Lakes important source of carbon emissions

How carbon is accounted around the globe for can be a tricky matter. Carbon moves from the land and sea into the atmosphere and back again. Too much in the atmosphere and we’ve got climate change. But figuring out where it’s all coming from is no small matter.

Scientists at the University of Helsinki this week published a paper in the journal Geophysical Research Letters, highlighting a source of emissions previously undetected. Lakes, it turns out, can be a big contributor to atmospheric carbon load. Large volumes of carbon erode off the land into lakes and once there the carbon exchanges with the air above. If carbon emissions over lakes are ignored, which they have been, an important source of the globe’s carbon budget is undetected.

The Finnish scientists took a peek above a boreal lake in their neck of the woods to see just how much carbon was seeping off into the atmosphere. They found Lake Valkea-Kotinen in southern Finland to be a net source of emissions, projecting upward of 100 grams of carbon per square meter per year. The surrounding old-growth boreal forest, on the other hand, was a net carbon sink. When considered alongside the forest, the lake’s emissions were responsible for dropping the forest’s carbon storage capacity by 10 percent.

This “natural leakage” of carbon through lakes could be worsened by climate change. Temperature and precipitation matter a great deal in how carbon gets cycled through the aquatic environment. The hotter and wetter the climate, the more carbon gets transported to the atmosphere. The UH scientists predict an increase in carbon emissions in Lake Valkea-Kotinen by as much as 26 percent by the 2050s.

Don’t forget to watch what’s happening with lakes, they say.