The biggest human influence on climate change and global warming is the release of greenhouse gases into the atmosphere.

Now research published in the journal Limnology and Oceanography Letters is the first to show how the size of lakes and the nutrients in their waters from fertilisers are contributing to that influence.

"Our research pioneers a new way of determining the global atmospheric effect of lakes using satellite information on lake greenness and size distribution," said Professor John Downing.

Professor Downing, a co-author of the paper and director of the University of Minnesota's Sea Grant, added: "This is important because the world's lakes and surface waters will emit more greenhouse gases as they become greener and more nutrient-rich."

Although the most well-known greenhouse gas is carbon dioxide, gases such as methane and nitrous oxide - which are also emitted from lakes - could be much more damaging.


Methane and nitrous oxide have much greater warming potential, according to the University of Minnesota.

"Our work shows conclusively that methane, which is emitted from lakes in bubbles, is the dominant greenhouse gas coming from lakes and surface waters globally," said lead author Dr Tonya DelSontro, now a researcher at the University of Geneva.

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"The greener or more eutrophic these water bodies become, the more methane is emitted, which exacerbates climate warming."

Water bodies turn green when agricultural fertilisers such as phosphorus and nitrogen are washed into them by the rain from farms and similar locations.

"Our research team assembled the largest global dataset on lake emission rates of carbon dioxide, methane and nitrous oxide," said Professor Downing.

"When we analysed the data, we found that emissions of greenhouse gases to the atmosphere were influenced by the amount of eutrophication but also that lake size matters a lot for carbon dioxide and nitrous oxide."

If the world's bodies of water become more eutrophic they could release so much methane it may negate the emissions reductions made by humanity moving away from fossil fuels.

"We need to know how much of these greenhouse gases are being emitted to be able to predict how much and how fast the climate will change," said Dr DelSontro.

"This paper is significant because we developed a more effective approach to estimate current and future global lake emissions."