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Improved forest management (IFM) has the potential to remove and store large quantities of carbon from the atmosphere. Around the world, 293 IFM offset projects have produced 11% of offset credits by voluntary offset registries to date, channeling substantial climate mitigation funds into forest management projects. This paper summarizes the state of the scientific literature for key carbon offset quality criteria—additionality, baselines, leakage, durability, and forest carbon accounting—and discusses how well currently used IFM protocols align with this literature. Our analysis identifies important areas where the protocols deviate from scientific understanding related to baselines, leakage, risk of reversal, and the accounting of carbon in forests and harvested wood products, risking significant over-estimation of carbon offset credits. We recommend specific improvements to the protocols that would likely result in more accurate estimates of program impact, and identify areas in need of more research. Most importantly, more conservative baselines can substantially reduce, but not resolve, over-crediting risk from multiple factors.

In tropical South America there has been substantial progress in atmospheric monitoring capacity, but the region still has a limited number of continental atmospheric stations relative to its large area, hindering net carbon flux estimates using atmospheric inversions. In this study, we use dry-air CO.sub.2 mole fractions measured at the Amazon Tall Tower Observatory (ATTO) and airborne vertical CO.sub.2 profiles in an atmospheric inversion system to estimate net carbon exchange in tropical South America from 2010 to 2018. Given previous knowledge of a bias due to undried samples in the airborne vertical profiles, we calculate the effect of this systematic uncertainty in our inverse estimates and propose a water-vapor correction to the airborne CO.sub.2 profiles. We focus our analysis on the biogeographic Amazon and its neighboring \"Cerrado and Caatinga\" biomes. Including the water-vapor correction changes the posterior ensemble median from -0.33 to -0.04 PgC yr.sup.-1 with a posterior uncertainty of 0.33 PgC yr.sup.-1 for the Amazon and for the Cerrado and Caatinga from 0.31 to 0.50 PgC yr.sup.-1, with an uncertainty of 0.24 PgC yr.sup.-1 . Our estimates of carbon exchange include the contributions from both net vegetation exchange and release from fires. Assuming that the correction brings the observational data closer to the truth implies that the Amazon is a weaker sink of carbon and that the Cerrado and Caatinga is a larger source. We do not find a strong spatial shift of fluxes within the biogeographic Amazon due to the correction, nor do we find a strong impact on the interannual variations. Finally, to further reduce the uncertainty in regional carbon balance estimates in tropical South America, we call for an expansion of the atmospheric monitoring network on the continent, mainly in the Amazon-Andes foothills.

Reducing emissions from deforestation and forest degradation (REDD+) has gained international attention over the past decade, as manifested in both United Nations policy discussions and hundreds of voluntary projects launched to earn carbon-offset credits. There are ongoing discussions about whether and how projects should be integrated into national climate change mitigation efforts under the Paris Agreement. One consideration is whether these projects have generated additional impacts over and above national policies and other measures. To help inform these discussions, we compare the crediting baselines established ex-ante by voluntary REDD+ projects in the Brazilian Amazon to counterfactuals constructed ex-post based on the quasi-experimental synthetic control method. We find that the crediting baselines assume consistently higher deforestation than counterfactual forest loss in synthetic control sites. This gap is partially due to decreased deforestation in the Brazilian Amazon during the early implementation phase of the REDD+ projects considered here. This suggests that forest carbon finance must strike a balance between controlling conservation investment risk and ensuring the environmental integrity of carbon emission offsets. Relatedly, our results point to the need to better align project- and national-level carbon accounting.

Most companies include carbon offsets in their net-zero strategy. However, many offset projects are poor quality and fail to reduce emissions as claimed. Here we focus on the twenty companies retiring the most offsets from the voluntary carbon market over 2020–2023. We examine if their offsets could be considered high quality and likely to benefit the climate. We curate an original company-level dataset to examine quality and climate benefits across four dimensions: (1) use of offsets from low/high-risk project types; (2) age of projects and credits; (3) price of credits; and (4) country of implementation. We find that companies have predominantly sourced low-quality, cheap offsets: 87% carry a high risk of not providing real and additional emissions reductions, with most offsets originating from forest conservation and renewable energy projects. Further, most offsets do not meet industry standards regarding age and country of implementation. These findings provide further evidence that the voluntary carbon market is not supporting effective climate mitigation. Particularly, we show that its persisting quality issues are exacerbated by the demand for low-quality offsets by individual companies. Trencher and colleagues investigate the twenty companies making the largest purchases of offsets from the voluntary carbon market from 2020 to 2023. They find that 87% of the purchased offsets carry a high risk of not providing real and additional emissions reductions. Further, most offsets do not meet industry standards regarding age and country of implementation. The findings reinforce concerns that the voluntary carbon market is failing to support effective climate mitigation.

Biodiversity offsets have become a widely accepted means of attempting to compensate for biodiversity loss from development, and are applied in planning and decision-making processes at many levels. Yet their use is contentious, and numerous problems with both the concept and the practice have been identified in the literature. Our starting point is the understanding that offsets are a kind of biodiversity compensation measure through which the goal of no net loss (or net gain) of biodiversity can be at least theoretically achieved. Based on a typology of compensation measures distinguishing between habitat protection, improvement (including restoration, habitat creation and improved management practices) and other compensation, we review the literature to develop a framework of conditions that must be met if habitat protection and improvement initiatives can be truly considered offsets and not merely a lesser form of compensation. It is important that such conceptual clarity is reflected in offset policy and guidance, if offsets are to be appropriately applied and to have any chance of fully compensating for biodiversity loss. Our framework can be used to support the review and ongoing development of biodiversity offset policy and guidance, with the aim of improving clarity, rigour and therefore the chances that good biodiversity outcomes can be achieved.

Offsetting is emerging as an important but controversial approach for managing environment–development conflicts. Biodiversity offsets are designed to compensate for damage to biodiversity from development by providing biodiversity gains elsewhere. Here, we suggest how biodiversity offset policies can generate behaviours that exacerbate biodiversity decline, and identify four perverse incentives that could arise even from soundly designed policies. These include incentives for (i) entrenching or exacerbating baseline biodiversity declines, (ii) winding back non‐offset conservation actions, (iii) crowding out of conservation volunteerism and (iv) false public confidence in environmental outcomes due to marketing offset actions as gains. Synthesis and applications. Despite its goal of improving biodiversity outcomes, there is potential for best‐practice offsetting to achieve the opposite result. Reducing this risk requires coupling offset crediting baselines to measured trajectories of biodiversity change and understanding the potential interaction between offsetting and other environmental policies.

Biodiversity offsets are applied in many countries to compensate for impacts on the environment, but research on regulatory frameworks and implementation enabling effective offsets is lacking. This paper reviews research on biodiversity offsets, providing a framework for the analysis of program design (no net loss goal, uncertainty and ratios, equivalence and accounting, site selection, landscape-scale mitigation planning, timing) and implementation (compliance, adherence to the mitigation hierarchy, leakage and trade-offs, oversight, transparency and monitoring). Some more challenging aspects concern the proper metrics and accounting allowing for program evaluation, as well as the consideration of trade-offs when regulations focus only on the biodiversity aspect of ecosystems. Results can be used to assess offsets anywhere and support the creation of programs that balance development and conservation.

A consistent analysis of signal-in-space ranging errors (SISREs) is presented for all current satellite navigation systems, considering both global average values and worst-user-location statistics. The analysis is based on 1 year of broadcast ephemeris messages of the Global Positioning System (GPS), GLONASS, Galileo, BeiDou and QZSS collected with a near-global receiver network. Position and clock values derived from the navigation data are compared against precise orbit and clock products provided by the International GNSS Service and its multi-GNSS experiment. Satellite laser ranging measurements are used for a complementary and independent assessment of the orbit-only SISRE contribution. The need for proper consideration of antenna offsets is highlighted and block-/constellation-specific radial antenna offset values for the center-of-mass correction of broadcast orbits are derived. Likewise, the need for application of differential code biases in the comparison of broadcast and precise clock products is emphasized. For GPS, the analysis of the legacy navigation message is complemented by a discussion of the CNAV message performance based on the first CNAV test campaign in June 2013. Global average SISRE values for the individual constellations amount to 0.7 ± 0.02 m (GPS), 1.5 ± 0.1 m (BeiDou), 1.6 ± 0.3 m (Galileo), 1.9 ± 0.1 m (GLONASS), and 0.6 ± 0.2 m (QZSS) over a 12-month period in 2013/2014.

Governments, businesses, and lenders worldwide are adopting an objective of no net loss (NNL) of biodiversity that is often partly achieved through biodiversity offsetting within a hierarchy of mitigation actions. Offsets aim to balance residual losses of biodiversity caused by development in one location with commensurate gains at another. Although ecological challenges to achieve NNL are debated, the associated gains and losses for local stakeholders have received less attention. International best practice calls for offsets to make people no worse off than before implementation of the project, but there is a lack of clarity concerning how to achieve this with regard to people’s use and nonuse values for biodiversity, especially given the inevitable trade-offs when compensating biodiversity losses with gains elsewhere. This is particularly challenging for countries where poor people depend on natural resources. Badly planned offsets can exacerbate poverty, and development and offset impacts can vary across spatial-temporal scales and by location, gender, and livelihood. We conceptualize the no-worse-off principle in the context of NNL of biodiversity, by exploring for whom and how the principle can be achieved. Changes in the spatial and temporal distribution of biodiversity-related social impacts of a development and its associated offset can lead to social inequity and negatively impact people’s well-being. The level of aggregation (regional, village, interest group, household, and individual) at which these social impacts are measured and balanced can again exacerbate inequity in a system. We propose that a determination that people are no worse off, and preferably better off, after a development and biodiversity offset project than they were before the project should be based on the perceptions of project-affected people (assessed at an appropriate level of aggregation); that their well-being associated with biodiversity losses and gains should be at least as good as it was before the project; and that this level of well-being should be maintained throughout the project life cycle. Employing this principle could help ensure people are no worse off as a result of interventions to achieve biodiversity NNL. Los gobiernos, negocios y financiadores están adoptando el objetivo de biodiversidad sin pérdida neta (NNL, en inglés), el cual comúnmente se logra parcialmente por medio de compensaciones por biodiversidad dentro de una jerarquía de acciones de mitigación. Las compensaciones buscan balancear las pérdidas residuales de la biodiversidad causadas por el desarrollo en una localidad con ganancias conmensuradas en otra localidad. Aunque los obstáculos ecológicos para alcanzar la NNL se debaten hoy en día, las ganancias y pérdidas para los accionistas locales han recibido menos atención. La mejor práctica internacional requiere compensaciones para que las personas no estén peor que antes de la implementación del proyecto, pero existe una falta de claridad con respecto a cómo lograr esto considerando el valor de uso o no de la biodiversidad por parte de las personas, especialmente dadas las compensaciones inevitables cuando se resarcen las pérdidas de biodiversidad con ganancias en otros lugares. Esto es un reto particularmente para los países en donde la gente pobre depende de los recursos naturales. Las compensaciones mal planeadas pueden exacerbar la pobreza, y los impactos del desarrollo y las compensaciones puede variar a lo largo de la escala espacio-temporal y por localidad, género, y sustento. Conceptualizamos el principio de no-peor-que en el contexto de la NNL de biodiversidad explorando para quién y cómo se puede lograr este principio. Los cambios en la distribución especial y temporal de los impactos sociales de un proyecto relacionados con la biodiversidad y sus compensaciones asociadas pueden resultar en una inequidad social e impactar negativamente el bienestar de las personas. El nivel de agregación (regional, aldea, grupo de interés. hogar, individual) en el que se miden y balancean estos impactos sociales también puede exacerbar la inequidad en un sistema. Proponemos que la determinación de que las personas no estén peor que antes, y de preferencia mejor que, después de un proyecto de desarrollo y de compensación por la biodiversidad debería basarse en las percepciones de las personas afectadas por el proyecto (evaluadas en un nivel apropiado de agregación); que su bienestar asociado con las pérdidas y ganancias de biodiversidad debería por lo menos ser tan bueno como era antes del proyecto; y que este nivel de bienestar debería mantenerse durante todo el ciclo de vida del proyecto. Si se emplea este principio, se podría ayudar a asegurarle a las personas que no estén peor que antes como resultado de las intervenciones para alcanzar la NNL de biodiversidad. 世界各国的政府、企业和贷款机构都在努力实现生物多样性无净损失(no net loss, NNL)的巨标，这一目 标一定程度上是通过分级减控行动中的生物多样性补偿实现的。补偿旨在平衡一千地区发展导致的生物多祥性 剩余损失与另ー个地区的同等收益。虽然实现无净损失面临的生态挑战仍受到争议，但当地的利益相关者的相 应收益和损失受到的关注甚至更少。目前，国际上的最优做法要求对人们的补偿应能够保i正其生活水平不会比 项目实施前更低，但就人们对生物多祥性的利用及菲利用价值来说如何达到这一要求还不明确，特別是考虑到 用其它地方的收益来补偿生物多祥性损失时所不可避免地产生的利弊权衡。而这ー问题在贫困人ロ依赖自然资 源生活的国家格外具有挑战性。计划不当的补偿可能会加剧贫困，发展和ネト偿的影响还会随时空尺度、地点、 性别和谋生方式而变化。我们在生物多祥性无净损失的背景下，通过分析无恶化原则将为谁实现、如何实现，构 建了该原则的概念。发展及其补偿所引起的生物多祥性相关的社会影响在时间和空间分布上的变化会导致社 会不平等，并对人们的福祉产生负面影响。在何种聚合程度上（地区、村庄、利益集团、家庭、十人）衡量和平 衡这些社会影响，可能会再次加剧系统中的不平等性。我们认为，发展及生物多祥性补偿项目对人们生活水平影 响(不应比项目开展前更差，最好有所改善)的测定应建立在对受项目影响人群的理解和认识上即在ー个合适 的綜合的水平上进行评估;另外，人们与生物多样性收益及损失相关的福祉也至少要与项目实施前一祥好，且项 目全程都保持这ー水平。采用这个原则有助于确保实现生物多祥性无净损失的干预不会导致人们生活水平下 降。