In XX century the lake began to accumulate 3-4 times more carbon than previously. This is mainly due to disturbances in the global cycle of phosphorus: its intake from surface runoff of fertilizers enhances carbon sequestration. Carbon, accumulated in lakes, in danger of falling into the atmosphere and contribute to climate change. The article is about a new evaluation of the role of lakes in the carbon cycle published in the journal Science Advances.
Lakes act as intermediaries in the transfer of carbon from land to the atmosphere, with some carbon for a long time is output from the biogeochemical cycle and settles in bottom sediments. Accurate quantitative assessment of the role of lakes in global carbon Cycling is critical to simulate the Earth’s climate, however, the dynamics of carbon burial in lakes and the extent of human influence on this process has not systematically evaluated.
Scientists led by John Anderson (John Anderson) from Loughborough University has created a database of 516 lakes in the 13 major biomes of the planet, for which information has been collected on carbon sequestration and its change in space and time — that is, the transition of carbon from carbon dioxide in the air into organic matter of bottom sediments during the twentieth century.
The overall global rate of burial of carbon in lakes increased from an average of 50 to 120 million tons per year over the past 100 years. Lake in boreal forests make the largest contribution to global carbon burial (24%) because of its huge area in this area, followed by lake in the tropical moist deciduous (18%) and mixed forests (16 per cent) and lakes located in the temperate grasslands and savannas (15%).
All these biomes are strongly affected by anthropogenic changes and especially from agriculture with use of fertilizers. Despite the large areas of tundra lakes, they contribute only 2 percent to global carbon sequestration due to their low speed grip (3.1 grams of carbon per square meter during one year). These speeds can quickly increase in the future as a result of lateral transfer of organic carbon from permafrost, which is melting due to climate change.
Global carbon sequestration in lakes are closely related (r = 0.9) with violation of the cycle P during the twentieth century is the application of fertilizers has led to surface runoff in the lake and intensify the capture of carbon. Increasing the concentration of carbon dioxide in the Earth’s atmosphere has not yet affected the carbon sequestration lakes, but scientists predict a rise in the influence of the lakes themselves on the climate: further eutrophication could lead to the release of stored carbon from lakes to the atmosphere. As mentioned earlier, the lake accumulated in a year to 120 million tons of carbon, and in carbon dioxide equivalent, this figure will increase several times. For comparison, all vehicles Moscow in the year highlights in the atmosphere of about one million tons of emissions, most of which is in carbon dioxide.
Previously, we wrote about the fact that the construction of shrimp farms released irreplaceable stocks of carbon in the atmosphere, and elephants, on the contrary help forests more effectively bind carbon.