Greenhouse gas production in low-latitude lake sediments responds strongly to warming

Abstract

Inland water sediments receive large quantities of terrestrial organic matter and are globally important sites for organic carbon preservation. Sediment organic matter mineralization is positively related to temperature across a wide range of high-latitude ecosystems, but the situation in the tropics remains unclear. Here we assessed temperature effects on the biological production of CO2 and CH 4 in anaerobic sediments of tropical lakes in the Amazon and boreal lakes in Sweden. On the basis of conservative regional warming projections until 2100 (ref.), we estimate that sediment CO2 and CH 4 production will increase 9-61% above present rates. Combining the CO2 and CH 4 as CO2 equivalents (CO2 eq; ref.), the predicted increase is 2.4-4.5 times higher in tropical than boreal sediments. Although the estimated lake area in low latitudes is 3.2 times smaller than that of the boreal zone, we estimate that the increase in gas production from tropical lake sediments would be on average 2.4 times higher for CO2 and 2.8 times higher for CH 4. The exponential temperature response of organic matter mineralization, coupled with higher increases in the proportion of CH 4 relative to CO2 on warming, suggests that the production of greenhouse gases in tropical sediments will increase substantially. This represents a potential large-scale positive feedback to climate change. © 2014 Macmillan Publishers Limited.