Recently, a research result published by the Nanjing Institute of Geology and paleontology of the Chinese Academy of Sciences (hereinafter referred to as the Nanjing Institute of paleontology) in cooperation with Nanjing University and the University of California Davis shows that during the late Paleozoic great ice age about 300 million years ago, similar to the current earth environment, there was a short huge amount of carbon emission event, which caused a significant reduction in marine hypoxia and marine biodiversity. Relevant research results were published in the proceedings of the National Academy of Sciences (PNAs) on May 2.
300 million years ago, the location of the earth's continents
What are the consequences of global warming? What kind of living environment will life on earth face? The answers to these questions can be found in the earth's historical period similar to the current changes in the earth's environment.
Today, the earth is in the Cenozoic ice chamber climate that began 34 million years ago. In the past century, the global temperature has increased rapidly under the background of ice chamber climate, the melting of polar glaciers has intensified, the sea level has risen, and the degree of ocean hypoxia has increased, resulting in the reduction of global biodiversity. So, how will the trend of global warming develop further?
Chen Jitao, a researcher at Nanjing Institute of paleontology, told China Science Daily that it is difficult to predict the long-term trend in the future based on the observed data of current environmental changes. In order to find the internal relationship between the warming of the global ice chamber climate background and the changes of marine hypoxia and biodiversity, and more accurately simulate and evaluate the degree of marine hypoxia, researchers find the answer through the study of the ice chamber climate in the earth's history.
Chen Jitao pointed out that the late Paleozoic great ice age of 360-280 million years was the longest lasting and largest ice chamber climate on the earth. It was also the only geological period since the establishment of terrestrial higher plants and terrestrial ecosystems to record the transformation of the earth from ice chamber climate to greenhouse climate. The concentration of atmospheric carbon dioxide and oxygen at that time was also similar to that in modern times, It can be well compared with the ice chamber climate environment in which human beings live today.
Therefore, the study of the impact of carbon emissions and global warming events that have occurred in the late Paleozoic great ice age will help researchers better understand the correlation and feedback mechanism within the earth system under the current ice chamber climate, so as to more accurately predict the future development trend of global climate environmental change and biodiversity.
The international cooperation team composed of Chen Jitao, Professor Wang Xiangdong of Nanjing University and Professor Isabel Monta? EZ of the University of California Davis has carried out comprehensive research on the Carboniferous strata in South China for nearly a decade, including stratigraphy, paleontology, sedimentology, sedimentary geochemistry and numerical simulation, A huge carbon emission event under the ice chamber climate in the Late Carboniferous was found for the first time.
It is understood that the naqing section in Luodian, Guizhou Province has developed a few continuously exposed Carboniferous marine strata in the world, which has completely recorded the geochemical information of seawater in the Late Carboniferous. The researchers tested and analyzed the carbon and uranium isotopes and major and trace elements of the samples with centimeter accuracy collected from the profile, numerically simulated the carbon emission and carbon source with the global carbon cycle model, calculated the degree of global ocean hypoxia at that time by using the coupled uranium model, and finally established the correlation mechanism between carbon emission and ocean hypoxia area in the event.
The results show that in the Late Carboniferous (about 304 million years ago) ice chamber climate, about 9 trillion tons of carbon were discharged into the atmosphere within 300000 years, which caused significant global warming at that time. During this period, the sea surface temperature increased by about 4 ℃, the global ocean anoxic area expanded to 22%, and the marine biodiversity decreased significantly in the short term.
The study of earth system model shows that during the global warming of ice chamber climate, extensive ocean hypoxia may be related to the enhancement of seawater stratification and the increase of nutrient input (oxygen consumption).
By comparing the carbon emission events in different climatic environments in geological history and the global warming and ocean hypoxia caused by them, the research team proposed for the first time that under the same carbon emission rate, the ocean under the ice chamber climate may have a more serious oxygen deficiency state than the greenhouse climate.
Chen Jitao said that through the study of similar climate and environmental events that have occurred in the process of geological history and the detailed identification of the occurrence, development and end process of the event, we can further reveal its impact on marine biodiversity and provide some reference for mankind on how to deal with the possible polar climate in the future.
Related paper information: https://doi.com org/10.1073/pnas. two billion one hundred and fifteen million two hundred and thirty-one thousand one hundred and nineteen