Carbon Cycle

The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the different components of the Earth System. The atmosphere, oceans and inland waters and land are key components of the natural carbon cycle (Figure 1).

Figure 1. Movement of carbon between land, atmosphere, and ocean in billions of tons (gigatons) per year. Yellow numbers are natural fluxes, red are human contributions, white numbers are stored carbon. Source: NASA Earth Observatory.

Carbon in the atmosphere can take various forms, amongst which carbon dioxide and methane, and is important because it contributes to retain energy within the Earth System through the so-called greenhouse effect. Human activities increase the amount of carbon in the atmosphere, by modifying the delicate balance of emission and absorption of carbon within the natural carbon cycle and by direct emissions (such as burning fossil fuels). The ocean and land continuously absorb about half of all the anthropogenic carbon dioxide emissions into the atmosphere, even as anthropogenic emissions have risen dramatically in recent decades.

Here in Uppsala, we investigate carbon exchanges between the atmosphere and both bodies of water and land. The exchange of carbon dioxide between the atmosphere and different water bodies is affected by a variety of parameters like water-side biogeochemistry, runoff from nearby land areas and atmospheric conditions (see the Air-Water theme). The exchange with land areas, through both soil and vegetation processes is heavily influenced by atmospheric variability on timescales ranging from hours to decades and longer. At the same time, changes in the amount of carbon absorbed, emitted or stored in terrestrial ecosystems affect the climate. By making use of satellite and in situ data, our work helps to better understand the complex interplay between the terrestrial and marine carbon cycles and climate.

Persons: Gabriele Messori, Erik Nilsson, Anna Rutgersson, Minchao Wu

Ongoing projects: