London, Jan 1 - The airborne fraction of carbon dioxide (CO2) has not increased either during the past 150 years or during the most recent five decades, research says.

Most of the CO2 emitted by human activity is absorbed by the oceans and our ecosystems. In fact, only about 45 percent of emitted CO2 stays in the air. However, some studies have suggested that the ability of oceans and plants to absorb CO2 recently may have begun to decline.

Because understanding of CO2 fraction in air 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.

Accordingly, Wolfgang Knorr of earth sciences, University of Bristol re-analysed available atmospheric CO2 and emissions data since 1850 and considered the uncertainties in the data.

He found that the airborne fraction of CO2 has not increased either during the past 150 years or during the most recent five decades, says a Bristol release.

The research is published in Geophysical Research Letters. (IANS)