Science Highlight

Attributing the increase of atmospheric CO₂ to emitters and absorbers

Ciais P, Gasser T, Paris JD, Caldeira K, Raupach MR, Canadell JG, Patwardhan A, Friedlingstein P, Piao SL, Gitz V.

Nature Climatic Change, Published online: 14 July 2013
DOI 10.1038/nclimate1942

Lead

Climate change policies need to consider the contribution of each emitting region to the increase in atmospheric carbon dioxide (CO₂), which includes both their CO₂ emissions and sinks. The study unambiguously attribute the largest share of the historical increase of CO₂ between pre-industrial times to developed countries. However, the excess CO₂ attributed to developing countries is greater than their share of cumulative CO₂ emissions, because a greater fraction of their emissions occurred more recently.

Paper Abstract

Climate change policies need to consider the contribution of each emitting region to the increase in atmospheric carbon dioxide (CO₂). We calculate regional attributions of increased atmospheric CO₂ using two different assumptions regarding land sinks.

In the first approach, each absorber region is attributed 'domestic sinks' that occurs within its boundaries.

In the second, alternative approach, each emitter region is attributed 'foreign sinks' that it created indirectly through its contribution to increasing CO₂.

We unambiguously attribute the largest share of the historical increase of CO₂ between pre-industrial times and the present-day period to developed countries.

However, the excess CO₂ in the atmosphere since pre-industrial times attributed to developing countries is greater than their share of cumulative CO₂ emissions. This is because a greater fraction of their emissions occurred more recently.

If emissions remain high over coming decades, the share of excess CO₂ attributable to developing countries will grow, and the sink service provided by forested regions, in particular regions with tropical forest, to other regions will depend critically on future tropical land-use change.

Manuscript

• Download paper: http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1942.html
• Contact lead author: Philippe Ciais

Media

• LSCE (in French pdf, 423kb)
• CSIRO online; (pdf, 64kb)

Illustrative Photos (available free if credited as specified).
Frozen soil sediment deposit in Siberia. Credit: Edward A. G. Schuur (1686 x 1812, jpg 490 kb)	Frozen peatland soil from the Hudson Bay Lowlands, Canada. Credit: Peter Khury. (431 x 644, jpg 68 kb)