Evidence assessment—identifying, evaluating, and synthesizing data and findings from previous studies—is important to inform environmental decision-making but can be slow and resource intensive. Users seeking efficiency have developed multiple definitions and methods for rapid evidence assessment (REA), raising concerns about consistency and rigor. To improve consistency and confidence in REA, we convened an international group of evidence users and researchers to define REA for environmental applications. Through a consensus-driven and iterative approach, we define REA as: a structured review process that aims to maximize rigor and objectivity given assessment needs and resource constraints; is transparent about trade-offs, risks, and biases; and can integrate multiple types of evidence . Our standardized definition of REA will improve transparency and facilitate decisions about the appropriate levels of rigor required for those who commission, conduct, and use REAs for environmental decision-making.

Mangroves provide numerous ecosystem services and are increasingly recognized as a natural climate solution. As a result, multiple recent initiatives have set ambitious mangrove restoration targets. However, there has been little research estimating the costs of achieving such targets, either site by site or in aggregate. Here, we spatially model the costs of restoring mangroves globally based on reported implementation costs from 249 restoration projects in 25 countries. Using multiple regression analysis, we find that implementation costs decrease with project size, with project year, for aquaculture ponds, and in deltas and increase with national GDP per capita, for eroded sites, and on open coasts. Restoring mangroves across 1.10 million ha globally would remove 0.93 GtCO2 at an implementation cost of $10.73 billion in 2022 international dollars (an average of $9,739 ha-1 or $11.49 tCO2-1 ). Our global map of low-cost, high-impact sites can aid spatial prioritization of mangrove restoration and climate mitigation efforts.

The greenhouse gas abatement costs for two forest restoration methods - natural regeneration and plantations - are estimated by integrating observations on the costs of reforestation projects with other biophysical and economic data. This analysis reveals that a mix of reforestation methods offers greater potential to mitigate climate change at low cost than previously estimated.

Upscaling Voluntary Sustainability Standards (VSS) can generate ecological and social benefits at a scale that is meaningful to address pressing environmental issues such as climate change and biodiversity losses. Lack of resources and risks of implementation gaps may, however, hinder the success of upscaling VSS. This paper aims to fill the gap in the literature regarding options to reduce certification costs to upscale VSS amid the limited financial resources available for certification. The paper presents the result of action research involving 3,507 independent oil palm farmers who are members of six farmer groups in two districts in Central Kalimantan to achieve Roundtable on Sustainable Palm Oil (RSPO) certification. The research found that achieving economies of scale by increasing the total number of certified farmers can reduce the certification costs per farmer. By establishing a district-level entity, the costs related to audits, RSPO membership fees, and the establishment of farmer groups, such as developing standard operating procedures (SOPs), can be lowered. Implementation gaps were not found with the increase of farmers joining the project based on the training frequency and the external audit findings reports on farmers' compliance with RSPO principles and criteria. The findings of this study provide a basis for promoting the upscaling of VSS, including through the RSPO jurisdictional approach.

Mitigating climate change cost-effectively requires identifying least-cost-per-ton GHG abatement methods. Here, we estimate and map GHG abatement cost (US$ per tCO2) for two common reforestation methods: natural regeneration and plantations. We do so by producing and integrating new maps of implementation costs and opportunity costs of reforestation, likely plantation genus and carbon accumulation by means of natural regeneration and plantations, accounting for storage in harvested wood products. We find natural regeneration (46%) and plantations (54%) would each have lower abatement cost across about half the area considered suitable for reforestation of 138 low- and middle-income countries. Using the more cost-effective method at each location, the 30 year, time-discounted abatement potential of reforestation below US$50 per tCO2 is 31.4 GtCO2 (24.2-34.3 GtCO2 below US$20-100 per tCO2)-44% more than natural regeneration alone or 39% more than plantations alone. We find that reforestation offers 10.3 (2.8) times more abatement below US$20 per tCO2 (US$50 per tCO2) than the most recent IPCC estimate. It is important to understand the cost-effectiveness of natural regeneration and plantations, which are common reforestation methods for mitigation. The authors estimate and map abatement costs for the two approaches across low- and mid-income countries, helping to guide reforestation initiatives.

This article updates our previous comprehensive meta-analysis of what drives and stops deforestation (Busch and Ferretti-Gallon 2017). By including six additional years of research, this article more than doubles the evidence base to 320 spatially explicit econometric studies published in peer-reviewed academic journals from 1996 to 2019. We find that deforestation is consistently associated with greater accessibility (as influenced by natural features such as slope and elevation and built infrastructure such as roads, cities, and cleared areas) and with higher economic returns (from agriculture, livestock, and timber). Some demographic variables are consistently associated with less deforestation (e.g., Indigenous people, poverty, and age) or more deforestation (e.g., population), and others are not associated with the level of deforestation (e.g., education and gender). Policies that directly influence allowable land-use activities are associated with less deforestation (e.g., protected areas, enforcement of forest laws, payments for ecosystem services, community forest management, and certification of sustainable commodities). But policies and institutions that primarily seek other ends are not consistently associated with more or less deforestation (e.g., democracy, general governance, conflict abatement, and land-tenure security). We introduce reforestation and forest degradation as new dependent variables alongside deforestation. Greater population is consistently associated with more forest degradation, whereas steeper slope, greater distance from cities, and lower population are consistently associated with more reforestation.

This comprehensive Dictionary brings together an extensive range of definitive terms in ecological economics. Assembling contributions from distinguished scholars, it provides an intellectual map to this evolving subject ranging from the practical to the philosophical.

Reforestation is a potentially large-scale approach for removing CO2 from the atmosphere, thereby helping China achieve its goal of carbon neutrality by 2060. Although China has set ambitious national targets, the cost of mitigating climate change through reforestation has yet to be identified across space and time over the next 40 years. We construct spatially disaggregated marginal abatement cost curves for reforestation by modeling the effects of compensation for enhanced CO2 removals on reforestation. We project that carbon prices (compensation) of US$20 tCO2−1 and US$50 tCO2−1 would motivate land users in China to enhance reforestation by 3.35 Mha (2.65%) and 8.53 Mha (6.74%) respectively from 2020 to 2060 relative to the business-as-usual (BAU) scenario (127 Mha). Carbon dioxide removals through reforestation between 2020 and 2060 in China would be enhanced by 0.0124 GtCO2/yr (1.7%) at US$20 tCO2−1 or 0.0315 GtCO2/yr (4.3%) at US$50 tCO2−1, relative to the BAU scenario (0.740 GtCO2/yr). The cost potential of carbon dioxide removal demonstrates significant spatial heterogeneity. The top 10 provinces (Yunnan, Sichuan, Guangxi, Guizhou, Hunan, Guangdong, Heilongjiang, Jiangxi, Fujian, and Zhejiang), which comprise 73.19% of low-cost abatement potential, should be identified as priority areas for reforestation. Our results confirm the vast potential for low-cost CO2 removal through reforestation to address China’s carbon neutrality challenges while underscoring that targeting reforestation to regions with the greatest potential for low-cost CO2 removal would significantly reduce the cost burden.

Economic growth commonly occurs at the expense of environmental quality, but there are exceptions. Here we use satellite data to identify places where exceptional economic growth and exceptional environmental improvement co-occurred between 1990 and 2015. We term as "bright spots of green growth" those spatial clusters with the most cells above the 95th percentile within their world region in both economic growth (as proxied by increase in nighttime lights) and one aspect of environmental improvement (forest area). Because the locations of bright spots are sensitive to methodological choices, we applied two different approaches to identifying bright spots. The two approaches differed in their choice of nighttime lights data (DSMP-OLS in Approach A vs. DSMP-VIIRS composite in Approach B); choice of forest area data (forest cover vs. forest land-use); time period (2000-2010 vs. 1990-2015); and clustering technique (visual inspection vs. HDBSCAN algorithm). We identified the top five bright spots in each of ten world regions using each of two approaches, for a total of 100 global bright spots of green growth. We then tested the extent to which the attributes of bright spots were consistent with four non-mutually exclusive theories of green growth. Of the bright spots we identified, around two-thirds (65% using Approach A; 71% using Approach B) had significantly higher-than-regional-average growth in the share of labor employed in services, consistent with sectoral shift and "tertiarization." Fewer than half (38%; 46%) had significantly higher growth in income, consistent with the "Environmental Kuznets Curve" theory. Some (54%; 29%) had significantly higher growth in timber plantation area, consistent with "ecoindustry"-driven rural development. Few (0%; 10%) had significantly higher growth in protected area coverage, consistent with public policy-induced forest conservation. Our findings suggest sectoral shift toward services, rather than rising income per se, may be a promising pathway for other regions seeking to combine economic growth and environmental improvement.

The lives lost and economic costs of viral zoonotic pandemics have steadily increased over the past century. Prominent policymakers have promoted plans that argue the best ways to address future pandemic catastrophes should entail, “detecting and containing emerging zoonotic threats.” In other words, we should take actions only after humans get sick. We sharply disagree. Humans have extensive contact with wildlife known to harbor vast numbers of viruses, many of which have not yet spilled into humans. We compute the annualized damages from emerging viral zoonoses. We explore three practical actions to minimize the impact of future pandemics: better surveillance of pathogen spillover and development of global databases of virus genomics and serology, better management of wildlife trade, and substantial reduction of deforestation. We find that these primary pandemic prevention actions cost less than 1/20th the value of lives lost each year to emerging viral zoonoses and have substantial cobenefits.

Demand-side restrictions on high-deforestation commodities are expanding as a climate policy, but their impact on reducing tropical deforestation and emissions has yet to be quantified. Here we model the effects of demand-side restrictions on high-deforestation palm oil in Europe on deforestation and emissions in Indonesia. We do so by integrating a model of global trade with a spatially explicit model of land-use change in Indonesia. We estimate a European ban on high-deforestation palm oil from 2000 to 2015 would have led to a 8.9% global price premium on low-deforestation palm oil, resulting in 21 374 ha yr(-1) (1.60%) less deforestation and 21.1 million tCO(2) yr(-1) (1.91%) less emissions from deforestation in Indonesia relative to what occurred. A hypothetical Indonesia-wide carbon price would have achieved equivalent emission reductions at $0.81/tCO(2). Impacts of a ban are small because: 52% of Europe's imports of high-deforestation palm oil would have shifted to non-participating countries; the price elasticity of supply of high-deforestation oil palm cropland is small (0.13); and conversion to oil palm was responsible for only 32% of deforestation in Indonesia. If demand-side restrictions succeed in substantially reducing deforestation, it is likely to be through non-price pathways.

Ecological fiscal transfers (EFT) transfer public revenue between governments within a country based on ecological indicators. EFT can compensate subnational governments for the costs of conserving ecosystems and in principle can incentivize greater ecological conservation. We review established EFT in Brazil, Portugal, France, China and India, and emerging or proposed EFT in ten more countries. We analyse common themes related to EFT emergence, design and effects. EFT have grown rapidly from US$0.35 billion yr −1 in 2007 to US$23 billion yr −1 in 2020. We discuss the scope of opportunity to expand EFT to other countries by ‘greening’ intergovernmental fiscal transfers.

Land‐based climate mitigation measures have gained significant attention and importance in public and private sector climate policies. Building on previous studies, we refine and update the mitigation potentials for 20 land‐based measures in >200 countries and five regions, comparing “bottom‐up” sectoral estimates with integrated assessment models (IAMs). We also assess implementation feasibility at the country level. Cost‐effective (available up to $100/tCO 2 eq) land‐based mitigation is 8–13.8 GtCO 2 eq yr −1 between 2020 and 2050, with the bottom end of this range representing the IAM median and the upper end representing the sectoral estimate. The cost‐effective sectoral estimate is about 40% of available technical potential and is in line with achieving a 1.5°C pathway in 2050. Compared to technical potentials, cost‐effective estimates represent a more realistic and actionable target for policy. The cost‐effective potential is approximately 50% from forests and other ecosystems, 35% from agriculture, and 15% from demand‐side measures. The potential varies sixfold across the five regions assessed (0.75–4.8 GtCO2eq yr −1 ) and the top 15 countries account for about 60% of the global potential. Protection of forests and other ecosystems and demand‐side measures present particularly high mitigation efficiency, high provision of co‐benefits, and relatively lower costs. The feasibility assessment suggests that governance, economic investment, and socio‐cultural conditions influence the likelihood that land‐based mitigation potentials are realized. A substantial portion of potential (80%) is in developing countries and LDCs, where feasibility barriers are of greatest concern. Assisting countries to overcome barriers may result in significant quantities of near‐term, low‐cost mitigation while locally achieving important climate adaptation and development benefits. Opportunities among countries vary widely depending on types of land‐based measures available, their potential co‐benefits and risks, and their feasibility. Enhanced investments and country‐specific plans that accommodate this complexity are urgently needed to realize the large global potential from improved land stewardship.

More than 15% of global terrestrial area is under some form of protection and there is a growing impetus to increase this coverage to 30% by 2030. But not all protection is effective and the reasons some countries’ protected areas (PAs) are more effective than others’ are poorly understood. We evaluate the effectiveness of national PA networks established between 2000 and 2012 globally in avoiding forest loss, taking into account underlying deforestation threats using a combination of matching methods and cross-sectional regressions. We then assess which demographic, agricultural, economic, and governance factors are most strongly associated with national PA effectiveness using machine learning methods. We estimate that national PAs established between 2000 and 2012 reduced deforestation in those areas by 72%, avoiding 86 062 km 2 of forest loss. The effectiveness of national PAs varied by strictness of protection based on International Union for Conservation of Nature category. Strictly PAs reduced forest loss by 81% compared to what would have occurred without protection, while less strictly PAs reduced forest loss by 67%. Thus, the 26% of new PAs that were strictly protected contributed 39% of the total forest loss avoided within PAs between 2000 and 2012. If every country’s PAs were as effective as the country with the most effective PAs within the same region, they would have increased the area of deforestation avoided by 38%, saving a further 119 082 km 2 of forest. Part of the variation in PA effectiveness across countries is explained by the placement of PA in areas facing higher deforestation threat. Countries with lower agricultural activity, higher economic growth and better governance are most strongly associated with greater country-level PA effectiveness.

The authority of state- and province-level governments (“second-tier governments”) to make decisions related to slowing deforestation independently of national governments varies widely across countries. Here we systematically catalog whether second-tier governments in 30 tropical countries with high projected future emissions from deforestation possess 14 distinct types of general and forest-related authority. We compile this information in a free, open-access database. Second-tier governments have broadest authority to reduce deforestation in India, Brazil, Indonesia, Malaysia, Papua New Guinea, Peru, China, Laos, Mozambique, and Vietnam. Second-tier governments have the least authority in Central African Republic, Gabon, Angola, Madagascar, Bolivia, Cambodia, Cameroon, Guyana, Suriname, Thailand, and Venezuela. Second-tier governments have intermediate authority in Democratic Republic of Congo, Ecuador, Mexico, the Philippines, Colombia, Myanmar, Tanzania, Zambia, Mexico, and Republic of Congo. Authorities that second-tier governments most commonly possess include development planning, taxation, budgeting, and roads. Authorities that second-tier governments least commonly possess include land ownership, police, permits for mining, Indigenous affairs, and protected areas. Authorities possessed by an intermediate number of second-tier governments include spatial planning, elections, courts, and permits for agriculture. More than one-quarter of future emissions from deforestation between 2020 and 2050 is projected to come from just seven out of 678 second-tier jurisdictions: Amazonas, Pará, and Mato Grosso (Brazil), Équateur and Orientale (Democratic Republic of Congo), Loreto (Peru), and El Beni (Bolivia). After weighting for authority, our list of the 50 second-tier jurisdictions in the tropics that are the highest priority for reducing emissions from deforestation shifts to include fewer second-tier jurisdictions in Africa (where second-tier governments have 4.2 authorities out of 14 in the average country) and Latin America (6.3 authorities out of 14) and more second-tier jurisdictions in Asia (8.5 authorities out of 14). Second-tier jurisdictions that have formally expressed interest in reducing emissions from deforestation, e.g., through the Governors' Climate and Forest Task Force, Under2 Coalition, or New York Declaration on Forests, possess greater authority to reduce deforestation on average than other jurisdictions. Information on second-tier governmental authority, when complemented with deeper country-specific knowledge, can help initiatives for reducing emissions from deforestation (REDD+) prioritize support across regions and across sectoral interventions.

Investments to prevent tropical deforestation and to limit wildlife trade will protect against future zoonosis outbreaks

Protected areas have been the cornerstone for conservation globally [1], but gaps still exist in preserving biodiversity [2]. Meanwhile, areas designated as protected have overlaps between designations and might vary in their management [3, 4]. All three phenomena-coverage gaps, overlapping designations, and disparities in management-are present in China [5, 6]. China plans to establish a national park system for the first time, aiming to reform the existing protected-area system [ ]. However, there has been no quantitative spatial analysis that can aid the planning of national parks. This study shows how an improved conservation gap analysis can inform the construction of new national parks. Taking the proposed Giant Panda National Park as an example, we analyzed the relationship between panda habitat and the existing protected areas, considering not only de jure designated coverage but also de facto levels of two types of potentially harmful activities (timber extraction and human disturbance). We find that, first, there are coverage gaps in the four mountains comprising the potential national park, and existing protected areas have overlaps between designations. Second, current protected areas have gaps and disparities in terms of restrictions on timber extraction and human disturbance. Third, overlapped designations and less restrictive management appear to have adverse effects on panda protection. On the basis of these results,we propose integrated management under a single national park administration, focusing on the key gaps, which we identify. This study can serve as a reference for the establishment of other national parks in China and the world.

Ecological fiscal transfers (EFTs) involve higher levels of government distributing funds to lower levels of government based on ecological indicators. In 2015 India established the world's largest system of EFTs when its 14th Finance Commission added forest cover to the formula that determines the amount of tax revenue the Union government distributes annually to each state. Here we gather state-by-state data on forestry budgets to assess whether India's EFTs incentivized states to protect and restore forests as evidenced by increases to their forestry budgets. We find that states increased their forestry budgets by 19% in absolute terms in the three years after the introduction of EFTs relative to the three years prior. However, forestry budgets as a share of overall state budgets shrank by 16% after the introduction of EFTs, from 0.99% to 0.83%. Furthermore, states that obtained a larger share of their budget from EFTs did not disproportionately increase their forestry budget. Taken together, this suggests the introduction of EFTs has not yet led states to increase their forestry budgets. We develop a causal chain that suggests two reasons this could be: (1) low expectations on the part of state government officials that EFTs would continue in such a way that increases in forest cover would be rewarded with increases in revenue; and/or (2) insufficient motivation to increase forestry budgets as an investment in future revenue from EFTs. The 15th Finance Commission has plausibly addressed low expectations by keeping forests in the tax revenue distribution formula for another period and updating the year for which forest cover is measured from 2013 to 2017. It has plausibly addressed insufficient motivation by increasing the weight on forests in the formula from 7.5% to 10%. Future research can show whether these modified EFTs incentivize states to increase forest protection and restoration.

Better land stewardship is needed to achieve the Paris Agreement's temperature goal, particularly in the tropics, where greenhouse gas emissions from the destruction of ecosystems are largest, and where the potential for additional land carbon storage is greatest. As countries enhance their nationally determined contributions (NDCs) to the Paris Agreement, confusion persists about the potential contribution of better land stewardship to meeting the Agreement's goal to hold global warming below 2°C. We assess cost-effective tropical country-level potential of natural climate solutions (NCS)—protection, improved management and restoration of ecosystems—to deliver climate mitigation linked with sustainable development goals (SDGs). We identify groups of countries with distinctive NCS portfolios, and we explore factors (governance, financial capacity) influencing the feasibility of unlocking national NCS potential. Cost-effective tropical NCS offers globally significant climate mitigation in the coming decades (6.56 Pg CO 2 e yr −1 at less than 100 US$ per Mg CO 2 e). In half of the tropical countries, cost-effective NCS could mitigate over half of national emissions. In more than a quarter of tropical countries, cost-effective NCS potential is greater than national emissions. We identify countries where, with international financing and political will, NCS can cost-effectively deliver the majority of enhanced NDCs while transforming national economies and contributing to SDGs. This article is part of the theme issue ‘Climate change and ecosystems: threats, opportunities and solutions’.