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Is the airborne fraction of anthropogenic CO 2 emissions increasing?
Author(s) -
Knorr Wolfgang
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl040613
Subject(s) - environmental science , fraction (chemistry) , atmospheric sciences , climate change , greenhouse gas , atmosphere (unit) , carbon cycle , climatology , meteorology , ecosystem , geography , geology , chemistry , ecology , oceanography , organic chemistry , biology
Several recent studies have highlighted the possibility that the oceans and terrestrial ecosystems have started loosing part of their ability to sequester a large proportion of the anthropogenic CO 2 emissions. This is an important claim, because so far only about 40% of those emissions have stayed in the atmosphere, which has prevented additional climate change. This study re‐examines the available atmospheric CO 2 and emissions data including their uncertainties. It is shown that with those uncertainties, the trend in the airborne fraction since 1850 has been 0.7 ± 1.4% per decade, i.e. close to and not significantly different from zero. The analysis further shows that the statistical model of a constant airborne fraction agrees best with the available data if emissions from land use change are scaled down to 82% or less of their original estimates. Despite the predictions of coupled climate‐carbon cycle models, no trend in the airborne fraction can be found.