Forest Climate Change Mitigation Research Articles

Spatial database of planted forests in East Asia

Planted forests are critical to climate change mitigation and constitute a major supplier of timber/non-timber products and other ecosystem services. Globally, approximately 36% of planted forest area is located in East Asia. However, reliable records of the geographic distribution and tree species composition of these planted forests remain very limited. Here, based on extensive in situ and remote sensing data, as well as an ensemble modeling approach, we present the first spatial database of planted forests for East Asia, which consists of maps of the geographic distribution of planted forests and associated dominant tree genera. Of the predicted planted forest areas in East Asia (948,863 km2), China contributed 87%, most of which is located in the lowland tropical/subtropical regions, and Sichuan Basin. With 95% accuracy and an F1 score of 0.77, our spatially-continuous maps of planted forests enable accurate quantification of the role of planted forests in climate change mitigation. Our findings inform effective decision-making in forest conservation, management, and global restoration projects.

Managing forest carbon and landscape capacities

Widespread impacts of a warming planet are fuelling climate change mitigation efforts world-wide. Decision makers are turning to forests, the largest terrestrial primary producer, as a nature-based contribution to mitigation efforts. Resource-based economies, however, have yet to include carbon (C) in their resource planning, slowing the implementation of these important measures for atmospheric greenhouse gas reduction. The realisation of forest mitigation potential depends greatly on our ability to integrate C-sequestration practices in our forest management applications. This requires robust C-estimates, an understanding of the natural potential for a specific landscape to sequester C, the current state of the landscape relative to this potential, and the evaluation of management practices as a tool to sequester forest C in the midst of all the other values forests offer humans. Discrepancies between models used in management decisions and C estimation are the first hurdle impeding the application of forest-based mitigation strategies. Here, we combine forest disturbance and management models with a well-established C model on an open-source simulation platform. We then use the modelling system to produce C estimates of the natural C-holding capacity (potential) and two management scenarios for a study area in BC, Canada. Our simulations provide an essential metric if forests are to be managed for C-sequestration: the natural landscape C-holding capacity. Our simulations also point to a decreasing trend in simulated C on the study area over time and to a bias of the current C-levels compared to the landscape C-holding capacity (477 vs 405.5 MtC). Our explanations for this bias may provide an avenue for improved current C-state estimates. We provide a framework and the information needed for the implementation of nature-based solutions using forests for climate change mitigation. This study is a step towards modelling systems that can unify scientifically based forest management and informed C-management.

The role of Swedish forests in climate change mitigation – A frame analysis of conflicting interests

Forests are assumed to play a significant role in relation to climate change mitigation. However, previous studies show that actor groups' perspectives vary regarding how to best utilize forests. This paper focuses on exploring frames in recent Swedish forest- and climate politics and to what extent they may form the basis for conflict resolution or contribute to perpetuate conflicts among actors. The analysis of recent forest- and climate policies, and actor groups' positioning on the issues, builds upon the pathways to sustainability approach in combination with frame analysis. The results showed that ideas based on “Ecological Modernisation” dominated within the forest-climate nexus, but also a clear presence of alternative frames promoting “Sustainable Development”. As a result, conflicting frames were identified within the policies on how to reach policy targets - stressing both the importance of consensus and neutral dialogue with actors, while concurrently prioritizing an economic perspective.

Patterns and drivers of tree carbon stocks in Kashmir Himalayan forests: implications for climate change mitigation

BackgroundTemperate forests are major carbon sinks because of their high storage potential and low decomposition processes. We quantified tree carbon (TC) storage from 143 plots distributed across three major forest types of Kashmir Himalaya, relative to differences in ecological factors. Combined regression and Random Forest (RF) analysis were used to examine the distribution of TC stock along ecological gradients and recognize the role of driving factors on TC stocks.ResultsAmong the three forest types, sub-alpine (SA) forest was the primary TC sink, accounting for 228.73 t ha−1 of carbon, followed by mixed conifer (MC; 181.29 t C ha−1) and blue pine (BP; 133.04 t C ha−1) forests. The distribution of TC stocks among the three forest types differed significantly (χ2 = 18.87; P = 0.000). Relative carbon stock analysis demonstrated that Abies pindrow and Pinus wallichiana accounted 91% of TC stocks across the landscape. Basal area, mean diameter at breast height (DBH), elevation, disturbance and precipitation had significant effects on TC stocks in bivariate regression models. The RF model explained 86% of the variation; basal area interpreted 30.15%, followed by mean DBH (17.96%), disturbance complex (10.64%), precipitation (8.00%) and elevation (7.34%).ConclusionsKashmir Himalayan forests are significant carbon sinks as they store a substantial quantum of carbon in trees. Forest carbon, an essential climatic indicator, is determined by a complex interaction of other ecological variables, particularly stand structural features. The study provides insights into the role of these natural forests in climate change mitigation and in REDD+/national commitments to offset the carbon.

From sink to source: changing climate and disturbance regimes could tip the 21st century carbon balance of an unmanaged mountain forest landscape

Abstract Forests are one of the most important components of the global carbon cycle. Consequently, forest protection as a nature-based climate solution has garnered increasing interest. Protected areas instated to safeguard biodiversity provide an opportunity to maximize carbon storage in situ, with important co-benefits between conservation and climate change mitigation. However, changing climate and disturbance regimes put this carbon storage function at risk. Here we investigated carbon sequestration and storage in a protected landscape in the German Alps (Berchtesgaden National Park) throughout the 21st century. We simulated the impacts of climate change as well as increasing wind and bark beetle disturbances on cumulative Net Ecosystem Production using a process-based forest landscape model. Considering a wide range of potential changes in wind frequency and speed under a variety of climate change scenarios, we addressed the question under which future conditions the landscape will turn from a carbon sink to a carbon source. While the landscape was a net carbon sink at the end of the simulation in 76 per cent of the simulation runs, increasing disturbances and climate change greatly reduced its carbon sink capacity. Under RCP2.6, the landscape remained a robust carbon sink even under elevated disturbance (probability of turning from sink to source between 0 per cent and 25 per cent). In contrast, carbon release was likely under RCP8.5 even with little change in the disturbance regime (probability: 30 per cent to 95 per cent). Productive areas in lower elevations that currently have the highest carbon density on the landscape were contributing most strongly to a reduction of the carbon sink strength. Our study reveals that the effect of protected areas acting as nature-based climate solutions might be overestimated if the risks from changing climate and disturbance regimes are neglected. We therefore call for a more explicit consideration of future forest dynamics in the discussion of the potential role of forests in climate change mitigation.

Strengthening the Role of Forests in Climate Change Mitigation through the European Union Forest Law Enforcement, Governance and Trade Action Plan

Forests influence climate change by either increasing or decreasing the atmospheric concentration of greenhouse gases. When unsustainably managed, forests can release more greenhouse gases than they can absorb, intensifying their atmospheric concentration with adverse climate and human health outcomes. Several frameworks and institutional arrangements have been adopted globally to help strengthen political commitment and actions to promote the sustainable management of forests and enhance forests’ contribution to climate change mitigation. Nevertheless, the destruction of tropical forests is accelerating at an alarming rate, making it an uphill battle to stop forest sector carbon emissions, limit the global average temperature rise to well below 2°C, and build a sustainable and climate-resilient future for all. The continuous release of forest-related emissions indicates that humanity has fallen short of meeting global forest and climate-related goals and, hence, reiterates the need to develop and apply additional tools to support international cooperation on mitigating forest carbon emissions. Considering deforestation’s challenge for voluntary frameworks such as the UN Forest Instrument and REDD+, opportunities/actions beyond non-legally binding agreements and principles must be harnessed promptly. Trade-related measures, such as the Forest Law Enforcement, Governance and Trade Action Plan, are relevant in addressing deforestation. Arguably, the Forest Law Enforcement, Governance and Trade Action Plan provides the most appropriate framework for future regional/global forest law reform.

Contrasting Effects of Forest Type and Stand Age on Soil Microbial Activities: An Analysis of Local Scale Variability.

Simple SummaryThe potentially important role of forests in climate change mitigation suggests a strong need for a more detailed understanding of these ecosystems. Besides climatic conditions, diverse forest vegetation creates varied conditions for the activity of soil microorganisms, and particular attention should be focused on a comprehensive study on the influence of different forest types on microbial activities. We conducted an experiment on six different forest soils (two coniferous, two deciduous, and two mixed sites comprising trees of different ages) collected from the same region (Lublin Upland, Poland) to assess the relationship between forest type and seasonal changes in microbial parameters. The annual mean values of the soil microbial indicators suggest that the mature deciduous stand was the most sustainable in microbial activities among the forest soils investigated. The diversity of the forest environment and the multifactorial dependence of the microbiological activity of forest soils necessitates further research in this field, especially using the same soil types. An understanding of forest ecosystem functioning can also be useful for forest management.Understanding the functioning of different forest ecosystems is important due to their key role in strategies for climate change mitigation, especially through soil C sequestration. In controlled laboratory conditions, we conducted a preliminary study on six different forest soils (two coniferous, two deciduous, and two mixed sites comprising trees of different ages) collected from the same region. The aim was to explore any differences and assess seasonal changes in soil microbial parameters (basal respiration BR, microbial biomass Cmic, metabolic quotient qCO2, dehydrogenase activity DHA, and Cmic:Corg ratio). Indicator- and forest-specific seasonality was assessed. In addition to litter input, soil parameters (pH, nutrient content, texture and moisture) strongly regulated the analyzed microbial indicators. PCA analysis indicated similarity between mature mixed and deciduous forests. Among annual mean values, high Cmic and DHA with simultaneously low qCO2 suggest that the mature deciduous stand was the most sustainable in microbial activities among the investigated forest soils. Research on the interrelationship between soil parameters and forest types with different tree ages needs to be continued and extended to analyze a greater number of forest and soil types.

Species diversity and stand structural diversity of woody plants predominantly determine aboveground carbon stock of a dry Afromontane forest in Northern Ethiopia

Aboveground carbon (AGC) stock in forests is affected by several biotic and abiotic factors. Understanding those factors is crucial in managing forests for climate change mitigation and other ecosystem services. This study examined effects of diversity attributes (species and stand structural diversity of woody plants) and topographic attributes (altitude and slope) on AGC stock of a dry Afromontane forest. Data from individual woody plants for estimating AGC were collected from 252 plots (20 × 20 m) established in a systematic grid (2 × 2 km) covering the entire forest area. Woody plant diameter diversity and woody plant height diversity were used as proxies for stand structural diversity. Structural equation modelling was applied to test the effects of the selected attributes on AGC stock, and together they explained 71% of the variation. Stand structural diversity was the most important driving factor for the AGC stock. Woody plant species diversity had both direct and indirect effects on AGC stock, but the indirect effect through its influence on stand structural diversity was more pronounced. Altitude and slope were both negatively but weakly associated with AGC stock. Our results provide insight on the effects of diversity and topographic attributes on AGC stock, which can assist future management of the forest. Enhancing stand structural diversity by means of selection cutting systems and woody plant species diversity by means of enrichment planting can be effective treatments. When considering dry Afromontane forests’ widespread distribution, the potential contribution in carbon sequestration and thereby mitigating climate change is substantial. Hence, the results and management suggestions from the present study may have practical interest for the management of dry Afromontane forests not only in Ethiopia but also in Africa at large.

Interrelationship between Forests and Climate Change : A Review

Climate change and forests are intrinsically linked and better forest management has key role to play in dealing with climate change. Forests influence atmospheric conditions causing rain and control temperature and provide clean air. They take in carbon dioxide during photosynthesis and provide oxygen. They protect soil from erosion and control floods. They are the house to many living organisms (macro and micro). A large number of people rely on forests for their livelihood. They serve as carbon sinks and are recognized as the principal contributor to climate change adaptation and mitigation. The main drivers of climate change are anthropogenic activities such as land-use change, over exploitation of forest resources, fossil fuel burning and industrial processes. The present review is aimed at providing the impacts of climate change on forests and the role of forests in climate change mitigation and adaptation particularly in Indian context.

Carbon prospecting in tropical forests for climate change mitigation

Carbon finance projects that protect tropical forests could support both nature conservation and climate change mitigation goals. Global demand for nature-based carbon credits is outpacing their supply, due partly to gaps in knowledge needed to inform and prioritize investment decisions. Here, we show that at current carbon market prices the protection of tropical forests can generate investible carbon amounting to 1.8 (±1.1) GtCO2e yr−1 globally. We further show that financially viable carbon projects could generate return-on-investment amounting to $46.0b y−1 in net present value (Asia-Pacific: $24.6b y−1; Americas: $19.1b y−1; Africa: $2.4b y−1). However, we also find that ~80% (1.24 billion ha) of forest carbon sites would be financially unviable for failing to break even over the project lifetime. From a conservation perspective, unless carbon prices increase in the future, it is imperative to implement other conservation interventions, in addition to carbon finance, to safeguard carbon stocks and biodiversity in vulnerable forests.

Global maps of twenty-first century forest carbon fluxes

Managing forests for climate change mitigation requires action by diverse stakeholders undertaking different activities with overlapping objectives and spatial impacts. To date, several forest carbon monitoring systems have been developed for different regions using various data, methods and assumptions, making it difficult to evaluate mitigation performance consistently across scales. Here, we integrate ground and Earth observation data to map annual forest-related greenhouse gas emissions and removals globally at a spatial resolution of 30 m over the years 2001–2019. We estimate that global forests were a net carbon sink of −7.6 ± 49 GtCO2e yr−1, reflecting a balance between gross carbon removals (−15.6 ± 49 GtCO2e yr−1) and gross emissions from deforestation and other disturbances (8.1 ± 2.5 GtCO2e yr−1). The geospatial monitoring framework introduced here supports climate policy development by promoting alignment and transparency in setting priorities and tracking collective progress towards forest-specific climate mitigation goals with both local detail and global consistency.

Relevance and magnitude of 'Blue Carbon' storage in mangrove sediments: Carbon accumulation rates vs. stocks, sources vs. sinks

Mangrove ecosystems store large amounts of 'Blue Carbon', in particular in the sediment. Research in the past decade has emphasized the quantitative significance of carbon storage in mangrove forests in climate change mitigation, mainly by determining carbon stocks and calculating potential CO2 emissions caused by mangrove degradation. However, while this approach focuses on the total amount of carbon that can be lost to degradation, it fails to capture the amount that is sequestered annually. Therefore, carbon accumulation in mangrove sediments also needs to be taken into account. This study (i) explains the differences between carbon stocks and carbon accumulation rates (CAR), (ii) it addresses the geographical variation of carbon storage and underlying factors and (iii) it assesses the global relevance of 'Blue Carbon' sequestration in mangrove sediments. Results indicate that reducing uncertainties in carbon storage estimates of individual systems requires a representative set of data that covers within-system variability. An example from Indonesia illustrates that a mangrove ecosystem with a high C stock can have a low CAR and vice versa. It is therefore conceivable that coastal environmental settings with high allochthonous supply of mineral sediment, organic matter and nutrients mostly have low carbon stocks, but high CARs. As these settings represent >80% of the global mangrove area they are most important in terms of long-term carbon storage. While a C stock is a measure of the "vulnerability potential" in the case of ecosystem degradation or total loss, a CAR is rather a measure of the "mitigation potential" of carbon storage in mangrove ecosystems. The global carbon storage in mangrove sediments of 32 Tg yr−1 estimated from CARs in this study is at the upper end of the range of global budgets (14.6–31.1 Tg yr−1, mean 22.9 Tg yr−1). It highlights that the mangrove carbon sink may be larger than previously thought, but the high variation in the global average CAR of 233 ± 280 g C m−2 yr−1 also indicates the need for further data.

Relevance and magnitude of 'Blue Carbon' storage in mangrove sediments: Carbon accumulation rates vs. stocks, sources vs. sinks

Mangrove ecosystems store large amounts of 'Blue Carbon', in particular in the sediment. Research in the past decade has emphasized the quantitative significance of carbon storage in mangrove forests in climate change mitigation, mainly by determining carbon stocks and calculating potential CO2 emissions caused by mangrove degradation. However, while this approach focuses on the total amount of carbon that can be lost to degradation, it fails to capture the amount that is sequestered annually. Therefore, carbon accumulation in mangrove sediments also needs to be taken into account. This study (i) explains the differences between carbon stocks and carbon accumulation rates (CAR), (ii) it addresses the geographical variation of carbon storage and underlying factors and (iii) it assesses the global relevance of 'Blue Carbon' sequestration in mangrove sediments. Results indicate that reducing uncertainties in carbon storage estimates of individual systems requires a representative set of data that covers within-system variability. An example from Indonesia illustrates that a mangrove ecosystem with a high C stock can have a low CAR and vice versa. It is therefore conceivable that coastal environmental settings with high allochthonous supply of mineral sediment, organic matter and nutrients mostly have low carbon stocks, but high CARs. As these settings represent >80% of the global mangrove area they are most important in terms of long-term carbon storage. While a C stock is a measure of the "vulnerability potential" in the case of ecosystem degradation or total loss, a CAR is rather a measure of the "mitigation potential" of carbon storage in mangrove ecosystems. The global carbon storage in mangrove sediments of 32 Tg yr−1 estimated from CARs in this study is at the upper end of the range of global budgets (14.6–31.1 Tg yr−1, mean 22.9 Tg yr−1). It highlights that the mangrove carbon sink may be larger than previously thought, but the high variation in the global average CAR of 233 ± 280 g C m−2 yr−1 also indicates the need for further data.

Carbon Stocks in Chir Pine (Pinus roxburghii) Forests on Two Different Aspects in the Mahabharat Region of Makawanpur, Nepal

Despite the significant contribution of forests in climate change mitigation, studies to establish the potential of sub-tropical forest ecosystems at different aspects in enhancing soil health indicators are only partly known. The study was carried out to quantify vegetation and soil carbon stocks of a natural Chir Pine (Pinus roxburghii) forest at two different aspects (northern and southern) of a typical sub-tropical environment in Nepal. Stratified random sampling was used for forest inventory and soil sample collection. Aboveground forest biomass was calculated using standard allometric models. Soil was sampled up to 60 cm depth and at 20 cm intervals. Walkey and Black method was used to determine soil organic carbon. Total aboveground plant biomass carbon in southern aspect (140.20 t ha-1) was higher compared to that on the northern aspect (115.34 t ha-1). Similarly, soil carbon stock on southern aspect (46.65 t ha-1) was higher than that of northern aspect (42.14 t ha-1). This resulted to total carbon stock on southern and northern aspect of P. roxburghii forest of 186.85 t ha-1 and 157.48 t ha-1 respectively. The total carbon stock of P. roxburghii forest is significantly higher on southern aspect than on northern aspect with p value 0.001 (p<0.05). Hence, we conclude that the southern aspect of the Mahabharat range favour the growth of P. roxburghii forest compared to the northern aspect. However, the contribution of the entire Chir pine forest ecosystem to carbon sequestration and global climate warming mitigation can’t be neglected.

Assessment of carbon stocks in oak forests along the altitudinal gradient: A case study in the Panchase Conservation Area in Nepal

Little study was done to understand the role of high-altitude oak forests in climate change mitigation. Here, we analyzed data from 30 sample plots collected along the four altitudinal gradients to assess species distribution and carbon stocks in the Panchase Conservation Area in Nepal. Three carbon pools were considered, namely aboveground carbon (AGC), belowground carbon (BGC), and carbon in litters (leaf litters, grass, and herb biomass, CiL). Seven species were found, of which two are oak tree species (Quercus semecarpifolia and Quercus lamellosa). Quercus semecarpifolia is the most dominant species in terms of stem density and carbon stocks, followed by Quercus lamellose. Average tree diameter, height, and total carbon stocks were 27.7 cm, 8.4 m, and 127.6 MgC ha−1, respectively. Our study found higher carbon stocks at the higher altitudinal gradient. Pearson’s correlation analysis shows a strong effect of altitudinal gradients on carbon stocks (r = 0.7124), moderate effect on tree height (r = 0.5263), and less effects on diameter (r = 0.1733). A stepwise multiple regression analysis shows strong relationship between carbon stocks with height (P = 0.0059) and carbon stocks with tree diameter (P = 0.0148). Our ground observations and random interviews indicate that the low carbon stocks at the low altitude were due to human disturbance. Oak forests at lower altitudes are sparse forest stands with poor regeneration capacity, overgrazing, and extensive lopping. If such disturbance is prevented, oak forest can increase carbon stocks to 361.7 MgC ha−1 as found at the higher altitude. Conservation of oak forests in the Panchase Conservation Area could result in emission reductions of 633.0 MgCO2 ha−1. These reductions could be eligible for financial incentives under the REDD + scheme.

Correction to: Plant trees for the planet: the potential of forests for climate change mitigation and the major drivers of national forest area

The original version of this article unfortunately contained a mistake in the Acknowledgement section.

Contextualizing Mangrove Forest Deforestation in Southeast Asia Using Environmental and Socio-Economic Data Products

Research Highlights: This paper provides an alternative approach to contextualize mangrove forest loss by integrating available environmental and socio-economic data sets and products. Background and Objectives: Mangrove forest ecosystems grow in brackish water especially in areas exposed to accumulation of organic matter and tides. This forest type is widely distributed in tropical and subtropical coastal areas. Recent studies have revealed that the mangrove forest ecosystem had significantly degraded due to Land Use and Cover Changes (LUCC) in the recent past. Therefore, contribution of mangrove deforestation drivers has to be assessed to ensure a comprehensive analysis for ecosystem conservation and restoration and facilitate decision making. Materials and Methods: Firstly, a correlation analysis was conducted between individual data products and mangrove deforestation. Each data product was associated with the Dominant Land Use of Deforested Mangrove Patches data for 2012. Next, calculations were performed for specific data combinations to estimate the contributions of anthropogenic factors to mangrove deforestation. Results: In general, our study revealed that 22.64% of the total deforested area was converted into agriculture, 5.85% was converted into aquaculture, 0.69% was converted into infrastructure, and 16.35% was not converted into any specific land use class but was still affected by other human activities. Conclusions: We discovered that the percentage of land affected by these anthropogenic factors varied between countries and regions. This research can facilitate trade-off analysis for natural resources and environmental sustainability policy studies. Diverse management strategies can be evaluated to assess the trade-offs between preserving mangrove forests for climate change mitigation and transforming them for economic purposes.

Forest carbon stocks in woody plants of Chilimo-Gaji Forest, Ethiopia: Implications of managing forests for climate change mitigation

Tropical forests play a key role in climate change mitigation by sequestering and storing carbon from the atmosphere. In Ethiopia, there are inadequate data in the form of carbon accumulation records or databank to assess the carbon sequestration potential of different forests. This study intended to estimate the living biomass and carbon stocks of woody plants in Chilimo-Gaji Forest. Totally, 10 circular plots with 20 m radius each having 1,256 m2, estimated the biomass of 17 tree species using the nondestructive allometric equation. The total woody biomass of the study area estimated to be 1013.3 t ha-1, of which, about 83.3 % (844.4 t ha-1) was aboveground, and 16.7% (168.9 t ha-1) was below ground biomass. The total carbon stocks and total carbon sequestration potential of the study area was about 506.7 t C ha-1 and 1859.45 t ha-1, respectively. The result indicates that the Chilimo-Gaji Forest has huge potential for carbon stock compared to research conducted on other remnant forests in Ethiopia. This is mainly due to the improvement in the forest stocks as a result of participatory forest management practices in the area. Generally, Chilimo-Gaji Forest is playing a vital role in carbon sequestration, thereby contributing to climate change mitigation. Therefore, in the future, the forest can generate carbon credits as financial benefits to the indigenous population, which could help to strengthen the conservation efforts of forest resources in the study area.

An AHP Assessment Of Barriers in Adopting Sustainable Forest Management Practices in The Context Of Carbon Emission Reductions in Cameroon

ABSTRACTAs the role of forests in climate change mitigation is explicitly recognized in the Paris Agreement, the need to enhance the adoption of Sustainable Forest Management (SFM) practices is crucial. Therefore, this paper aims at identifying and evaluating barriers in adopting SFM practices in the context of forest carbon emission reductions. A total of 15 barriers in adopting SFM practices are listed through literature and expert inputs. Using Cameroon as a case study, the listed barriers are then evaluated by experts to determine their relative importance using the Analytical Hierarchy Process (AHP) method. According to our findings, the ‘Regulatory and Legislative frameworks’ barrier category was attributed to the highest importance among other categories, in adopting SFM practices in the forestry sector. ‘Inadequate political will and incentive to enforce regulations’ appears to be the major obstacle in adopting SFM practices in Cameroon. As carbon emission reduction initiatives are being developed, there is need to move from broad to concrete suggestions that will overcome these barriers. However, proper diagnosis is necessary in order to target barriers with the right incentives and enabling conditions that will support carbon programs and projects to deliver effective emission reductions.

Plant trees for the planet: the potential of forests for climate change mitigation and the major drivers of national forest area

Forests are one of the most cost-effective ways to sequester carbon today. Here, I estimate the world’s land share under forests required to prevent dangerous climate change. For this, I combine newest longitudinal data of FLUXNET on forests’ net ecosystem exchange of carbon (NEE) from 78 forest sites (N = 607) with countries’ mean temperature and forest area. This straightforward approach indicates that the world’s forests sequester 8.3 GtCO2year−1. For the 2 °C climate target, the current forest land share has to be doubled to 60.0% to sequester an additional 7.8 GtCO2year−1, which demands less red meat consumption. This afforestation/reforestation (AR) challenge is achievable, as the estimated global biophysical potential of AR is 8.0 GtCO2year−1 safeguarding food supply for 10 billion people. Climate-responsible countries have the highest AR potential. For effective climate policies, knowledge on the major drivers of forest area is crucial. Enhancing information here, I analyze forest land share data of 98 countries from 1990 to 2015 applying causal inference (N = 2494). The results highlight that population growth, industrialization, and increasing temperature reduce forest land share, while more protected forest and economic growth generally increase it. In all, this study confirms the potential of AR for climate change mitigation with a straightforward approach based on the direct measurement of NEE. This might provide a more valid picture given the shortcomings of indirect carbon stock-based inventories. The analysis identifies future regional hotspots for the AR potential and informs the need for fast and forceful action to prevent dangerous climate change.