Since the 1950s, CO2 emissions into the atmosphere have quadrupled, but the Earth has been able to capture half of the carbon released, thanks to its carbon sinks. The Earth has natural devices that allow it to fight against the impact on the climate of greenhouse gas emissions generated by human activity, including the oceans, soils and plants spread throughout the planet.
But according to some recent studies, the efficiency of these carbon sinks seems to be stagnating, or even decreasing, in several regions of the globe, both on land and at sea. Against these studies, Ashley Ballantyne of the University of Boulder in Colorado, published a study in the journal Nature in August 2012, which contradicts these claims.
According to the study, the Earth would absorb twice as much carbon today as it did fifty years ago, with terrestrial biospheres and oceans capturing about half of the carbon produced by anthropogenic activities and forest fires. The scientist first conducted an analysis of various works and reports, including those from the U.S.
Department of Energy’s CO2 Information Analysis Center regarding the estimated amount of CO2 emitted into the atmosphere over the past 50 years. These data were compared with measurements of carbon dioxide concentration made during the same period at 40 different sites around the world by the U.S. Atmospheric and Oceanographic Agency and the Scripps Institution of Oceanography.
Between 1959 and 2010, nearly 350 billion tons of carbon were released into our environment, including 33.6 billion in 2010 alone, indicating that emissions have increased fourfold in fifty years. Over the same period, the average carbon capture rate would have increased from 2.4 to 5 billion tons per year.
This evolution in the rate of CO2 capture has made it possible to absorb about 55% of the carbon emitted by humans and to significantly limit the consequences of CO2 emissions on the environment and the climate. However, the atmospheric concentration of CO2 remains very high, rising from 280 ppm or parts per million before the industrial revolution to 394 ppm in 2012. Ashley Ballantyne’s study also points to the instability within the carbon cycle, where CO2 capture can vary greatly from year to year or decade to decade. For example, in the decade 1900/2000, CO2 capture decreased and then increased again in the decade 2000/2010.
These results show that studies on the carbon cycle must be carried out over the long term to be as reliable as possible, but they also question the possibility for forests and oceans to continue to capture more and more carbon, as their storage capacity is not infinite. It is necessary to question the consequences when the saturation level of the current carbon sinks is reached and for the oceans in particular on the effects of carbon dioxide capture on aquatic life. In the oceans, CO2 is transformed into carbonic acid, a substance that is harmful to corals, while coral reefs are home to nearly 25% of the world’s fish.