Total Climate Impact Research Articles

Climate Assessment of Vegetable Oil and Biodiesel from Camelina Grown as an Intermediate Crop in Cereal-Based Crop Rotations in Cold Climate Regions

The oilseed crop winter camelina (Camelina sativa) is attracting increasing interest for biofuel production. This study assessed the climate impacts of growing camelina as an intermediate crop in northern Europe (Sweden) for the production of vegetable oil and biofuel. Climate impacts were analyzed using life cycle assessment (LCA), while impacts on biodiversity and eutrophication were discussed. Three functional units were considered: 1 ha of land use, 1 kg of oil, and 1 MJ biofuel (hydrogenated vegetable oil, HVO). The results showed that dry matter yield over the whole crop rotation was higher in the camelina crop rotation, despite the lower yield of peas due to relay cropping with camelina. In the whole camelina crop rotation, fat production more than doubled, protein and fiber production marginally increased, and the production of carbohydrates decreased. Higher climate impacts related to field operations and fertilizer use in the camelina crop rotation, with associated N2O emissions, were compensated for by increased soil carbon accumulation due to the increased return of organic matter from the additional crop in the rotation. The total climate impact was around 0.5 kg CO2 eq/kg camelina oil when macronutrient allocation was used. The global warming potential was 15 g CO2 eq/MJ HVO, or 27 g CO2 eq/MJ HVO when soil organic carbon effects were not included, representing an 84% and 71% reduction, respectively, compared with fossil fuels.

Life cycle impact on climate change caused by metal production from deep sea manganese nodules versus land-based deposits

At the "UN Climate Change Conference" (COP27), France called for a ban on deep sea mining. The topic has gained momentum over the last years as some businesspeople and politicians are promoting the mining of manganese nodules as a less CO2-intensive way to meet the rising demand for the battery metals nickel, copper, cobalt and manganese. In this study, we modelled the impact on climate change caused by metal production from manganese nodules vs. mining on land. The total climate impact of producing these metals from manganese nodules (∼2.0 kg CO2eq/kg dry nodules) compared to current land-based projects is about 27% lower. Comparing it to values reported in the literature by industry associations and by the ecoinvent database, the climate impact from manganese nodules is about 16% lower or 28% higher, respectively. Based on their monetary values, the allocation of the total climate impact to each metal assigns the highest contribution to FeMn. Our research shows that producing Ni, Cu, Co and FeMn from manganese nodules could lead to higher or lower impact on climate change depending on the model input data and methodological choices. The authors share the opinion that climate change should not be the central argument regarding the realization of manganese nodule projects. The discussion should instead explicitly include further environmental impacts, e.g., biodiversity or plumes as well as economic considerations.

Climate change impact of food distribution: The case of reverse logistics for bread in Sweden

Efficient and purposeful transport of food, from primary production to waste management, is essential to drive the necessary transition towards sustainable production and consumption of food within planetary boundaries. This is particularly the case for bread, one of the most frequently wasted food items in Europe. In Sweden, bread is often sold under a take-back agreement where bakeries are responsible for transportation up to the supermarket shelf and for the collection of unsold products. This provides an opportunity for reverse logistics, but creates a risk of inefficient transport that could reduce the environmental benefits of prevention and valorization of surplus bread. This study assessed the climate change impact of bread transport in Sweden and evaluated the impact of alternative food transport pathways. Life cycle assessment revealed the climate change impact of conventional bread transport, from bakery gate to waste management, to be on average 49.0 g CO2e per kg bread with 68 % deriving from long-distance transport, 26 % from short-distance delivery, and 6 % from waste transport. Evaluation of alternative bread transport pathways showed the highest climate savings with a collaborative transport approach that also reduced the need for small vehicles and decreased transport distances. The overall contribution of waste transport to the total climate impact of food transport was low for all scenario routes analyzed, suggesting that food waste management facilitating high-value recovery and valorization could be prioritized without increasing the climate impact due to longer transport. It has been claimed that conventional take-back agreements are responsible for most of the climate change impact related to bread transport, but we identified long distances between bakeries and retailers as the main contributor to transport climate impacts.

Food waste amount, type, and climate impact in urban and suburban regions in Finnish households

Households produce about half the food waste in Europe, significantly affecting the environment and society. To measure and understand all the impact, there is a need for both primary and direct data, as well as an evaluation of methods. To respond to this need, new knowledge about households' FW and the applicability of waste composition analysis method in urban housing and areas is provided. This knowledge is applicable for planning FW studies, considering various measurement methods, the extrapolation of country-level FW values, and the introduction of decreasing interventions for households. The novelty of this study lies in its comprehensiveness: outcomes from three different city regions are analysed, and the method's robustness is evaluated. The goal of this research was to study the amount and quality of food waste in mixed waste and separately collected biowaste in Finnish households. Other goals were to estimate the unnecessary climate impact of lost food and to assess the validity of the chosen methodology. The study responds to the lack of comprehensive and recent first-hand data and reports results from three different city areas, using a relatively large number of samples that encompass 98,000 inhabitants, or about 50,000 households. The data were collected on four separate occasions: in the Helsinki area during September 2015 and October 2018, in the Turku area during June 2019, and in the Tampere area during September 2016. The results suggested that the average amount of food waste varied between 53.0 kg/cap/y and 62.1 kg/cap/y, and the amount of originally edible food waste varied between 23.0 kg/cap/y and 28.4 kg/cap/y. When extrapolating the food waste results to all study areas, the Helsinki produced about 57,000–62,000 t/y, Tampere about 16,000 t/y, and Turku about 25,000 t/y, for a total of about 100,000 t/y. The Meat and fish type group contributed most to the climate impact of originally edible FW (37–47%), while its share of food waste was much smaller, at 10–12%. The total climate impact was assessed as 0.10 Mt CO2eq/y when the climate impacts per capita annually ranged from 52.9 kg CO2eq/cap/y to 61.4 kg CO2eq/cap/y in the different regions. Due to the results' consistency, the waste composition analysis methodology can be recommended for measuring FW from both mixed and biowaste flows in urban and suburban areas. The study was conducted in cooperation with local waste management companies to increase resource efficiency and the opportunities to share facilities and to decrease study costs.

Regional and Seasonal Dependence of the Potential Contrail Cover and the Potential Contrail Cirrus Cover over Europe

Ambient weather conditions strongly impact contrail formation and persistence. The implementation of contrail avoidance and mitigation strategies, therefore, requires regional and altitude-dependent information on the frequency of contrail occurrence. To this end, we have developed a method to quantify the potential contrail cover based on 10 years of high-resolution reanalysis of climatology and weather data from the European Center for Medium-Range Weather Forecast (ECMWF). We use the Schmidt–Appleman threshold temperature for contrail formation and additionally select thresholds for the relative humidity to evaluate the occurrence of persistent contrails and assess their regional and seasonal variation. We find a potential contrail cirrus cover of 10% to 20% above Europe at higher altitudes of 200 and 250 hPa in the 10-year climatology and a weak seasonal variation. At lower altitudes, near 300 hPa, a steep onset and a high potential contrail cirrus cover of 20% is found in late fall and in winter, decreasing to 2% potential contrail cirrus cover in summer. In comparison to ECMWF data, evaluations using data from the National Centers for Environmental Prediction (NCEP) show a significantly lower potential contrail cirrus cover. Our results help to investigate the seasonal and altitude dependence of contrail mitigation strategies, in particular for warming nighttime contrails that contribute strongly to the total climate impact from aviation.

Design Principles for a Contrail-Minimizing Trial in the North Atlantic

The aviation industry has committed to decarbonize its CO2 emissions. However, there has been much less industry focus on its non-CO2 emissions, despite recent studies showing that these account for up to two-thirds of aviation’s climate impact. Parts of the industry have begun to explore the feasibility of potential non-CO2 mitigation options, building on the scientific research undertaken in recent years, by establishing demonstrations and operational trials to test parameters of interest. This paper sets out the design principles for a large trial in the North Atlantic. Considerations include the type of stakeholders, location, when to intervene, what flights to target, validation, and other challenges. Four options for safely facilitating a trial are outlined based on existing air-traffic-management processes, with three of these readily deployable. Several issues remain to be refined and resolved as part of any future trial, including those regarding meteorological and contrail forecasting, the decision-making process for stakeholders, and safely integrating these flights into conventional airspace. While this paper is not a formal concept of operations, it provides a stepping stone for policymakers, industry leaders, and other stakeholders with an interest in reducing aviation’s total climate impact, to understand how a large-scale warming-contrail-minimizing trial could work.

Aviation’s climate impact allocated to inbound tourism: decision-making insights for “climate-ambitious” destinations

The climate impact from international aviation was 2.4% of the world’s total climate impact in 2018, and is expected to grow. International regulation of this impact is not aligned with trajectories to stay below 1.5 °C of global warming. Conventional approaches to allocating climate impact to international aviation also lack one of the important drivers for air travel: tourism. Existing studies have focused on the carbon footprint of residents’ outbound air travel, but there is a lack of focus on the climate impact from inbound air travel. This article quantifies the climate impact of inbound air travel, and presents it alongside the impact of outbound air travel, to get a full picture of the climate impact of tourism-driven air travel and provide insights for tourism’s decision-makers. This was done in a case study for Sweden. The results show that the emissions from inbound air travel have grown 3 times more than emissions from outbound air travel each year, at a faster rate than the yearly growth for all international air travel. Responsibility for the climate impacts of inbound and outbound air travel is discussed, along with further actions such as demarketing and focusing on closer source markets.

Albedo impacts of current agricultural land use: Crop-specific albedo from MODIS data and inclusion in LCA of crop production

Agricultural land use and management practices affect the global climate due to greenhouse gas (GHG) fluxes and changes in land surface properties. Increased albedo has the potential to counteract the radiative forcing and warming effect of emitted GHGs. Thus considering albedo could be important to evaluate and improve agricultural systems in light of climate change, but the albedo of individual practices is usually not known. This study quantified the albedo of individual crops under regional conditions, and evaluated the importance of albedo change for the climate impact of current crop production using life cycle assessment (LCA). Seven major crops in southern Sweden were assessed relative to a land reference without cultivation, represented by semi-natural grassland. Crop-specific albedo data were obtained from a MODIS product (MCD43A1 v6), by combining its spatial response pattern with geodata on agricultural land use 2011–2020. Fluxes of GHGs were estimated using regional data and models, including production of inputs, field operations, and soil nitrogen and carbon balances. Ten-year mean albedo was 6–11% higher under the different crops than under the reference. Crop-specific albedo varied between years due to weather fluctuations, but differences between crops were largely consistent. Increased albedo countered the GHG impact from production of inputs and field operations by 17–47% measured in GWP100, and the total climate impact was warming. Using a time-dependent metric, all crops had a net cooling impact on global mean surface temperature on shorter timescales due to albedo (3–12 years under different crops), but a net warming impact on longer timescales due to GHG emissions. The methods and data presented in this study could support increasingly comprehensive assessments of agricultural systems. Further research is needed to integrate climatic effects of land use on different spatial and temporal scales, and direct and indirect consequences from a systems perspective.

What Is the Impact of Mass Timber Utilization on Climate and Forests?

As the need to address climate change grows more urgent, policymakers, businesses, and others are seeking innovative approaches to remove carbon dioxide emissions from the atmosphere and decarbonize hard-to-abate sectors. Forests can play a role in reducing atmospheric carbon. However, there is disagreement over whether forests are most effective in reducing carbon emissions when left alone versus managed for sustainable harvesting and wood product production. Cross-laminated timber is at the forefront of the mass timber movement, which is enabling designers, engineers, and other stakeholders to build taller wood buildings. Several recent studies have shown that substituting mass timber for steel and concrete in mid-rise buildings can reduce the emissions associated with manufacturing, transporting, and installing building materials by 13%-26.5%. However, the prospect of increased utilization of wood products as a climate solution also raises questions about the impact of increased demand for wood on forest carbon stocks, on forest condition, and on the provision of the many other critical social and environmental benefits that healthy forests can provide. A holistic assessment of the total climate impact of forest product demand across product substitution, carbon storage in materials, current and future forest carbon stock, and forest area and condition is challenging, but it is important to understand the impact of increased mass timber utilization on forests and climate, and therefore also on which safeguards might be necessary to ensure positive outcomes. To thus assess the potential impacts, both positive and negative, of greater mass timber utilization on forests ecosystems and emissions associated with the built environment, The Nature Conservancy (TNC) initiated a global mass timber impact assessment (GMTIA), a five-part, highly collaborative research program focused on understanding the potential benefits and risks of increased demand for mass timber products on forests and identifying appropriate safeguards to ensure positive outcomes.

Influence of weather situation on non-CO<sub>2</sub> aviation climate effects: the REACT4C climate change functions

Abstract. Emissions of aviation include CO2, H2O, NOx, sulfur oxides, and soot. Many studies have investigated the annual mean climate impact of aviation emissions. While CO2 has a long atmospheric residence time and is almost uniformly distributed in the atmosphere, non-CO2 gases and particles and their products have short atmospheric residence times and are heterogeneously distributed. The climate impact of non-CO2 aviation emissions is known to vary with different meteorological background situations. The aim of this study is to systematically investigate the influence of characteristic weather situations on aviation climate effects over the North Atlantic region, to identify the most sensitive areas, and to potentially detect systematic weather-related similarities. If aircraft were re-routed to avoid climate-sensitive regions, the overall aviation climate impact might be reduced. Hence, the sensitivity of the atmosphere to local emissions provides a basis for the assessment of weather-related, climate-optimized flight trajectory planning. To determine the climate change contribution of an individual emission as a function of location, time, and weather situation, the radiative impact of local emissions of NOx and H2O to changes in O3, CH4, H2O and contrail cirrus was computed by means of the ECHAM5/MESSy Atmospheric Chemistry model. From this, 4-dimensional climate change functions (CCFs) were derived. Typical weather situations in the North Atlantic region were considered for winter and summer. Weather-related differences in O3, CH4, H2O, and contrail cirrus CCFs were investigated. The following characteristics were identified: enhanced climate impact of contrail cirrus was detected for emissions in areas with large-scale lifting, whereas low climate impact of contrail cirrus was found in the area of the jet stream. Northwards of 60∘ N, contrails usually cause climate warming in winter, independent of the weather situation. NOx emissions cause a high positive climate impact if released in the area of the jet stream or in high-pressure ridges, which induces a south- and downward transport of the emitted species, whereas NOx emissions at, or transported towards, high latitudes cause low or even negative climate impact. Independent of the weather situation, total NOx effects show a minimum at ∼250 hPa, increasing towards higher and lower altitudes, with generally higher positive impact in summer than in winter. H2O emissions induce a high climate impact when released in regions with lower tropopause height, whereas low climate impact occurs for emissions in areas with higher tropopause height. H2O CCFs generally increase with height and are larger in winter than in summer. The CCFs of all individual species can be combined, facilitating the assessment of total climate impact of aircraft trajectories considering CO2 and spatially and temporally varying non-CO2 effects. Furthermore, they allow for the optimization of aircraft trajectories with reduced overall climate impact. This also facilitates a fair evaluation of trade-offs between individual species. In most regions, NOx and contrail cirrus dominate the sensitivity to local aviation emissions. The findings of this study recommend considering weather-related differences for flight trajectory optimization in favour of reducing total climate impact.

Dietary climate impact: Contribution of foods and dietary patterns by gender and age in a Swedish population

Dietary climate impact in a Swedish population (56–95 years old) was estimated based on self-reported food intake from 50 000 men and women within two population-based cohorts and on climate data, covering emissions from farm to fork, for 600 foods representative for the Swedish market. Aims were to assess variation in dietary climate impact between population groups and between food categories. Mean dietary climate impact was 2.0 tons of CO2e/person/year, with about a threefold variation between high and low impact individuals. Food loss and waste accounted for 18%. Older individuals and women on average had lower total dietary climate impact per year, while differences between gender were smaller per 1000 kcal. Climate impact was greatly affected by dietary composition and especially by the content of animal-based and discretionary foods, responsible for 71% and 12% of total climate impact, respectively. Results indicate a large potential for reduced climate impact by adopting realistic dietary patterns. Suggested strategies to reach climate goals include reduction of red meat and prioritising lower impact foods within meat, dairy and seafood categories, limited consumption of discretionary foods and decreased over-consumption of total calories, combined with improvements in production including reduction of food loss and waste.

Climate-Optimized Trajectories and Robust Mitigation Potential: Flying ATM4E

Aviation can reduce its climate impact by controlling its CO2-emission and non-CO2 effects, e.g., aviation-induced contrail-cirrus and ozone caused by nitrogen oxide emissions. One option is the implementation of operational measures that aim to avoid those atmospheric regions that are in particular sensitive to non-CO2 aviation effects, e.g., where persistent contrails form. The quantitative estimates of mitigation potentials of such climate-optimized aircraft trajectories are required, when working towards sustainable aviation. The results are presented from a comprehensive modelling approach when aiming to identify such climate-optimized aircraft trajectories. The overall concept relies on a multi-dimensional environmental change function concept, which is capable of providing climate impact information to air traffic management (ATM). Estimates on overall climate impact reduction from a one-day case study are presented that rely on the best estimate for climate impact information. Specific weather situation that day, containing regions with high contrail impact, results in a potential reduction of total climate impact, by more than 40%, when considering CO2 and non-CO2 effects, associated with an increase of fuel by about 0.5%. The climate impact reduction per individual alternative trajectory shows a strong variation and, hence, also the mitigation potential for an analyzed city pair, depending on atmospheric characteristics along the flight corridor as well as flight altitude. The robustness of proposed climate-optimized trajectories is assessed by using a range of different climate metrics. A more sustainable ATM needs to integrate comprehensive environmental impacts and associated forecast uncertainties into route optimization in order to identify robust eco-efficient trajectories.

Soil N2O emissions, N leaching and marine eutrophication in life cycle assessment – A comparison of modelling approaches

Nitrogen fertilisation is an essential part of modern agriculture, providing food for a growing human population, but also causing environmental impacts when reactive nitrogen (N) is released to the environment. The amount and impact of these emissions are difficult to quantify in life cycle assessment (LCA), due to their site-dependent nature. This study compared seven models for direct soil nitrous oxide (N2O) emissions, seven models for N leaching and five characterisation models for marine eutrophication impact assessment, selected to represent medium-effort options for accounting for spatial variation in emissions and impact assessment. In a case study, the models were applied to wheat cultivation at two Swedish sites to estimate climate and marine eutrophication impact. Direct N2O emissions estimated by the models varied by up to five-fold at one of the sites and contributed 21–56% of the total climate impact. Site-dependent models gave both lower and higher N2O emissions estimates than the site-generic Tier 1 model from the Intergovernmental Panel on Climate Change (IPCC). Estimated N leaching also varied by up to fivefold at one of the sites and contributed 47–93% of the total eutrophication potential, depending on model choice. All site-dependent models estimated lower N leaching than the site-generic IPCC Tier 1 model. Marine eutrophication impact estimates varied by almost an order of magnitude depending on characterisation model choice. The large variation between models found in this study highlights the importance of model choice for N emissions and marine eutrophication impact assessment in LCA of crop cultivation. Due to the divergence of model outcomes and different limitations of some of the models, no general recommendations on choosing soil N2O emissions model, N leaching model or characterisation model for marine eutrophication could be given.

Land-use and abandonment alters methane and nitrous oxide fluxes in mountain grasslands

Grasslands cover more than one fifth of total land area in Europe and contribute significantly to the total greenhouse gas budget. The impact of management and land use on the carbon cycle and carbon sequestration in grasslands has been well-studied, however effects on emissions of N2O and CH4 remain uncertain. Additionally, the majority of studies have focussed on management differences between intensively managed grasslands, with few results available for lightly managed grasslands and in particular grassland abandonment. We present N2O and CH4 flux measurements for an abandonment trajectory at low land-use intensity, comparing meadow (fertilized and cut), pasture (grazed) and abandoned (unmanaged since 1983) grassland sites located in the Austrian Alps.Mean growing season N2O fluxes were 0.07, 0.07 and − 0.13 nmol m−2 s−1 and CH4 fluxes were − 1.0, − 0.5 and − 1.6 nmol m−2 s−1 for the meadow, pasture and abandoned sites respectively. Variability for both gases at the abandoned site was dominated by ‘hot moments', while ’hot spots' dominated at the managed meadow and pasture sites. Consideration of the diurnal cycle observed at the abandoned site, linear correlations within all data sets, and principal components analyses of the full data set revealed increased consumption of both N2O and CH4 with increasing temperature, but hardly any relationship between fluxes and soil moisture. Upscaled over a year, the observed fluxes correspond to enhanced non-CO2 greenhouse gas uptake of 172 g CO2-equiv. m−2 y−1 following abandonment. These results show that non-CO2 greenhouse gases form an important part of the total climate impact of land use change and grassland abandonment, such that abandoned grassland is a net sink for both CH4 and N2O.

The climate impact of Norwegians’ travel behavior

Transportation is the largest sector in Norway in terms of greenhouse gas emissions. The mitigation potential of this sector can be better understood by investigating the climate impact of disaggregated data on travel behavior. Here, we use travel behavior data for Norwegians travelling domestically and abroad in 2009 to explore mitigation potential in Norwegian transportation. The climate impact of this aggregated data is calculated by including the impact of all relevant long-lived greenhouse gases and short-lived climate forcers. The climate responses have been compared by using a range of emission metrics (both global temperature change and integrated radiative forcing, both pulse and sustained emissions for time horizons up to 100years). For most choices, the total climate impact is dominated about equally by air (55±20%) and car transport (36±19%), with air transport having a slightly stronger impact for a majority of the cases. The highest income quintile causes a climate impact that is 240% larger than the lowest income quintile. The few trips longer than 100km contribute to 68% of the impact. In addition, we analyze what the effect would be from several proposed mitigation policy targets in Norway and find that policies focused on technology have larger impacts than those on travel behavior.

How shorter black carbon lifetime alters its climate effect

Black carbon (BC), unlike most aerosol types, absorbs solar radiation. However, the quantification of its climate impact is uncertain and presently under debate. Recently, attention has been drawn both to a likely underestimation of global BC emissions in climate models, and an overestimation of BC at high altitudes. Here we show that doubling present day BC emissions in a model simulation, while reducing BC lifetime based on observational evidence, leaves the direct aerosol effect of BC virtually unchanged. Increased emissions, together with increased wet removal that reduces the lifetime, yields modelled BC vertical profiles that are in strongly improved agreement with recent aircraft observations. Furthermore, we explore the consequences of an altered BC profile in a global circulation model, and show that both the vertical profile of BC and rapid climate adjustments need to be taken into account in order to assess the total climate impact of BC.

The climate impact of travel behavior: A German case study with illustrative mitigation options

Abstract Global greenhouse gas mitigation should include the growing share of emissions from transportation. To help understand the mitigation potential of changing travel behavior requires disaggregating the climate impacts of transportation by transport mode, distance, and travel behavior. Here we use disaggregated data on travel behavior to calculate the climate impact of Germans traveling nationally and internationally in 2008 and develop some illustrative mitigation options. We include all relevant long-lived greenhouse gases and short-lived climate forcers and use global temperature change for 50 years of sustained emissions as the emission metric. The total climate impact is determined almost entirely by car (∼46%) and air travel (∼45%), with smaller contributions from public transportation. The climate impact from the highest income group is 250% larger than from the lowest income group. However, the middle classes account for more than two thirds of the total impact. The relatively few trips beyond 100 km contribute more than half of the total impact because of the trip distance and use of aircraft. Individual behavioral changes, like shifting transport modes or reducing distance and frequency, can lead to useful emission reductions. However, a comprehensive package of mitigation options is necessary for deep and sustained emission reductions.

Climate-neutrality versus carbon-neutrality for aviation biofuel policy

We model global aviation biofuel uptake under a future emissions trading policy, and compare aviation CO2 emission reductions with climate impact reductions (CO2 and non-CO2). We find that climate impacts in terms of global warming potential are less favourable than CO2 climate impacts for biofuel use, dependent on the time horizon of the chosen output climate metric. Results indicate that widespread use of aviation biofuel may lead to a scenario in which aviation growth is accompanied by flat or decreasing carbon emissions but an increasing total climate impact.

The Devil in the Deal: Trade Embedded Emissions and the Durban Platform

Several commentators have expressed concern that the Durban Platform does not include more specific language about the need for equitable mitigation efforts. Meanwhile, other commentators have argued that the differentiated approach adopted by the Kyoto Protocol set up an opposition between the developed and developing nations; resulting in an impasse which has prevented the achievement of adequately ambitious, agreeable and binding mitigation commitments. In this commentary I propose that the political impasse is not due to the equity track per se, but rather to the territorial and production-based accounting system upon which it was built. Under the UNFCCC, parties are required to provide inventories of GHG emissions within their national borders. There are several problems with this method, but most important given the argument here, is that the production-approach has resulted in a significant misrepresentation of the total climate impact of developed nations. Because GHG emissions are not confined by geopolitical borders, it is important to understand the climate impact of contemporary consumption and trade, regardless of where emissions are produced. I argue that supplementing production-based accounting with a consideration of the emissions embedded in trade has the potential to provide a more agreeable and politically viable path for closing the ambition gap and ensuring equity.

Health and climate benefits of cookstove replacement options

The health and climate impacts of available household cooking options in developing countries vary sharply. Here, we analyze and compare these impacts (health; climate) and the potential co-benefits from the use of fuel and stove combinations. Our results indicate that health and climate impacts span 2 orders of magnitude among the technologies considered. Indoor air pollution is heavily impacted by combustion performance and ventilation; climate impacts are influenced by combustion performance and fuel properties including biomass renewability. Emission components not included in current carbon trading schemes, such as black carbon particles and carbon monoxide, can contribute a large proportion of the total climate impact. Multiple ‘improved’ stove options analyzed in this paper yield roughly equivalent climate benefits but have different impacts on indoor air pollution. Improvements to biomass stoves can improve indoor air quality, which nonetheless remains significantly higher than for stoves that use liquid or gaseous hydrocarbons. LPG- and kerosene-fueled stoves have unrivaled air quality benefits and their climate impacts are also lower than all but the cleanest stoves using renewable biomass.