The deployment of hydrogen offers significant opportunities for decarbonization and advancing the energy transition. However, hydrogen itself acts as an indirect greenhouse gas (GHG) by extending methane’s atmospheric lifetime, contributing to tropospheric ozone and stratospheric water vapour formation. Currently, the primary anthropogenic source of hydrogen emissions is the incomplete combustion of fossil fuels, biomass and waste. However, the development of a hydrogen economy might lead to significant amounts of hydrogen emissions due to leakage throughout the value chain. Additionally, hydrogen production, storage, transport, and end-use can lead to emissions of GHGs and ambient air pollutants. This study employs the gas—air pollution interactions and synergies model to quantify global emissions of hydrogen, from combustion sources and leakages, as well as GHG and air pollutants associated with the hydrogen economy. We apply a range of energy demand scenarios and evaluate the sensitivity to different hydrogen production methods and emission control strategies. Our results indicate that anthropogenic hydrogen emissions in 2020 were approximately 10 Mt H _2 , primarily from the incomplete combustion of gasoline and fuelwood. Projections indicate that anthropogenic hydrogen emissions could increase to up to 20 Mt H _2 by 2050, driven by both incomplete combustion and fugitive sources. Increased air pollutant emissions related to the hydrogen economy are generally easier to manage than hydrogen emissions using existing control technologies and regulatory frameworks. The study also provides a comprehensive documentation of the integration of emissions related to the hydrogen-economy into a modelling framework to support further analysis and potential policy implications.

Economic and social development in the Association of Southeast Asian Nations (ASEAN) region has led to increased greenhouse gas (GHG) emissions and elevated levels of fine particulate matter (PM2.5), contributing to global warming and severe health impacts. More than 75 percent of population (about 500 million) is exposed to PM2.5 levels above WHO guidelines with over 17 percent of urban residents experiencing concentrations above 35 µg/m3. Despite national and regional commitments on emission reductions, their current and future impacts on air quality and health remain poorly understood.Using the Greenhouse Gases - Air Pollution Interactions and Synergies (GAINS) modelling framework, we projected CO2 and PM2.5 precursor emissions (primary PM2.5, SO2, NOX, NH3 and VOC), PM2.5 population exposure and associated premature mortality from 2020 to 2040 under different policy scenarios. We also identified the contributing sectors with the largest mitigation potential.We estimate CO2 emissions of around 1,685 Mt in 2020 in the ASEAN region, and ASEAN-wide mean PM2.5 exposure levels around 15 µg/m3, leading to 210,000 premature deaths. In a counterfactual scenario without further mitigation measures beyond those implemented in 2015, CO2 emissions are projected to double and PM2.5 levels increase by 33 percent by 2040 and doubling the number of urban residents exposed to PM2.5 levels above 35 µg/m3.While committed climate policies in power and transportation sectors achieve substantial CO2 emission reductions (25 percent by 2040), they lead only to marginal improvements on PM2.5 exposure and health co-benefits. The effective implementation of current legislation on air pollution on top of the climate measures reduces 2040 PM2.5 exposure to about 2020 levels, however, premature mortality still exceeds current levels due to a higher share of exposure to very high levels especially in cities and to population aging.Ample potential exists to reduce PM2.5 exposure with existing technologies. Our maximum emission control scenario suggests that tightening air pollution controls could reduce health impacts by over two-thirds across ASEAN region, with largest emission reduction potential identified in the transport, industry and agriculture sectors.These findings show that significant co-benefits of climate policies for air pollution related health impacts are not achieved without stringent measures beyond existing policies in the ASEAN region. The assessment lays the basis for developing regional strategies integrating climate and air pollution policies.

Exposure to outdoor air pollution results in millions of premature deaths and illnesses that are associated with substantial economic loss. According to the Global Burden of Disease, outdoor air pollution was responsible for 4.7 million deaths in 2021. Climate change mitigation policies could provide cobenefits by reducing air pollution. The Intergovernmental Panel on Climate Change AR6 report explores scenarios using an updated carbon budget approach—the net-zero pathways—designed to avoid temporary overshoot of the 1.5°C temperature limit. We assess whether net-zero pathways consistently improve air pollution outcomes using a global source-receptor air pollution model to estimate concentrations, health impacts, and economic damages. To analyze key uncertainties, we apply multiple relative risk functions and economic damage models. Our findings show that stringent climate policies, avoiding overshoot and keeping below 2°C, offer substantial health and economic cobenefits, particularly for China and India, and avoid 207,000 premature deaths and 2269 billion USD2020 in damages by 2030.

Context: Increasing use of hydrogen (H2) across the economy is currently seen as an important strategy for decarbonization of fossil fuel-dependent sectors. Energy scenarios, especially those aiming at net-zero GHG emission targets, project that surplus electricity produced from renewable sources, such as solar and wind, will be converted and stored as H2 by electrolysis. The use of pure hydrogen would require the replacement or significant modification of some of the infrastructure (e.g. steel pipelines) and end-use appliances (e.g. combustion engines) by H2-dedicated equipment (e.g. PE/PVC pipelines, fuel cells); in fact, many sectors are already moving towards these solutions. However, hydrogen can also be blended into natural gas and used in the same applications. The combustion of such blends enables reduction of carbon intensity in several sectors without significant technological retrofits. However, hydrogen combustion under lean air conditions leads to higher thermal formation of nitrogen oxides (NOx), when compared to natural gas. The amount depends on the burner type, load and hydrogen blending ratio. While NOx emissions pose a direct risk to human health and act as a precursor to the O3 and particulate matter, deployment of H2 would also result in direct leakages to atmosphere and associated climate impacts. Objective: This study seeks to quantify and evaluate the potential NOx increases in the European Union (EU27) countries due to the combustion of hydrogen blended with natural gas. Methodology: We use GAINS model framework to conduct this analysis assuming that hydrogen combustion will mostly take place in the buildings, industry (boilers and furnaces) and power generation sectors. The exclusion of the transport sector is justified by the predominant use of hydrogen in fuel cell vehicles, which do not contribute to NOx formation. Since hydrogen blends will be used in the same devices as currently natural gas, existing abatement technologies as well as their adoption rates are kept across all sectors and regions. Expected Results: We expect the results of this study will allow us a better understanding of hydrogen impacts in terms of pollutant emissions. While the paper asserts that the findings are unlikely to influence the development or viability of future hydrogen economies in Europe, it acknowledges the importance of the analysis in revealing potential emissions trends and identifying local or country-specific trade-offs. The emphasis on existing regulations and emission control strategies in Europe provides context for the limited air quality impacts expected on the overall trajectory of hydrogen adoption. Moreover, these preliminary results could lead to relevant insights regarding expected H2 fugitive emissions which may impact climate mitigation targets and economical viability.

The Multi-Compartment Hg (mercury) Modeling and Analysis Project (MCHgMAP) is an international multimodel research initiative intended to simulate and analyze the geospatial distributions and temporal trends of environmental Hg to inform effectiveness evaluations of two multilateral environmental agreements (MEAs): the Minamata Convention on Mercury (MC) and the Convention on Long-Range Transboundary Air Pollution (LRTAP). This MCHgMAP overview paper presents its science objectives, background, and rationale; experimental design (multimodel ensemble (MME) architecture, inputs and evaluation data, simulations, and reporting framework); and methodologies for the evaluation and analysis of simulated environmental Hg levels. The primary goals of the project are to facilitate detection and attribution of recent (observed) and future (projected) spatial patterns and temporal trends of global environmental Hg levels and identification of key knowledge gaps in Hg science and modeling to improve future effectiveness evaluation cycles of the MEAs. The current advances and challenges of Hg models, emission inventories, and observational data are examined, and an optimized multimodel experimental design is introduced to address the key policy questions of the MEAs. A common set of emissions, environmental conditions, and observation datasets is proposed (where possible) to enhance the MME comparability. A novel harmonized simulation approach between atmospheric, land, oceanic, and multimedia models is proposed to account for the short- and long-term changes in secondary Hg exchanges and to achieve mechanistic consistency of Hg levels across environmental matrices. A comprehensive set of model experiments is proposed and prioritized to ensure systematic analysis and participation of a variety of models from the scientific community.

The global net-zero transition needed to combat climate change may have profound effects on the energy-food-water-air quality nexus. Accomplishing the net-zero target while addressing other environmental challenges to achieve sustainable development is a policy pursuit for all. Here we develop a multi-model interconnection assessment framework to explore and quantify the co-benefits and trade-offs of climate action for environment-related sustainable development goals in China. We find that China is making progress towards many of the sustainable development goals, but still insufficiently. The net-zero transition leads to substantial sustainability improvements, particularly in energy and water systems. However, the co-benefits alone cannot ensure a sustainable energy-food-water-air quality system. Moreover, uncoordinated policies may exacerbate threats to energy security and food security as variable renewables and bioenergy expand. We urge the implementation of pragmatic measures to increase incentives for demand management, improve food system efficiency, promote advanced irrigation technology and further strengthen air pollutant control measures. The net-zero transition will bring co-benefits to various sectors but also potential trade-offs that could undermine sustainable development efforts. A study shows that in China, the co-benefits from the transition alone will not secure a sustainable energy-food-water-air quality system.

Anthropogenic mercury (Hg) emissions to the atmosphere are a long-lived hazard to human and environmental health. The UN Minamata Convention on Mercury is seeking to lower anthropogenic mercury emissions through a mix of policies from banning certain Hg uses to reducing unintentional Hg release from different activities. In addition to independent Hg policy, strategies to mitigate greenhouse gases, particulate matter (PM) and SO2 may also lower Hg emissions as a co-benefit. This study uses the Greenhouse Gas–Air Pollution Interactions and Synergies (GAINS) model to examine the effect of different clean air and climate policies on future global Hg emissions. The baseline scenario assumes current trends for energy use and Hg emissions as well as current legislation for clean air, mercury and climate policy. In addition, we explore the impact of the Minamata Convention, the co-benefits of climate and stringent air pollution policies, and maximum feasible reduction measures for Hg. Hg emission projections until 2050 show noticeable reductions in combustion sectors for all scenarios due to a decrease in global fossil fuel and traditional biomass use, leading to emission reductions of 33 % at baseline and up to 90 % when combining stringent climate controls and the most efficient Hg controls. Cement and non-ferrous metal emissions increase in all scenarios with current air pollution policy but could be reduced by up to 72 % and 46 %, respectively, in 2050 with stringent Hg-specific measures. Other emissions (including waste) are a significant source of uncertainty in this study, and their projections range between a 22 % increase and a 54 % decrease in 2050, depending on both climate and clean air policy. The largest absolute reduction potential for Hg abatement but also the largest uncertainties regarding absolute emissions lie in small-scale and artisanal gold production, where abatement measures could eliminate annual Hg emissions in the range of 601–1371 t (95 % confidence interval), although the uncertainties in the estimate are so high that they might eclipse reduction efforts in all other sectors. In total, 90 % of Hg emissions are covered by provisions of the Minamata Convention. Overall, the findings emphasize the necessity to implement targeted Hg control policies in addition to stringent climate, PM and SO2 policies to achieve significant reductions in Hg emissions.

Countdownsubstantial increases in extreme drought conditions from 2000-09 to 2010-19 (indicator 1.2.2).Moreover, in 2021, climate change resulted in almost 12 million additional people affected by moderate or severe food insecurity in Europe (indicator 1.5.1). Deepening health inequities in a warming worldThese interconnected health impacts tend to be unevenly distributed among populations due to differences in exposure, sensitivity, and adaptive capacity-often reflecting intersecting patterns of socioeconomic development, marginalisation, and historical and ongoing patterns of inequity.Populations most affected tend to be those least responsible and less likely to be recognised or prioritised.Southern Europe tends to be more affected by heat-related illnesses, wildfires, food insecurity, drought, and leishmaniasis, whereas northern Europe is equally or more impacted by Vibrio and ticks (section 1).Within countries, ethnic minoritised and Indigenous people, low-income communities, migrants and displaced people, sexual and gender minoritised people, and women experiencing pregnancy and childbirth tend to be more severely affected by climaterelated health impacts.This report shows that heat-related mortality was twice as high in women compared with men (indicator 1.1.4),low-income households had a substantially higher probability of people experiencing food insecurity (indicator 1.5.1),deaths attributable to an imbalanced diet were higher among women (indicator 3.4.2),and exposure to wildfire-PM 2.5 was higher in highly deprived areas.Poorly designed adaptation strategies, such as nature-based solutions (indicator 2.2.2) or mechanisms to improve thermal comfort (indicator 2.2.3) that do not adequately consider equity, can perpetuate environmental and health inequities.As not all indicators can incorporate analyses on different population groups, our report offers only a glimpse of the much larger picture and emphasises the importance of more robust research to delve deeper into the unequal impacts of climate change on health to inform health protection measures for all populations.Despite climate change exacerbating existing inequalities, indicators on governance and politics show little engagement with aspects of equality, equity, or justice in climate and health research, policy, and media (section 5).Furthermore, environmental equity, including addressing disproportionate socio-spatial distributions of climate change exposure and health risks, is not an explicit goal within existing EU policies.

Ammonia has been proposed to replace heavy fuel oil (HFO) in the shipping industry by 2050. When produced with low-carbon electricity, ammonia can reduce greenhouse gas emissions. However, ammonia emissions also contribute to local air pollution via the formation of secondary particulate matter. We estimate the potential ammonia emissions from storage and bunkering operations for shipping in Singapore, a port that accounts for 20% of global bunker fuel sales, and their impacts on air quality and health. Fuel storage and bunkering can increase total gaseous ammonia emissions in Singapore by up to a factor of four and contribute to a 25%–50% increase in ambient PM _2.5 concentration compared to a baseline scenario with HFO, leading to an estimated 210–460 premature mortalities in Singapore (30%–70% higher than the baseline). Proper abatement on storage and bunkering can reduce these emissions and even improve ambient PM _2.5 concentrations compared to the baseline. Overall, while an energy transition from HFO to ammonia in the shipping industry could reduce global greenhouse gas and air pollutant burdens, local policies will be important to avoid negative impacts on the communities living near its supply chain.

Abstract Outdoor air pollution is responsible for a substantial amount of premature deaths, severe illnesses, and economic damages. In 2019, according to the Global Burden Disease, it caused 4.505 million [3.625-5.364 95% CI] deaths. However, we can expect air pollution co-benefits from climate change mitigation policies in the next decades. Some scenarios revised by the recent IPCC AR6 report follow a new carbon budget design --- the net-zero pathways --- which avoids temperature overshoot. We examine if the net-zero pathways can consistently deliver improved air pollution outcomes. Here, we use a global source-receptor air pollution model to estimate concentrations and the health impacts and economic damages of climate mitigation scenarios. Moreover, we sought to investigate the primary factors contributing to uncertainty in air pollution mortality and damages, as well as how they interact, with particular emphasis on the significance of non-overshooting scenarios. We implement several relative risk functions to compute premature deaths and a set of air pollution damage functions. We conclude that stringent climate policies, keeping well below 2ºC, and net-zero pathways consistently improve the health and economic co-benefits and reduce the risk of extreme mortality outcomes. Improvements are particularly important for China and India. These results are robust across several air pollution damage estimation methods and normative choices. Globally, net-zero policies avoid 211 thousand [133-274 95% CI] premature deaths and 748 billion [724-766 95% CI] USD/2010 of damages relative to end-of-century in 2030.

Air pollution is still one of the most severe problems in northern China, especially in the Jing-Jin-Ji region around Beijing. In recent years, China has implemented many stringent policies to address the air quality issue, including promoting energy transition toward cleaner fuels in residential sectors. But until 2020, even in the Jing-Jin-Ji region, nearly half of the rural households still use solid fuels for heating. For residents who are not covered by the clean heating campaign, we analyze five potential mitigation strategies and evaluate their environmental effects as well as the associated health benefits and costs. We estimate that substitution with electricity or gas would reduce air pollution and premature mortality more strongly, while the relatively low investment costs of implementing clean coal or biomass pellet lead to a larger benefit-cost ratio, indicating higher cost efficiency. Hence, clean coal or biomass pellet could be transitional substitution options for the less developed or remote areas which cannot afford a total transition toward electricity or natural gas in the short term.

<p>Global anthropogenic mercury (Hg) emissions are a long-lived hazard to human and environmental health. Targeted efforts to ban anthropogenic uses and trade and other releases of mercury and its compounds are underway through the UN Minamata Convention on Mercury [1]. However, more than half of Hg emissions in 2015 were linked to unintentional release via the combustion of fossil fuels (especially coal) and industrial activities such as metals production. Thus, in addition to mercury-specific policies and interventions, global action on climate change and the accompanying transition in energy systems, as well as the demand for metals and cement are important drivers of future mercury emissions.</p> <p>The Greenhouse Gas – Air Pollution Interactions and Synergies (GAINS) model is an integrated assessment model that explores cost-effective multi-pollutant emission control strategies which aim at maximizing impacts of improved local and global air quality and emissions abatement. Hg-GAINS, as developed by Rafaj et al. [2] is one of few models which currently represents all anthropogenic mercury emission sources on a sector-by-sector basis. A recent update enhances representation of the co-benefits for mercury emissions from particulate matter (PM) and SO<sub>2</sub> controls and extended the representation of Hg-specific control technologies. Climate and energy policy is represented through exogenous inputs into the model.</p> <p>We quantify the relative importance of climate policy, co-benefits from PM and SO<sub>2</sub> controls and technological mercury pollution control measures by comparing six scenarios of global mercury emissions in 5-year steps from 2010 up to 2050. Three energy scenarios from IEA World Energy Outlook 2022 (A - “Stated Policies (STEPS)”,  B - “Advanced Pledges (AP)”,  C - “Net Zero Emissions (NZE)”  [3]) are combined with two strategies of mercury emission control (1 - Current Legislation (CLE) , assuming technical mercury control compliant with the Minamata convention and national emission standards, relying mainly on co-benefits from PM and SO2 control; 2 - Maximum Feasible Reduction (MFR), assuming utilisation of the most efficient Hg-specific technologies and measures across all sectors). The share of Hg emissions from fossil fuel combustion is decreasing significantly in the Net Zero scenario (NZE-CLE) by 2050. Additionally, stringent air pollution policy reduces Hg emissions from this sector globally in all energy CLE scenarios. However, material and metal demand, driven by the deployment of renewable energy, as well as population growth both lead to a net increase of Hg even in NZE-CLE, which can only be resolved by applying stringent MFR controls for mercury (NZE-MFR).</p> <p><br />[1] UNEP (2019). Minamata Convention on Mercury. Text and Annexes. www.mercuryconvention.org.</p> <p>[2] Rafaj, P., Bertok, I., Cofala, J., and Schöpp, W. (2013). Scenarios of global mercury emissions from anthropogenic sources. Atmospheric Environment, 79:472–479.</p> <p>[3] International Energy Agency (2022). World Energy Outlook 2022.</p>

Many children in India face the double burden of high exposure to ambient (AAP) and household air pollution, both of which can affect their linear growth. Although climate change mitigation is expected to decrease AAP, climate policies could increase the cost of clean cooking fuels. Here, we develop a static microsimulation model to project the air pollution-related burden of child stunting in India up to 2050 under four scenarios combining climate change mitigation (2 °C target) with national policies for AAP control and subsidised access to clean cooking. We link data from a nationally representative household survey, satellite-based estimates of fine particulate matter (PM2.5), a multi-dimensional demographic projection and PM2.5 and clean cooking access projections from an integrated assessment model. We find that the positive effects on child linear growth from reductions in AAP under the 2 °C Paris Agreement target could be fully offset by the negative effects of climate change mitigation through reduced clean cooking access. Targeted AAP control or subsidised access to clean cooking could shift this trade-off to result in net benefits of 2.8 (95% uncertainty interval [UI]: 1.4, 4.2) or 6.5 (UI: 6.3, 6.9) million cumulative prevented cases of child stunting between 2020–50 compared to business-as-usual. Implementation of integrated climate, air quality, and energy access interventions has a synergistic impact, reducing cumulative number of stunted children by 12.1 (UI: 10.7, 13.7) million compared to business-as-usual, with the largest health benefits experienced by the most disadvantaged children and geographic regions. Findings underscore the importance of complementing climate change mitigation efforts with targeted air quality and energy access policies to concurrently deliver on carbon mitigation, health and air pollution and energy poverty reduction goals in India.

South Africa currently faces a serious problem of air pollution in its cities. The approach used to manage air quality has not yet met the desired outcomes. In this study, potential mitigation options for ambient PM 2.5 in the Vaal Triangle Airshed Priority Area (VTAPA)—one of the most industrialised regions in South Africa—were explored using the GAINS (Greenhouse Gas and Air Pollution Interactions and Synergies) model. Based on projections of economic activities and population, changes in PM 2.5 concentrations were quantified, applying different assumptions on application rates of end-of-pipe control technologies for key emission sources of PM 2.5 and its precursor gases NO x and SO 2 . Ambient PM 2.5 concentrations were used to estimate the potential human health benefits of emission reductions. Our findings reveal that PM 2.5 concentrations for the VTAPA will not reach recommended air quality limits by 2035 under the current legislation. By introducing stringent controls, emissions will be reduced by more than half, and national air quality standards are attained. Trajectories show that implementation costs in the alternative scenario will nearly be twice as high as those for the current policies. Analysis using the GAINS model has demonstrated the value of assessing the multiple dimensions of air pollution through applying an integrated approach to provide evidence-based support for policy decision-making.

A shift from fossil fuel to renewable energy is crucial in limiting global temperature increase to 2 °C above preindustrial levels. However, renewable energy technologies, solar photovoltaics, wind turbines, and electric vehicles are metal-intensive, and the mining and smelting processes to obtain the needed metals are emission-intensive. We estimate the future PM2.5 emissions from mining and smelting to meet the metal demand of renewable energy technologies in two climate pathways to be 0.3–0.6 Tg yr−1 in the 2020–2050 period, which are projected to contribute 10%–30% of total anthropogenic primary PM2.5 combustion emissions in many countries. The concentration of mineral reserves in a few regions means the impacts are also regionally concentrated. Rapid decarbonization could lead to a faster reduction of overall anthropogenic PM2.5 emissions but also could create more unevenness in the distributions of emissions relative to where demand occurs. Options to reduce metal-related PM2.5 emissions by over 90% exist and are well understood; introducing policy requiring their installation could avoid emission hotspots.

Summary Background Nationally determined contributions (NDCs) serve to meet the goals of the Paris Agreement of staying "well below 2°C", which could also yield substantial health co-benefits in the process. However, existing NDC commitments are inadequate to achieve this goal. Placing health as a key focus of the NDCs could present an opportunity to increase ambition and realise health co-benefits. We modelled scenarios to analyse the health co-benefits of NDCs for the year 2040 for nine representative countries (ie, Brazil, China, Germany, India, Indonesia, Nigeria, South Africa, the UK, and the USA) that were selected for their contribution to global greenhouse gas emissions and their global or regional influence. Methods Modelling the energy, food and agriculture, and transport sectors, and mortality related to risk factors of air pollution, diet, and physical activity, we analysed the health co-benefits of existing NDCs and related policies (ie, the current pathways scenario) for 2040 in nine countries around the world. We compared these health co-benefits with two alternative scenarios, one consistent with the goal of the Paris Agreement and the Sustainable Development Goals (ie, the sustainable pathways scenario), and one in line with the sustainable pathways scenario, but also placing health as a central focus of the policies (ie, the health in all climate policies scenario). Findings Compared with the current pathways scenario, the sustainable pathways scenario resulted in an annual reduction of 1·18 million air pollution-related deaths, 5·86 million diet-related deaths, and 1·15 million deaths due to physical inactivity, across the nine countries, by 2040. Adopting the more ambitious health in all climate policies scenario would result in a further reduction of 462 000 annual deaths attributable to air pollution, 572 000 annual deaths attributable to diet, and 943 000 annual deaths attributable to physical inactivity. These benefits were attributable to the mitigation of direct greenhouse gas emissions and the commensurate actions that reduce exposure to harmful pollutants, as well as improved diets and safe physical activity. Interpretation A greater consideration of health in the NDCs and climate change mitigation policies has the potential to yield considerable health benefits as well as achieve the "well below 2°C" commitment across a range of regional and economic contexts. Funding This work was in part funded through an unrestricted grant from the Wellcome Trust (award number 209734/Z/17/Z) and supported by an Engineering and Physical Sciences Research Council grant (grant number EP/R035288/1).

Palm oil production has boomed over the last decade, resulting in an expansion of the global oil palm planting area from 10 to 17 Million hectares between 2000 and 2012. Previous studies showed that a significant share of this expansion has come at the expense of tropical forests, notably in Indonesia and Malaysia, the current production centers. Governments of developing and emerging countries in all tropical regions increasingly promote oil palm cultivation as a major contributor to poverty alleviation, as well as food and energy independence. However, being under pressure from several non-governmental environmental organizations and consumers, the main palm oil traders have committed to sourcing sustainable palm oil. Against this backdrop we assess the area of suitable land and what are the limits to future oil palm expansion when several constraints are considered. We find that suitability is mainly determined by climatic conditions resulting in 1.37 billion hectares of suitable land for oil palm cultivation concentrated in twelve tropical countries. However, we estimate that half of the biophysically suitable area is already allocated to other uses, including protected areas which cover 30% of oil palm suitable area. Our results also highlight that the non-conversion of high carbon stock forest (>100 t AGB/ ha) would be the most constraining factor for future oil palm expansion as it would exclude two-thirds of global oil palm suitable area. Combining eight criteria which might restrict future land availability for oil palm expansion, we find that 234 million hectares or 17% of worldwide suitable area are left. This might seem that the limits for oil palm expansion are far from being reached but one needs to take into account that some of this area might be hardly accessible currently with only 18% of this remaining area being under 2 h transportation to the closest city and that growing demand for other agricultural commodities which might also compete for this land has not been yet taken into account. ã 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Low-carbon pathways consistent with the 2 °C and 1.5 °C long-term climate goals defined in the Paris Agreement are likely to induce substantial co-benefits for air pollution and associated health impacts. In this analysis, using five global integrated assessment models, we quantify the emission reductions in key air pollutants resulting from the decarbonization of energy systems and the resulting changes in premature mortality attributed to the exposure to ambient concentrations of fine particulate matter. The emission reductions differ by sectors. Sulfur emissions are mainly reduced from power plants and industry, cuts in nitrogen oxides are dominated by the transport sector, and the largest abatement of primary fine particles is achieved in the residential sector. The analysis also shows that health benefits are the largest when policies addressing climate change mitigation and stringent air pollution controls are coordinated. We decompose the key factors that determine the extent of health co-benefits, focusing on Asia: changes in emissions, urbanization rates, population growth and ageing. Demographic processes, particularly due to ageing population, counteract in many regions the mortality reductions realized through lower emissions.

Despite low per capita emissions, with over a billion population, India is pivotal for climate change mitigation globally, ranking as the third largest emitter of greenhouse gases. We linked a previously published multidimensional population projection with emission projections from an integrated assessment model to quantify the localised (i.e. state-level) health benefits from reduced ambient fine particulate matter in India under global climate change mitigation scenarios in line with the Paris Agreement targets and national scenarios for maximum feasible air quality control. We incorporated assumptions about future demographic, urbanisation and epidemiological trends and accounted for model feedbacks. Our results indicate that compared to a business-as-usual scenario, pursuit of aspirational climate change mitigation targets can avert up to 8.0 million premature deaths and add up to 0.7 years to life expectancy (LE) at birth due to cleaner air by 2050. Combining aggressive climate change mitigation efforts with maximum feasible air quality control can add 1.6 years to LE. Holding demographic change constant, we find that climate change mitigation and air quality control will contribute slightly more to increases in LE in urban areas than in rural areas and in states with lower socio-economic development.