Global warming is unequivocal. The Paris Agreement requires that countries undertake a global stocktake beginning in 2023 at the 28th Conference of Parties to be held in Doha and every five years thereafter. Countries will demonstrate aggregate progression towards balancing greenhouse gases by sources and removals, adapting to the threats from climate change, the flow of climate finances, and contribution to the achievement of sustainable development goals. This paper designs an Enhanced Climate Mitigation Actions and Safeguard (ECMAS) Indicator Framework and applies it to 188 Nationally Determined Contributions (NDCs). It assesses the implications of the quality of the information provided to improve clarity, transparency, and understanding of the NDCs. Findings show inconsistencies in terms used to describe emission reduction (ER) targets, unmet mitigation ambitions, and poorly elaborated safeguards. The study concludes that the information in the NDCs may jeopardize the sustainability and inclusiveness of net-zero ER targets and Paris Agreement goals, and the ECMAS Indicator Framework can help countries design and pursue appropriate pathways. Our findings recommend the need for policy guidelines to harmonize terminologies in NDCs, promotion of tools for enhancing net-zero ER targets and strengthening of institutional arrangements for elaborating and ensuring safeguards against socio-ecological inequalities are promoted and respected.

Urban centers are places with a high human population concentration, and they can pose social, economic, and environmental challenges. These challenges are accentuated by the increased use of available open space for housing and industrial expansion, leading to elevated energy consumption, increased pollution, higher carbon emissions, and, consequently, adverse effects on human health. Many of these issues also contribute to the acceleration of climate change. There are several ways to decrease these problems through the expansion of greenspaces that conserve biodiversity, decrease air pollution, improve human well-being, and reduce human health risks, while also allowing people to enjoy the benefits of ecosystem services. This review is aimed at professionals who can manage urban landscapes - including adjacent forests, urban parks, tree beds, or home gardens that produce biomass that, together with other non-chemically treated wood waste, could be used to produce and use biochar. Biochar-amended soils provide the benefits of increased carbon sequestration, water retention, and soil productivity and can also decrease stormwater runoff. In addition, a small number of cities around the world have adopted biochar as a nature-based solution to decrease the impacts of climate change. We point out the opportunities and benefits of converting urban wood waste into biochar, how cities can improve their green environments, and, at the same time, produce energy from waste that would otherwise end in landfills with no use or value. Finally, based on previous assessments of wood waste in the United States of America, we estimate the biochar potential to sequester CO₂.

Remote sensing offers an effective and efficient solution to provide information on the biodiversity of seagrass ecosystems, which is currently lacking in most parts of the world. Therefore, this study aimed to map the biodiversity of seagrass ecosystems in parts of Rote Island, which is one of the seagrass biodiversity hotspots, using multi-generation PlanetScope magery to see how they compare. The most frequently used biodiversity indicators were identified, including the major benthic habitat (coral, seagrass, macroalgae, bare substrate) and the composition of seagrass species based on life forms. We also aim to understand the actual biodiversity indicators of seagrass ecosystems captured by PlanetScope imagery. To achieve this, field data was integrated with the resulting ISODATA classification results to assess what ISODATA class clusters represent in the field, and new classification schemes are developed accordingly. The random forest algorithm was used to carry out the classification, with seagrass field data serving as training data. Independent field data was subsequently used to assess the accuracy. The results showed that the accuracy of benthic habitat and seagrass mapping ranged from 60%-70%. However, through the use of a classification scheme built on ISODATA clustering, the spatial distribution of classes and accuracy of all PlanetScope images was significantly improved to > 90%. This highlighted the importance of understanding which indicators of seagrass biodiversity were effectively captured by PlanetScope images to achieve higher mapping accuracy. Overall, this approach optimized the ability of PlanetScope images to map seagrass biodiversity while obtaining a higher number of biodiversity indicator classes and mapping accuracy than the commonly used biodiversity indicator classification scheme.

The aim of this study was to provide an evaluation of the current methods used to assess carbon sequestration (C_seq) rates from intertidal Zostera spp. meadows in central Southern England. This study evaluated the use of ²¹⁰Pb dating methods to calculate sediment accretion rates from four intertidal seagrass meadows along the southern central coast of England. Results obtained were then used to determine C_seq rates, following different models. The mean rate of C_seq calculated in this study using the CRS model was 75.12 g m^-2 year^-1, comparable to other global regions and within the estimated global range. However, results revealed that other, conservative methods, provide much lower C_seq rates, highlighting the need for caution when choosing appropriate methods and reporting results related to seagrass carbon sequestration potential. Moreover, these results highlight the importance of local assessments of C_seq, and the need to create robust models that include the effects of mixing, erosion, and disturbance, to better understand the possible effects of extreme climate events and anthropogenic impacts on seagrass ecosystems' carbon sequestration potential.

Seagrasses take up carbon dioxide and transform it into organic carbon, some of which is buried in meadow sediments. Very high carbon burial rates have been claimed for seagrass meadows globally, and international protocols have been developed with a view to awarding carbon offset credits. However, recent geochemical work has shown that a misunderstanding of how marine sediment buries and processes organic carbon has led to overestimates of at least an order of magnitude. Common blue carbon methodology does not adequately account for bioturbation or remineralization in surface sediment, and there is often a conflation of standing stock with ongoing burial. To determine accurate seagrass carbon burial rates requires the following steps: (1) Determine the sediment accumulation rate below the surface mixed layer, using ²¹⁰Pb and porosity; (2) Determine the burial concentration of organic carbon; (3) Multiply the sediment accumulation rate by the buried % organic carbon; (4) If excluding allochthonous carbon burial, use biomarkers to determine the proportion of seagrass-derived organic carbon; and (5) Account for the offset due to the burial of carbonate formed inside the meadow. Seagrass meadows provide valuable habitat and protect coastlines from erosion. They can also play a role in short-term carbon sequestration. However, if carbon credits are awarded based on inflated estimates and used to offset emissions elsewhere, the net effect could be an increase in carbon dioxide emissions to the atmosphere.