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Countries have pledged to different national and international environmental agreements, most prominently the climate change mitigation targets of the Paris Agreement. Accounting for carbon stocks and flows (fluxes) is essential for countries that have recently adopted the United Nations System of Environmental-Economic Accounting - ecosystem accounting framework (UNSEEA) as a global statistical standard. In this paper, we analyze how spatial carbon fluxes can be used in support of the UNSEEA carbon accounts in five case countries with available in-situ data. Using global multi-date biomass map products and other remotely sensed data, we mapped the 2010–2018 carbon fluxes in Brazil, the Netherlands, the Philippines, Sweden and the USA using National Forest Inventory (NFI) and local biomass maps from airborne LiDAR as reference data. We identified areas that are unsupported by the reference data within environmental feature space (6–47% of vegetated country area); cross-validated an ensemble machine learning (RMSE=9–39 Mg C ha - 1 and R 2 =0.16–0.71) used to map carbon fluxes with prediction intervals; and assessed spatially correlated residuals (<5 km) before aggregating carbon fluxes from 1-ha pixels to UNSEEA forest classes. The resulting carbon accounting tables revealed the net carbon sequestration in natural broadleaved forests. Both in plantations and in other woody vegetation ecosystems, emissions exceeded sequestration. Overall, our estimates align with FAO-Forest Resource Assessment and national studies with the largest deviations in Brazil and USA. These two countries used highly clustered reference data, where clustering caused uncertainty given the need to extrapolate to under-sampled areas. We finally provide recommendations to mitigate the effect of under-sampling and to better account for the uncertainties once carbon stocks and flows need to be aggregated in relatively smaller countries. These actions are timely given the global initiatives that aim to upscale UNSEEA carbon accounting. [ABSTRACT FROM AUTHOR]

It is well recognized that commercial beef cattle production systems have a major impact on climate change, mainly due to the emission of enteric methane (CH4). The objective of this research was to evaluate if integrating animal + pasture + timber production in silvopastoral systems (SPS) would help neutralize the impact of enteric CH4 emission by facilitating carbon storage as soil organic carbon (SOC). This paper reports a study conducted in Brazil with a herd of 150 cows in 100 ha of Urochloa brizantha with Eucalyptus urograndis, on four tree configurations: SPS 1-clone GG-100 at 2 × 3 × 15 m spacing; SPS 2-clone i-144 at 2 × 3 × 15 m; SPS 3-clone GG-100 at 3 × 15 m; and SPS 4-clone i-144 at 3 × 15 m. Based on data collected through eight consecutive years, the gas balance was estimated. For all SPS treatments average, the carbon dioxide equivalent (CO2e) of additional C stock exceeded the emissions. Considering only C sequestration from trees, the average CO2e sequestration was − 26.27 Mg·CO2e ha−1, while the average emissions of CO2 e was 23.54 Mg·CO2e ha−1 for enteric CH4 + pasture + tree, giving a net balance of − 2.73 Mg·CO2e ha−1. The "loss" of CO2e analyzed was compensated by the soil C sequestration in long-lived SOC pools, enhancing the resilience of farming systems by increasing soil organic matter and soil fertility capacity, mitigating greenhouse gas emissions, therefore, providing benefits in livestock production and for environmental remediation. [ABSTRACT FROM AUTHOR]

Abstract: Continental shelves have the potential to remove atmospheric carbon dioxide via the biological pump, burying it in seafloor sediments. The efficiency of marine carbon sequestration changes rapidly due to variations in biological productivity, organic carbon oxidation, and burial rate. Here we present a high temporal resolution record of marine carbon sequestration changes from a western South Atlantic shelf site sensitive to Brazil Current-driven upwelling. The comparison of biological records to rare earth element (REE) patterns from authigenic oxides shows a strong relationship between higher biological productivity and stronger particle reactive element cycling (i.e. REE cycling) during rapid climate change events. This is the first evidence that authigenic oxides archive past changes in upper ocean REE cycling by the exported organic carbon. In addition, our data suggest that Brazil Current-driven upwelling varies on millennial-scales and in time with continental precipitation anomalies as registered in Brazilian speleothems during the Holocene. This indicates an ocean–atmosphere control on the biological pump, most probably related to South American monsoon system variability. [ABSTRACT FROM AUTHOR]

Tropical secondary forests sequester carbon up to 20 times faster than old-growth forests. This rate does not capture spatial regrowth patterns due to environmental and disturbance drivers. Here we quantify the influence of such drivers on the rate and spatial patterns of regrowth in the Brazilian Amazon using satellite data. Carbon sequestration rates of young secondary forests (<20 years) in the west are ~60% higher (3.0 ± 1.0 Mg C ha−1 yr−1) compared to those in the east (1.3 ± 0.3 Mg C ha−1 yr−1). Disturbances reduce regrowth rates by 8–55%. The 2017 secondary forest carbon stock, of 294 Tg C, could be 8% higher by avoiding fires and repeated deforestation. Maintaining the 2017 secondary forest area has the potential to accumulate ~19.0 Tg C yr−1 until 2030, contributing ~5.5% to Brazil's 2030 net emissions reduction target. Implementing legal mechanisms to protect and expand secondary forests whilst supporting old-growth conservation is, therefore, key to realising their potential as a nature-based climate solution. This study uses regional and global remote sensing data to assess the regrowth of secondary forests in the Brazilian Amazon biome. The authors find differences of regrowth rates due to climate, forest fires and deforestation actions and further quantify their carbon capture potential. [ABSTRACT FROM AUTHOR]

The Nationally Determined Contributions (NDCs) to the Paris Agreement (PA) submitted so far do not put the world on track to meet the targets of the Agreement and by 2020 countries should ratchet up ambition in the new round of NDCs. Brazil's NDC to the PA received mixed reviews and has been rated as "medium" ambition. We use the Brazil Land Use and Energy System (BLUES) model to explore low-emission scenarios for Brazil for the 2010–2050 period that cost-effectively raise ambition to levels consistent with PA targets. Our results reinforce the fundamental role of the agriculture, forest, and land use (AFOLU) sectors and explore inter-sectoral linkages to power generation and transportation. We identify transportation as a prime candidate for decarbonization, leveraging Brazil's already low-carbon electricity production and its high bioenergy production. Results indicate the most important mitigation measures are electrification of the light-duty vehicle (LDV) fleet for passenger transportation, biodiesel and biokerosene production via Fischer-Tropsch synthesis from lignocellulosic feedstock, and intensification of agricultural production. The use of carbon capture and storage (CCS) as well as netzero deforestation make significant contributions. We identify opportunities for Brazil, but synergies and trade-offs across sectors should be minded when designing climate policies. [ABSTRACT FROM AUTHOR]

Coastal ecosystems are considered environments with great potential for carbon storage. Given the difficulties in quantifying biomass, allometric equations and remote sensing have become fundamental tools in the studies of quantification of vegetation biomass and carbon stocks. Thus, the objective of this study is to quantify and estimate the spatial distribution of vegetation biomass and to quantify the carbon stock of the Parnaíba River Delta vegetation. The study was carried out in part of the Parnaíba River Delta Environmental Protection Area and in the Parnaíba River Delta Marine Extractive Reserve, in NE Brazil, in five spots within distinct vegetation types: psammophile pioneer vegetation, dune subevergreen vegetation, mangrove evergreen vegetation, floodplain vegetation and vegetation associated with carnaubals. At 26 collection points, 10 × 20 m plots were marked, in which the diameter at breast height and height of all individuals were measured. The collected data were used in allometric equations for vegetation biomass estimates and these values were converted into carbon stocks. The spatial distribution of aboveground vegetation biomass (AGB) was also estimated by remote sensing, where we extracted and selected spectral variables obtained from Landsat-8 OLI sensor images, on three different dates. Prediction models were calculated by multiple linear regression analysis. It was observed that the mangrove evergreen vegetation obtained higher vegetation biomass and carbon stock than the others. The models obtained through remote sensing that provided the best estimates of AGB were those of November 12th, 2016 (EAM = 6.84; RMSE = 47.89 Mg ha−1; R2 = 0.72) and November 28th, 2016 (EAM = 9.63; RMSE = 34.67 Mg ha−1; R2 = 0.58). [ABSTRACT FROM AUTHOR]

In recent years, nations, states and provinces have been proactively combating climate change, supported by the 21st Conference of the Parties of the United Nations Framework Convention on Climate Change (UNFCCC) outcomes. In the meantime, several studies have evaluated regional strategies for greenhouse gas (GHG) mitigation. Although these studies propose scenarios that meet the climate policy pledges, most of them are based on measures that have not been commercially demonstrated yet, such as carbon capture and storage (CCS). The aim of this work is to develop a low-carbon scenario for the energy sector in Sao Paulo, Brazil (whose emissions are significant at the regional and national level) until 2050 and to verify if a proven, technology-based approach meets the current policy goals. Although the analysis is based on a developing country, Sao Paulo state is the most developed region in Brazil. Consequently, the analysis presented in this work may be replicated in other regional settings, with distinct development stages, which demand increasing energy futures. In the business-as-usual (BAU) scenario, energy demand increases 2.6% per year until 2050, and emissions consequently increase 2.8% per year, reaching 235 million metric tons of carbon dioxide (tCO2). If four alternatives proposed in the low-carbon (LC) scenario were implemented, 28% of the BAU emissions would be avoided. However, even with this LC scenario, Sao Paulo would not meet the state pledge, remaining 44% above the policy emission cap. This result means that more audacious measures are needed to achieve an effective result. Such measures must push the current technical, scientific, and industrial knowledge and may require a biodiesel share over 20% in diesel blend, extensive increases in renewable energy supply, CCS, and bioenergy associated with CCS. Finally, we suggest some key points to apply this analysis in other regions, considering their own energy mix. [ABSTRACT FROM AUTHOR]

groforestry systems can play a major role in the sequestration of carbon (C) because of their higher input of organic material to the soil. The importance of organic carbon to the physical, chemical, and biological aspects of soil quality is well recognized. However, total organic carbon measurements might not be sensitive indicators of changes in soil quality. Adoption of procedures that can extract the more labile fraction preferentially might be a more useful approach for the characterization of soil organic carbon resulting from different soils. This study aimed to evaluate organic carbon (C) fractions distribution in different soil layers up to 50 cm depth in two soil orders under cacao ( Theobroma cacao) agroforestry systems (AFS) in Bahia, Brazil. Soil samples were collected from four depth classes (0-5, 5-10, 10-30 and 30-50 cm) under two cacao agroforestry systems (30-year-old stands of cacao with Erythrina glauca, as shade trees) in Latosol and Cambisol, in Bahia, Brazil. The determination of oxidizable carbon by a modified Walkley-Black method was done to obtain four C fractions with different labile forms of C (fraction 1: labile fraction; fraction 2: moderate labile fraction; fraction 3: low labile fraction and fraction 4: recalcitrant fraction). Overall, at two cacao AFS, the C fractions generally declined with increase in soil depth. The C fractions 1 and 2 were 50% higher on upper layers (0-5 and 5-10 cm). More than 50% of organic C was found in more labile fraction (fraction 1) in all depths for both soils. High value of C fraction 1 (more labile C)-to-total organic C ratio was obtained (around 54-59%, on Latosol and Cambisol, respectively), indicating large input of organic matter in these soils. [ABSTRACT FROM AUTHOR]

Sugarcane (Saccharum officinarum L.) cultivation leaves behind around 20 t ha−1 of biomass residue after harvest and processing. We investigated the potential for sequestering carbon (C) in soil with these residues by partially converting them into biochar (recalcitrant carbon-rich material). First, we modified the RothC model to allow changes in soil C arising from additions of sugarcane-derived biochar. Second, we evaluated the modified model against published field data, and found satisfactory agreement between observed and predicted soil C accumulation. Third, we used the model to explore the potential for soil C sequestration with sugarcane biochar in São Paulo State, Brazil. The results show a potential increase in soil C stocks by 2.35 ± 0.4 t C ha−1 year−1 in sugarcane fields across the State at application rates of 4.2 t biochar ha−1 year−1. Scaling to the total sugarcane area of the State, this would be 50 Mt of CO2 equivalent year−1, which is 31% of the CO2 equivalent emissions attributed to the State in 2016. Future research should (a) further validate the model with field experiments; (b) make a full life cycle assessment of the potential for greenhouse gas mitigation, including additional effects of biochar applications on greenhouse gas balances. [ABSTRACT FROM AUTHOR]