Climate-dependent CO₂ emissions from lakes

Inland waters, just as the world's oceans, play an important role in the global carbon cycle. While lakes and reservoirs typically emit CO₂, they also bury carbon in their sediment. The net CO₂ emission is largely the result of the decomposition or preservation of terrestrially supplied carbon. What regulates the balance between CO₂ emission and carbon burial is not known, but climate change and temperature have been hypothesized to influence both processes. We analyzed patterns in carbon dioxide partial pressure (pCO₂) in 83 shallow lakes over a large climatic gradient in South America and found a strong, positive correlation with temperature. The higher pCO₂ in warmer lakes may be caused by a higher, temperature-dependent mineralization of organic carbon. This pattern suggests that cool lakes may start to emit more CO₂ when they warm up because of climate change.