As a scientist, I know more about climate change than I want to, and when reading about the real world gets my head in a bad place, I tend to escape into books. A few years back, I heard a review on the radio for a book that had as one of its plot points the release of a massive amount of carbon dioxide (CO2) from a lake and how it killed a large number of people. While that sounds terrible, the book sounded awesome, but because I was driving I didn’t write down its name. I still want to read that book, and I’m thinking about it now because, in the middle of all of today’s ugly science, there is a story on carbon dioxide and methane release from African lakes.

[If you know the name of the book, please let me know. I’m at starstryder with a y on Twitter. 🙂 ]

As for the science, in a new paper in Science Advances that is led by Alberto Borges, researchers look at the natural creation and release of these greenhouse gases in lakes by algae. While a lot of research has been done to understand the carbon cycle in the oceans, the same data hasn’t been collected for the majority of the world’s lakes. We lack an understanding of how lakes sequester carbon into life and release it through that life’s respiration.

Data we have from North American and Scandinavian lakes allow for estimates, but a lake in Finland is going to be very different from a lake in the Congo. In their work, this team measured the actual emissions of lakes in Africa, and according to Borges: The micro-algae that make up the phytoplankton are very fond of the warm and luminous conditions of the tropical ‘endless summer’ which means that some of the African lakes that we have studied are extremely productive. However, through photosynthesis, phytoplankton remove CO2 from the water, and these lakes, therefore, sequester CO2 in the form of organic matter buried at the bottom of the lakes in the sediments. They, therefore, act as carbon sinks, whereas until now it had always been assumed that lakes emitted CO2 in very large quantities into the atmosphere, as do boreal lakes.

Now, there are plenty of volcanic lakes that emit CO2 (that’s what was happening in that novel I want to read), but all those non-volcanic lakes – the majority of the lakes – are one small bright spot that are taking in more greenhouse gasses than they are releasing.

Celebrate slimy lakes full of algae people. That algae is our future.

More Information

University of Liège press release

“Greenhouse gas emissions from African lakes are no longer a blind spot,” Alberto V. Borges et al., 2022 June 24, Science Advances