No Rise of Atmospheric Carbon Dioxide Fraction in Past 160 Years, New Research 
Finds

ScienceDaily (Dec. 31, 2009) — Most of the carbon dioxide emitted by human 
activity does not remain in the atmosphere, but is instead absorbed by the 
oceans and terrestrial ecosystems. In fact, only about 45 percent of emitted 
carbon dioxide stays in the atmosphere.

However, some studies have suggested that the ability of oceans and plants to 
absorb carbon dioxide recently may have begun to decline and that the airborne 
fraction of anthropogenic carbon dioxide emissions is therefore beginning to 
increase.

Many climate models also assume that the airborne fraction will increase. 
Because understanding of the airborne fraction of carbon dioxide is important 
for predicting future climate change, it is essential to have accurate 
knowledge of whether that fraction is changing or will change as emissions 
increase.

To assess whether the airborne fraction is indeed increasing, Wolfgang Knorr of 
the Department of Earth Sciences at the University of Bristol reanalyzed 
available atmospheric carbon dioxide and emissions data since 1850 and 
considers the uncertainties in the data.

In contradiction to some recent studies, he finds that the airborne fraction of 
carbon dioxide has not increased either during the past 150 years or during the 
most recent five decades.

The research is published in Geophysical Research Letters.


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