Twin Cities WRS Seminar

Global Trends in Carbon Burial by Lakes


Dr. Adam Heathcote
St. Croix Watershed Research Station

November 17, 2017


Lakes are hotspots within the global carbon cycle that process large amounts of terrestrially derived organic carbon (OC). The potential for lakes to bury this OC, and sequester it long-term, is increasingly recognized as an important sink for carbon that might otherwise end up in the atmosphere as CO2 or CH4. Despite this, the global mean OC burial rate is not well constrained due to sparse and regionally biased sampling combined with high spatial and temporal variability. Here we report a global estimate of limnic OC burial derived from dated sediment cores from over 500 lakes across 6 continents and 11 major biomes. The global OC burial rate has tripled over the last 150 years and this increase reflects a range of drivers coincident with the onset of the Anthropocene, notably disruption of nutrient cycles and land-cover change acting synchronously across the planet. Combining biome-specific OC burial rates with the global lake distribution, we estimate the annual sequestration rate may offset annual CO2 emission from lakes by 30%. The trends and timescale of increasing lake OC burial parallel those of the trend in the residual terrestrial carbon sink. These findings further support lakes as disproportionately important to the global carbon cycle relative to their areal coverage and highlights the integrated nature of human impacts on global biogeochemistry.

Dr. Adam Heathcote has been a Research Scientist at the Science Museum of Minnesota's St. Croix Watershed Research Station since 2015. He came to the Museum from the Université du Québec à Montréal, where he had a 2-year appointment as a postdoctoral fellow for the NSERC Industrial Chair in Carbon Biogeochemistry in Boreal Aquatic Systems (CarBBAS). Adam received his Ph.D. in 2013 from Iowa State University with a dissertation focused on the effects of anthropogenic eutrophication on aquatic systems. Currently, his research focuses on assessing the combined role of global and local anthropogenic drivers on the biogeochemical cycling of lakes.