Washington: Oceans, forests and other ecosystems continue to soak up about half the carbon dioxide (CO2) released by human activities, but US researchers fear this may not continue indefinitely as the rate of emissions are increasing rapidly.
Scientists from the University of Colorado and the National Oceanic and Atmospheric Administration (NOAA) analysed 50 years of global CO2 measurements and found that the processes by which the planet`s oceans and ecosystems absorb the greenhouse gas are not yet at capacity.
"Globally, these carbon dioxide `sinks` have roughly kept pace with emissions from human activities, continuing to draw about half of the emitted CO2 back out of the atmosphere. However, we do not expect this to continue indefinitely," said NOAA`s Pieter Tans, a climate researcher who co-authored the study with Colorado`s Ashley Ballantyne, reports the journal Nature.
The CO2 is emitted into the air mainly by fossil fuel combustion but also by forest fires and some natural processes. The gas can also be pulled out of the atmosphere into the tissues of growing plants or absorbed by the waters of the Earth`s oceans, according to a Colorado and NOAA statement.
A series of recent studies suggested that natural sinks of CO2 might no longer be keeping up with the increasing rate of emissions. If that were to happen, it would cause a faster-than-expected rise in atmospheric carbon dioxide and projected climate change impacts.
Ballantyne, Tans and their colleagues saw no faster-than-expected rise, however. Their estimate showed that overall, oceans and natural ecosystems continue to pull about half of people`s carbon dioxide emissions out of the atmosphere.
Since emissions of CO2 have increased substantially since 1960, Ballantyne said: "Earth is taking up twice as much CO2 today as it was 50 years ago." The rest continues to accumulate in the atmosphere, where it is likely to accelerate global warming.