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The Chilean Climate Change Law excludes tree monocultures as a solution to the climate crisis, offering an opportunity for resilience and climate mitigation in Latin America. The Chilean experience with mega-fires in extensive, homogeneous forest plantations provides important lessons that could inform climate policies in other countries. [ABSTRACT FROM AUTHOR]

• Implementation costs are a more relevant constraint to afforestation than opportunity costs. • Financial incentives for afforestation are constrained by market access and market prices. • Carbon-neutral and food multi-oriented land policies need further exploration. • Collaboration among global carbon markets can enhance CO 2 removal efficiency. Afforestation is a promising nature-based climate solution for mitigating climate change, but it is subject to a complex web of biophysical, cost-benefit, market, and policy processes. Although its biophysical feasibility has been established, the cost, market, and policy constraints that affect climate change mitigation through afforestation are still unclear. Here, we estimate such cost, market, and policy constraints on the basis of biophysical feasibility. Our findings reveal that implementation costs are a more relevant constraint than opportunity costs on mitigating climate change through afforestation. The China Certified Emission Reduction market currently provides only a 0.308 % incentive for climate change mitigation through afforestation, due to market access constraints. The current market prices of China Certified Emission Reduction, China Carbon Emissions Trading Exchange, and Nature Based Carbon Offset in Voluntary Carbon Market constrain 88.15 %, 87.95 %, and 85.75 % of CO 2 removal actions through afforestation, compared to the carbon price scenario (US$62.97 tCO 2 -1) of the EU Emissions Trading System. Moreover, land policy under the scenarios of prohibiting conversion of cultivated land to forest and forest restoration in degraded areas exhibit 8.87–29.59 % and 65.16–74.10 % constraints, respectively, on mitigating climate change through afforestation compared to land-use freedom conversion scenarios from 2020 to 2060. Thus, enhancing the incentive price of CO 2 removal, addressing the market access barrier, strengthening cooperation between global carbon markets, and exploring carbon–neutral and food multi-oriented land policies can be valuable sources of mitigation efforts over the next 40 years. [ABSTRACT FROM AUTHOR]

• The nexus between forest-based climate mitigation and health is poorly researched. • This scoping review identified exposure pathways and health co-benefits from forests. • There is potential for synergies between forest management and health benefits. • Interdisciplinary efforts are required for advancement of research and understanding. Climate change is a pressing global challenge with profound implications for human health. Forest-based climate change mitigation strategies, such as afforestation, reforestation, and sustainable forest management, offer promising solutions to mitigate climate change and simultaneously yield substantial co-benefits for human health. The objective of this scoping review was to examine research trends related to the interdisciplinary nexus between forests as carbon sinks and human health co-benefits. We developed a conceptual framework model, supporting the inclusion of exposure pathways, such as recreational opportunities or aesthetic experiences, in the co-benefit context. We used a scoping review methodology to identify the proportion of European research on forest-based mitigation strategies that acknowledge the interconnection between mitigation strategies and human impacts. We also aimed to assess whether synergies and trade-offs between forest-based carbon sink capacity and human co-benefits has been analysed and quantified. From the initial 4,062 records retrieved, 349 reports analysed European forest management principles and factors related to climate change mitigation capacity. Of those, 97 studies acknowledged human co-benefits and 13 studies quantified the impacts on exposure pathways or health co-benefits and were included for full review. Our analysis demonstrates that there is potential for synergies related to optimising carbon sink capacity together with human co-benefits, but there is currently a lack of holistic research approaches assessing these interrelationships. We suggest enhanced interdisciplinary efforts, using for example multideterminant modelling approaches, to advance evidence and understanding of the forest and health nexus in the context of climate change mitigation. [ABSTRACT FROM AUTHOR]

• A RCM is used to study the effect of LCC on climate extremes in Europe. • LCC significantly changes the occurrence frequency and duration of extreme climate. • Increasing understanding of land cover change-climate interactions. • Findings are helpful in developing future land management strategies in Europe. Extremes in climate and weather can pose significant challenges to economy, ecosystems and human health. Changes in land cover are one of the drivers for variability in frequency and magnitude of extreme climate at regional and local levels. In this study, a regional climate model (COSMO-CLM v4.8) is used to simulate effects in climate extremes from two different idealized land cover change scenarios in Europe. These two simulations involve abrupt large-scale conversion of today forestland to herbaceous vegetation (deforestation), and of today cropland to evergreen needle-leave forest (afforestation). A control simulation with today land cover distribution is used to identify differences in extreme climate. We find significant changes in extreme climate in both deforestation and afforestation simulations, with seasonal and spatial differences. Deforestation causes a warmer summer (with higher annual maximum temperature) and a colder winter (with lower annual minimum temperature). Afforestation slightly increases the average intensity of the hot extremes, although with high spatial variability (a reduction is common in several locations), and mitigates cold extremes in winter. Changes in extreme indices show that deforestation increases both the frequency and duration of hot and cold extremes, while afforestation causes a lower frequency of extreme cold climate. The two simulations show opposing results in the number of frozen days, as they increase for deforestation and decrease for afforestation. A drier climate is found after deforestation, whereas a wetter climate is observed after afforestation. In general, deforestation and afforestation increase the frequency of hot extreme climate as they reduce the return period and increase the return level. Overall, our findings show the potential critical effects that land cover changes can have on climate extremes, and the possible synergies that land management strategies and planning can have for climate change mitigation and adaptation at a regional scale. [ABSTRACT FROM AUTHOR]

Projected increases in population, income and consumption rates are expected to lead to rising pressure on the land system. Ambitions to limit global warming to 2 °C or even 1.5 °C could also lead to additional pressures from land-based mitigation measures such as bioenergy production and afforestation. To investigate these dynamics, this paper describes five elaborations of the Shared Socio-economic Pathways (SSP) using the IMAGE 3.0 integrated assessment model framework to produce regional and gridded scenarios up to the year 2100. Additionally, land-based climate change mitigation is modelled aiming for long-term mitigation targets including 1.5 °C. Results show diverging global trends in agricultural land in the baseline scenarios ranging from an expansion of nearly 826 Mha in SSP3 to a decrease of more than 305 Mha in SSP1 for the period 2010–2050. Key drivers are population growth, changes in food consumption, and agricultural efficiency. The largest changes take place in Sub-Saharan Africa in SSP3 and SSP4, predominantly due to high population growth. With low increases in agricultural efficiency this leads to expansion of agricultural land and reduced food security. Land use also plays a crucial role in ambitious mitigation scenarios. First, agricultural emissions could form a substantial component of emissions that cannot be fully mitigated. Second, bioenergy and reforestation are crucial to create net negative emissions reducing emissions in SSP2 in 2050 by 8.7 Gt CO 2 /yr and 1.9 Gt CO 2 /yr, respectively (1.5 °C scenario compared to baseline). This is achieved by expansion of bioenergy area (516 Mha in 2050) and reforestation. Expansion of agriculture for food production is reduced due to REDD policy (290 Mha in 2050) affecting food security especially in Sub-Saharan Africa indicating an important trade-off of land-based mitigation. This set of SSP land-use scenarios provides a comprehensive quantification of interacting trends in the land system, both socio-economic and biophysical. By providing high resolution data, the scenario output can improve interactions between climate research and impact studies. [ABSTRACT FROM AUTHOR]

The optimal forest management strategies for mitigating climate change are hotly debated during political negotiations, because afforestation and forest management can increase atmospheric CO 2 removal, and the wood produced can provide a substitute for fossil fuel. Studies quantifying the carbon balance of the forest sector apply a wide variety of management and wood-use scenarios. Some model studies include future climate change effects on forest growth, but others ignore them. Here, a conceptual empirical model of sequestration efficiency, the fraction of net primary production stored in the biosphere and anthroposhere, simulates European forest carbon pools and fluxes. The sensitivity of the sequestration efficiency of European forests was quantified by varying model parameters along the forest growth and wood transformation chain: environment and climate change, harvest intensity, rotation length, fraction of harvest residues left on site and substitution efficiency. Irrespective of the evolution of the sink, the forest sector as a whole remains a net carbon absorber in 99% of the simulations at a time horizon of 100 years, even if in 25% of the simulations the forests themselves become sources. However, if the goal is to enhance the current sequestration efficiency to mitigate emissions, only in 25% of the simulations the sink efficiency was found to be enhanced. If the current sink were to reverse to a source, no management action or change in wood use would result in an increase in the current forest sequestration efficiency. In all other cases, increasing harvest levels would lead to an increase in forest sector carbon emissions, highlighting the pivotal role of the baseline used to set the emission reduction targets. Our results show that the uncertainty on the response of European forest to climate change undermines the quest for a carbon-optimal management strategy. The uncertainty in whether climate change will maintain the current forest sink or turn it into a carbon source is largely overlooked in the debate over the best forest management strategy to reduce the growth of atmospheric CO 2 concentration, yet it is large enough to change the merit order of different alternatives. [ABSTRACT FROM AUTHOR]

Reforestation of landscapes is being used as a method for tackling climate change through carbon sequestration and land restoration, as well as increasing biodiversity and improving the provision of ecosystem services. The success of reforestation activities can be reduced by adverse field conditions, including those that reduce germination and survival of plants. One method for improving success is biochar addition to soil, which is not only known to improve soil carbon sequestration, but is also known to improve growth, health, germination and survival of plants. In this study, biochar was applied to soil at rates of 0, 1, 3 and 6 t ha − 1 along with a direct-seed forest species mix at three sites in western Victoria, Australia. Changes in soil chemistry, including total carbon, and germination and survival of species were measured over an 18 month period. Biochar was found to significantly increase total carbon by up to 15.6% on soils low in carbon, as well as alter electrical conductivity, Colwell phosphorous and nitrate- and ammonium-nitrogen. Biochar also increased the number of species present, and stem counts of Eucalyptus species whilst decreasing stem counts of Acacia species. Biochar has the potential to positively benefit reforestation activities, but site specific and plant–soil–biochar responses require targeted research. [ABSTRACT FROM AUTHOR]

• We present the diagnostic biophysical land-system and GHG emission model BioBaM-GHG 2.0. • BioBaM is designed for evaluating the feasibility and associated GHG emissions of large numbers of agro-food system and land-use scenarios at various scales. • We present model algorithms, data structures and the software environment. • As illustrative example, we analyse scenarios for the expansion of agro-ecological measures in the European Union. • As second example, we present an assessment of global potentials for afforestation as climate mitigation measure. Close to 40% of Earth's land area is used for agriculture to provide humankind with plant- and animal-based food, fibers or bioenergy. Future trends in agricultural land use, livestock husbandry and associated environmental pressures are determined by developments in the food sector, agricultural productivity, technology, and many other influencing factors. Scenario analysis helps to understand their complex interaction and obtain quantitative insight. We here present an in-depth description of the agricultural land use model BioBaM-GHG 2.0 ("BioBaM"), designed for evaluating large numbers of agricultural and livestock production scenarios assembled on the basis of exogenous assumptions on food systems, crop yields and other factors. BioBaM determines the feasibility of specific parameter combinations and the corresponding greenhouse gas (GHG) emissions from agricultural activities, livestock husbandry, land-use change and other activities. We provide a description of the software environment, the model's data structures, input and output variables and model algorithms. To illustrate the model's capabilities and the scope of model applications, we describe two exemplary studies performed with BioBaM: We assess implications of agro-ecological innovations and the feasibility of their widespread application in order to illustrate their implications in terms of agricultural self-sufficiency and GHG emissions. This first case study aligns a small number of individual scenarios with qualitative storylines. We also showcase a "biophysical option space approach", which represents a comprehensive sensitivity analysis regarding the multidimensional uncertainties inherent to main influencing parameters, i.e. projections for diets and yields; assumptions on cropland use for bioenergy, and regarding grassland intensification. The global potential of forest regeneration for climate change mitigation serves as an example for this second approach. The option space comprises 90 scenarios and encompasses the full range of literature estimates on GHG mitigation from afforestation in 2050 (0.5 – 7 Gt CO 2 /yr). It further shows that the potential is zero under certain diet-yield-combinations. Assuming zero energy crop cultivation and global convergence to a healthy reference diet, the sequestration potential of afforestation rises to 10 Gt CO 2 /yr in 2050. These exemplary applications illustrate how option spaces developed with BioBaM can complement scenario-based assessments that usually focus on small numbers of individual scenarios: Option spaces shift attention to a wider scope of conceivable futures and thus support a comprehensive view on systemic relations and dependencies, whereas analyses with few scenarios allow apprehension of much more detailed scenario narratives and qualifications. [ABSTRACT FROM AUTHOR]

Growing energy demand due to population growth and economic progress has led to the need for intensive climate change mitigation. Negative emissions technologies (NETs) will play an important role in limiting global warming by reducing greenhouse gas concentration in the atmosphere. Available options for NETs can be integrated into energy and climate change policies. However, this strategy requires an assessment tool to select a suitable set of NETs to be integrated. A mathematical framework considering multiple environmental and economic factors under uncertainty is needed for the assessment tool. This paper has two main contributions: (1) development of a novel multi-criteria decision analysis tool based on data envelopment analysis method under neutrosophic environment, and (2) application of this tool in the evaluation of NETs considering the risks associated with the uncertainties in these technologies. The model incorporates uncertainties that result in risks when higher performance levels are assumed. A novel neutrosophic data envelopment analysis (NDEA) model is developed for evaluating NETs; this approach uses neutrosophic set theory to account for membership, nonmembership and indeterminacy in uncertain parameter values. A case study is presented to illustrated this technique. Then, a representative case study considering four alternative options for bioenergy with carbon capture and storage (BECCS) is used to demonstrate the tool. The performance assessment of candidate NETs based on literature data is made. Results show different characteristics of NETs in terms of their sensitivity to expert's risk attitude and perception towards the different dimensions of neutrosophic decision-making environment. For instance, the preference of underground storage over ocean storage for BECCS is evident when improving the technology is assumed to be challenging. Various NETs are evaluated; technologies such as BECCS, and afforestation and reforestation show consistent ranking in different decision environments. The capability of the model to account for uncertainties can allow useful insights to be drawn by policy-makers, and thus, accelerate the deployment of NETs. [ABSTRACT FROM AUTHOR]

• Abnormal correlation was verified between the actual evaporation (AE) and evaporation demands (ED) in the humid region. • Penman and Budyko equations were combined to assess the integrated response chain from a changing environment to AE. • The compensation function of afforestation was highlighted for the decrease in AE against the impact of decreasing ED. • Transformation mechanism of the Penman into Bouchet hypotheses is investigated in the regional water-energy balance. Generally, atmospheric evaporation demand (AED) shows a positive correlation with actual evaporation (AE) in the Yangtze River basin. In order to explore whether and why abnormal correlation exits in its five sub-basins, the temporal changes between AED and AE were compared, and then the impacts of climate change and human activities on abnormal correlations were assessed using the sensitivity method of Penman equation and the decomposition method of Budyko equation. The results indicated: (1) Pan evaporation and potential evaporation (indicators of AED) decreased at rates of up to -0.04 and -0.06 mm d−1 decade−1, respectively. In contrast, the water budget-derived evaporation (an indicator of AE) increased at the rate of 0.09 mm d−1 decade−1 in the Fuhe River basin and remained stable in other basins. Abnormal correlations (nonpositive correlations) were observed. (2) Decreasing net radiation and wind speed were major climate factors resulting in simultaneous temporal decreases in AED and AE. In contrast, afforestation was a major human factor leading to an increase in annual AE of 78 mm, but had no effect on AED. Afforestation was the primary driving force of the abnormal correlation. These results could provide water-energy guidance for urban climate change mitigation and flood/drought disaster management. [ABSTRACT FROM AUTHOR]