A review of trends and drivers of greenhouse gas emissions by sector from 1990 to 2018

Abstract. To track progress towards keeping global warming well below 2 ∘C or even 1.5 ∘C, as agreed in the Paris Agreement, comprehensive up-to-date and reliable information on anthropogenic emissions and removals of greenhouse gas (GHG) emissions is required. Here we compile a new synthetic dataset on anthropogenic GHG emissions for 1970–2018 with a fast-track extension to 2019. Our dataset is global in coverage and includes CO2 emissions, CH4 emissions, N2O emissions, as well as those from fluorinated gases (F-gases: HFCs, PFCs, SF6, NF3) and provides country and sector details. We build this dataset from the version 6 release of the Emissions Database for Global Atmospheric Research (EDGAR v6) and three bookkeeping models for CO2 emissions from land use, land-use change, and forestry (LULUCF). We assess the uncertainties of global greenhouse gases at the 90 % confidence interval (5th–95th percentile range) by combining statistical analysis and comparisons of global emissions inventories and top-down atmospheric measurements with an expert judgement informed by the relevant scientific literature. We identify important data gaps for F-gas emissions. The agreement between our bottom-up inventory estimates and top-down atmospheric-based emissions estimates is relatively close for some F-gas species (∼ 10 % or less), but estimates can differ by an order of magnitude or more for others. Our aggregated F-gas estimate is about 10 % lower than top-down estimates in recent years. However, emissions from excluded F-gas species such as chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs) are cumulatively larger than the sum of the reported species. Using global warming potential values with a 100-year time horizon from the Sixth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global GHG emissions in 2018 amounted to 58 ± 6.1 GtCO2 eq. consisting of CO2 from fossil fuel combustion and industry (FFI) 38 ± 3.0 GtCO2, CO2-LULUCF 5.7 ± 4.0 GtCO2, CH4 10 ± 3.1 GtCO2 eq., N2O 2.6 ± 1.6 GtCO2 eq., and F-gases 1.3 ± 0.40 GtCO2 eq. Initial estimates suggest further growth of 1.3 GtCO2 eq. in GHG emissions to reach 59 ± 6.6 GtCO2 eq. by 2019. Our analysis of global trends in anthropogenic GHG emissions over the past 5 decades (1970–2018) highlights a pattern of varied but sustained emissions growth. There is high confidence that global anthropogenic GHG emissions have increased every decade, and emissions growth has been persistent across the different (groups of) gases. There is also high confidence that global anthropogenic GHG emissions levels were higher in 2009–2018 than in any previous decade and that GHG emissions levels grew throughout the most recent decade. While the average annual GHG emissions growth rate slowed between 2009 and 2018 (1.2 % yr−1) compared to 2000–2009 (2.4 % yr−1), the absolute increase in average annual GHG emissions by decade was never larger than between 2000–2009 and 2009–2018. Our analysis further reveals that there are no global sectors that show sustained reductions in GHG emissions. There are a number of countries that have reduced GHG emissions over the past decade, but these reductions are comparatively modest and outgrown by much larger emissions growth in some developing countries such as China, India, and Indonesia. There is a need to further develop independent, robust, and timely emissions estimates across all gases. As such, tracking progress in climate policy requires substantial investments in independent GHG emissions accounting and monitoring as well as in national and international statistical infrastructures. The data associated with this article (Minx et al., 2021) can be found at https://doi.org/10.5281/zenodo.5566761.

The role of global waste management and circular economy towards carbon neutrality

Agricultural transformation towards delivering deep carbon cuts in China’s arid inland areas

Agriculture is responsible for a large share of global greenhouse gas (GHG) emissions, especially for methane and nitrous oxide emissions. Applying a bio-economic whole-farm model, we assessed five GHG mitigation options on their economic suitability to reduce emissions from grassland-based suckler cow farms. Among the assessed options, only compensation by agroforestry systems and the choice of an adequate production system showed the potential to significantly reduce emissions. If an adequate production system is chosen, GHG emissions per kilogram of meat can be reduced by up to 18% – from 21.9 to 18 kg CO2-eq./kg of meat – while total gross margin can be increased by up to 14%. Through the application of an agroforestry system, GHG emissions in all systems can be further reduced to 7.5 kg CO2-eq./kg meat – equating to a reduction of GHG emissions of 48% to 66% – at costs between 0.03 CHF/kg meat and 0.38 CHF/kg meat depending on the production system and the state of the system before the reduction. In contrast, the addition of lipids to the diet or a cover to the slurry tank has neither the potential to reduce GHG emissions significantly nor are they cost-effective enough to be implemented. Nitrification inhibitors can reduce GHG emissions up to 10%, but costs for this reduction are much higher than for agroforestry systems. The application of agroforestry systems to suckler farming in Switzerland therefore seems to be an adequate option to reduce GHG emission significantly for a relatively low price.

Comparative lifecycle greenhouse gas emissions and their reduction potential for typical petrochemical enterprises in China

Shipping remains a crucial element of global trade and commerce, facilitating over 90% of international trade by volume. The maritime industry’s advanced logistics chains are vital for the timely delivery of goods, supporting both economic growth and employment. However, it is also a significant source of pollution, accounting for approximately 3% of global greenhouse gas (GHG) emissions, and contributing 13% of nitrogen oxides (NOx) and 12% of sulfur oxides (SOx). Additionally, shipping emits harmful pollutants, including particulate matter (PM), black carbon (BC), and methane (CH4). These emissions not only impact the global climate but also pose severe health risks to communities near shorelines, contributing to asthma, respiratory and cardiovascular diseases, lung cancer, and premature death.The International Maritime Organization (IMO) is actively engaged in mitigating these environmental impacts as part of its support for the UN Sustainable Development Goal 13, which addresses climate change in alignment with the 2015 Paris Agreement. The IMO has implemented several regulations to curb GHG emissions from shipping, beginning with mandatory energy efficiency measures introduced on July 15, 2011. Subsequent regulations include the Initial IMO GHG Strategy (2018) and the updated Strategy on Reduction of GHG Emissions from Ships (2023). The 2023 strategy sets ambitious targets to achieve near-zero GHG emissions from international shipping by around 2050, with interim goals of reducing emissions by at least 20% by 2030 and 70-80% by 2040. It also aims to cut the carbon intensity of international shipping by at least 40% by 2030, measured as CO2 emissions per unit of transport work. As of January 1, 2023, ships are required to calculate their Energy Efficiency Existing Ship Index (EEXI) and establish an annual operational Carbon Intensity Indicator (CII), with ratings from A to E indicating energy efficiency (International Maritime Organization).In response to evolving regulations aimed at reducing GHG emissions, we propose a machine learning framework to improve emission predictions, with a particular focus on the Saint Lawrence River. Currently, emissions in the Canadian shipping sector are calculated a posteriori, with Environment and Climate Change Canada (ECCC) providing a national marine emissions inventory and a comprehensive visualization tool. This tool enables users to analyze shipping activities and emissions across Canada by filtering data through various parameters.Our proposed work is designed to predict GHG emissions for vessels navigating the Saint Lawrence River, with plans for broader application across Canada. By employing a bottom-up methodology, we create a detailed emissions inventory based on individual vessel activities, leveraging Automatic Identification System (AIS) data to capture the spatiotemporal dynamics of shipping (Spire). To enhance accuracy, we incorporate vessel-specific information from CLARKSONS, including engine type, fuel type, and power, along with meteorological data such as current speed to account for external factors affecting emissions. Machine learning models, particularly deep learning techniques, are employed in the prediction phase, enabling the model to continually improve with new data. This scalable approach not only enhances environmental monitoring but also supports national efforts to reduce GHG emissions from marine transportation across Canada.

Determining end user computing device Scope 2 GHG emissions with accurate use phase energy consumption measurement

China is one of the largest contributors to global greenhouse gas (GHG) emissions, and the livestock sector is a major source of non-CO2 GHG emissions. Mitigation of GHG emissions from the livestock sector is beneficial to the sustainable development of the livestock sector in China. This study investigated the provincial level of GHG emissions from the livestock sector between 2000 and 2020 in China, to determine the driving factors affecting the provincial-level GHG emissions from the livestock sector, based on the logarithmic mean Divisia index (LMDI) model, which took into account of technological progress, livestock structure, economic factor, and agricultural population. Moreover, a gray model GM (1, 1) was used to predict livestock GHG emissions in each province until 2030 in China. The results showed that the GHG of Chinese livestock sector was decreased from 195.1 million tons (MT) CO2e in 2000 to 157.2 MT CO2e in 2020. Henan, Shandong, and Hebei provinces were the main contributors to the reduction in Chinese livestock GHG emissions, with their livestock GHG emissions reduced by 60.1%, 53.5% and 45.5%, respectively, in 2020 as compared to 2000. The reduction in GHG emissions from the Chinese livestock sector can be attributed to two main factors: technological progress and the shrinking of the agricultural laborers. In contrast, the agricultural economic development model with high input and high emissions showed a negative impact on GHG emission reduction in China’s livestock sector. Furthermore, the different livestock structure in each province led to different GHG reduction effects on the livestock sector. Under the gray model GM (1,1), the GHG emissions of the livestock sector will be reduced by 33.7% in 2030 as compared with 2020 in China, and the efficiency factor will account for 76.6% of the positive effect of GHG reduction in 2030. The eastern coastal region will be the main contributor to the reduction of GHG emissions from the Chinese livestock sector in 2030. Moreover, recommendations (such as upgrading livestock management methods and promoting carbon emission mitigation industries) should be proposed for the environmentally sustainable development of the livestock sector in the future.

Advanced wastewater treatment processes and novel technologies are adopted to improve nutrient removal from wastewater so as to meet stringent discharge standards. Municipal wastewater treatment plants are one of the major contributors to the increase in the global greenhouse gas (GHG) emissions and therefore it is necessary to carry out intensive studies on quantification, assessment and characterization of GHG emissions in wastewater treatment plants, on the life cycle assessment from GHG emission prospective, and on the GHG mitigation strategies. Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants summarises the recent development in studies of greenhouse gases’ (CH4 and N2O) generation and emission in municipal wastewater treatment plants. It introduces the concepts of direct emission and indirect emission, and the mechanisms of GHG generations in wastewater treatment plants’ processing units. The book explicitly describes the techniques used to quantify direct GHG emissions in wastewater treatment plants and the protocol used by the Intergovernmental Panel on Climate Change (IPCC) to estimate GHG emission due to wastewater treatment in the national GHG inventory. Finally, the book explains the life cycle assessment (LCA) methodology on GHG emissions in consideration of the energy and chemical usage in municipal wastewater treatment plants. In addition, the strategies to mitigate GHG emissions are discussed. The book provides an overview for researchers, students, water professionals and policy makers on GHG emission and mitigation in municipal wastewater treatment plants and industrial wastewater treatment processes. It is a valuable resource for undergraduate and postgraduate students in the water, climate, and energy areas; for researchers in the relevant areas; and for professional reference by water professionals, government policy makers, and research institutes. ISBN: 9781780406305 (Print) ISBN: 9781780406312 (eBook) ISBN: 9781780409054 (ePUB)

Operational insights into carbon dynamics and decarbonization pathways in megacity water supply plants.

The refining industry is the third-largest source of global greenhouse gas (GHG) emissions from stationary sources, so it is at the forefront of the energy transition and net zero pathways. The dynamics of contributors in this sector such as crucial countries, leading enterprises, and key emission processes are vital to identifying key GHG emitters and supporting targeted emission reduction, yet they are still poorly understood. Here, we established a global sub-refinery GHG emission dataset in a long time series based on life cycle method. Globally, cumulative GHG emissions from refineries reached approximately 34.1 gigatons (Gt) in the period 2000-2021 with an average annual increasing rate of 0.7%, dominated by the United States, EU27&UK, and China. In 2021, the top 20 countries with the largest GHG emissions of oil refining accounted for 83.9% of global emissions from refineries, compared with 79.5% in 2000. Moreover, over the past two decades, 53.9-57.0% of total GHG emissions came from the top 20 oil refining enterprises with the largest GHG emissions in 12 of these 20 countries. Retiring or installing mitigation technologies in the top 20% of refineries with the largest GHG emissions and refineries with GHG emissions of more than 0.1 Gt will reduce the level of GHG emissions by 38.0%-100.0% in these enterprises. Specifically, low-carbon technologies installed on furnaces and boilers as well as steam methane reforming will enable substantial GHG mitigation of more than 54.0% at the refining unit level. Therefore, our results suggest that policies targeting a relatively small number of super-emission contributors could significantly reduce GHG emissions from global oil refining.

The Paris Agreement's central aim is to strengthen the global response to the threat of climate change by keeping the global temperature rise during this century well below 2°C above preindustrial levels and to pursue efforts to further limit the temperature increase to less than 1.5°C above the preindustrial levels. China has already signed the Paris Agreement, and its action plays a vital role in determining the outcome of the Agreement. As the largest developing country, it accounted for 26% of total global greenhouse gas (GHG) emissions in 2016. China's emissions grew very rapidly during the reform period of the past 40 years. If China does not comply with the Agreement, then it is hard for the world to achieve the goals it has set for itself. But it is by no means an easy task for China. Although the aggregate size of GHG emissions already dominate the global picture, China's per capita emissions are still significantly below the levels of many developed and developing countries. It would be difficult to convince the Chinese public that China should cut emissions aggressively, especially if this comes with a significant economic cost. As some Chinese commentators put it: since all the advanced countries had their GHG emissions during their early stages of economic development, why should China now be stripped of the right to develop its economy? So the question is if deep cuts to GHG emissions would be harmful for the Chinese economy. In their paper (Jiang et al., 2021), Jiang and his research team provide an excellent analytical foundation for thinking about the issues of GHG emission cuts, not only for the public, but also for policymakers. By building a quantitative model, Jiang et al. are able to derive numerical results on the likely impact on the macroeconomy, industrial structure, and the composition of energy. The most important finding, in my view, is that achievement of the “2°C” goal could actually result in China's gross domestic product (GDP) in 2050 being 1.5% higher, and consumption being 1.7% higher, compared with the baseline scenario. Indeed, this is very encouraging. Of course, the efforts trying to achieve the “2°C” goal could force a lot of structural changes in the Chinese economy. But these structural changes could make the overall economy more efficient, while bringing about new investment at the same time. The common perception that deep cuts to GHG emissions will mean a loss for China is simply wrong. By significantly reducing GHG emissions, China not only contributes to the global environment, but also improves its own economy. With this empirical judgment, Jiang and his colleagues should be more effective in convincing their bosses at the National Development and Reform Commission (NDRC) and the State Council to set a more ambitious target of peaking of CO2 emissions earlier – it is not only doable, but also beneficial. In fact, the Chinese economy is already in the middle of important structural changes in favor of GHG emission reduction. The share of the manufacturing sector in the overall economy peaked in 2012 and the weight of the service sector is rising quickly. Such changes and other efforts trying to improve efficiency could make the “2°C” goal or even the “1.5°C” goal more attainable. However, these results do not imply that implementation of deep cuts to GHG emissions will be painless. As Jiang et al. (2021) demonstrate, important adjustments will have to take place in order to achieve the policy goal, including changing the composition of energy supply, raising the share of electrification and upgrading technology in the transportation sector. Some industrial sectors, such as the steel, cement and chemical industries, could experience major changes. Therefore, success or failure of the “deep cut” policy depends not only on the government's determination, but also, more importantly, on policy skills to smooth the transition process. This calls for policy measures to help workers, factories, and regions that are affected by the transition process. This will be a key test for the Chinese government, including Jiang and his colleagues at the NDRC.

Sustainable Diet Studies Show Co-Benefits for Greenhouse Gas Emissions and Public Health

The transportation sector is a significant contributor to global greenhouse gas (GHG) emissions, accounting for approximately 14 % of all anthropogenic GHG emissions. Despite the increasing popularity of electric vehicles, internal combustion engines (ICEs) continue to dominate the global vehicle fleet, making it essential to find a way to reduce GHG emissions from this sector. One potential solution is the use of efuels, also known as synthetic fuels, which can significantly reduce GHG emissions from transportation. While there are still several challenges associated with their production and use, the benefits of efuels make them a solution worth pursuing. Continued research and development are necessary to improve the efficiency and cost-effectiveness of efuel production and to ensure that they are a sustainable and environmentally responsible solution for the future of transportation. This paper will explore efuels and their potential to decarbonize the transportation sector.

The shipping industry is responsible for 3% of global greenhouse gas (GHG) emissions, emissions mainly resulting from the combustion of fuels in naval energy aggregates. The current requirements for a 50% reduction in GHG emissions by 2050 represent a challenge for maritime transport, as there is no effective solution to reduce this emissions from ships. Thus, the current problem is represented by insufficient methods to reduce CO2 emissions on board ships, in particular for ships which are in service for more than 10 years, which are the most affected by these environmental requirements, since their design did not take into account the reduction of ecological parameters. In this context, even if military vessels are not subject to IMO GHG emission reduction requirements, they must be aligned with global emissions reduction efforts. This article presents actually operational and technological solutions to reduce CO2 emissions that can be deployed on board military vessels, until other technical solutions or power supply solutions for non-polluting renewable energy aggregates are identified.