Anthropogenic alteration of nutrient supply increases the global freshwater carbon sink

Lakes have a disproportionate effect on the global carbon (C) cycle relative to their area, mediating C transfer from land to atmosphere, and burying organic-C in their sediments. The magnitude and temporal variability of C burial is, however, poorly constrained, and the degree to which humans have influenced lake C cycling through landscape alteration has not been systematically assessed. Here, we report global and biome specific trajectories of lake C sequestration based on 516 lakes and show that some lake C burial rates (i.e., those in tropical forest and grassland biomes) have quadrupled over the last 100 years. Global lake C-sequestration (similar to 0.12 Pg year(-1)) has increased by similar to 72 Tg year(-1) since 1900, offsetting 20% of annual CO2 freshwater emissions rising to similar to 30% if reservoirs are included and contributing to the residual continental C sink. Nutrient availability explains similar to 70% of the observed increase, while rising temperatures have a minimal effect.

Jaar van publicatie:2020

Toegankelijkheid:Open