Tg CO2 Research Articles

Carbon-negative transition by utilizing overlooked carbon in waste landfills

<p>Landfills play a crucial role in urban climate solutions, as the decomposition of their “hidden” carbon stock contributes to 8.8% of global methane emissions. While controlling landfill gas emissions is the most commonly used intervention, a systematic approach to manage the carbon cycle in landfills remains elusive. In this study, we developed a quantitative solid-water-gas coupling model to estimate the carbon stock in landfills across 346 cities in China. Our findings reveal a standing landfill carbon stock 506.3 ± 4.2Tg, which could potentially substitute for 20% of soil organic carbon in green spaces and 1 year of residential electricity consumption of cities. Our scenario analyses show that by implementing a life-cycle package of interventions (incl., input minimization, stock utilization, and leakage reduction), the total carbon stock in landfills could be reduced to 230.1 Tg with a negative annual carbon emission (-57.1 Tg CO<sub>2</sub> eq/year) reached by 2030. These interventions could cumulativly cut greenhouse gas (GHG) by 753.3 Tg, representing 62.2% of the landfill-related GHG emissions and 2.0% of China’s carbon debt towards the 1.5℃ warming targets. Landfill mining contributes 52.3% of these reductions, while in-situ aerobic restoration accounts for 14.4%, positioning landfills as a potential carbon-negative sector that can drive cities towards carbon-neutrality.</p>

Potential Reductions in Carbon Emissions from Indonesian Forest Concessions Through Use of Reduced-Impact Logging Practices

To estimate the potential and realized carbon emission reductions from implementation of reduced-impact logging (RIL) in Indonesia, we compiled logging emissions data from 15 concessions in Kalimantan and 10 from the Papuan provinces. Committed emissions data were collected for harvested timber as well as from collateral damage caused by felling, skidding, and clearing for haul roads and log yards. Emissions expressed as mean ± standard error per cubic meter of timber harvested, per area harvested, and per Mg of timber harvested (i.e., the ‘Carbon Impact Factor’) were 1.30 ± 0.15 Mg C m−3, 27.52 ± 4.44 Mg C ha−1, and 6.88 ± 0.84 Mg Mg−1, respectively. Among the sampled concessions, felling, hauling, and skidding caused 18–86%, 2–48%, and 6–75% of these emissions, respectively. Potential emission reductions calculated as the difference between observed emissions and those of the five best-performing concessions are 0.67 ± 0.15 Mg C m−3, 21.11 ± 4.38 Mg C ha−1, and 4.20 ± 0.83 Mg Mg−1, which represents reductions of 51%, 76%, and 61%, respectively. Extrapolating these estimates to all of Indonesia using average log production data from 2018 to 2021 results in an estimated annual emissions reduction of 14.47 Tg CO2 from full adoption of RIL, which is 2.9% of Indonesia’s nationally determined contribution (NDC) from the forestry sector.

Application of the wildland fire emissions inventory system to estimate fire emissions on forest lands of the United States

BackgroundForests are significant terrestrial biomes for carbon storage, and annual carbon accumulation of forest biomass contributes offsets affecting net greenhouse gases in the atmosphere. The immediate loss of stored carbon through fire on forest lands reduces the annual offsets provided by forests. As such, the United States reporting includes annual estimates of direct fire emissions in conjunction with the overall forest stock and change estimates as a part of national greenhouse gas inventories within the United Nations Framework Convention on Climate Change. Forest fire emissions reported for the United States, such as the 129 Tg CO2 reported for 2022, are based on the Wildland Fire Emissions Inventory System (WFEIS). Current WFEIS estimates are included in the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2022 published in 2024 by the United States Environmental Protection Agency. Here, we describe WFEIS the fire emissions inventory system we used to address current information needs, and an analysis to confirm compatibility of carbon mass between estimated forest fire emissions and carbon in forest stocks.ResultsThe summaries of emissions from forests are consistent with previous reports that show rates and interannual variability in emissions and forest land area burned are generally greater in recent years relative to the 1990s. Both emissions and interannual variability are greater in the western United States. The years with the highest CO2 emissions from forest fires on the 48 conterminous states plus Alaska were 2004, 2005, and 2015. In some years, Alaska emissions exceed those of the 48 conterminous states, such as in 2022, for example. Comparison of forest fire emission to forest carbon stocks indicate there is unlikely any serious disconnect between inventory and fire emissions estimates.ConclusionsThe WFEIS system is a user-driven approach made available via a web browser. Model results are compatible with the scope and reporting needs of the annual national greenhouse gas inventories.

A Review of Options and Costs for Mitigating GHG Emissions from the U.S. Dairy Sector

The U.S. dairy sector is a significant emitter of methane and nitrous oxide, with the US EPA estimating it produced around 90 Tg CO2 eq. in 2021. This paper reviews the literature on and evaluates various mitigation actions for reducing GHG emissions in the U.S. dairy sector, focusing on both direct and indirect emission sources. We conducted a narrative literature review based on the cradle to gate life-cycle assessment method, covering the entire dairy supply chain up until milk enters retail establishments, including dairy and feed producing farm practices, processing, transportation, and their associated emissions/costs. The papers included were selected over a three year process depending on discussions with experts and issues mentioned in the emerging literature. We review significant opportunities for the U.S. dairy sector to reduce emissions, particularly through improved enteric fermentation and manure management practices. Additionally, we cover the potential for mitigating indirect emissions from feed production, processing, and transportation, areas less frequently covered in existing studies. This review also covers a gap in the literature by integrating economic findings including cost analysis and incentives to mitigate based on the social value of emissions reductions.

The Net GHG Balance and Budget of the Permafrost Region (2000–2020) From Ecosystem Flux Upscaling

AbstractThe northern permafrost region has been projected to shift from a net sink to a net source of carbon under global warming. However, estimates of the contemporary net greenhouse gas (GHG) balance and budgets of the permafrost region remain highly uncertain. Here, we construct the first comprehensive bottom‐up budgets of CO2, CH4, and N2O across the terrestrial permafrost region using databases of more than 1000 in situ flux measurements and a land cover‐based ecosystem flux upscaling approach for the period 2000–2020. Estimates indicate that the permafrost region emitted a mean annual flux of 12 (−606, 661) Tg CO2–C yr−1, 38 (22, 53) Tg CH4–C yr−1, and 0.67 (0.07, 1.3) Tg N2O–N yr−1 to the atmosphere throughout the period. Thus, the region was a net source of CH4 and N2O, while the CO2 balance was near neutral within its large uncertainties. Undisturbed terrestrial ecosystems had a CO2 sink of −340 (−836, 156) Tg CO2–C yr−1. Vertical emissions from fire disturbances and inland waters largely offset the sink in vegetated ecosystems. When including lateral fluxes for a complete GHG budget, the permafrost region was a net source of C and N, releasing 144 (−506, 826) Tg C yr−1 and 3 (2, 5) Tg N yr−1. Large uncertainty ranges in these estimates point to a need for further expansion of monitoring networks, continued data synthesis efforts, and better integration of field observations, remote sensing data, and ecosystem models to constrain the contemporary net GHG budgets of the permafrost region and track their future trajectory.

Quantifying landscape fragmentation and forest carbon dynamics over 35 years in the Brazilian Atlantic Forest

The Brazilian Atlantic Forest (AF) covers 13% of Brazil but retains only 26% of its original forest area. Utilizing a Morphological Spatial Pattern Analysis (MSPA), we generated 30 m spatial resolution fragmentation maps for old-growth and secondary forests across the AF. We quantified landscape fragmentation patterns and carbon (C) dynamics over 35 years using MapBiomas data between the years 1985 and 2020. We found that from 1985 to 2020 the forest suffered continuous fragmentation, losing core (nuclei forest fragments) and bridge (areas that connect different core areas) components of the landscape. About 87.5% (290 468.4 km2) of the remaining forest lacked core areas, with bridges (38.0%) and islets (small, isolated fragments) (35.4%) being predominant. Secondary forests (1986–2020) accounted for 99 450.5 km2 and played a significant role in fragmentation pattern, constituting 44.9% of the areas affected by edge effects (perforation, edge, bridge, and loop), 53.7% of islets, and comprising only 1.4% of core forest. Additionally, regeneration by secondary forests contributed to all fragmentation classes in 2020. Even with the regrowth of forests, the total forested area in the biome did not increase between 1985 and 2020. Deforestation emissions reached 818 Tg CO2, closely paralleled by edge effects emissions at 810 Tg CO2, highlighting a remarkable parity in C emissions between the two processes. Despite slow changes, AF biome continues to lose its C stocks. We estimated that around 1.96 million hectares (19 600 km2) of regenerated forest would be required to offset the historical C emissions over the analysed period. Hence, MSPA can support landscape monitoring, optimizing natural or active forest regeneration to reduce fragmentation and enhance C stocks. Our study’s findings are critical for guiding land-use policies focusing on minimizing emissions, promoting forest regrowth, and monitoring its permanence. This study offers biome scale, spatially explicit information, critical for AF conservation and management.

The Greenhouse Gas Budget of Terrestrial Ecosystems in East Asia Since 2000

AbstractEast Asia (China, Japan, Koreas, and Mongolia) has been the world's economic engine over at least the past two decades, exhibiting a rapid increase in fossil fuel emissions of greenhouse gases (GHGs) and has expressed the recent ambition to achieve climate neutrality by mid‐century. However, the GHG balance of its terrestrial ecosystems remains poorly constrained. Here, we present a synthesis of the three most important long‐lived greenhouse gases (CO2, CH4, and N2O) budgets over East Asia during the decades of 2000s and 2010s, following a dual constraint approach. We estimate that terrestrial ecosystems in East Asia is close to neutrality of GHGs, with a magnitude of between −46.3 ± 505.9 Tg CO2eq yr−1 (the top‐down approach) and −36.1 ± 207.1 Tg CO2eq yr−1 (the bottom‐up approach) during 2000–2019. This net GHG sink includes a large land CO2 sink (−1229.3 ± 430.9 Tg CO2 yr−1 based on the top‐down approach and −1353.8 ± 158.5 Tg CO2 yr−1 based on the bottom‐up approach) being offset by biogenic CH4 and N2O emissions, predominantly coming from the agricultural sectors. Emerging data sources and modeling capacities have helped achieve agreement between the top‐down and bottom‐up approaches, but sizable uncertainties remain in several flux terms. For example, the reported CO2 flux from land use and land cover change varies from a net source of more than 300 Tg CO2 yr−1 to a net sink of ∼−700 Tg CO2 yr−1. Although terrestrial ecosystems over East Asia is close to GHG neutral currently, curbing agricultural GHG emissions and additional afforestation and forest managements have the potential to transform the terrestrial ecosystems into a net GHG sink, which would help in realizing East Asian countries' ambitions to achieve climate neutrality.

Potential of continuous cover forestry on drained peatlands to increase the carbon sink in Finland

Land-based mitigation measures are needed to achieve climate targets. One option is the mitigation of currently high greenhouse gas (GHG) emissions of nutrient-rich drained peatland forest soils. Continuous cover forestry (CCF) has been proposed as a measure to manage this GHG emission source; however, its emission reduction potential and impact on timber production at regional and national scales have not been quantified. To quantify the potential emission reduction, we simulated four management scenarios for Finnish forests: (i) The replacement of clear-cutting by selection harvesting on nutrient-rich drained peatlands (CCF) and (ii) the current forest management regime (BAU), and both at two harvest levels, namely (i) the mean annual harvesting (2016–2018) and (ii) the maximum sustainable yield. The simulations were conducted at the stand scale with a forest simulator (MELA) coupled with a hydrological model (SpaFHy), soil C model (Yasso07) and empirical GHG exchange models. Simulations showed that the management scenario that avoided clear-cutting on nutrient-rich drained peatlands (i.e. CCF) produced approximately 1 Tg CO2 eq. higher carbon sinks annually compared with BAU at equal harvest level for Finland. This emission reduction can be attributed to the maintenance of a higher biomass sink and to the mitigation of soil emissions from nutrient-rich drained peatland sites.

Carbon dioxide emissions through land use change, fire, and oxidative peat decomposition in Borneo

Borneo has accumulated an abundance of woody carbon in its forests and peat. However, agricultural land conversion accompanied by plantation development, dead wood burning, and peat drying from drainage are major challenges to climate change mitigation. This study aimed to develop a method of estimating carbon dioxide (CO2) emissions from land use change, forest and peat fires, and oxidative peat decomposition, and CO2 uptake from biomass growth across Borneo using remote sensing data from 2001 to 2016. Although CO2 uptake by biomass growth in vast forests has shown a significant increasing trend, an annual net release of 461.10 ± 436.51 (average ± 1 standard deviation) Tg CO2 year−1 was observed. The estimated emissions were predominantly characterized by land use changes from 2001 to 2003, with the highest emissions in 2001. Land use change was evaluated from annual land use maps with an accuracy of 92.0 ± 1.0% (average ± 1 standard deviation). Forest and peat fires contributed higher emissions in 2002, 2006, 2009, 2014, and 2015 compared to other years and were strongly correlated with the Southern Oscillation Indexes. These results suggest that more CO2 may have been released into the atmosphere than previously thought.

Estimating blue carbon storage in the mangrove forest of Gaz-Harra wetland, Strait of Hormoz

Mangrove forests efficiently absorb and fix carbon ecosystems, playing an influential role in reducing greenhouse gases. In this study, we measured the whole and top 1 m soil carbon (C) stock and the carbon stored in the above- and belowground parts of mangroves in 10 stations within the Gaz-Hara Wetland (GHW). GIS-based satellite image processing indicated that the total area of the GHW mangrove forest is 1038 ha, and Rizophora mucronata, mixed, high-density Avicennia marina, and low-density A. marina habitats comprise 12.5, 30, 35.5 and 22% of the forest area, respectively. Soil organic C content ranged from 0.45–3.01%, with A. marina habitats having a higher content than the R. mucronata habitats. The average top 1 m soil C stock of mangrove is 108 MgC ha−1, with high-density A. marina habitat accounting for 37% of it. This amount is within the global average range of mangroves in dry subtropical areas. The total amount of soil C stock in the area is 220,867 MgC. Furthermore, 361,000 MgC has been sequestered in the mangrove trees of GHW, 69% of which is accumulated in the aboveground and the rest in the belowground portions. The soil and trees of the GHW habitats have stored 537 Gg C, equivalent to 1.97 Tg CO2, of which 220 and 317 Gg C have been accumulated in the soil and the biomass of mangrove trees, respectively. Deforestation of GHW mangroves would result in a potential CO2 emission of 1.33 Tg CO2 (1.16 Tg CO2 by trees and 0.17 Tg CO2 by the top 1 m of soil).

Uncovering the effects of policies, climate, and economic development on carbon neutrality in southern Tibet, China

Partitioning the contributions of climate, economic growth, and policy to a region’s carbon flows is an important process for the Chinese government seeking to optimize their regional development policies to achieve carbon neutrality by 2060. A combination of the carbon emission analysis and human appropriation of net primary production (HANPP) framework was applied to a village in the Lhasa river valley, Tibet, to quantify the contributions of these different factors to carbon flows and neutrality. From 2010 to 2019, the average annual net sequestration of CO2 was 374.9 g CO2 m−2 a−1. Changes in climate conditions and the regional policy of Grassland Ecological Protection Subsidy and Reward increased carbon sequestrations by 409.5 and 25.7 g CO2 m−2 a−1, respectively. Socioeconomic development, policies for reducing poverty, and promotion of forage production led to the increase in CO2 emissions by 103.5, 88.8, and 4.3 g CO2 m−2 a−1, respectively. The cumulative CO2 emissions (including HANPP) caused by land use were 298.92 Tg CO2 (2479.63 g CO2 m−2; 1 Tg = 1012 g), while the cumulative CO2 emissions due to energy use were only 11.22 Tg CO2 (93.07 g CO2 m−2), equal to 3.75% of the CO2 emissions driven by land use. Livestock grazing and cropland cultivation were the two main land use factors affecting the carbon balance. We argue that unhooking economic growth from traditional nomadic animal husbandry and lifestyles through policy optimizations would highly contribute the carbon neutrality in Tibet.

Planting hedgerows: Biomass carbon sequestration and contribution towards net-zero targets

Agroforestry practices, such as hedgerow planting, are widely encouraged for climate change mitigation and there is an urgent need to assess their contribution to national ‘net-zero’ targets. This study examined the impact that planting hedgerows at different rates could make to UK net-zero goals over the next 40 years, with a focus on 2050. We analysed the carbon (C) content of native hedgerow species and determined hedge aboveground biomass (AGB) C stock via destructive sampling of hedges of known ages. AGB C stocks ranged from 8.34 Mg C ha−1 in the youngest hedges, to 40.42 Mg C ha−1 in old ones. Knowing the age of the hedgerows, we calculated their annual average AGB C sequestration rate, which was highest in young hedges (2.09 Mg C ha−1 yr−1), and lowest in 39 year old mature, regularly trimmed hedgerows (0.86 Mg C ha−1 yr−1). We present a time series of the annual AGB C sequestration rate change between hedge age categories, which increases from 2.09 Mg C ha−1 yr−1 in the first 6 years after planting, to 2.26 Mg C ha−1 yr−1 in the next 6 years, and then decreases to 0.43 Mg C ha−1 yr−1 between years 13 and 40. Our results indicate that, if encouraged widely, hedgerow planting can be a valuable tool for atmospheric CO2 capture and storage, contributing towards net-zero targets. However, current planting rates (1778.8 km yr−1) are too low to reach the net-zero goal set by the UK Climate Change Committee of increasing hedgerow length by 40 % by 2050. An increased planting rate of 7148.1 km yr−1 will achieve this goal by 2050, and, over 40 years, store 3.41 Tg CO2 in hedge AGB, or 10.13 Tg CO2 in hedge total biomass and in the soil, annually offsetting 1.5 %–4.5 % of UK annual agricultural CO2 emissions.

Renewable Energy Potential and CO2 Performance of Main Biomasses Used in Brazil

This review investigates the effects of the Brazilian agriculture production and forestry sector on carbon dioxide (CO2) emissions. Residual biomasses produced mainly in the agro-industrial and forestry sector as well as fast-growing plants were studied. Possibilities to minimize source-related emissions by sequestering part of carbon in soil and by producing biomass as a substitute for fossil fuel were extensively investigated. The lack of consistency among literature reports on residual biomass makes it difficult to compare CO2 emission reductions between studies and sectors. Data on chemical composition, heating value, proximate and ultimate analysis of the biomasses were collected. Then, the carbon sequestration potential of the biomasses as well as their usability in renewable energy practices were studied. Over 779.6 million tons of agricultural residues were generated in Brazil between 2021 and 2022. This implies a 12.1 million PJ energy potential, while 4.95 million tons of forestry residues was generated in 2019. An estimated carbon content of 276 Tg from these residues could lead to the production of approximately 1014.2 Tg of CO2. Brazilian biomasses, with a particular focus on agro-forest waste, can contribute to the development of sustainable alternative energy sources. Moreover, agro-waste can provide carbon credits for sustainable Brazilian agricultural development.

Mixed matrix membranes based on soluble perfluorinated metal-organic cage and polyimide for CO2/CH4 separation

Emerging as a new type of porous materials, metal-organic cages (MOCs) show great potential in adsorption and separation. The high porosity and solubility of MOCs have generated increasing interest in their use as fillers for preparing mixed matrix membranes (MMMs). Herein, we present a series of zirconocene-based MOCs (MOC-1, MOC-1-NH2, and MOC-1-4F), which were used to fabricate MMMs with polyimide 6FDA-DAM. Particularly, the perfluorinated MOC (MOC-1-4F) could form a clear casting solution with 6FDA-DAM in some solvents. The resultant MMMs were analyzed by AFM, SEM, EDX-mapping, XRD, CSM, Raman, TG, and DSC measurements, indicating that MOC-1-4F were homogeneously dispersed in 6FDA-DAM, and the Tg values, mechanical property, CO2 solubility and diffusivity of the membrane were promoted after the introduction of MOC-1-4F. The MOC-1-4F based membranes also outperformed the membranes with MOC-1 or MOC-1-NH2 as filler in CO2/CH4 separation. A low MOC-1-4F loaded MMM (MOC-1-4F-2.17%) exhibited 57% improved CO2 permeability (1228 barrer) in comparison with 6FDA-DAM membrane, and the CO2/CH4 selectivity reached 22, surpassing the 2008 Robeson upper-bound. The plasticization effect was significantly alleviated in MOC-1-4F-2.17%, indicating that the MOC-1-4F-2.17% is potential for CO2/CH4 separation. This work demonstrates that the gas separation performance of MOC-based MMMs could be fine-tuned by the structural tailoring of MOCs.

Sustainable Planning Strategy of Dairy Farming in China Based on Carbon Emission from Direct Energy Consumption

The mechanical and electrical development in dairy farming in China increases energy-related carbon emission (CE). To support the sustainable planning strategy of the department, this study calculated the CE and the carbon emission intensity (CI) of the direct energy consumed in dairy farms from 21 provinces in China. Through four dimensions analysis including the national level, farm scale, inter-provincial distribution, and main producing area, this study illustrates the impact of the environment, production, and management on CE. The total CE of nationwide dairy farming was about 2.4 Tg CO2 eq. in 2019, and the CIs of the 21 provinces varied from 0.009 to 0.216 kg CO2 eq. per kg of milk. The results indicate that the management mode applied in large-scale dairy farms (500 heads and above) varies considerably due to inadequate adaptation to climate. In general, semi-arid and semi-humid regions are more suitable for dairy farming than arid and humid regions. In the main milk-producing area, the spatial aggregation effect is visible in the carbon reduction potential. The present study suggests that further steps to promote sustainability and milk productivity are embodied when the replacement of fossil fuels and the management standardization are adapted to regional characteristics.

Climate change mitigation potential of Louisiana's coastal area: Current estimates and future projections.

Coastal habitats can play an important role in climate change mitigation. As Louisiana implements its climate action plan and the restoration and risk reduction projects outlined in its 2017 Louisiana Coastal Master Plan, it is critical to consider potential greenhouse gas (GHG) fluxes in coastal habitats. This study estimated the potential climate mitigation role of existing, converted, and restored coastal habitats for years 2005, 2020, 2025, 2030, and 2050, which align with the Governor of Louisiana's GHG reduction targets. An analytical framework was developed that considered 1) available scientific data on net ecosystem carbon balance fluxes per habitat and 2) habitat areas projected from modeling efforts used for the 2017 Louisiana Coastal Master Plan to estimate the net GHG flux of coastal area. The coastal area was estimated as net GHG sinks of -38.4 ± 10.6 and - 43.2 ± 12.0 Tg CO2 equivalents (CO2 e) in 2005 and 2020, respectively. The coastal area was projected to remain a net GHG sink in 2025 and 2030, both with and without implementation of Coastal Master Plan projects (means ranged from -25.3 to -34.2 Tg CO2 e). By 2050, with model-projected wetland loss and conversion of coastal habitats to open water due to coastal erosion and relative sea level rise, Louisiana's coastal area was projected to become a net source of greenhouse gas emissions both with and without the Coastal Master Plan projects. However, at year 2050, Louisiana Coastal Master Plan project implementation was projected to avoid the release of +8.8 ± 1.3 Tg CO2 e compared to an alternative with no action. Reduction in current and future stressors to coastal habitats, including impacts from sea level rise, as well as the implementation of restoration projects could help to ensure coastal areas remain a natural climate solution.

Carbon uptake in Eurasian boreal forests dominates the high-latitude net ecosystem carbon budget.

Arctic-boreal landscapes are experiencing profound warming, along with changes in ecosystem moisture status and disturbance from fire. This region is of global importance in terms of carbon feedbacks to climate, yet the sign (sink or source) and magnitude of the Arctic-boreal carbon budget within recent years remains highly uncertain. Here, we provide new estimates of recent (2003-2015) vegetation gross primary productivity (GPP), ecosystem respiration (Reco ), net ecosystem CO2 exchange (NEE; Reco - GPP), and terrestrial methane (CH4 ) emissions for the Arctic-boreal zone using a satellite data-driven process-model for northern ecosystems (TCFM-Arctic), calibrated and evaluated using measurements from >60 tower eddy covariance (EC) sites. We used TCFM-Arctic to obtain daily 1-km2 flux estimates and annual carbon budgets for the pan-Arctic-boreal region. Across the domain, the model indicated an overall average NEE sink of -850 Tg CO2 -C year-1 . Eurasian boreal zones, especially those in Siberia, contributed to a majority of the net sink. In contrast, the tundra biome was relatively carbon neutral (ranging from small sink to source). Regional CH4 emissions from tundra and boreal wetlands (not accounting for aquatic CH4 ) were estimated at 35 TgCH4 -C year-1 . Accounting for additional emissions from open water aquatic bodies and from fire, using available estimates from the literature, reduced the total regional NEE sink by 21% and shifted many far northern tundra landscapes, and some boreal forests, to a net carbon source. This assessment, based on in situ observations and models, improves our understanding of the high-latitude carbon status and also indicates a continued need for integrated site-to-regional assessments to monitor the vulnerability of these ecosystems to climate change.

Flower strips as a carbon sequestration measure in temperate croplands

PurposeFlower strips have been shown to increase insect biodiversity and improve agricultural yields through increased pollination and pest predation. Less is known about their potential to increase soil organic carbon (SOC). We aimed to investigate the biomass production and SOC sequestration potential of flower strips as a sustainable management option of temperate agricultural soils.Methods23 flower strips across varying soil types and climatic regions in Germany were sampled for aboveground and belowground peak biomass in order to estimate the annual carbon input to the soil. Those were used as 23 scenarios to model the potential SOC sequestration of the flower strips compared to a business-as-usual scenario for 1533 sites of the German Agricultural Soil Inventory using the RothC model.ResultsOn average, flower strips sequestered 0.48 ± 0.36 Mg C ha−1 year−1 in the initial 20-year period after establishment. Converting 1 % of the total German cropland area into flower strips would thus lead to a mitigation of 0.24 Tg CO2 year−1, which equals 0.4 % of current agricultural greenhouse gas emissions in Germany.We found a negative correlation between C sequestration rate and the number of plant species in the flower strips, mainly related to grasses outcompeting herbaceous species.ConclusionFlower strips are one overlooked option for increasing SOC stocks of croplands that has multiple benefits for agro-ecosystems. However, within a flower strip it might not be possible to maximise both plant biodiversity and SOC sequestration.

India’s Contribution to Greenhouse Gas Emission from Freshwater Ecosystems: A Comprehensive Review

In the modern era, due to urbanization, industrialization, and anthropogenic activities in the catchment, greenhouse gas (GHG; CO2, CH4, and N2O) emissions from freshwater ecosystems received scientific attention because of global warming and future climate impacts. A developing country such as India contributes a huge share (4% of global) of GHGs from its freshwater ecosystems (e.g., rivers, lakes, reservoirs) to the atmosphere. This is the first comprehensive review dealing with the GHG emissions from Indian freshwater bodies. Literature reveals that the majority of GHG from India is emitted from its inland water, with 19% of CH4 flux and 56% of CO2 flux. A large part of India’s gross domestic product (GDP) is manipulated by its rivers. As a matter of fact, 117.8 Tg CO2 year−1 of CO2 is released from its major riverine waters. The potential of GHG emissions from hydropower reservoirs varies between 11–52.9% (mainly CH4 and CO2) because of spatio-temporal variability in the GHG emissions. A significant contribution was also reported from urban lakes, wetlands, and other inland waters. Being a subtropical country, India is one of the global GHG hotspots, having the highest ratio (GHG: GDP) of 1301.79. However, a large portion of India’s freshwater has not been considered yet, and there is a need to account for precise regional carbon budgets. Therefore, in this review, GHG emissions from India’s freshwater bodies, drivers behind GHG emissions (e.g., pH, mean depth, dissolved oxygen, and nutrients), and long-term climatic risks are thoroughly reviewed. Besides research gaps, future directions and mitigation measures are being suggested to provide useful insight into the carbon dynamics (sink/source) and control of GHG emissions.

Impact of coal mining on land use changes, deforestation, biomass, and C losses in Central India: Implications for offsetting CO2 emissions

AbstractDespite the continuous growth in renewable sources of energy, coal remains the primary source of energy security in developing countries and accounted for 1.1 Gt of CO2 annually. The present study was conducted to examine the dynamic land cover changes, deforestation, and carbon (C) emissions in the mined landscape of Central India. Geospatial techniques coupled with field measurements were conjunctively employed for quantifying land use and vegetation changes from the period of 2001 to 2020. The unchecked mining (6.4–30 km2) along with the rapid expansion of agriculture (586.7–642.5 km2) were identified as major drivers of deforestation, which resulted in the net loss of 115.3 km2 area under intact sal (Shorea robusta) dominated forest. The mining and associated activities increased the fragmentation of intact forest that had not only decreased density, basal area, and diversity of vegetation but also a huge loss of biomass of ~2.5 Tg that contributed to a net loss of 1.08 Tg C (~3.98 Tg of CO2) in the past 20 years. The study explored the use of land management options and confirmed that C offset ensued from land use changes without hampering coal production for the next two decades. The scenarios will provide valuable information to the policymakers for devising sustainable coal mining by underpinning the ecological compensation for deforestation while promoting cleaner production technologies through decarbonization to counteract emissions, which could help in achieving ambitious goals set by India for planned C reduction targets as Intended Nationally Determined Commitments under the Paris Agreement (2015).