As people's understanding of carbon emissions deepens, just one word "carbon" can no longer easily summarize all research and discussions related to the dual-carbon problem. An article published in the journal " Nature " pointed out that in order to promote the interdisciplinary development of carbon research, people have begun to combine color spectrum to define the properties and distribution of different "carbons", and use different color-based terms to help more people deepen their understanding of carbon emissions and carbon cycles. This article introduces several relatively mainstream categories to you.
Black CarbonhtmlBlack Carbon
Black Carbon (also known as carbon soot) is undoubtedly one of the most well-known carbon colors. It does not refer to the colorless and odorless gas carbon dioxide , but the by-product of incomplete combustion of , such as fossil fuels. In the smoke and coal smoke produced by fires, brick kiln firing, these small black solid particles often remain. Black carbon has many direct or indirect effects on the climate. For example, as a light-absorbing substance, black carbon can strongly absorb solar short-wave radiation, release infrared radiation, heat the surrounding atmosphere, and retain it in the atmosphere for several days to several weeks, thus creating a regional warming effect; for example, when black carbon adheres to white surfaces such as iceberg snow covers, it will absorb heat while hinder reflection, accelerate the melting of icebergs, ice fields and Arctic ice sheets and trigger sea level rise in . In Himalaya and other areas, the impact of black carbon on glacier melting may be equivalent to carbon dioxide. A study published in 2013 by JGR (Journal of Geophysical Research) pointed out that the warming effect of black carbon is about two-thirds of that of carbon dioxide, and in some regions, such as the northern United States, Canada, northern Europe and northern Asia, its actual impact may be more significant than that of methane . This, in turn, means that reducing black carbon emissions can be seen as one of the most effective ways to mitigate regional climate change in the short term.
brown carbon Brown Carbon
At present, the Arctic region is warming rapidly at twice the speed of other regions in the world. Glacier melting and sea ice reduction have led to abnormal global atmospheric circulation and reduced regional biodiversity, which has triggered a series of environmental, ecological and economic problems. This phenomenon is also closely related to the other color of carbon - brown carbon. Brown carbon is a light-absorbing organic aerosol released by fossil fuel combustion, biomass combustion, etc. It often coexists with black carbon, but has a more complex chemical composition and source than black carbon. It has a strong absorption effect on solar radiation in the near-ultraviolet band, which can increase the net radiation flux obtained by the earth, resulting in climate warming.
Due to its outstanding light absorption, the climatic impact of brown carbon on on plateaus and polar regions has gradually attracted the attention of researchers in recent years. A recent study published in the journal One Earth, jointly conducted by many domestic and foreign units including the School of Earth Systems Sciences of Tianjin University and the MaxPhotos Institute of Chemistry in Germany, showed that in the Arctic, the heating effect of water-soluble brown carbon is about 30% of black carbon, and biomass combustion at mid- and high latitudes of the northern hemisphere contributes about 60% of the brown carbon heating effect in the Arctic. If the frequency, intensity and range of wildfires in mid- and high latitude areas continue to increase in the future, more brown carbon aerosols may be released, further accelerating the warming of these areas and causing more frequent wildfire burning, forming a vicious cycle. Therefore, it is crucial to clarify the heating effect of brown carbon and its main sources as soon as possible to mitigate plateaus, polar regions and even global climate change.
Red Carbon
Red Carbon is a newly proposed carbon color, which mainly refers to "all living biological particles that reduce albedo survival on ice and snow", such as red snow algae. "Red" here refers to some common red, yellow, and purple pigments produced by these microorganisms. These colors can absorb light from green and blue wavelengths, thereby melting ice and snow and releasing other substances in the ice crystals, such as nitrogen and phosphorus.In recent years, the "watermelon snow" that scientists have discovered in the polar regions, the Alps and other mountains is actually the snow that has lived in a large number of red snow algae. Red Snow Algae need liquid water and nutrients in the water to thrive, so when enough red Snow Algae gather together, they absorb more sun energy, which speeds up the melting of the glaciers.
Climate warming will cause the melting of the pole ice caps and the increase in the deposition of air particles (such as agricultural dust containing nutrients). These changes will create a more favorable growth environment for red snow algae, which will in turn trigger more glaciers to melt and cause sea levels to continue to rise. Therefore, the concept of red carbon is proposed to promote people to accelerate research on how microorganisms act on glaciers and find ways to avoid the occurrence of vicious cycles as soon as possible.
Green Carbon
Green Carbon is now considered a well-known concept, namely "carbon absorbed by terrestrial ecosystems". The reason why it is called "green" is because this carbon dioxide is absorbed by plants on land through photosynthesis , and photosynthesis depends on green chlorophyll in plant leaves.
There is no doubt that as a potential buffer for greenhouse gas accumulation, the green carbon ecosystem plays a key role in affecting the level of greenhouse gas concentration in the atmosphere. Forests covering one-third of the earth's land not only provide habitat for 80% of land species, but also absorb nearly 30% of the earth's carbon emissions. However, today's forests are facing the impact of threats such as deforestation and forest fires. According to data from World Bank , between 1990 and 2015, the average global loss of forests equivalent to 1,000 football fields per hour. The disappearance of natural forests can cause carbon dioxide from plants to be released back into the atmosphere, exacerbating the climate crisis. Therefore, maximizing conservation and expanding forests around the world is crucial to slowing down climate change.
Blue Carbon
Compared with the green carbon on land, the process of using marine activities and marine organisms to absorb carbon dioxide in the atmosphere and fixing and storing it in the ocean is called "blue carbon". Its definitions were initially focused on mangrove , salt marsh and seaweed , but now also include a wider range of seaweed and sediments.
blue carbon has the characteristics of large carbon sequestration, high efficiency, and long storage time. It is the largest and most active carbon reservoir on the earth. The carbon absorbed and stored per unit of marine ecological area is dozens of times more than terrestrial forests, and the marine carbon storage cycle can reach more than thousands of years. According to the global average, the annual carbon sink of the three coastal blue carbon ecosystems in my country alone, mangroves, seagrass beds and coastal salt marshes, can reach up to about 3.08 million tons. Today, the development of blue carbon has become one of the most cutting-edge areas for effectively slowing greenhouse gas emissions and achieving the carbon neutrality goal. Especially for China, my country is one of the few countries in the world that have three major blue carbon ecosystems at the same time. The development of blue carbon will be an important tool for China to participate in global climate governance and actively respond to climate change.
green carbon Teal Carbon
green carbon is also a newer concept, which is related to "carbon stored in inland freshwater wetlands". Inland freshwater wetlands are between land ecology (green carbon) and tidal brine ecology (blue carbon), so they are called green carbon. Relevant estimates show that inland freshwater wetlands that account for only 7% of the land surface can account for 20%-30% of the land soil carbon reservoir. In some countries and regions with a wider area of inland wetlands, green carbon is not less important than blue carbon in regional carbon storage and regulating greenhouse gases. For example, a 2016 study showed that freshwater inland wetlands in the United States had nearly 10 times more carbon than the tidal brine sites evaluated by the Institute.
However, since the beginning of the 18th century, 87% of the world's wetlands have disappeared, and they are constantly threatened by man-made activities such as land use changes, pollution, water resource exploitation and landscape transformation, and are likely to re-release large amounts of carbon dioxide and methane back into the atmosphere.Therefore, more and more researchers are now trying to quantify the contribution of inland wetland ecosystem to carbon storage, and call for improvement of inland freshwater wetland protection and management strategies to increase the total global carbon sink and help achieve the carbon neutrality goal.
article | Zhu Lin
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