"In the third week of March, the east Antarctic research station recorded unprecedented temperatures, 40 degrees Celsius higher than the monthly average." In a recent article on the U.N. website, scientists again warned that rising temperatures and increased melting of antarctica's ice sheet should be given enough attention. Climate change has led to extreme weather, droughts, rising temperatures, melting glaciers and rising sea levels, pushing the Earth's environment and human life to a tipping point. People are experiencing climate change in different ways.
Today, the 53rd Earth Day, let's focus on "Earth, Oceans and Blue Carbon". Co-sponsored by Tencent Research Institute, Tencent Strategic Development Department and SSV Carbon Neutrality Laboratory, this issue of Tengyan Interview will talk with Professor Dai Minhan, Academician of the Chinese Academy of Sciences, Chemical Oceanographer and Director of the Department of Earth Sciences and Technology of Xiamen University, who will analyze the impact of the ocean on climate, ocean-based carbon neutral solutions, and explore the empowerment of digital technologies on marine technology and blue carbon development from a professional perspective.
He believes that the sustainable prosperity of the oceans of the future can only be achieved through the joint design and effective synergy of global cross-borders. Solutions for sustainable ocean prosperity can be expressed as a formula that:
Prosperous Ocean = (Scientific Cognition + Technological Revolution + Scientific Governance + Blue Finance) × Co-design 2
Interviewees:
Dai Minhan is an academician of the Chinese Academy of Sciences, a chemical oceanographer, and the director of the Department of Earth Sciences and Technology of Xiamen University
Interlocutors (hereinafter referred to as T):
Senior Consultant of Strategic Development Department of Zhai Yongping Tencent
Senior Researcher of Tencent Research Institute
Ocean-based
Carbon neutral solutions make a lot of sense
T: Everyone knows that climate change has an impact on the oceans, such as melting glaciers, global sea level rise, etc., but how the oceans play a regulatory role in climate change, it seems that very little is known, as a scientist in the field of oceans and global climate change, can you tell us about the relationship between the ocean and climate?
Dai Minhan: If we sum up the relationship between the ocean and the climate in one sentence, it is that the ocean and its ecosystems are both powerful "implementers" and "victims" of climate change.
First, the oceans are huge "buffers" and "regulators" of climate change. This can be seen from the perspective of the Earth's energy balance and carbon balance. For a long time, the absorption and release of energy in the Earth system has been in a state of dynamic equilibrium, ensuring the habitability of the Earth. A kilogram of sea water absorbs a large amount of heat, 4 times that of air, and the huge volume of the ocean, which has a huge heat capacity, is the core of maintaining the energy balance of the Earth system. Since 1950, the oceans have absorbed about 90 percent of the heat that enters the climate system, driving ocean warming, the effects of which have reached the deep oceans, and the trend continues. The latest observations show that in 2021, the heat absorbed by the two kilometers of the upper layer of the global ocean will increase by 14×1021 joules compared to 2020 – this heat is equivalent to 500 times the amount of electricity generated by China in 2020.
These data strongly support the idea that the oceans absorb most of the excess heat in the climate system caused by greenhouse gases emitted by human activities, are the largest buffer against the earth's energy imbalances, and play a vital role in mitigating global climate change. If there is no ocean or the "heat absorption" capacity of the ocean reaches the upper limit, under the action of the "greenhouse effect", the huge excess energy originally absorbed by the ocean can neither be released outward nor absorbed by the surface (the surface heat capacity is much lower than that of the ocean), which in turn will lead to a sharp increase in surface temperature, which will further aggravate extreme weather and climate events, and even a serious disaster that is difficult for human beings to bear.
The ocean is the largest carbon reservoir in the surface system, with 50 times the carbon storage of the atmosphere, 98% of which exists in the form of dissolved Inorganic Carbon (DIC). Dissolved inorganic carbon systems, also known as carbonate systems, build seawater carbonate buffer systems. Atmospheric carbon dioxide enters the ocean through the exchange of sea air and undergoes a series of chemical reactions, thus breaking the original equilibrium of the seawater carbonate system. Some of the carbon dioxide that enters the ocean is converted into other forms, so that the concentration of carbon dioxide in the seawater increases less than in non-buffer systems. At different depths of the ocean, the residence time of seawater also varies greatly, with surface water staying the shortest, reaching a depth of 1,000 meters for hundreds or even thousands of years. If the DIC of the ocean's surface is transported deep into the ocean, it can be isolated from the atmosphere for a long time, achieving carbon sequestration, while promoting further absorption of carbon dioxide from the atmosphere by the upper ocean. Marine carbon pumps, including "solubility pumps", "biological pumps" and "carbonate pumps", have taken over the task of transporting and storing carbon.
The ocean is one of the main destinations for anthropogenic emissions of carbon dioxide. Since the Industrial Revolution, the oceans have cumulatively absorbed about 25% of anthropogenic emissions of carbon dioxide. Without terrestrial ecosystems and oceanic systems absorbing atmospheric carbon dioxide, atmospheric carbon dioxide concentrations could have long exceeded the 2°C temperature-controlled target of the Paris Agreement. There is also a carbon budget since the Industrial Revolution, from 1850 to 2020, numerically, the carbon dioxide released into the atmosphere by changes in land use patterns is offset by carbon dioxide absorbed by terrestrial ecosystems, and net carbon dioxide consumption is very low for land, while carbon dioxide produced by fossil fuel combustion is as high as 462 billion tons of carbon, of which the ocean absorbs 36%, and the remaining 64% remains in the atmosphere. It is envisaged that without oceans, the carbon dioxide released by the burning of fossil fuels will remain entirely in the atmosphere, and the concentration of atmospheric carbon dioxide will increase faster, further exacerbating the risk of climate change.
Secondly, the negative impact of the ocean's continuous heat absorption and carbon storage on the marine environment and ecology has become increasingly prominent, including ocean warming, acidification, deoxygenation, sea level rise, and biodiversity loss.
Shenzhen Futian Mangrove Forest (Photo by Zhou Haichao, Shenzhen University)
T: Increasing the carbon sink increment of ecosystems has become one of the important ways to achieve the "double carbon" goal, what role will blue carbon and marine carbon sinks play in the process of addressing global climate change and achieving the "double carbon" goal of the mainland?
Dai Minhan: China's commitment to achieve carbon neutrality by 2060 is to follow a sustainable and high-quality development path, and for the sake of all human civilizations, so as to build a global climate governance system under the framework of a community with a shared future for mankind, and is an initiative to promote the joint efforts of the international community to achieve the Paris Agreement's targets of 2 °C temperature control and "ambition" within 1.5 °C.
The concept of blue carbon was originally proposed relative to the green carbon of terrestrial ecosystems. According to the Blue Carbon Report, jointly released by the United Nations Environment Programme, FAO and UNESCO's Intergovernmental Oceanographic Commission in 2009, blue carbon is defined as organic carbon captured and stored by marine and offshore ecosystems through photosynthesis. Ocean carbon sinks, on the other hand, are relative to atmospheric carbon dioxide, which means that the ocean absorbs carbon dioxide through physical, chemical, and biological processes and stores it inside. Therefore, the full expression of ocean carbon sinks should be "atmospheric carbon dioxide sinks", and the fixed form and sequestration of this part of carbon in the ocean (i.e., the depth of separation from the exchange with the atmosphere) determines the time scale of ocean carbon sinks.
From the perspective of combating global climate change, the oceans have played a central role in the past, present and future. As mentioned above, since the Industrial Revolution, the oceans have played a central and sustained role in absorbing anthropogenic carbon dioxide. Looking ahead, under a net-zero or negative emission scenario, atmospheric carbon dioxide concentrations will gradually decrease, and if the ocean and the atmosphere cannot achieve simultaneous carbon reduction, the ocean carbon sink capacity will be weakened, and may even release the carbon dioxide absorbed in the past back into the atmosphere, which will seriously threaten the carbon reduction effect.
Of course, the importance of the ocean is also reflected in its enormous potential for foreign exchange. As atmospheric carbon dioxide increases, the rate at which the ocean absorbs carbon dioxide is determined by the rate at which atmospheric carbon dioxide concentration increases on the one hand, and by the speed of vertical exchange within the ocean on the other. For example, it takes only about a year for surface seawater carbon dioxide to reach equilibrium with the atmosphere, but it takes years or even centuries for surface and medium- and deep seawater to complete a mixing process. Therefore, the marine carbon sink formed since the Industrial Revolution is still mainly in the upper layer of the ocean. Limited by this, the ocean currently absorbs only 15% of its maximum capacity of anthropogenic carbon dioxide, and the ocean still has up to 85% of its potential to absorb atmospheric carbon dioxide, especially in the vast deep oceans.
Measures to increase the contribution of marine and coastal ecosystems include the protection and restoration of coastal blue carbon ecosystems, carbon sequestration in seaweed farming, seawater alkalinization, marine fertilization and sink enhancement. Marine carbon aggregates are sequestered for long periods of time and may be eco-friendly, slowing ocean acidification, increasing fisheries, or becoming raw materials for food, fuel and durable products.
At the regional or national level, marine carbon sink inventories, stability, evolutionary trends and their control mechanisms need to be further studied to empower national carbon neutrality strategies and actions. The marginal seas adjacent to the mainland, such as the South China Sea, the East China Sea, and the Yellow Sea, are located in the land-ocean junction zone, and in addition to receiving material input from major rivers such as the Pearl River, the Yangtze River, and the Yellow River, they also continue to exchange materials with the neighboring northwest Pacific Ocean. Thus, in addition to absorbing about 10 million tonnes of carbon directly from the atmosphere, the continental marginal sea also carries lateral inputs (including carbon) from land and oceans, indirectly contributing to terrestrial and oceanic carbon sinks. The coastal coastal sea is affected by both anthropogenic activities and global changes, in which the physical and biogeochemical processes are far more complex than the oceans, and the carbon source pattern can be dynamically switched on different spatial and temporal scales, which to a certain extent increases the difficulty of clarifying the list of china's sea carbon source sinks. In addition, the process of quantitatively identifying natural and anthropogenic sources/sinks in offshore waters is also a challenging scientific proposition, so it is necessary to accelerate the relevant research.
In addition, the mainland has an ocean land area of 3 million square kilometers, which is nearly twice the area of land forests, is also an important part of the natural ecology, and has great potential for increasing foreign exchange. However, the role and potential of the oceans and seas are far from being given sufficient attention in international discussions on nationally determined contributions so far. Therefore, challenges and opportunities coexist, and it is urgent to form a theory of marine carbon sinks and develop blue carbon sink enhancement technology.
Of course, ocean-based carbon neutral solutions must accurately assess the ecological effects of carbon sinks to achieve a synergy of "ecological priority, green development" and "carbon neutrality", which is highly consistent with the mainland's original intention to formulate a "double carbon" strategy. I would like to emphasize in particular that the oceans have great potential and strategic significance as a new strategic space and economic form (the blue economy) in terms of the achievement of carbon neutrality goals and the choice of sustainable development paths.
Scientific governance and realization of blue carbon and
Sustainable development of the oceans is challenging
T: How do you see the synergy between ocean carbon sinks, blue carbon and sustainable ecosystem development? What are the main problems facing the development of marine carbon sinks and blue carbons?
Dai Minhan: The mainland's "double carbon" strategy is an important part of the construction of ecological civilization, and marine carbon sinks, including blue carbon, are indispensable elements for achieving carbon neutrality goals and decision-making on strategic paths. However, there is still a considerable lack of scientific understanding of marine carbon sinks, and there are also a number of misunderstandings: first, people tend to only pay attention to the amount of carbon dioxide directly absorbed by the atmosphere as their carbon sink function, while ignoring that the continental offshore system is in a highly active zone of land-sea-ocean-air interaction, carrying materials (including carbon) imported laterally by land and oceans, indirectly contributing to land and ocean carbon sinks; second, the carbon dioxide captured by the ocean is not permanently sequestered, if the marine carbon sink is not solidified, On certain timescales, the oceans may even release carbon back into the atmosphere, which will seriously threaten the carbon reduction effect; third, from a national and regional perspective, clarifying the list of marine carbon sources and sinks and their dynamic changes is a necessary condition for planning a carbon neutral strategic path. Lack of scientific understanding of marine carbon sinks and blue carbon may make estimation of continental offshore marine carbon source inventories more difficult.
We need to fully recognize that carbon sinks are one of the most important ecological service functions of marine ecosystems, but they are not the only ecological service functions. The implementation of the blue carbon ecosystem-based programme to serve the "double carbon" objective and address climate change requires a comprehensive assessment of the ecological and environmental effects behind the programme, including impacts on coastal ecosystems, synergies with other terrestrial and marine systems, and impacts on natural marine carbon sinks. For example, mangroves have a very strong carbon sequestration capacity, more than 40 times that of forests, and at the same time have the functions of wind and waves, promoting siltation, and revetment, but in the process of promoting and developing mangrove ecosystems, they have also experienced lessons worthy of warning. The Xiangshan Wetlands in northwestern Taiwan Island have had considerable negative impacts on the local ecosystem since 1997, including loss of benthic and bird habitat caused by encroachment on light beaches, and sediment accumulation that increases the risk of flooding. Subsequently, in 2015, the Mangrove Removal Project was launched in Xiangshan Wetland. Therefore, before implementing a "double carbon" service scheme based on natural blue carbon, it is necessary to comprehensively assess and manage it in accordance with the laws of sustainable development of the ecosystem.
Early economic development processes led to varying degrees of destruction of coastal habitats, thereby weakening the functioning of some of the continent's natural blue-carbon ecosystems. Restoring ecosystems, improving the quality of the ecological environment, curbing biodiversity loss, maintaining and enhancing the carbon sink function of blue carbon ecosystems, and developing a blue economy are a major opportunity.
T: The central government proposes that all localities should determine the direction of industrial restructuring and the "double carbon" action plan according to local conditions, as the Guangdong-Hong Kong-Macao Greater Bay Area with the longest coastline in the country, what are the opportunities and challenges in terms of blue carbon development?
Dai Minhan: The Guangdong-Hong Kong-Macao Greater Bay Area has abundant blue carbon resources, and the development of coastal blue carbon has unique advantages. According to statistics, the coastal wetland area of the Guangdong-Hong Kong-Macao Greater Bay Area exceeds 3,200 square kilometers, accounting for 5.5% of the country's coastal wetland area, of which the mangrove ecosystem area accounts for 10% of the country's existing mangrove forests. In addition, the unique geological conditions of the Guangdong-Hong Kong-Macao Greater Bay Area give it considerable carbon sequestration potential. The potential carbon sequestration space of the four major offshore sedimentary basins in the northern South China Sea adjacent to the Greater Bay Area is estimated at 400 billion tons, more than 1,000 times the total annual carbon emissions of the Greater Bay Area. At present, the Greater Bay Area and its adjacent seas have successively developed a number of carbon capture, utilization and storage demonstration projects, among which CNOOC's Enping offshore carbon storage platform in the Pearl River Estuary Basin has a design carbon storage capacity of 300,000 tons per year, which has been at the forefront of the world.
Some of the coastal wetlands in the Guangdong-Hong Kong-Macao Greater Bay Area have been protected through the establishment of wetlands of international importance and national and provincial nature reserves and wetland parks, including futian mangrove forest in Shenzhen, Maipu wetland in Hong Kong, Qi'ao Island in Zhuhai, and Huidong mangrove forest. Among them, Futian Mangrove Forest is the only national nature reserve located in the hinterland of the city in the mainland. The establishment of these nature reserves and wetland parks not only ensures that coastal wetlands play their functions such as carbon sequestration and biodiversity protection, but also serves as a base for tourism, education and science popularization, and raises public awareness of the importance of protecting coastal wetland ecosystems. In 2021, Shenzhen Mangrove Forest, as a successful example of "harmonious coexistence between man and nature", was selected as a "Typical Case of Chinese Practice of Nature-Based Solutions" jointly released by the Ministry of Natural Resources and the International Union for Conservation of Nature (IUCN).
In addition, the Guangdong-Hong Kong-Macao Greater Bay Area, as one of the regions with the highest per capita GDP and the strongest economic strength in the mainland, can make full use of its advantages in scientific and technological innovation and coastal areas, while maintaining economic growth, with the help of social and economic forces to carry out ecosystem restoration, and promote the coordinated improvement of ecosystem service functions; at the same time, it can give full play to the role of the two carbon emission exchanges in Guangzhou and Shenzhen, introduce a variety of trading products such as "blue carbon" resources, and build and improve carbon capture, utilization and storage policies and diversification. The multi-level carbon trading market mechanism promotes the application of technology and the comprehensive green transformation of the economy and society, and achieves the regional "carbon neutrality" goal with a sustainable development model.
Of course, opportunities and challenges coexist. The Guangdong-Hong Kong-Macao Greater Bay Area is one of the most densely populated areas in the mainland, the current economic development trend of the Greater Bay Area is strong, the energy consumption base is high, especially the carbon emissions of Guangdong Province are still showing a trend of increasing year by year, and the carbon emissions per unit of GDP in areas such as Jiangmen and Huizhou are 30-50% higher than the mainland average. In addition, population growth and economic development have brought about huge ecological and environmental pressures, such as land use changes caused by the occupation of living space, landfilling of domestic waste and discharge of urban sewage, and the destruction of ecosystems by biological invasions. Between 1990 and 2015, the area of construction land in the Greater Bay Area nearly doubled, occupying a large amount of wetland resources, and at the same time, urban sewage was even directly discharged into wetlands on the edge of the city, resulting in the deterioration of the wetland environment and further reduction of the area. Although the Greater Bay Area has launched and continued to carry out restoration projects and the construction of wetland parks in recent years, there is still a long way to go to protect coastal wetlands.
How to improve the scientific understanding of marine carbon sinks, innovate and apply technologies for carbon capture, utilization and storage, strengthen ecosystem-based scientific governance, give full play to financial leverage, and organically coordinate the above aspects to achieve blue carbon development and sustainable prosperity of the ocean, it is still very challenging.
Explore digital technology pairs
Empowerment of marine technology and blue carbon development
T: Digital technologies play an important role in helping the global response to climate change. What are the current applications of digital technologies in the field of marine technology and blue carbon development? What other areas are likely to be breakthroughs in digital technologies in the future?
Dai Minhan: The sustainable development and utilization of the ocean is the core concept of the integration and harmonious development of man and sea. However, the problems facing the oceans now are so great and deep that they are no longer simply a question of the intensity of development, but a question of the development model of the economic and social system. At this moment, if mankind takes advantage of the fourth industrial revolution and vigorously develops the digital ocean model, with the means of consolidating scientific cognition, innovating and applying technology, strengthening scientific governance, and exerting financial leverage, through global cross-border joint design and effective collaboration, the sustainable prosperity of the future ocean can be realized. Solutions for sustainable ocean prosperity can be expressed as a formula that:
Prosperous Ocean = (Scientific Cognition + Technological Revolution + Scientific Governance + Blue Finance) × Co-design 2
To further consolidate the understanding of marine science, digital technology is very critical. In recent years, with the application of remote sensing technology, numerical simulation and other technologies in the ocean, ocean observation data has grown exponentially, and the role of digital technology in marine economic strategy has become increasingly prominent; making full use of marine multi-source data assimilation technology, combining satellite remote sensing, field observation and other data with marine numerical simulation technology to generate reanalysis data products, which is an important direction for the development of marine numerical simulation, and the digital twin ocean (Digital Twin of the Ocean, DTO) came into being.
The digital twin ocean is simply based on the digital ocean and iteratively optimized with high-performance computing models and massive amounts of data, providing an accurate and comprehensive description of the current state of the ocean and helping to explore, discover, and visualize past, present, and future ocean conditions.
It is foreseeable that under the background of the fourth technological revolution with intelligence as the main feature, the digital twin ocean will be further developed. The United Nations Decade of the Ocean plans to create an integrated digital twin of the ocean as one of the top ten challenges. In 2020, the European Union and the United Nations launched the Digital Twin Ocean Project to support the United Nations 2030 Agenda for Sustainable Development; mainland scientists are also working hard to promote digital twin ocean technologies.
As a breakthrough in the fourth technological revolution, the digital twin ocean can also contribute to the monitoring, verification, predictive assessment and management decision-making of marine carbon sinks and blue carbon to cope with and adapt to climate change. The application of digital twin oceans to carbon footprint detection, carbon sink measurement and assessment can improve the spatio-temporal resolution of carbon source sink observations, and integrate multi-source marine big data to build a global blue carbon virtual perception network, improve the intelligent processing level of blue carbon data, realize a "measurable, reportable, verifiable" digital intelligent observation and evaluation system, and reduce the uncertainty of carbon inventory accounting.
On the basis of improving the accurate monitoring of natural and anthropogenic carbon sinks, digital twin marine technology can further simulate and assess the impact of marine carbon sinks and blue carbon on the future climate under different scenarios, identify their influencing factors and predict the trend, and provide scientific basis, program optimization and numerical prediction for marine carbon dioxide decarbonization projects. From the perspective of national strategy and management decision-making, the digital twin ocean helps to construct the continent's autonomous carbon neutral numerical simulation system, and build a decision support system for marine blue carbon and negative emissions, so as to dynamically adjust and optimize the carbon neutrality path in a timely manner.