The role of ocean carbon sinks in global climate change mitigation and carbon neutrality is still affected by lack of research. Aiming at overcoming the present limitations, a comprehensive and ...holistic framework and accounting method of ocean carbon sink evaluation are proposed in this study, which consider both carbon sink types and their characteristic carbon storage cycle timescales. The results show that (1) China’s total ocean carbon sink is 69.83–106.46 Tg C/year, among which the mariculture, coastal wetlands, and offshore carbon sinks are 2.27–4.06, 2.86–5.85, and 64.70–96.55 Tg C/year, respectively; (2) ocean-based solutions such as coastal protection and restoration, mariculture development, ocean alkalization, ocean fertilization, and marine bioenergy with carbon capture and storage have substantial mitigation potential, but further investigation is required before large-scale deployment; (3) although China’s ocean carbon sinks only counterbalanced 3.27–4.99% of its fossil fuel emissions, their tremendous enhancing potential and specific advantages cannot be ignored, and enhancing measures must be taken according to regional characteristics; (4) some uncertainties and limitations still exist, and problems such as double counting, carbon sink offset, and so forth need to be further considered. In a word, this study provides a basis for the development of ocean-based solutions on closing climate mitigation gaps.
The Chinese government has made a strategic decision to reach ‘carbon neutrality’ before 2060. China’s terrestrial ecosystem carbon sink is currently offsetting 7–15% of national anthropogenic ...emissions and has received widespread attention regarding its role in the ‘carbon neutrality’ strategy. We provide perspectives on this question by inferring from the fundamental principles of terrestrial ecosystem carbon cycles. We first elucidate the basic ecological theory that, over the long-term succession of ecosystem without regenerative disturbances, the carbon sink of a given ecosystem will inevitably approach zero as the ecosystem reaches its equilibrium state or climax. In this sense, we argue that the currently observed global terrestrial carbon sink largely emerges from the processes of carbon uptake and release of ecosystem responding to environmental changes and, as such, the carbon sink is never an intrinsic ecosystem function. We further elaborate on the long-term effects of atmospheric CO
2
changes and afforestation on China’s terrestrial carbon sink: the enhancement of the terrestrial carbon sink by the CO
2
fertilization effect will diminish as the growth of the atmospheric CO
2
slows down, or completely stops, depending on international efforts to combat climate change, and carbon sinks induced by ecological engineering, such as afforestation, will also decline as forest ecosystems become mature and reach their late-successional stage. We conclude that terrestrial ecosystems have nonetheless an important role to play to gain time for industrial emission reduction during the implementation of the ‘carbon neutrality’ strategy. In addition, science-based ecological engineering measures including afforestation and forest management could be used to elongate the time of ecosystem carbon sink service. We propose that the terrestrial carbon sink pathway should be optimized, by addressing the questions of ‘when’ and ‘where’ to plan afforestation projects, in order to effectively strengthen the terrestrial ecosystem carbon sink and maximize its contribution to the realization of the ‘carbon neutrality’ strategy.
Decadal trends in the ocean carbon sink DeVries, Tim; LeQuéré, Corinne; Andrews, Oliver ...
Proceedings of the National Academy of Sciences - PNAS,
06/2019, Volume:
116, Issue:
24
Journal Article
Peer reviewed
Open access
Measurements show large decadal variability in the rate of CO₂ accumulation in the atmosphere that is not driven by CO₂ emissions. The decade of the 1990s experienced enhanced carbon accumulation in ...the atmosphere relative to emissions, while in the 2000s, the atmospheric growth rate slowed, even though emissions grew rapidly. These variations are driven by natural sources and sinks of CO₂ due to the ocean and the terrestrial biosphere. In this study, we compare three independent methods for estimating oceanic CO₂ uptake and find that the ocean carbon sink could be responsible for up to 40% of the observed decadal variability in atmospheric CO₂ accumulation. Data-based estimates of the ocean carbon sink from pCO₂ mapping methods and decadal ocean inverse models generally agree on the magnitude and sign of decadal variability in the ocean CO₂ sink at both global and regional scales. Simulations with ocean biogeochemical models confirm that climate variability drove the observed decadal trends in ocean CO₂ uptake, but also demonstrate that the sensitivity of ocean CO₂ uptake to climate variability may be too weak in models. Furthermore, all estimates point toward coherent decadal variability in the oceanic and terrestrial CO₂ sinks, and this variability is not well-matched by current global vegetation models. Reconciling these differences will help to constrain the sensitivity of oceanic and terrestrial CO₂ uptake to climate variability and lead to improved climate projections and decadal climate predictions.
In order to promote the development of the carbon sink fisheries and the construction of national parks in Changdao, this paper calculated the carbon sink data of marine bivalves and seaweeds in ...Changdao for the first time, comprehensively evaluated the carbon sink capacity of mariculture in Changdao and its influencing factors, and put forward countermeasures and suggestions. The results showed that mariculture in Changdao had a certain carbon sink capacity. The average carbon sink of shellfish cultured in Changdao from 2016 to 2020 was 29 400 tons, and the carbon sink of shellfish, especially scallop, was significantly higher than that of algae; the structure and yield of mariculture were the main factors affecting the carbon sink capacity of Changdao mariculture, and the yield of mariculture was also affected by the scale, environment and technology. In the future, the development of carbon sink fisheries in Changdao should further optimize mariculture structure, establish mariculture carbon sink accountin
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The terrestrial ecosystem in China mitigates 21%–45% of the national contemporary fossil fuel CO2 emissions every year. Maintaining and strengthening the land carbon sink is essential ...for reaching China’s target of carbon neutrality. However, this sink is subject to large uncertainties due to the joint impacts of climate change, air pollution, and human activities. Here, we explore the potential of strengthening land carbon sink in China through anthropogenic interventions, including forestation, ozone reduction, and litter removal, taking advantage of a well-validated dynamic vegetation model and meteorological forcings from 16 climate models. Without anthropogenic interventions, considering Shared Socioeconomic Pathways (SSP) scenarios, the land sink is projected to be 0.26–0.56 Pg C a−1 at 2060, to which climate change contributes 0.06–0.13 Pg C a−1 and CO2 fertilization contributes 0.08–0.44 Pg C a−1 with the stronger effects for higher emission scenarios. With anthropogenic interventions, under a close-to-neutral emission scenario (SSP1-2.6), the land sink becomes 0.47–0.57 Pg C a−1 at 2060, including the contributions of 0.12 Pg C a−1 by conservative forestation, 0.07 Pg C a−1 by ozone pollution control, and 0.06–0.16 Pg C a−1 by 20% litter removal over planted forest. This sink can mitigate 90%–110% of the residue anthropogenic carbon emissions in 2060, providing a solid foundation for the carbon neutrality in China.
In the context of climate change and the circular economy, biochar has recently found many applications in various sectors as a versatile and recycled material. Here, we review application ...of biochar-based for carbon sink, covering agronomy, animal farming, anaerobic digestion, composting, environmental remediation, construction, and energy storage. The ultimate storage reservoirs for biochar are soils, civil infrastructure, and landfills. Biochar-based fertilisers, which combine traditional fertilisers with biochar as a nutrient carrier, are promising in agronomy. The use of biochar as a feed additive for animals shows benefits in terms of animal growth, gut microbiota, reduced enteric methane production, egg yield, and endo-toxicant mitigation. Biochar enhances anaerobic digestion operations, primarily for biogas generation and upgrading, performance and sustainability, and the mitigation of inhibitory impurities. In composts, biochar controls the release of greenhouse gases and enhances microbial activity. Co-composted biochar improves soil properties and enhances crop productivity. Pristine and engineered biochar can also be employed for water and soil remediation to remove pollutants. In construction, biochar can be added to cement or asphalt, thus conferring structural and functional advantages. Incorporating biochar in biocomposites improves insulation, electromagnetic radiation protection and moisture control. Finally, synthesising biochar-based materials for energy storage applications requires additional functionalisation.
A study on the value accounting of forest carbon sink services can promote the rapid development of the carbon sink market and help better understand the impact of forest carbon sinks on climate ...change and economic development. However, few studies have evaluated the value of China’s current forest carbon sink services. Based on research on carbon peak and carbon neutrality, according to the characteristics of China’s forest ecosystems and forest resource inventory data, the stock volume method was used to measure the amount and value of forest carbon sinks in China in 2009–2013 and 2014–2018. The results showed that: (1) the physical amount of forest carbon aggregates in China increased from 2009 to 2013 and from 2014 to 2018. The carbon storage of natural and plantation forests both showed an upward trend. Among them, the growth rate of the carbon storage of plantation forests was higher than that of natural forests. (2) The state, adjoint, and coupling equations of forest carbon sinks were employed to ascertain the best price for China’s forest carbon sinks in 2020. The results showed that the price of China’s forest carbon sinks was slightly higher than the internationally accepted carbon sink price, reflecting that the changes in the value of China’s forest carbon sinks and international carbon sinks were roughly the same. (3) We obtained an appropriate accounting model for China’s forest carbon sinks. (4) The value of China’s forest carbon sinks increased from 2009 to 2013 and from 2014 to 2018. Although the price of carbon sinks has declined, the overall forest resource stock has increased, especially in plantation forests. The increase in the value of carbon sinks was as high as 24.7%, resulting in an overall increase in the value of forest carbon sinks, which was also in line with the physical amount of forest carbon sinks. The measurement conclusions were consistent. Several key points to note based on these findings are as follows: (1) China’s current forest carbon sink transactions are all project-level certified emission reduction transactions, and diversified non-market means should be constructed to comprehensively promote carbon sink transactions. (2) China’s current carbon sink transactions are mainly clean development mechanism projects, with few transactions between enterprises, and the carbon trading market situation is not optimistic. (3) The key to effective forest carbon sequestration trading is the accurate accounting of forest carbon storage and carbon sequestration value. Thus, it is of great significance to establish a forest carbon sequestration measurement method that is economical, simple, and accurate. (4) The physical amount and value of carbon sequestration of China’s forest resources are rising, and the contribution rate is increasing year by year. However, there is still a gap in per capita forest area and storage compared with those in other countries worldwide. Thus, China must be vigilant in times of peace and further strengthen the protection and construction of forest resources.
Seagrass meadows are sites of high rates of carbon sequestration and they potentially support ‘blue carbon’ strategies to mitigate anthropogenic CO₂emissions. Current uncertainties on the fate of ...carbon stocks following the loss or revegetation of seagrass meadows prevent the deployment of ‘blue carbon’ strategies. Here, we reconstruct the trajectories of carbon stocks associated with one of the longest monitored seagrass restoration projects globally. We demonstrate that sediment carbon stocks erode following seagrass loss and that revegetation projects effectively restore seagrass carbon sequestration capacity. We combine carbon chronosequences with²¹⁰Pb dating of seagrass sediments in a meadow that experienced losses until the end of 1980s and subsequent serial revegetation efforts. Inventories of excess²¹⁰Pb in seagrass sediments revealed that its accumulation, and thus sediments, coincided with the presence of seagrass vegetation. They also showed that the upper sediments eroded in areas that remained devoid of vegetation after seagrass loss. Seagrass revegetation enhanced autochthonous and allochthonous carbon deposition and burial. Carbon burial rates increased with the age of the restored sites, and 18 years after planting, they were similar to that in continuously vegetated meadows (26.4 ± 0.8 gCₒᵣgm⁻² year⁻¹). Synthesis. The results presented here demonstrate that loss of seagrass triggers the erosion of historic carbon deposits and that revegetation effectively restores seagrass carbon sequestration capacity. Thus, conservation and restoration of seagrass meadows are effective strategies for climate change mitigation.
Ocean acidification is likely to impact marine ecosystems and human societies adversely and is a carbon cycle issue of great concern. Projecting the degree of ocean acidification and the ...carbon-climate feedback will require understanding the current status, variability, and trends of ocean inorganic carbon system variables and the ocean carbon sink. With this goal in mind, we reconstructed total alkalinity (TA), dissolved inorganic carbon (DIC), CO
2
partial pressure (
p
CO
2
sea), sea–air CO
2
flux, pH, and aragonite saturation state (Ω
arg
) for the global ocean based on measurements of
p
CO
2
sea and TA. We used a multiple linear regression approach to derive relationships to explain TA and DIC and obtained monthly 1° × 1° gridded values of TA and DIC for the period 1993–2018. These data were converted to
p
CO
2
sea, pH, and Ω
arg
, and monthly sea-air CO
2
fluxes were obtained in combination with atmospheric CO
2
. Mean annual sea–air CO
2
flux and its rate of change were estimated to be − 2.0 ± 0.5 PgC year
−1
and − 0.3 (PgC year
−1
) decade
−1
, respectively. Our analysis revealed that oceanic CO
2
uptake decreased during the 1990s and has been increasing since 2000. Our estimate of the globally averaged rate of pH change, − 0.0181 ± 0.0001 decade
−1
, was consistent with that expected from the trend of atmospheric CO
2
growth. However, rates of decline of pH were relatively slow in the Southern Ocean (− 0.0165 ± 0.0001·decade
−1
) and in the western equatorial Pacific (− 0.0148 ± 0.0002·decade
−1
). Our estimate of the globally averaged rate of pH change can be used to verify Indicator 14.3.1 of Sustainable Development Goals.
For the estimation of global karst carbon sink, a few conventional methods usually require the parameters that are difficult to measure, resulting in the big cost. Moreover, under the constraints of ...incomplete and timeliness issues in the collection of data over a large region, it has remained a challenge for these methods to study global karst carbon sink. Therefore, this paper proposes estimating the global karst carbon sink, and analyzing the suitability of the response surface methodology and the fluctuating variation of karst carbon sink in global karst regions from 1951 to 2050. This paper shows that the proposed method can reduce the time of numerical calculation and is suitable for application in global weathering models; The global karst carbon sink in the future changes not only displays an upward trend but also exposures its fluctuating trend largely. This fluctuation is probably due to global warming.
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