Net Carbon Sink Research Articles

Simulated sensitivity of the Amazon rainforest to extreme drought

Abstract The Amazon rainforest is highly biodiverse and the largest intact, tropical forest in the world. Undisturbed tropical forests act as a carbon sink by taking up about 15% of anthropogenic carbon emissions per year. In the past decades, a declining trend in the carbon sink capacity in the Amazon rainforest has been observed due to increased carbon losses and tree mortality. The causes are disputed, but increasing temperatures and more frequent severe droughts are potentially major drivers. We employ a novel modelling framework and hypothesize that previously rare, extreme droughts in the Amazon, such as the ones in 2005 and 2010, constitute the main cause behind the decline of the net carbon sink in aboveground biomass. Our dynamic vegetation model simulates process-based plant hydraulics and drought-induced mortality, and accounts for the diversity of strategies in plant responses to drought based on observed hydraulic vulnerability curves. The simulated impact of the 2005 drought event temporarily turned the annual Amazon net carbon sink to a carbon source of about 0.25 MgC ha-1. In contrast to other dynamic vegetation models our model simulated an increasing trend in carbon losses and a declining trend in the Amazon carbon sink over the past 25 years (net sink rate of -0.018 Mg C ha-1 year-1 or -0.22 Mg C ha-1 per decade) which corresponds well with long-term forest monitoring data (net sink rate of -0.016 Mg C ha-1 year-1). We show that this trend is entirely attributable to drought-induced forest mortality during extreme years. The simulations show a threshold-like behaviour between drought intensity and biomass loss, which is due to xylem vulnerability, indicating the potentially high sensitivity of Amazon forests to extreme drought. Further increases in the severity and frequency of droughts might thus lead to greater carbon release and tree mortality than previously assumed.

Assessment of Landscape‐Scale Fluxes of Carbon Dioxide and Methane in Subtropical Coastal Wetlands of South Florida

AbstractCoastal wetlands play a significant role in the storage of “blue carbon,” indicating their importance in the carbon biogeochemistry in the coastal zone and in global climate change mitigation strategies. We present airborne eddy covariance observations of CO2 and CH4 fluxes collected in southern Florida as part of the NASA BlueFlux mission during April 2022, October 2022, February 2023, and April 2023. The flux data generated from this mission consists of over 100 flight hours and more than 6,000 km of horizontal distance over coastal saline and freshwater wetlands. We find that the spatial and temporal heterogeneity in CO2 and CH4 exchange is primarily influenced by season, vegetation type, ecosystem productivity, and soil inundation. The largest CO2 uptake fluxes of more than 20 μmol m−2 s−1 were observed over mangroves during all deployments and over swamp forests during flights in April. The greatest CH4 effluxes of more than 250 nmol m−2 s−1 were measured at the end of the wet season in October 2022 over freshwater marshes and swamp shrublands. Although the combined Everglades National Park and Big Cypress National Preserve region was a net sink for carbon, CH4 emissions reduced the ecosystem carbon uptake capacity (net CO2 exchange rates) by 11%–91%. Average total net carbon exchange rates during the flight periods were −4 to −0.2 g CO2‐eq m−2 d−1. Our results highlight the importance of preserving mangrove forests and point to potential avenues of further research for greenhouse gas mitigation strategies.

Tracking tree demography and forest dynamics at scale using remote sensing.

Capturing how tree growth and survival vary through space and time is critical to understanding the structure and dynamics of tree-dominated ecosystems. However, characterising demographic processes at scale is inherently challenging, as trees are slow-growing, long-lived and cover vast expanses of land. We used repeat airborne laser scanning data acquired across 25 km2 of semi-arid, old-growth temperate woodland in Western Australia to track the height growth, crown expansion and mortality of 42 213 individual trees over 9 yr. We found that demographic rates are constrained by a combination of tree size, competition and topography. After initially investing in height growth, trees progressively shifted to crown expansion as they grew larger, while mortality risk decreased considerably with size. Across the landscape, both tree growth and survival increased with topographic wetness, resulting in vegetation patterns that are strongly spatially structured. Moreover, biomass gains from woody growth generally outpaced losses from mortality, suggesting these old-growth woodlands remain a net carbon sink in the absence of wildfires. Our study sheds new light on the processes that shape the dynamics and spatial structure of semi-arid woody ecosystems and provides a roadmap for using emerging remote sensing technologies to track tree demography at scale.

Response Mechanism and Evolution Trend of Carbon Effect in the Farmland Ecosystem of the Middle and Lower Reaches of the Yangtze River

The farmland system in the global terrestrial ecosystem has dual attributes as both a carbon source and a carbon sink, playing a crucial role in controlling carbon emissions and mitigating global warming. Using carbon source and sink accounting of farmland ecosystems, we applied methods such as standard deviation ellipse, Tapio decoupling theory, and Markov chain to analyze the spatiotemporal changes, response mechanisms, and evolutionary trends of regional carbon effects. The results indicated that from 2011 to 2021, the farmland ecosystem in the middle and lower reaches of the Yangtze River consistently acted as a carbon sink. However, the net carbon sink showed slight fluctuations and significant spatial differences. The migration range of the net carbon sink center in the farmland ecosystem of the middle and lower reaches of the Yangtze River was relatively small, ranging from 115.52 to 115.77° E and 30.14 to 30.27° N. The decomposition of the Tapio decoupling index between the net carbon sink of the farmland ecosystem and agricultural output value showed the order of effects on their coupling relationship as follows: agricultural mechanization level > agricultural mechanization efficiency > agricultural output value > planting scale. The probability of maintaining the original state of net carbon sink in various cities in the middle and lower reaches of the Yangtze River (over 77%) was much higher than the probability of transfer, making it difficult to achieve a leapfrog growth in net carbon sink. The net carbon sink at the city scale exhibits the Matthew effect and spatial spillover effect. The above research results clarify the spatiotemporal changes in carbon effects in agricultural production at multiple levels, including city, province, and region. They also provide a theoretical basis for formulating differentiated regional emission reduction and sink enhancement strategies in the middle and lower reaches of the Yangtze River, promoting the rapid development of low-carbon agriculture in China.

Estimated in-situ carbon sequestration rates in a weathered silicate basin, southwestern Idaho, U.S.A.

Silicate weathering can induce calcite precipitation from groundwater, enabling carbon dioxide (CO2) sequestration in the critical zone (CZ), which acts as a net carbon sink with significant implications for the global carbon budget. In weathered silicates, secondary calcite dissolution accompanies precipitation-dissolution reactions, and it is unclear how calcite dissolution affects CO2 consumption in natural settings. At the Reynolds Creek Experimental Watershed - Critical Zone Observatory (RCEW-CZO), southwestern Idaho, USA, we estimate in-situ carbon sequestration rates in a semi-arid weathered silicate aquifer using hydrochemical compositions and age tracers from 6 springs and 10 wells. We delineate water-rock interactions by using observed groundwater chemistry to model open system carbon evolution, evapoconcentration in wells, silicate weathering, and formation of clays along groundwater flowpaths. We suggest carbonate precipitation under closed system conditions in deep groundwater, as calcite saturation is reached and CZ CO2 drops to just 41 % of initial concentrations in older waters. In a closed system, we estimate approximately 9 % of CZ CO2 would precipitate, indicating that on-going water-rock interactions in our weathered silicate system appear to drive continued carbon sequestration. Carbon sequestration rates via silicate weathering may help to explain a missing C sink observed at the RCEW-CZO and in other weathered silicate basins.

Seasonal variability and seagrass traits affect methane fluxes in a subtropical meadow

Abstract Plant traits which vary both within and between species often drive biogeochemical cycling. Understanding the relative role of within‐ and between‐species trait variability in driving carbon cycling is essential to scaling site measurements to global carbon budgets. In seagrass meadows, carbon and nitrogen mineralization rates and associated greenhouse gas emissions are highly variable, impeding our ability to reliably predict whether meadows are net carbon sinks. Evaluating the influence of within‐ and between‐species trait variability on greenhouse gas fluxes will improve our understanding of local‐scale drivers of greenhouse gas production and consumption in seagrass meadows. To test the effects of plant traits on dissolved greenhouse gas fluxes, we performed mesocosm incubations with live, intact seagrass plants. We compared methane (CH4) and nitrous oxide (N2O) fluxes under dark and light conditions from sediments dominated by Halodule wrightii and Thalassia testudinum across dormant, early and peak growing seasons in a subtropical meadow along the west coast of peninsular Florida. We also measured oxygen (O2) fluxes to interpret greenhouse gas fluxes within the context of community metabolism. We measured several seagrass traits, such as above‐ and below‐ground biomass and leaf and root area and assessed their impact as well as the impact of species identity on dissolved gas fluxes. We found that abiotic factors linked to metabolism (i.e. light and temperature) influenced greenhouse gas fluxes across seasons. In addition to light conditions and sampling month, plant size (a composite trait variable) was a significant predictor of O2 consumption and CH4 production under dark conditions, and better predicted fluxes than individual plant traits. CH4 production was slightly higher in H. wrightii‐dominated sediments, but species identity was less important than plant size in driving CH4 production. N2O fluxes were low and not influenced by plant traits or species identity. Synthesis: Our results indicate that within‐species more so than between‐species trait variability drives the direction and magnitude of CH4 fluxes in seagrass meadows. We identified a trade‐off where seagrass biomass is often associated with enhanced sediment carbon storage, but in our study, plant size promoted CH4 production, potentially offsetting the benefits of long‐term storage.

Quantitative Analysis of Agricultural Carbon Emissions and Absorption from Agricultural Land Resources in Shaanxi Province from 2010 to 2022

Agriculture is not only a significant source of greenhouse gas emissions but also a vast carbon sink system. Achieving the “dual carbon” goals—carbon peaking and carbon neutrality—is a major strategic objective for China in the near future. This study focuses on agricultural data from 2010 to 2022 in Shaanxi Province. It begins by analyzing the current economic and environmental conditions of the province and its resource endowment. This study then quantitatively assesses carbon absorption, carbon emissions, and the net carbon sink in agriculture over this period. Additionally, a vector autoregression (VAR) model is used to empirically analyze the relationship between agricultural carbon emissions and their influencing factors in Shaanxi Province. Key findings include the following: (1) From 2010 to 2022, the total carbon emissions from agriculture in Shaanxi Province were controlled to around 3 million tons, showing an overall trend of “growth-slow decline” with fluctuations. The carbon emissions from fertilizer application accounted for approximately 60% of the total carbon emissions from agriculture in Shaanxi Province, with a total volume ranging from 1.623 to 2.164 million tons. The total carbon absorption from agriculture in Shaanxi Province showed an increasing trend with fluctuations year by year from 2010 to 2022, with an average annual increase of 1.367%. (2) Fertilizers, pesticides, agricultural films, and agricultural diesel are the primary contributors to agricultural carbon emissions. (3) Results from the Johansen cointegration test reveal a long-term equilibrium relationship between agricultural carbon emissions in Shaanxi Province and influencing factors such as fertilizers and pesticides in the short term. The contributions of fertilizers, pesticides, agricultural films, and agricultural diesel to agricultural carbon emissions are 1.351%, 1.888%, 10.663%, and 0.258%, respectively. (4) The long-term contributions of fertilizers and pesticides to agricultural carbon emissions initially increased before undergoing a gradual attenuation, with average attenuation rates of 1.351% and 1.888%, respectively.

Greenhouse Gas Emissions from a 20-Year-Old Restored Peatland

Peatlands are ecosystems with unique hydrological and ecological properties that serve as critical carbon reservoirs, helping facilitate the reduction of greenhouse gases (GHG). In Canada, the peat industry uses vacuum harvesting to extract peat for horticultural use. This disturbs the natural ecosystem, increasing CO2 and decreasing CH4 emissions due to complete removal of surface vegetation and lowering of the water table. Following years of extraction, if these peatlands are not properly restored, GHG emissions will increase, negatively impacting the climate. The moss layer transfer technique (MLTT) is the primary method for restoring peatlands in Canada. The MLTT allows peatlands to regain their natural ecosystem function and to reaccumulate peat. This is done by revegetation of key species including sphagnum moss, and rewetting of the peatland through the blockage of drainage ditches. My research project investigates a peatland in Pointe-Lebel, Quebec restored in 2004 using MLTT following vacuum extraction. I used the closed chamber method to measure the CO2 and CH4 exchanges at the plant community scale and three repetitions of each of moss, shrubs, and cotton grass communities were followed throughout the summer. Wells at each collar provided the water table depth; a controlling variable for GHG fluxes. I conducted a vegetation survey at peak plant productivity to characterize the proportions of the plant communities and to allow chamber measurements of GHG to be scaled by the contribution of each plant community. If successful, a restored peatland will be a net sink of carbon. Preliminary data analysis at this 20-year-old restored site indicates a net CO2 sink during the summer of 2024. My data also suggests that the site is a small source of CH4. The results from my project will aid in advancing research on peatlands, stressing the importance of taking the proper steps towards restoration.

Characteristics and regulatory mechanisms of net ecosystem CO2 exchange at the water-air interface in coastal aquaculture ponds

Coastal aquaculture ponds represented a biogeochemical hotspot in the global carbon cycle. However, there was a limited understanding of their dynamics. In this study, the eddy covariance (EC) technique was applied to quantify the net ecosystem CO2 exchange (NEE) over coastal aquaculture ponds in the Liaohe River estuary in northern China during 2020, aiming to investigate and quantify the carbon exchange characteristics of this region. The results showed that (a) a predominant “U” shaped diurnal NEE pattern throughout the year. During the sea cucumber monoculture phase, the ponds exhibited a consistent daytime carbon sink and nighttime carbon source pattern. In contrast, during the shrimp and sea cucumber polyculture phase, the ponds mostly remained in a net carbon sink state. (b) NEE was negatively correlated with photosynthetically active radiation (PAR), air temperature (Tair), and wind speed (WS), while showing a positive correlation with atmospheric pressure (AP). (c) Overall, the entire study area (complex underlying surfaces) functioned as a carbon sink in 2020, with a total net carbon sequestration of 281.533 g C·m−2. This was approximately four times greater than the restored wetlands that naturally formed from decommissioned coastal aquaculture ponds. Adjusting for surface heterogeneity revealed that the complex surfaces led to a 34.28 % underestimation of the aquaculture region's unit area carbon sequestration capacity. This study was crucial for assessing the carbon cycling and sequestration functions of coastal aquaculture pond ecosystems and provided a scientific basis for related ecological restoration projects.

Increase in gross primary production of boreal forests balanced out by increase in ecosystem respiration

Changes in the net carbon sink of boreal forests constitute a major source of uncertainty in the future global carbon budget and, hence, climate change projections. The annual net ecosystem exchange of carbon dioxide (CO2) controlling the terrestrial carbon stock results from the small difference between respiratory CO2 release and the photosynthetic CO2 uptake by vegetation. The boreal forest, and the boreal biome in general, is regarded as a persistent and even increasing net carbon sink. However, decreases in photosynthetic CO2 uptake and/or concurrent increases in respiratory CO2 release under a changing climate may turn boreal forests from a net sink to a net source of CO2. Here, we assessed the interannual variability of the boreal forest net CO2 sink-source strength and its two component fluxes from 1981 to 2018. Our remote sensing approach - trained by net CO2 flux observations at eddy covariance sites across the circumpolar boreal forests - employs satellite-derived retrievals of snowmelt timing, landscape freeze-thaw status, and yearly maximum estimates of the normalized difference vegetation index as a proxy for peak vegetation productivity. Our results suggest that for the period 2000–2018, the mean annual evergreen boreal forest CO2 photosynthetic uptake (gross primary productivity) was 2.8±0.2 Pg C y−1 (1.6±0.1 Pg C y−1 for Eurasia and 1.2±0.1 Pg C y−1 for North America). In contrast to earlier studies results obtained here do not indicate a clear increasing trend in the circumpolar evergreen boreal forest CO2 sink. The increase in photosynthetic CO2 uptake is compensated by increasing respiratory releases with both component fluxes showing considerable interannual variabilities.

Calcification increases carbon supply, photosynthesis, and growth in a globally distributed coccolithophore

AbstractCoccolithophores fix organic carbon and produce calcite plates (coccoliths) that ballast organic matter and facilitate carbon export. Photosynthesis consumes carbon dioxide, while calcification produces it, raising questions about whether coccolithophores are a net sink or source of carbon. We characterized the physiology of calcified and noncalcified (“naked”) phenotypes of Emiliania huxleyi (CCMP374) and investigated the relationship between calcification and photosynthesis across a gradient of light (25–2000 μmol photons m−2 s−1) spanning the euphotic zone. Growth and photophysiological parameters increased with light until reaching a mid‐light (150 μmol photons m−2 s−1) maximum for both phenotypes. Calcified cells were characterized by enhanced photophysiology and less photoinhibition. Further, enhanced bicarbonate transport in calcified cells led to higher rates of particulate organic carbon fixation and growth compared to naked cells at mid‐light to high light (150–2000 μmol photons m−2 s−1). Coccolith production was similarly high at mid and high light, but the rate of coccolith shedding was >3‐fold lower at high‐light (1.2 vs. 0.35 coccoliths cell−1 h−1). The cellular mechanims(s) of this differential shedding remain unknown and underly light‐related controls on coccosphere maintenance. Our data suggest coccoliths shade cells at high light and that enhanced bicarbonate transport associated with calcification increases internal carbon supplies available for organic carbon fixation.

Multiobjective layout optimization for low impact development considering its ecosystem services

The augmented proportion of impervious surfaces and heavy rainfall have resulted in waterlogging, nonpoint source pollution, and environmental degradation. Low impact development (LID) is an effective storm management practice. Based on six different LID paving scenarios, a four objective simulation-optimization framework coupled with stormwater management model (SWMM) and NSGA-Ⅱ that incorporates the ecosystem service value (ESV) was proposed for the optimal layout of LID facilities. A case study in Beijing, China, was taken as an example. The results showed that the rain garden paving scenario is remarkable compared to the other scenarios in realizing ESV, with the dominant ESV of net carbon sinks. The optimization revealed that the change in pollution control rate was more sensitive than the runoff reduction rate. Simultaneously, the optimization of these two indicators will be accompanied by more cost and lower ESV. The optimal solution achieved 32.48 % of runoff reduction rate, 82.22 % of water pollution control rate, 0.73×105 CNY of ESV, and 2.29×106 CNY of cost. The framework provides reference and technical support to achieve the synergistic objectives among cost, water quality and quantity control, and ecosystem services.

Assessing the Environmental Impact of Empty Fruit Bunches for Electricity Generation in Malaysia: A Life Cycle Perspective

Abstract Empty fruit bunches (EFB) constitute a significant residual byproduct of the palm oil mill industry in Malaysia, representing approximately 22% of the weight of every fresh fruit bunch. This study aims to evaluate the environmental impacts associated with electricity generation utilizing EFB as a primary fuel through a cradle – to – grave life cycle assessment (LCA) approach. The system boundary encompasses the power plant construction, fuel preparation, electricity generation and all transportation activities throughout its life cycle. The EFBs are sourced from seven palm mills situated within a 50-kilometer radius of the plant. SimaPro 9.4.02 software integrated with Ecoinvent 3.8 database was employed to quantify the magnitudes of significant environmental indicators, such as global warming potential (GWP), ozone depletion potential (ODP), acidification potential (AP), eutrophication potential (EP), and photochemical oxidant creation potential (POCP), based on a functional unit of 1 kWh of electricity produced. The emission rate for the biomass plant stands at – 5.31 kgCO2eq/kWh, signifying a net carbon sink. The electricity generation process accounts for a substantial 96.48% of the total CO2eq/kWh emissions, thus bearing the greatest environmental burden. The construction phase of the biomass plant contributes approximately 3.06% of the total emissions, while the EFB transportation to the power plant represents a minor 0.19% of the overall emissions. A sensitivity analysis was conducted to evaluate the plant’s efficiency across fiscal years 2018 to 2021 and its corresponding global warming impacts. In 2021, the plant’s operations resulted in the most significant carbon avoidance, given the combustion of a high volume of EFB (188 kilotons) to produce 49.3GWh of electricity. The findings from this study serve as a valuable benchmark for evaluating emissions in the context of the empty fruit bunch-based plant in Peninsular Malaysia, hence offering profound insights into the environmental sustainability of the palm oil industry.

Contributions of China's terrestrial ecosystem carbon uptakes to offsetting CO2 emissions under different scenarios over 2001–2060

China is committed to achieving carbon neutrality by 2060, which requires that CO2 emissions from fossil fuels and industrial processes (referred to as CO2 emissions) be offset by carbon uptake through its terrestrial ecosystems. This study quantified the contributions of China's terrestrial carbon sinks to offsetting CO2 emissions over 2001–2060 by combining vegetation model simulations and multiple datasets of CO2 emission projections across different future emission scenarios. Our results showed that China's CO2 emissions will increase from 0.99 Pg C yr−1 in 2001 to >4 Pg C yr−1 in 2060 under the SSP3–7.0 and SSP5–8.5 scenarios; however, for SSP1–2.6, CO2 emissions will eventually decrease to 0.50 Pg C yr−1. Conversely, China's net terrestrial carbon sink was projected to increase from −0.14 Pg C yr−1 (2000s) to [−0.35, −0.40] Pg C yr−1 (2050s) under different SSP scenarios based on vegetation modelling. As a result, China's net terrestrial carbon sink will contribute only approximately 10% to offsetting its CO2 emissions under scenarios SSP3–7.0 and SSP5–8.5, implying an almost certain failure of the carbon-neutral strategy. In contrast, under scenario SSP1–2.6, approximately 50%–80% of CO2 emissions can be offset by the terrestrial carbon sink by 2060, in line with the possible success of the carbon-neutral goal. This study underscores the critical role of terrestrial carbon sink in achieving carbon neutrality in China and hightlights the remaining challenges for further reducing CO2 emissions.

Optimising the reintroduction of a specialist peatland butterfly Coenonympha tullia onto peatland restoration sites

The two main goals of peatland restoration are habitat improvement and climate change mitigation by reducing greenhouse gas emissions from damaged peatlands and providing a net carbon sink. The biodiversity of specialist peatland species is threatened because of habitat destruction and the large heath butterfly Coenonympha tullia has become a flagship species for peatland ecosystem restoration, with a species reintroduction programme currently underway on a peatland restoration site within Chat Moss, Greater Manchester, UK. The aim of this study was to improve our quantitative understanding of C. tullia habitat resource requirements to optimise habitat restoration for further reintroduction attempts. We monitored butterfly micro-distribution and dispersal during the first three flight seasons (2020, 2021 and 2022) of the reintroduction using high-accuracy GPS, combined with a distance-bearing protocol. Analysis of butterfly flight points and rest points in relation to plant species distribution and abundance, identified the most important habitat resources. Using logistic regression, treatment-response curves were constructed, enabling us to identify critical thresholds for the abundance of these important habitat resources. The break of slope near the top of the logistic curve was identified using segmented regression, giving an estimate of the near-optimal abundance; fourteen Eriophorum vaginatum tussocks per 2 m quadrat and 13.4% Erica tetralix cover.Implications for insect conservationDuring ecosystem restorations, prior to the reintroduction of species with specialist habitat requirements, it is necessary to have a clear understanding of the abundance of the important habitat resources that need to be provided. The quantitative approach we describe defines the most significant environmental factors and habitat resources, then uses segmented regression to estimate the near-optimal habitat resource requirements; increasing the likelihood of reintroduced populations thriving and reintroduction programmes achieving long-term success.

The Role of Ocean Mesoscale Variability in Air‐Sea CO2 Exchange: A Global Perspective

AbstractOcean mesoscale flows significantly influence nutrient distribution and biological productivity, yet the scarcity of eddy‐permitting observational data sets and climate modeling hinders understanding their role in carbon sequestration. Using an eddy‐resolving global simulation, this study investigates the significance of ocean mesoscales in air‐sea carbon dioxide (CO2) exchange. Results show over 30% of CO2 flux variance in energetic regions attributed to flows with horizontal scales smaller than 2°. Mesoscale flows can drive a cumulative CO2 flux that is either a net carbon sink or source depending on region, with magnitudes on the order of 105 tonnes of carbon per year. Variations in this mesoscale‐related CO2 flux are correlated with local relative vorticity and the background gradient of ocean partial pressure of CO2. This analysis underscores the importance of considering ocean mesoscales in monitoring carbon flux, highlighting the need to explore the influence of increasing eddy activity on carbon uptake in a changing climate.

Assessment of the carbon neutral capacity of ecological slopes: A case study of wet-spraying vegetation concrete ecological river revetment

ABSTRACT This study evaluates the carbon neutrality of eco-slope protection projects to understand their role in climate change mitigation. Utilizing life cycle assessment, it defines system boundaries and compiles inventories to calculate and analyze carbon emissions and assimilations of a wet-spraying vegetation concrete eco-slope protection project in China, simplifying previous methodologies and emphasizing the critical role of vegetation. Findings indicate lifecycle carbon emissions total 608.01 tCO2e, broken down by source as follows: material (54.69%), maintenance (40.11%), energy (3.27%), transport (1.32%), and workforce (0.6%). Slope protection plants are estimated to assimilate 2,676.30 tCO2. The project is estimated to reach carbon neutrality in its 4.59th year, with an anticipated net carbon sink contribution of 2,068.29 tons over its lifespan. These results underscore eco-slope protection projects’ significant carbon neutral capacity, highlighting their importance in combating climate change and fostering the civil engineering industry's green transformation.

Long‐Term Response of Peatland Carbon Exchange to Climatic Changes in the Hudson Bay Lowlands

AbstractNorthern peatlands have been a persistent net sink of atmospheric carbon (C) due to the greater rates of gross primary production (GPP) compared to ecosystem respiration (ER). Global warming has raised concerns about the C sink strength of northern environments. In the vast peatlands of the Hudson Bay Lowlands (HBL) region of Canada, warming‐induced changes in sea ice dynamics over the Bay have altered its advective influence on the adjacent lowlands. Despite our knowledge of the short‐term C exchange in these peatlands, there remain uncertainties in the long‐term combined response of GPP and ER to climate change. In this study, the satellite‐data‐driven Vegetation Photosynthesis and Respiration Model was employed to investigate the response of peatland GPP, ER, and net ecosystem exchange to temperature and moisture changes. The results show contrasting net CO2 exchange at the two peatland sites over the last 20 years, with the fen acting as a net C source (+24 g C m−2) to the atmosphere and the bog serving as a net C sink (−130 g C m−2). There is ample evidence that a warmer and wetter climate enhanced GPP more than ER, while cooler temperatures weakened the peatland net C sink, regardless of the moisture conditions. Additionally, the advective influence of Hudson Bay on the lowlands produced markedly different C dynamics between offshore and onshore winds, with higher respiration rates (12%–26%) during offshore winds. We discuss the implications for peatland C balance under more frequent onshore winds in the region.

Analysis of the spatial mismatch pattern of net carbon in agriculture and its influencing factors

Agricultural production has dual functions as a carbon emitter and sink, and fully exploiting the carbon sink function of agriculture is highly valuable for ensuring carbon neutrality. The layout of net carbon in agriculture shows an imbalance, i.e., underscaling in areas with a net carbon advantage or overscaling in areas with a net carbon disadvantage, which restricts the fulfillment of agricultural carbon sinks. Clarifying the global pattern of net carbon imbalances in agriculture and their drivers is highly important for improving the overall net carbon. In this regard, this paper focuses on the global net carbon in agriculture in 155 countries and regions, and a spatial mismatch index of net carbon in agriculture (MNCA) is constructed based on the relative difference between net carbon and cultivated land. Spatial autocorrelation analysis and the standard deviation ellipse are used to reflect its spatiotemporal evolution pattern. In addition, through geographically weighted regression, we explored the effects of agricultural structure, agricultural economic development, the scale of labor and cultivated land and organized the mismatches into carbon and area effects. The results show that (1) global agricultural production represents net carbon emissions, while developing countries represent net carbon sinks, and there is a mismatch of net agricultural carbon in most regions; (2) the MNCA is characterized by low-low clustering in North America, Asia and Europe, with its center of gravity falling in western Africa and migrating northeastward; and (3) the main factors influencing the MNCA are the agricultural structure and economic level. Underscaling in areas with a net carbon advantage is a major problem. To increase the global agricultural carbon sink capacity, we suggest that North America, South Asia and other regions strictly implement agricultural emission reduction policies and that Central America, South America and Africa tentatively upgrade agricultural technology and their economies to alleviate farmland pressure through transnational cooperation. In this paper, the global net carbon imbalance in agriculture is identified and the overall implementation path of increasing carbon sinks is explored to provide a reference for achieving carbon neutrality. SynopsisThis study reports a global mismatch in net carbon in agriculture and identifies the wasted carbon sink advantage of developing countries as the root problem.

Increased harvested carbon of cropland in China

Crop harvested carbon (HC) is one of the most important components of the carbon cycle in cropland ecosystems, with a significant impact on the carbon budget of croplands. China is one of the most important crop producers, however, it is still unknown on the spatial and temporal variations of HC. This study collected statistical data on crop production at the province and county levels in China for all ten crop types from 1981 to 2020 and analyzed the magnitude and long-term trend of harvested crop carbon. Our results found a substantial increase of HC in cropland from 0.185 Gt C yr−1 in 1981 to 0.423 Gt C yr−1 in 2020 at a rate of 0.006 Gt C yr−1. The results also highlighted that the average annual carbon sink removal from crop harvesting in China from 1981 to 2020 was 0.32 Gt C yr−1, which was comparable to the net carbon sink of the entire terrestrial ecosystems in China. This study further generated a gridded dataset of HC from 2001 to 2019 in China by using jointly the statistical crop production and distribution maps of cropland. In addition, a model-data comparison was carried out using the dataset and results from seven state-of-the-art terrestrial ecosystem models, revealing substantial disparities in HC simulations in China compared to the dataset generated in the study. This study emphasized the increased importance of HC for estimating cropland carbon budget, and the produced dataset is expected to contribute to carbon budget estimation for cropland ecosystems and the entire China.