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The CICERO Simple Climate Model (CICERO-SCM) is a lightweight, semi-empirical model of global climate. Here we present a new open-source Python port of the model for use in climate assessment and research. The new version of CICERO-SCM has the same scientific logic and functionality as the original Fortran version, but it is considerably more flexible and also open-source via GitHub. We describe the basic structure and improvements compared to the previous Fortran version, together with technical descriptions of the global thermal dynamics and carbon cycle components and the emission module, before presenting a range of standard figures demonstrating its application. A new parameter calibration tool is demonstrated to make an example calibrated parameter set to span and fit a simple target specification. CICERO-SCM is fully open-source and available through GitHub (https://github.com/ciceroOslo/ciceroscm , last access: 23 August 2024). [ABSTRACT FROM AUTHOR]

Background: The Cameroon government has set a target that, by 2030, 58% of the population will be using Liquefied Petroleum Gas (LPG) as a cooking fuel, in comparison with less than 20% in 2014. The National LPG Master Plan (Master Plan) was developed for scaling up the LPG sector to achieve this target. Objectives: This study aimed to estimate the potential impacts of this planned LPG expansion (the Master Plan) on population health and climate change mitigation, assuming primary, sustained use of LPG for daily cooking. Methods: We applied existing and developed new mathematical models to calculate the health and climate impacts of expanding LPG primary adoption for household cooking in Cameroon over two periods: a) short-term (2017-2030): Comparing the Master Plan 58% target with a counterfactual LPG adoption of 32% in 2030, in line with current trends; and b) long-term (2031-2100, climate modeling only), assuming Cameroon will become a mature and saturated LPG market by 2100 (73% adoption, based on Latin American countries). We compared this with a counterfactual adoption of 41% by 2100, in line with current trends. Results: By 2030, successful implementation of the Master Plan was estimated to avert about 28,000 (minimum = 22,000, maximum = 35,000) deaths and 770,000 (minimum = 580,000 maximum = 1 million) disability-adjusted life years. For the same period, we estimated reductions in pollutant emissions of more than a third in comparison with the counterfactual, leading to a global cooling of -0.1 milli [degrees]C in 2030. For 2100, a cooling impact from the Master Plan leading to market saturation (73%) was estimated to be -0.70milli [degrees]C in comparison with to the counterfactual, with a range of -0.64 to -0.93 milli [degrees]C based on different fractions of nonrenewable biomass. Discussion: Successful implementation of the Master Plan could have significant positive impacts on population health in Cameroon with no adverse impacts on climate. https://doi.org/10.1289/EHP4899, Introduction Household air pollution (HAP) is a major risk factor for disease and disability in low- and middle-income countries (LMICs) (Gakidou et al. 2017). HAP is caused by incomplete combustion [...]

In sub-Saharan Africa, four out of five people use biomass fuels for household energy, with associated health and environmental problems. Interventions for clean cooking transitions tend to simplify agency and adoption motivations, with knowledge gaps in policy design. Drawing perspectives from own research from Tanzania, we focus on four key dimensions: household energy needs, climate, health, and the policy context. Six recommendations are highlighted for future research to inform evidence-based policy. First, gender is intrinsically associated with energy use patterns contradicting the common narrative that modern energy technologies can empower women. Second, fuel stacking is very common, and higher quality data is needed to better assess health and climate impacts from the energy use mix. Third, fossil LPG results in lower climate impacts than biomass energy, especially in contexts with high rates of deforestation. This challenges the dichotomy of renewable and non-renewable energy. Fourth, we query the polarity of clean vs. non-clean fuels, with charcoal found to be less polluting indoors once the stove has been lit outside. Fifth, energy policy effectiveness may be increased by combining Pay-As-You-Go fuel technologies with social services and policies beyond the energy sector. Sixth; poverty exacerbates the challenges of making decisions on essential household expenditure. Hence, policies should address poverty to ensure widespread adoption of clean fuels. The policy perspectives presented here are relevant for low and middle-income countries where the majority of the population relies on biomass fuels for their household energy. [Display omitted] • Gender affects energy use patterns. • Fuel stacking has implications on household air pollution and climate impact. • Distinctions in clean, renewable or fossil can be more nuanced. • Combine Pay-As-You-Go with other measures for policy effectiveness. • Reduce extreme energy poverty by addressing poverty. [ABSTRACT FROM AUTHOR]

Mitigation of non-CO 2 emissions plays a key role in meeting the Paris Agreement ambitions and sustainable development goals. Implementation of respective policies addressing these targets mainly occur at sectoral and regional levels, and designing efficient mitigation strategies therefore relies on detailed knowledge about the mix of emissions from individual sources and their subsequent climate impact. Here we present a comprehensive dataset of near- and long-term global temperature responses to emissions of CO 2 and individual short-lived climate forcers (SLCFs) from 7 sectors and 13 regions – for both present-day emissions and their continued evolution as projected under the Shared Socioeconomic Pathways (SSPs). We demonstrate the key role of CO 2 in driving both near- and long-term warming and highlight the importance of mitigating methane emissions from agriculture, waste management, and energy production as the primary strategy to further limit near-term warming. Due to high current emissions of cooling SLCFs, policies targeting end-of-pipe energy sector emissions may result in net added warming unless accompanied by simultaneous methane and/or CO 2 reductions. We find that SLCFs are projected to play a continued role in many regions, particularly those including low- to medium-income countries, under most of the SSPs considered here. East Asia, North America, and Europe will remain the largest contributors to total net warming until 2100, regardless of scenario, while South Asia and Africa south of the Sahara overtake Europe by the end of the century in SSP3-7.0 and SSP5-8.5. Our dataset is made available in an accessible format, aimed also at decision makers, to support further assessment of the implications of policy implementation at the sectoral and regional scales. [ABSTRACT FROM AUTHOR]

Anthropogenic emissions of short-lived climate forcers (SLCFs) affect both air quality and climate. How much regional temperatures are affected by ambitious SLCF emission mitigation policies is, however, still uncertain. We investigate the potential temperature implications of stringent air quality policies by applying matrices of regional temperature responses to new pathways for future anthropogenic emissions of aerosols, methane (CH4), and other short-lived gases. These measures have only a minor impact on CO2 emissions. Two main options are explored, one with climate optimal reductions (i.e., constructed to yield a maximum global cooling) and one with the maximum technically feasible reductions. The temperature response is calculated for four latitude response bands (90–28 ∘ S, 28 ∘ S–28 ∘ N, 28–60 ∘ N, and 60–90 ∘ N) by using existing absolute regional temperature change potential (ARTP) values for four emission regions: Europe, East Asia, shipping, and the rest of the world. By 2050, we find that global surface temperature can be reduced by -0.3±0.08 ∘ C with climate-optimal mitigation of SLCFs relative to a baseline scenario and as much as -0.7 ∘ C in the Arctic. Cutting CH4 and black carbon (BC) emissions contributes the most. The net global cooling could offset warming equal to approximately 15 years of current global CO2 emissions. On the other hand, mitigation of other SLCFs (e.g., SO2) leads to warming. If SLCFs are mitigated heavily, we find a net warming of about 0.1 ∘ C, but when uncertainties are included a slight cooling is also possible. In the climate optimal scenario, the largest contributions to cooling come from the energy, domestic, waste, and transportation sectors. In the maximum technically feasible mitigation scenario, emission changes from the industry, energy, and shipping sectors will cause warming. Some measures, such as those in the agriculture waste burning, domestic, transport, and industry sectors, have large impacts on the Arctic, especially by cutting BC emissions in winter in areas near the Arctic. [ABSTRACT FROM AUTHOR]

We present a case study where emission metric values from different studies are applied to estimate global and Arctic temperature impacts of emissions from a northern European country. This study assesses the climate impact of Finnish air pollutants and greenhouse gas emissions from 2000 to 2010, as well as future emissions until 2030. We consider both emission pulses and emission scenarios. The pollutants included are SO2 , NOx , NH3 , non-methane volatile organic compound (NMVOC), black carbon (BC), organic carbon (OC), CO, CO2 , CH4 and N2O , and our study is the first one for Finland to include all of them in one coherent dataset. These pollutants have different atmospheric lifetimes and influence the climate differently; hence, we look at different climate metrics and time horizons. The study uses the global warming potential (GWP and GWP *), the global temperature change potential (GTP) and the regional temperature change potential (RTP) with different timescales for estimating the climate impacts by species and sectors globally and in the Arctic. We compare the climate impacts of emissions occurring in winter and summer. This assessment is an example of how the climate impact of emissions from small countries and sources can be estimated, as it is challenging to use climate models to study the climate effect of national policies in a multi-pollutant situation. Our methods are applicable to other countries and regions and present a practical tool to analyze the climate impacts in multiple dimensions, such as assessing different sectors and mitigation measures. While our study focuses on short-lived climate forcers, we found that the CO2 emissions have the most significant climate impact, and the significance increases over longer time horizons. In the short term, emissions of especially CH4 and BC played an important role as well. The warming impact of BC emissions is enhanced during winter. Many metric choices are available, but our findings hold for most choices. [ABSTRACT FROM AUTHOR]

We present a case study where emission metric values from different studies are applied to estimate global and Arctic temperature impacts of emissions from a Northern European country. This study assesses the climate impact of Finnish air pollutant and greenhouse gas emissions in 2000-2010 as well as future emissions until 2030. The pollutants included are SO2, NOX, NH3, NMVOC, BC, OC and CO as well as CO2, CH4 and N2O, and our study is the first one for Finland to include all of them in one coherent dataset. These pollutants have different atmospheric lifetimes and influence the climate differently; hence, we look at different climate metrics and time horizons. The study uses the Global Warming Potential (GWP), the Global Temperature change Potential (GTP) and the Regional Temperature change Potential (RTP) with different time scales for estimating the climate impacts by species and sectors globally and in the Arctic. We compare the climate impacts of emissions occurring in winter and summer. This assessment is an example of how the climate impact of emissions from small countries and sources can be estimated, as it is challenging to use climate models to study the climate effect of national policies in a multi-pollutant situation. Our methods are applicable to other countries and regions and present a practical tool to analyse the climate impacts in multiple dimensions, such as assessing different sectors and mitigation measures. While our study focuses on short-lived climate forcers, we find that the CO2 emissions have the most significant climate impact, and the significance increases with longer time horizons. In the short term, emissions of especially CH4 and BC played an important role as well. The warming impact of BC emissions is enhanced during winter. There can be relatively large differences between results from studies using different metrics, which can partly be explained by different study setup and inherent uncertainty. [ABSTRACT FROM AUTHOR]

For short-lived climate forcers (SLCFs), the impact of emissions depends on where and when the emissions take place. Comprehensive new calculations of various emission metrics for SLCFs are presented based on radiative forcing (RF) values calculated in four different (chemicaltransport or coupled chemistry-climate) models. We distinguish between emissions during summer (May-October) and winter (November-April) for emissions in Europe and East Asia, as well as from the global shipping sector and global emissions. The species included in this study are aerosols and aerosol precursors (BC, OC, SO2, NH3), as well as ozone precursors (NOx, CO, VOCs), which also influence aerosols to a lesser degree. Emission metrics for global climate responses of these emissions, as well as for CH4, have been calculated using global warming potential (GWP) and global temperature change potential (GTP), based on dedicated RF simulations by four global models. The emission metrics include indirect cloud effects of aerosols and the semi-direct forcing for BC. In addition to the standard emission metrics for pulse and sustained emissions, we have also calculated a new emission metric designed for an emission profile consisting of a ramping period of 15 years followed by sustained emissions, which is more appropriate for a gradual implementation of mitigation policies. For the aerosols, the emission metric values are larger in magnitude for emissions in Europe than East Asia and for summer than winter. A variation is also observed for the ozone precursors, with largest values for emissions in East Asia and winter for CO and in Europe and summer for VOCs. In general, the variations between the emission metrics derived from different models are larger than the variations between regions and seasons, but the regional and seasonal variations for the best estimate also hold for most of the models individually. Further, the estimated climate impact of an illustrative mitigation policy package is robust even when accounting for the fact that the magnitude of emission metrics for different species in a given model is correlated. For the ramping emission metrics, the values are generally larger than for pulse or sustained emissions, which holds for all SLCFs. For SLCFs mitigation policies, the dependency of metric values on the region and season of emission should be considered. [ABSTRACT FROM AUTHOR]

Dedicated model simulations by four general circulation and chemistry-transport models are used to establish a matrix of specific radiative forcing, defined as the radiative forcing per unit change in mass emitted, as a function of the near-term climate forcer emitted, its source region, and the season of emission. Emissions of eight near-term climate forcers are reduced: sulphur dioxide, the precursor to sulphate aerosols; black carbon aerosols; organic carbon aerosols; ammonia, a precursor to nitrate aerosols; methane; and nitrogen oxides, carbon monoxide, and volatile organic compounds, the precursors to ozone and to secondary organic aerosols. The focus is on two source regions, Europe and East Asia, but the shipping sector and global averages are also included. Emission reductions are applied over two time periods: May–Oct and Nov–Apr. Models generally agree on the sign and ranking of specific radiative forcing for different emitted species, but disagree quantitatively. Black carbon aerosols, methane, and carbon monoxide exert positive specific radiative forcings. Black carbon exerts the strongest specific radiative forcing, even after accounting for rapid adjustments from the semi-direct effect, and is most efficient in local summer. However, although methane and carbon monoxide are less efficient in a specific sense, the potential for decreasing the mass emitted is larger. Organic carbon aerosols, sulphur dioxide, ammonia, and emissions by the shipping sector exert negative specific radiative forcings, with local summer emission changes being again more efficient. Ammonia is notable for its weak specific radiative forcing. For aerosols, specific radiative forcing exerted by European emissions is stronger than for East Asia, because the European baseline is less polluted. Radiative forcing of European and East Asian emission reductions is mainly exerted in the mid-latitudes of the Northern Hemisphere, but atmospheric transport yields sizeable radiative forcings in neighbouring regions, such as the Arctic. Models disagree on the sign of the net radiative forcing exerted by reductions in the emissions of nitrogen oxides and volatile organic compounds, because those reductions trigger complex changes in the oxidising capacity of the atmosphere, translating into radiative forcings by aerosols, methane, and ozone of different signs. The response of nitrate aerosols to nitrogen oxide reductions is particularly important in determining the sign of the corresponding radiative forcing. Model diversity comes from different modelled lifetimes, different unperturbed baselines, and different numbers of species and radiative forcing mechanisms represented. The strength of the aerosol-chemistry coupling is also diverse, translating into aerosol responses to perturbations of ozone precursors of different magnitudes. [ABSTRACT FROM AUTHOR]

The Life Cycle Assessment (LCA) impact category "global warming" compares emissions of long-lived greenhouse gases (LLGHGs) using Global Warming Potential (GWP) with a 100-year time-horizon as specified in the Kyoto Protocol. Two weaknesses of this approach are (1) the exclusion of short-lived climate forcers (SLCFs) and biophysical factors despite their established importance, and (2) the use of a particular emission metric (GWP) with a choice of specific time-horizons (20, 100, and 500 years). The GWP and the three time-horizons were based on an illustrative example with value judgments and vague interpretations. Here we illustrate, using LCA data of the transportation sector, the importance of SLCFs relative to LLGHGs, different emission metrics, and different treatments of time. We find that both the inclusion of SLCFs and the choice of emission metric can alter results and thereby change mitigation priorities. The explicit inclusion of time, both for emissions and impacts, can remove value-laden assumptions and provide additional information for impact assessments. We believe that our results show that a debate is needed in the LCA community on the impact category "global warming" covering which emissions to include, the emission metric(s) to use, and the treatment of time. [ABSTRACT FROM AUTHOR]

BSTRACT The impact on snow pack albedo from local elemental carbon (EC) sources in Svalbard has been investigated for the winter of 2008. Highly elevated EC concentrations in the snow are observed around the settlements of Longyearbyen and Svea (locally >1000 ng g [ABSTRACT FROM AUTHOR]

Reducing global carbon dioxide (CO 2 ) emissions is often thought to be at odds with economic growth and poverty reduction. Using an integrated assessment modeling approach, we find that China can cap CO 2 emissions at 2015 level while sustaining economic growth and reducing the urban-rural income gap by a third by 2030. As a result, the Chinese economy becomes less dependent on exports and investments, as household consumption emerges as a driver behind economic growth, in line with current policy priorities. The resulting accumulated greenhouse gas emissions reduction 2016–2030 is about 60 billion ton (60 Mg) CO 2 e. A CO 2 tax combined with income re-distribution initially leads to a modest warming due to reduction in sulfur dioxide (SO 2 ) emissions. However, the net effect is eventually cooling when the effect of reduced CO 2 emissions dominates due to the long-lasting climate response of CO 2 . The net reduction in global temperature for the remaining part of this century is about 0.03 ± 0.02 °C, corresponding in magnitude to the cooling from avoiding one year of global CO 2 emissions. [ABSTRACT FROM AUTHOR]