Nowadays, global warming has become the hottest topic in the world. Recently, an international research team has come to an amazing conclusion by observing the carbon dioxide emissions and the carbon dioxide concentration in the atmosphere in the past 60 years: the efficiency of carbon absorption in the land and marine environment has improved. This study was summarized into a paper entitled "Keeping the net carbon absorption in step with the increase of fossil fuel emissions", which was published in the scientific journal Nature.

Because people burn chemical fuels such as oil and coal, burn and cut down forests, a lot of carbon dioxide gas is produced. These greenhouse gases can absorb a lot of infrared rays, which leads to the rise of the earth's temperature and the formation of greenhouse effect. Global warming will lead to the redistribution of global precipitation, melting of glaciers and frozen soil, rising sea level and other consequences, which will not only endanger the balance of natural ecosystems, but also affect human health and even threaten human survival.

At present, more and more countries realize the importance of energy conservation and emission reduction. People try to offset the carbon dioxide produced by human activities by planting trees and reducing energy use, and strive to achieve the carbon neutral goal that carbon emissions are equal to carbon absorption.

In fact, during the continuous cycle of carbon, the main absorbers of carbon dioxide are land, ocean and other environments. People use the term "carbon sink" to represent the ability of the environment to absorb and store carbon dioxide, and divide carbon sinks into forest, grassland, cultivated land, soil and ocean.

At present, a key problem in predicting future climate change is whether these carbon sinks are consistent with the growing atmospheric footprint of human beings, or whether they have saturated and accelerated climate change. In order to solve this problem, an international research team from the Netherlands and the United States studied carbon sinks in the natural environment. Because of the large spatial and temporal variability, it is difficult for people to directly monitor the carbon sink efficiency, so the team inferred the carbon sink by monitoring the change of carbon dioxide concentration in the atmosphere. The lower the concentration, the higher the carbon sink efficiency.

During the research, the team found for the first time that about half of the carbon dioxide emitted by human beings remained in the atmosphere. However, due to the lack of carbon emission data of deforestation in the past, they have no way to know whether the concentration of carbon dioxide in the air has changed today compared with before.

Therefore, researchers used indirect methods to record the carbon emissions from deforestation in the past 60 years. Because people often burn forests during logging, the smoke produced by forest fires will reduce visibility, so the visibility in forests is closely related to carbon emissions. They found visibility data regularly measured by weather stations, including data sets of two key areas: Amazon and Indonesian rainforests. Through estimation, the research team sorted out the anthropogenic carbon dioxide emissions of 1959 to 20 19.

Next, the research team found that the emissions from deforestation rose from a relatively low level of 1959 to a stable level since the end of the 1990s. This means that before the 1980s, the total amount of anthropogenic emissions caused by fossil fuel combustion and land use change was lower than previously expected, so the concentration of carbon dioxide in the atmosphere during this period was higher than the usual assumption. The researchers also found that in recent years, the content of carbon dioxide in the atmosphere showed a downward trend. This trend shows that the terrestrial and marine environment now absorbs more man-made carbon dioxide than in the past.

References: doi:/articles/s 41586-021-04376-4.

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Source | Yangcheng Evening News Yangcheng School

Edit | Chen Qian