Australia: The Land Where Time Began

A biography of the Australian continent 

Carbon Fluxes from Land to Ocean - Anthropic Perturbations

Photosynthesis and chemical weathering takes up a substantial amount of atmospheric carbon on land which is subsequently transported laterally from terrestrial ecosystems in uplands along the aquatic continuum to the ocean. According to the authors¹ estimates of global carbon budgets have so far implicitly assumed that the transformation and lateral transport along this aquatic continuum has not changed since pre-industrial times. A  synthesis of published work has revealed the magnitude of lateral carbon fluxes from the land to the ocean at the present time, and the extent by which these fluxes have been altered by human activities. In this paper the authors¹ show that the flux of carbon to inland waters may have been increased by as much as 1.0 Pg C/yr since pre-industrial time by human perturbation, mainly by the enhanced carbon export from soils. Most of this input of carbon to upstream rivers is either emitted back to the atmosphere as carbon dioxide (about 0.4 Pg C/yr) or is sequestered in sediments (about 0.5 Pg C/yr) along the continuum of freshwater bodies to estuaries to coastal waters, the remaining perturbation carbon input of about 0.1 Pg C/yr entering the open ocean. The authors¹ say the results of their analysis indicate that about 0.9 Pg C/yr are presently stored in terrestrial ecosystems, a figure which agrees with forest inventories, though it differs significantly from the 1.5 Pg C/yr that has previously been estimated when the lateral carbon flux changes were ignored. The authors¹ suggest that in global carbon dioxide budgets carbon fluxes along the aquatic continuum from land to ocean need to be included.

Sources & Further reading

1. Regnier, Pierre, Pierre Friedlingstein, Philippe Ciais, Fred T. Mackenzie, Nicolas Gruber, Ivan A. Janssens, Goulven G. Laruelle, et al. "Anthropogenic Perturbation of the Carbon Fluxes from Land to Ocean." Nature Geosci 6, no. 8 (08//print 2013): 597-607.