mediaThis story has appeared in the following news outlets:

  • YottaFire, "Study finds rivers and streams release more greenhouse gas than all lakes"
  • Market Business News, "More CO2 escapes from rivers and streams globally than all lakes"
  • Canadian Consulting Engineer, "Rivers and streams release more C02 than lakes"
  • Headlines & Global News, "Streams and Rivers Release More Carbon Dioxide Than Lakes and Reservoirs Combined"
  • Red Orbit, "Rivers, Streams Release Far More Carbon Dioxide Than Do Lakes: Study"
  • Smithsonian.com, "World's rivers and streams leak a lot of carbon dioxide"
  • Nature World News, "Rivers and Streams Emit Five Times as Much Carbon as Lakes and Reservoirs"
  • Science World Report, "Rivers and streams release more greenhouse gases than lakes"
  • Science Daily, "Rivers and streams release more greenhouse gas than all lakes"
  • as well as the Kingston Whig-Standard, The Edmonton Sun, The London Free Press, simcoereformer.ca, The Welland Tribune, Woodstock Sentinel-Review, and the Toronto Sun.
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