The carbon sequestration effect of forest area is very significant. This is the densely forested Saihanba Mechanical Forest Farm in Hebei. Xinhua News Agency reporter Jin Haoyuan photo
Mangroves are typical carbon storage experts. This is the mangrove in Lianzhou Bay, Hepu County, Beihai City, Guangxi. Photo by Lin Qibo
Whether it is to reduce carbon emissions during the use of fossil energy, or to study the use of non-carbon energy to replace it, it is a discussion of how to reduce emissions from the emission side. To achieve the dual-carbon goal, it is also necessary to work on the carbon sequestration side, through ecological construction, soil carbon sequestration, carbon capture, utilization and storage and other projects and technologies to remove the carbon dioxide that has to be emitted.
makes full use of terrestrial ecosystems to sequester carbon, which is the most economical and environmentally friendly. Carbon sequestration can sequester excess carbon and not release it into the atmosphere.
"At present, there are mainly two methods of physical carbon fixation and biological carbon fixation." Institute of Atmospheric Physics, Chinese Academy of Sciences researcher Chen Kexin introduced that physical carbon fixation is the long-term storage of carbon dioxide in exploited oil and gas wells, coal seams and deep seas. ; Biological carbon sequestration is the use of plant photosynthesis to convert carbon dioxide into carbohydrates and fix it in the plant body or soil in the form of organic carbon.
In the past 10 years, people have paid more and more attention to nature-based solutions. Biological carbon sequestration is considered to be the most promising way to alleviate global warming.
Chinese Academy of Sciences academician Fang Jingyun said: “Terrestrial ecosystems absorb a large amount of carbon dioxide in the atmosphere through photosynthesis of vegetation. Using terrestrial ecosystems to sequester carbon is the most economically feasible and environmentally friendly way to slow the increase in atmospheric carbon dioxide concentration. Therefore, how to improve the carbon storage and carbon sequestration capacity of terrestrial ecosystems is not only a hot area of global change research, but also a focus of widespread attention by the international community."
Forests are the main body of terrestrial ecosystems.It is also the largest "carbon pool" on land, and it plays an important role in regulating climate and alleviating global warming.
So, what is the status quo of our country in this regard?
Ding Zhongli, an academician of the Chinese Academy of Sciences, said: “About 56% of China’s terrestrial carbon sink comes from areas related to the construction of six major ecological projects. Some of the history of these projects can even be traced back to the last century. After years of accumulation, They are playing an increasingly important role."
The team of Liu Yi from the Institute of Atmospheric Physics, Chinese Academy of Sciences, released the latest research results in Nature this year, showing that my country's ecosystems have a huge carbon sequestration capacity. The study found that the huge carbon sink capacity of my country's terrestrial ecosystem mainly comes from the carbon sequestration contribution of my country's important forest areas, especially the southwest forest area. At the same time, my country's northeast forest area also has a very strong carbon sink effect in summer. This is also the result of my country's restoration of natural forest vegetation and strengthening of plantation cultivation in the past 40 years.
develops carbon capture and storage technology to strengthen the resource utilization of carbon dioxide emitted by fossil fuels
Research believes that the carbon storage process needs to increase the concentration of carbon dioxide in order to improve efficiency and increase storage capacity, thereby reducing costs. At the same time, most of the utilization scenarios also require high concentrations of carbon dioxide to increase the utilization conversion rate. Therefore, capture technology has become a key technology in the process of carbon dioxide utilization and storage.
In the 1980s, the United Nations Intergovernmental Panel on Climate Change proposed the "carbon capture and storage" technology, which mainly transports the captured carbon dioxide through a certain method to a suitable location for storage to isolate it from the atmosphere. Reduce the emission of carbon dioxide into the atmosphere and promote the rebalancing of the atmospheric carbon cycle. But the biggest problem with this technology is the high cost of construction and operation.
Carbon capture, utilization and storage technology is a new development trend of carbon capture and storage technology, that is, to purify the carbon dioxide emitted during the production process, and then put it into a new production process, which can be recycled and reused instead of simply being stored . Compared with carbon capture and storage technology, it can reuse carbon dioxide as a resource, which can produce economic benefits.It is also more practical.
From carbon capture and storage technology to carbon capture, utilization and storage technology, it further strengthens the resource utilization of carbon dioxide emitted during the use of fossil fuels.
At present, with the global response to climate change and the carbon neutral goal, carbon capture, utilization and storage as carbon reduction and carbon sequestration technologies have become an important part of many national carbon neutral action plans. Data show that as of 2020, there are 26 such large-scale demonstration projects in operation worldwide, which can capture and store about 40 million tons of carbon dioxide each year.
On the road to carbon neutrality, certain physical and chemical processes, such as chemical weathering of rocks, can also capture and store carbon dioxide, which is called natural carbon capture and storage technology.
"For example, the alkaline soil in the arid and semi-arid regions of our country contains a lot of calcium ions. These calcium ions combine with carbon dioxide in the atmosphere and they will be leached to form calcium carbonate precipitation during precipitation." Ding Zhongli said, " China has a large area of arid and semi-arid regions. This natural process is a very important process for carbon fixation.”
Ding Zhongli said that although carbon capture and storage technology, silicate rock weathering and other negative emission technologies are The potential for carbon sequestration and emission reduction is huge, but these technologies need further research. "We estimate that forests will reach the peak of carbon sequestration before 2060, and then the rate of carbon sequestration will decrease. Therefore, before the peak of carbon sequestration, it is best not to simply store them, as it will not produce economic benefits, but we must find a way. Use carbon dioxide."
Ocean carbon storage can reach nearly 20 times that of the land and 50 times that of the atmosphere. The potential of ocean carbon sinks should be exerted
In addition to the fixation of carbon dioxide by green plants through photosynthesis, the ocean also absorbs and stores carbon dioxide. The role of.
According to experts, the ocean covers about 70% of the earth's surface, and its carbon storage is nearly 20 times that of land and 50 times that of the atmosphere. It is also an important regulator of climate. From a global perspective, take the coastal zone plant biomass as an example,Although it is only 0.05% of the biomass of land plants, its annual carbon sequestration is equivalent to that of land plants.
From a time scale, compared with carbon stored in terrestrial ecosystems for decades, organic carbon buried in the soil of coastal wetlands and inert inorganic carbon dissolved in seawater can be stored for thousands of years.
my country is a big ocean country, the ocean should play an important role in the national emission reduction and sink increase, and the potential of ocean carbon sinks should be exerted vigorously.
Seagrass beds, mangroves and salt marshes These three coastal ecosystems are typical carbon storage experts. Studies have found that fish, large seaweeds, shellfish and micro-organisms also play a role in fixing and storing carbon.
But carbon sequestration is not equal to carbon storage, and high carbon content is not equal to high carbon sinks. Many particles of organic carbon will be degraded in the process of sedimentation, and have been severely attenuated when buried on the seabed.
Researchers are paying more and more attention to improving the efficiency of ocean carbon storage. Professor Jiao Nianzhi, academician of the Chinese Academy of Sciences and Xiamen University , led the team to propose a micro-biological carbon pump, a marine carbon sink mechanism. They found that marine microbes can convert active dissolved organic carbon into inert dissolved organic carbon, allowing long-term storage of organic carbon. Studies have shown that micro-biological carbon pumps are also helpful for carbon hydrochloric acid pumps.
On the basis of continuously deepening the understanding of the ocean carbon sink mechanism, scientific researchers put forward some suggestions on the efficient use of ocean carbon sink.
First, protect the three major coastal ecosystems, increase seagrass bed area and seagrass coverage, build and restore mangroves, protect salt marsh wetlands, etc., adhere to the implementation of marine carbon sink projects, and promote marine ecological protection and sustainable development.
Secondly, we must adhere to land and sea coordination, reduce emissions and increase foreign exchange. Jiao Nianzhi introduced that many estuaries and coasts in my country are discharged into excessive amounts of nitrogen and phosphorus, causing eutrophication . "Eutrophication seems to be'fertilization'. There are more phytoplankton, and the amount of carbon sequestration increases. In fact, the opposite is true. The organic carbon in an environment with excessive nutrients is easily degraded. The more organic matter, the more prosperous bacteria are. Organic carbon is breathed into carbon dioxide and released.Jiao Nianzhi explained that only by maintaining an appropriate amount of nutrient input and maximizing the synergistic effect of micro-biological carbon pumps and biological pumps, can it be conducive to sustainable development.
The Xiamen Carbon and Emissions Trading Center has completed the first ocean carbon sink transaction. Experts suggest that in addition to exploring and improving the efficiency of ocean carbon sinks through science and technology, it is also necessary to establish more scientific ocean carbon sink resource value accounting standards as soon as possible, and explore and build more Standardize the ocean carbon sink trading market and improve the ecological compensation mechanism. (Reporter Wu Yuehui, Liu Shiyao, Yu Sinan)
(Author: Wu Yuehui, Liu Shiyao, Yu Sinan)
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