A fast method for updating global fossil fuel carbon dioxide emissions

Abstract. This synthesis discusses the emissions of carbon dioxide from fossil-fuel combustion and cement production. While much is known about these emissions, there is still much that is unknown about the details surrounding these emissions. This synthesis explores our knowledge of these emissions in terms of why there is concern about them; how they are calculated; the major global efforts on inventorying them; their global, regional, and national totals at different spatial and temporal scales; how they are distributed on global grids (i.e., maps); how they are transported in models; and the uncertainties associated with these different aspects of the emissions. The magnitude of emissions from the combustion of fossil fuels has been almost continuously increasing with time since fossil fuels were first used by humans. Despite events in some nations specifically designed to reduce emissions, or which have had emissions reduction as a byproduct of other events, global total emissions continue their general increase with time. Global total fossil-fuel carbon dioxide emissions are known to within 10 % uncertainty (95 % confidence interval). Uncertainty on individual national total fossil-fuel carbon dioxide emissions range from a few percent to more than 50 %. This manuscript concludes that carbon dioxide emissions from fossil-fuel combustion continue to increase with time and that while much is known about the overall characteristics of these emissions, much is still to be learned about the detailed characteristics of these emissions.

’s (2012) conclusion that observed climate change is comparableto projections, and in some cases exceeds projections, allows further inferences ifwe can quantify changing climate forcings and compare those with projections.The largest climate forcing is caused by well-mixed long-lived greenhouse gases.Here we illustrate trends of these gases and their climate forcings, and we discussimplications. We focus on quantities that are accurately measured, and we includecomparison with fixed scenarios, which helps reduce common misimpressionsabout how climate forcings are changing.Annual fossil fuel CO

BackgroundCities contribute more than 70% of global anthropogenic carbon dioxide (CO2) emissions and are leading the effort to reduce greenhouse gas (GHG) emissions through sustainable planning and development. However, urban greenhouse gas mitigation often relies on self-reported emissions estimates that may be incomplete and unverifiable via atmospheric monitoring of GHGs. We present the Hestia Scope 1 fossil fuel CO2 (FFCO2) emissions for the city of Baltimore, Maryland—a gridded annual and hourly emissions data product for 2010 through 2015 (Hestia-Baltimore v1.6). We also compare the Hestia-Baltimore emissions to overlapping Scope 1 FFCO2 emissions in Baltimore’s self-reported inventory for 2014.ResultsThe Hestia-Baltimore emissions in 2014 totaled 1487.3 kt C (95% confidence interval of 1158.9–1944.9 kt C), with the largest emissions coming from onroad (34.2% of total city emissions), commercial (19.9%), residential (19.0%), and industrial (11.8%) sectors. Scope 1 electricity production and marine shipping were each generally less than 10% of the city’s total emissions. Baltimore’s self-reported Scope 1 FFCO2 emissions included onroad, natural gas consumption in buildings, and some electricity generating facilities within city limits. The self-reported Scope 1 FFCO2 total of 1182.6 kt C was similar to the sum of matching emission sectors and fuels in Hestia-Baltimore v1.6. However, 20.5% of Hestia-Baltimore’s emissions were in sectors and fuels that were not included in the self-reported inventory. Petroleum use in buildings were omitted and all Scope 1 emissions from industrial point sources, marine shipping, nonroad vehicles, rail, and aircraft were categorically excluded.ConclusionsThe omission of petroleum combustion in buildings and categorical exclusions of several sectors resulted in an underestimate of total Scope 1 FFCO2 emissions in Baltimore’s self-reported inventory. Accurate Scope 1 FFCO2 emissions, along with Scope 2 and 3 emissions, are needed to inform effective urban policymaking for system-wide GHG mitigation. We emphasize the need for comprehensive Scope 1 emissions estimates for emissions verification and measuring progress towards Scope 1 GHG mitigation goals using atmospheric monitoring.

Abstract. Understanding carbon sources and sinks across the Earth's surface is fundamental in climate science and policy; thus, these topics have been extensively studied but have yet to be fully resolved and are associated with massive debate regarding the sign and magnitude of the carbon budget from global to regional scales. Developing new models and estimates based on state-of-the-art algorithms and data constraints can provide valuable knowledge and contribute to a final ensemble model in which various optimal carbon budget estimates are integrated, such as the annual global carbon budget paper. Here, we develop a new atmospheric inversion system based on the 4D local ensemble transform Kalman filter (4D-LETKF) coupled with the GEOS-Chem global transport model to infer surface-to-atmosphere net carbon fluxes from Orbiting Carbon Observatory-2 (OCO-2) V10r XCO2 retrievals. The 4D-LETKF algorithm is adapted to an OCO-2-based global carbon inversion system for the first time in this work. On average, the mean annual terrestrial and oceanic fluxes between 2015 and 2020 are estimated as − 2.02 and − 2.34 GtC yr−1, respectively, compensating for 21 % and 24 %, respectively, of global fossil carbon dioxide (CO2) emissions (9.80 GtC yr−1). Our inversion results agree with the CO2 atmospheric growth rates reported by the National Oceanic and Atmospheric Administration (NOAA) and reduce the modeled CO2 concentration biases relative to the prior fluxes against surface and aircraft measurements. Our inversion-based carbon fluxes are broadly consistent with those provided by other global atmospheric inversion models, although discrepancies still occur in the land–ocean flux partitioning schemes and seasonal flux amplitudes over boreal and tropical regions, possibly due to the sparse observational constraints of the OCO-2 satellite and the divergent prior fluxes used in different inversion models. Four sensitivity experiments are performed herein to vary the prior fluxes and uncertainties in our inversion system, suggesting that regions that lack OCO-2 coverage are sensitive to the priors, especially over the tropics and high latitudes. In the further development of our inversion system, we will optimize the data-assimilation configuration to fully utilize current observations and increase the spatial and seasonal representativeness of the prior fluxes over regions that lack observations.

Abstract. Fossil-fuel (FF) burning releases carbon dioxide (CO2) together with many other chemical species, some of which, such as nitrogen dioxide (NO2) and carbon monoxide (CO), are routinely monitored from space. This study examines the feasibility of estimation of FF CO2 emissions from large industrial regions by using NO2 and CO column retrievals from satellite measurements in combination with simulations by a mesoscale chemistry transport model (CTM). To this end, an inverse modeling method is developed that allows estimating FF CO2 emissions from different sectors of the economy, as well as the total CO2 emissions, in a given region. The key steps of the method are (1) inferring "top-down" estimates of the regional budget of anthropogenic NOx and CO emissions from satellite measurements of proxy species (NO2 and CO in the case considered) without using formal a priori constraints on these budgets, (2) the application of emission factors (the NOx-to-CO2 and CO-to-CO2 emission ratios in each sector) that relate FF CO2 emissions to the proxy species emissions and are evaluated by using data of "bottom-up" emission inventories, and (3) cross-validation and optimal combination of the estimates of CO2 emission budgets derived from measurements of the different proxy species. Uncertainties in the top-down estimates of the NOx and CO emissions are evaluated and systematic differences between the measured and simulated data are taken into account by using original robust techniques validated with synthetic data. To examine the potential of the method, it was applied to the budget of emissions for a western European region including 12 countries by using NO2 and CO column amounts retrieved from, respectively, the OMI and IASI satellite measurements and simulated by the CHIMERE mesoscale CTM, along with the emission conversion factors based on the EDGAR v4.2 emission inventory. The analysis was focused on evaluation of the uncertainty levels for the top-down NOx and CO emission estimates and "hybrid" estimates (that is, those based on both atmospheric measurements of a given proxy species and respective bottom-up emission inventory data) of FF CO2 emissions, as well as on examining consistency between the FF NO2 emission estimates derived from measurements of the different proxy species. It is found that NO2 measurements can provide much stronger constraints to the total annual FF CO2 emissions in the study region than CO measurements, the accuracy of the NO2-measurement-based CO2 emission estimate being mostly limited by the uncertainty in the top-down NOx emission estimate. Nonetheless, CO measurements are also found to be useful as they provide additional constraints to CO2 emissions and enable evaluation of the hybrid FF CO2 emission estimates obtained from NO2 measurements. Our most reliable estimate for the total annual FF CO2 emissions in the study region in 2008 (2.71 ± 0.30 Pg CO2) is found to be about 11 and 5 % lower than the respective estimates based on the EDGAR v.4.2 (3.03 Pg CO2) and CDIAC (2.86 Pg CO2) emission inventories, with the difference between our estimate and the CDIAC inventory data not being statistically significant. In general, the results of this study indicate that the proposed method has the potential to become a useful tool for identification of possible biases and/or inconsistencies in the bottom-up emission inventory data regarding CO2, NOx, and CO emissions from fossil-fuel burning in different regions of the world.

Global warming and the significance of fossil fuels Energy for industrial, commercial and residential purposes, electricity generation and transportation is primarily supplied by fossil fuels (coal, gas and oil) and nuclear power. It is now widely believed that climate change is strongly linked to the increased level of greenhouse gases in the atmosphere, and that human activity especially through the combustion of fossil fuels is a major contributing factor. One of the main greenhouse gases, accounting for 65% of global warming, is carbon dioxide. Fossil fuels are the stored energy or ‘ancient sunlight’ of aeons and millennia ago that mankind has been burning extensively over a few centuries and more prolifically in recent decades. When such fossil fuels are burned for energy, carbon dioxide that has been locked away for all those years is released into the atmosphere greatly adding to global greenhouse gases. In contrast, when present-day plant material is burned the carbon locked into the biomass for a relatively short period of time is released back into the atmosphere thus recycling the carbon dioxide. Consequently, the system is relatively carbon neutral unlike the burning of fossil fuels. Global emissions of carbon dioxide from fossil fuels over the first five years of this third millennium were four times greater than for the preceding ten years, despite the decisions of the Kyoto Agreement to reduce carbon dioxide emissions.

The world is watching expectantly as the clock winds down towards the United Nations Climate Change Conference (COP15; http://en.cop15.dk/) to be held 7–18 December 2009 in Copenhagen. While most are now convinced of the need for a strong and concerted response to the climate challenge, the exact nature and extent of that response remains uncertain. There is evidence (Barnett 2009) that current estimates of emissions now exceed all but the most extreme emission scenarios developed by the Intergovernmental Panel on Climate Change (IPCC). If that increase in emissions persists then temperature increases of 4 °C by 2060 have been predicted (Barnett 2009). An inevitable result of the potential for such extreme climate change is to advance the need for multiple adaptation strategies to decision making about, for example, infrastructure, urban planning and forest management. These strategies need to do more than incremental adaptation (Barnett 2009); instead transformative approaches may be required to adapt. The timing of the response is also proving to be a critical determining factor in the effectiveness of global actions. Using a simple conceptual model of emissions, Vaughan and co-workers (Vaughan et al 2009) show that avoiding dangerous climate change is more effective if such action begins early. Early action is also more effective than acting more aggressively later (Vaughan et al 2009).

In the aftermath of the catastrophic 2019–2020 bushfires, the corona virus disease of 2019 pandemic and recent devastating floods in New South Wales and Queensland, Australians voted for climate action in the 2022 Federal election, and a new Climate Change Bill1 has already passed the House of Representatives. Climate change is recognised by scientists, public health experts, Indigenous leaders, economists and the Australian public at large as the most pressing issue at our doorstep.2-5 As we consider the veracity of net zero emission election commitments and the architecture of a post-pandemic recovery in Australia, we use science, public health expertise and a common chronic condition to explain the links between key issues and outline a road map for action in Australia. In this commentary, we highlight current evidence on the relationships between climate change, air pollution, fossil fuel use and their associated impacts on public health. We use asthma as a case study to examine the economic and human health burden arising from this climate-air pollution-fossil fuel triad. Australia's dependence on fossil fuels and gaps in energy policy are underscored as drivers of negative climate and public health outcomes. We provide a roadmap for action consisting of a mandate for: rapid de-carbonisation of Australia's energy systems; adoption of a healthcare without harm framework; and preparing public health systems to prevent and control asthma exacerbations. Climate change is the greatest threat to public health of the 21st century.6 The planet has warmed significantly over the past century by on average 0.8°C, largely as a result of increased global emissions of carbon dioxide and other greenhouse gases (GHG).7 Human activity and fossil fuel-based, carbon intensive energy systems have contributed substantially to global heating. Climate change is having profound effects on weather systems, exemplified by the increased frequency and duration of extreme weather events including floods, drought and bushfires. Climate change also adversely impacts on atmospheric air quality and air pollution.1 The relationship between climate change and air quality is bi-directional: climate change can exacerbate or increase existing air pollutants (e.g., atmospheric heating increases ground level ozone); air polluting emissions influence the climate (e.g., release of carbon-based materials such as black soot have a heating effect); several sources of air pollution are sources of GHGs (e.g., methane locks heat in the atmosphere, triggering climate change). Incomplete combustion of fossil fuels is a primary source of air pollutants (e.g., particulate matter [PM]2.5) and is harmful to human health.8 Higher temperatures and carbon dioxide levels arising from climate change also increase airborne allergenic pollens contributing to allergic asthma.9 The energy sector is the largest contributor to GHG emissions in Australia.8 Australia's primary energy consumption is dominated by fossil fuels (i.e., coal 40%, oil 34% and gas 22%)10 and its electricity system is founded on centralised, carbon-intensive coal-fired generation. Australia's coal burning (and exports) contributes to climate change and air pollution and hence health impacts. Every step of coal's lifecycle produces air pollutants that affect human health. Burning coal produces fly ash and particulate matter (PM2.5), which lodge in the lungs, causing irritation and inflammation.11 Transport (energy) is the second largest source of emissions after electricity production.12 The road transport sector, including passenger and commercial vehicles, is reliant on petroleum-based fossil fuels and is a significant contributor to air pollution in cities and regions.13 For example, petrol and diesel emissions arising from road traffic are a major culprit in asthma exacerbations: Nitrogen dioxide (NO2) exposure and living in close proximity to a major road are associated with an increase in the likelihood of asthma in children and adults.14, 15 Asthma is one of the most common and costly of all chronic disease conditions affecting more than 260 million people globally, and both its prevalence and incidence is strongly associated with air quality and atmospheric pollution16 In 2021, 2.7 million people (10.7%) of the Australian population had asthma, making it a common non-communicable disease17 and accounting for 417 deaths in 2020.18 Nationally, there were over 37 000 hospitalisations with asthma as the principal diagnosis in 2016 and around 2% of all general practitioner encounters were for asthma, representing the 14th most common reason for a general practitioner consultation in that year.19, 20 As asthma is a lifelong condition, the costs associated with the condition are high, both to the individual as well as to the health service, where it accounts for $770 million in direct expenditures annually.19 Studies of coal mine fires and coal town residency illuminate the fossil fuel, air pollution and asthma relationship. The Hazelwood coal mine fire in the Latrobe Valley, Victoria in 2014 created plumes of smoke and ash with high PM2.5 for 45 days. Guo et al.21 found increased risks of all-causes, respiratory diseases, and asthma related emergency presentations and hospital admissions. Casey et al.11 found living near coal-fired power plants is linked to higher rates of respiratory disease and increased asthma exacerbations, while shutting down a coal plant or upgrading emission controls decreases inhaler use, emergency department visits and hospitalisation for asthma among local residents. Gas has also been associated with childhood asthma: one study of Australian children reported the population attributable fraction for childhood asthma associated with household gas stoves (which release PM2.5, NO2) for childhood asthma was approximately 12%, corresponding to over 2700 disability adjusted life years.15 Climate change is increasing the frequency and intensity of bushfires in Australia. Smoke from bushfires is a major risk factor for asthma exacerbations: the 2019–2020 summer bushfires have been linked to 429 premature deaths, more than 2000 hospitalisations for respiratory health issues and 1500 emergency department presentations with asthma.235 The health-related economic costs of the 2019–2020 bushfires was estimated AU$1.95 billion, with the majority due to the economic costs of premature mortality associated with the bushfires; AU$25 million of healthcare costs, $24 million for cardiovascular and respiratory hospitalisations, and AU$1 million for asthma emergency department attendances.22 Climate change effects allergic diseases.23 Thunderstorm asthma is an allergic asthma response to airborne allergenic pollens that rupture due to osmotic shock following a thunderstorm event, and thereby allowing smaller allergenic sub-pollen particles to reach the lower airways to trigger the potentially deadly allergic response24 (see Figure 1). In November 2016, the phenomenon of thunderstorm asthma caused 10 deaths in Australia and more than 3300 ED presentations.19, 24 Several studies have shown that plants growing in highly polluted air produce more allergenic pollen.25 When combined with pollen rupture, it results in a volatile mix that turns such pollens into ‘biological time bombs’. Knox et al.26 have shown that the major allergen of rye grass pollen has the capacity to directly interact with diesel exhaust carbon particles (DECP). They assert allergen-loaded DECP has the capacity to penetrate the lower airways and prompt an episode of asthma. Figure 1 describes the relationship between air pollution, climate change, fossil fuels and thunderstorm asthma as a public health issue. Healthcare—one of the world's largest industries—contributes to climate change and air pollution. The Australian healthcare system is responsible for ~7% of national GHGs.27 In the United States, one study has estimated that healthcare-related air pollution was responsible for 9% of respiratory disease burden from PM emissions.28 Similar estimates of disease impact are not available locally, but Australian healthcare is responsible for around 3% of national PM footprint.29 Paradoxically, some asthma treatments are significant contributors to GHGs. Metered-dose inhalers for asthma contribute an estimated 3.9% of the total carbon footprint of the UK National Health Service,30 due to the extremely potent GHGs used as propellants in some delivery systems. Australian estimates are not available, but the same products are widely used in this country. This scenario demonstrates perverse feedback loops—air pollution and climate change drive each other, and both drive increasing asthma incidence through various pathways, while treating asthma can itself further drive climate change through GHG emissions. This is a critical decade. Linear, single issue and reductionist approaches will not cut through the complex public health challenges arising from the climate change, air pollution and fossil fuel triad. Here we offer the new federal government and health sector a three-point roadmap for action. The roadmap highlights key public health-oriented interventions, which will prevent health-harming emissions, promote a healthy recovery from the pandemic and help Australians prepare for increasing asthma prevalence due to environmental triggers. Australia remains heavily dependent on fossil fuels and is unlikely to keep its commitments to the Paris Agreement to which it is a signatory. Since 1990, there has only been a 10% reduction in the share of electricity generation produced from non-renewable fuels (89.9% in 1990 to 80.2% in 2019) with more than half of total generation still reliant on coal.31 Stopping fossil fuel development and decarbonising energy systems are the most urgent and far reaching challenges of this decade.32 To prevent health harming air polluting emissions and to meet the goals of the Paris Agreement, Australia requires a coherent and timely policy framework that enables disinvestment in fossil fuels and a rapid transition to renewable energy. Central to this policy framework are climate change mitigation targets—an essential upstream and long-term public health strategy for managing the underlying causes of the increasing bushfire risk and thunderstorm asthma. This critical, foundational government policy framework will also support emission reduction efforts within the Australian healthcare sector.33 Action must be taken now, as limiting global heating to 1.5°C will require deep emissions reductions of at least 45% from 2010 levels by 2030.7 Australia's healthcare sector needs to reduce its total emissions to net zero. By 2030, an 80% reduction in emissions is required for healthcare to help meet the 1.5°C Paris Agreement commitments and minimise the predicted catastrophic public health consequences of climate change.33, 34 Australian hospitals and health systems must implement interventions which will decarbonize healthcare delivery to ‘first do no harm’ whilst maintaining and improving health. Healthcare systems can take cost-effective action to transition toward zero emissions energy, buildings, travel and transport, waste management as well as low emissions pharmaceuticals, sustainable food system ectera.35 There are multiple health service level examples of successful action (see Global Green and Health Hospitals36) and state and territory government policy leadership can support compliance and implementation. Substitution of high emission products with more climate friendly alternatives and incentivising the production of green medications is another key strategy. This is particularly relevant to asthma medication. Alternative delivery mechanisms to metered dose inhalers without the high global heating potential propellants, such as dry powder based inhalers, are available and suitable for the majority of patients.35 Wilkinson et al.30 study found that switching to low global warming potential asthma inhalers has co-benefits for reducing GHGs and drug costs. Many peak health and medical bodies have declared a climate emergency. We support the call by Australia's peak associations including Doctors for the Environment Australia, Australian Medical Association, Royal Australian College of Physicians and the Climate and Health Alliance for the establishment of an Australian Sustainable Healthcare Unit to lead and coordinate initiatives and collaboration nationwide.33 Australia's recent bushfire smoke-related and thunderstorm asthma epidemics were climate change and air pollution driven disasters of national and/or state level significance. Both events tested public health system preparedness and responsiveness and capacity to prevent and control environmental health hazards. We support the Royal Commission into National Natural Disaster Arrangement's recommendations, specifically those pertaining to community education, air quality and health.37 Further, we endorse Vardoulakis et al.'s38 perspective that consistency of air quality information and related public health advice across jurisdictions in Australia is essential. We support their call for an independent national expert committee on air pollution and health protection to be established to support environmental health decision making in Australia. Likewise, the impact of climate change (longer pollen seasons, more extreme weather events) on asthma prevalence and severity needs to prioritised in public health planning and surveillance efforts. Notably, the current National Asthma Strategy (2018) is mute on climate change and air pollution. Australians voted for action on climate change in the 2022 federal election. The evidence is clear, we need rapid transition from fossil fuel toward renewable-energy powered systems, including net zero healthcare systems, which will provide benefits for public health, climate and economy. Yet, it remains to be seen whether the pace of change envisaged in the Climate Change Bill 2022 is sufficiently fast, or whether new coal and gas generation and mining projects will be phased out. Continued failure to rapidly act on the climate-air pollution-fossil fuel triad in Australia is likely to result in increased asthma prevalence and severity and exert an inexorable toll on the health, social and economic wellbeing of future generations. Asthma is just the tip of the iceberg. Health and medical groups have a key role in helping chart a new course with the incoming federal government to avert the cascading impacts of this ubiquitous climate-driven public health crisis. Open access publishing facilitated by Deakin University, as part of the Wiley - Deakin University agreement via the Council of Australian University Librarians. None. The authors declare no conflicts of interest except Rebecca Patrick. Data sharing not applicable to this article as no datasets were generated or analysed during the current study.

Rethinking wedges

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil-fuel combustion and cement production (EFF) are based on energy statistics, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated for the first time in this budget with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2 and land cover change (some including nitrogen–carbon interactions). All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2003–2012), EFF was 8.6 ± 0.4 GtC yr−1, ELUC 0.9 ± 0.5 GtC yr−1, GATM 4.3 ± 0.1 GtC yr−1, SOCEAN 2.5 ± 0.5 GtC yr−1, and SLAND 2.8 ± 0.8 GtC yr−1. For year 2012 alone, EFF grew to 9.7 ± 0.5 GtC yr−1, 2.2% above 2011, reflecting a continued growing trend in these emissions, GATM was 5.1 ± 0.2 GtC yr−1, SOCEAN was 2.9 ± 0.5 GtC yr−1, and assuming an ELUC of 1.0 ± 0.5 GtC yr−1 (based on the 2001–2010 average), SLAND was 2.7 ± 0.9 GtC yr−1. GATM was high in 2012 compared to the 2003–2012 average, almost entirely reflecting the high EFF. The global atmospheric CO2 concentration reached 392.52 ± 0.10 ppm averaged over 2012. We estimate that EFF will increase by 2.1% (1.1–3.1%) to 9.9 ± 0.5 GtC in 2013, 61% above emissions in 1990, based on projections of world gross domestic product and recent changes in the carbon intensity of the economy. With this projection, cumulative emissions of CO2 will reach about 535 ± 55 GtC for 1870–2013, about 70% from EFF (390 ± 20 GtC) and 30% from ELUC (145 ± 50 GtC). This paper also documents any changes in the methods and data sets used in this new carbon budget from previous budgets (Le Quéré et al., 2013). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP_2013_V2.3).

The concern that the global emissions or carbon mitigation plans have not yielded the much desired significant improvement in health, air and environmental quality especially since the Conference of Paris has further created some ambiguities. This has further made environmentalists and policymakers wonder if the December 2015 Paris Climate Agreement is “better than no agreement”. In advancing the studies of global temperature and carbon emission nexus, the current study rather applied the time-frequency dependency of average global mean temperature anomalies and global carbon dioxide (CO2) emissions from fossil fuels for the annual data from 1851 to 2017. The present study uses the wavelet coherence technique and the Toda and Yamamoto causality approach that allows the investigation of both the long- and short-term causal relationship between the global average temperature and global CO2 emissions. The findings of this study indicate that (i) significant vulnerabilities in global average temperature and global CO2 emissions are observed at different time periods and different frequency levels; (ii) global CO2 emissions have a strong power for explaining global average temperature at different time periods; (iii) between 1880 and 1910, global average temperature and global CO2 emissions are positively correlated at medium term; and (iv) the outcome of Toda and Yamamoto causality reveals that global CO2 emissions cause global average temperature and this outcome is in line with the outcome of wavelet coherence approach.

Why nuclear energy is sustainable and has to be part of the energy mix

International efforts to avoid dangerous climate change aim for global carbon dioxide (CO2) emissions to be net-zero by midcentury. Such a goal will require both drastically reducing emissions from high-income countries and avoiding large increases in emissions from still-developing countries. Yet most analyses focus on rich-country emissions reductions, with much less attention to trends in low-income countries. Here, we use a Kaya framework to analyze patterns and trends in CO2 emissions from the combustion of fossil fuels in Africa between 1990 and 2017. In total, African CO2 emissions were just 4% of global fossil fuel emissions in 2017, or 1185 MtCO2, having grown by 4.6% yr−1 on average over the period 1990–2017 (cf the global growth rate of 2.2% yr−1 over the same period). In 2017, 10 countries accounted for about 87% of the continent’s emissions. Despite modest recent reductions in some countries’ CO2 emissions, projections of rapid growth of population and per capita GDP will drive future increases in emissions. Indeed, if the continent-wide average growth rate of 2010–2017 persists, by 2030 Africa’s emissions will have risen by ∼30% (to 1545 MtCO2). Moreover, if increases in carbon intensity also continue, Africa’s emissions would be substantially higher. In either case, such growth is at odds with international climate goals. Achieving such goals will require that the energy for African countries’ development instead come from non-emitting sources.

Sectoral carbon dioxide emissions and environmental sustainability in Pakistan

Nearly three-quarters of the growth in global carbon emissions from the burning of fossil fuels and cement production between 2010 and 2012 occurred in China. Yet estimates of Chinese emissions remain subject to large uncertainty; inventories of China's total fossil fuel carbon emissions in 2008 differ by 0.3 gigatonnes of carbon, or 15 per cent. The primary sources of this uncertainty are conflicting estimates of energy consumption and emission factors, the latter being uncertain because of very few actual measurements representative of the mix of Chinese fuels. Here we re-evaluate China's carbon emissions using updated and harmonized energy consumption and clinker production data and two new and comprehensive sets of measured emission factors for Chinese coal. We find that total energy consumption in China was 10 per cent higher in 2000-2012 than the value reported by China's national statistics, that emission factors for Chinese coal are on average 40 per cent lower than the default values recommended by the Intergovernmental Panel on Climate Change, and that emissions from China's cement production are 45 per cent less than recent estimates. Altogether, our revised estimate of China's CO2 emissions from fossil fuel combustion and cement production is 2.49 gigatonnes of carbon (2 standard deviations = ±7.3 per cent) in 2013, which is 14 per cent lower than the emissions reported by other prominent inventories. Over the full period 2000 to 2013, our revised estimates are 2.9 gigatonnes of carbon less than previous estimates of China's cumulative carbon emissions. Our findings suggest that overestimation of China's emissions in 2000-2013 may be larger than China's estimated total forest sink in 1990-2007 (2.66 gigatonnes of carbon) or China's land carbon sink in 2000-2009 (2.6 gigatonnes of carbon).