Earth still absorbing CO2 even as emissions rise, says new CU-led study | University of Colorado Boulder
Ballantyne said recent studies by others have suggested carbon sinks were declining in some areas of the globe, including parts of the Southern Hemisphere and portions of the worlds oceans. But the new Nature study showed global CO2 uptake by Earths sinks essentially doubled from 1960 to 2010, although increased variations from year-to-year and decade-to-decade suggests some instability in the global carbon cycle, he said.
According to the study, the scientists observed decreased CO2 uptake by Earths land and oceans in the 1990s, followed by increased CO2 sequestering by the planet from 2000 to 2010. Seeing such variation from decade to decade tells us that we need to observe Earths carbon cycle for significantly longer periods in order to help us understand what is occurring, said Ballantyne.
From the Abstract...
http://www.nature.com/nature/journal/v488/n7409/full/nature11299.html
One of the greatest sources of uncertainty for future climate predictions is the response of the global carbon cycle to climate change1. Although approximately one-half of total CO2 emissions is at present taken up by combined land and ocean carbon reservoirs2, models predict a decline in future carbon uptake by these reservoirs, resulting in a positive carbonclimate feedback3. Several recent studies suggest that rates of carbon uptake by the land4, 5, 6 and ocean7, 8, 9, 10 have remained constant or declined in recent decades. Other work, however, has called into question the reported decline11, 12, 13
Here we use global-scale atmospheric CO2 measurements, CO2 emission inventories and their full range of uncertainties to calculate changes in global CO2 sources and sinks during the past 50 years.
Our mass balance analysis shows that net global carbon uptake has increased significantly by about 0.05 billion tonnes of carbon per year and that global carbon uptake doubled, from 2.4?±?0.8 to 5.0?±?0.9 billion tonnes per year, between 1960 and 2010. Therefore, it is very unlikely that both land and ocean carbon sinks have decreased on a global scale. Since 1959, approximately 350 billion tonnes of carbon have been emitted by humans to the atmosphere, of which about 55 per cent has moved into the land and oceans. Thus, identifying the mechanisms and locations responsible for increasing global carbon uptake remains a critical challenge in constraining the modern global carbon budget and predicting future carbonclimate interactions
