PNNL

Abstract

Comprehensive and reliable information on anthropogenic sources of greenhouse gas emissions is required to track progress towards keeping warming well below 2°C as agreed upon in the Paris Agreement. Here we provide a dataset on anthropogenic GHG emissions 1970-2019 with a broad country and sector coverage. We build the dataset from recent releases from the “Emissions Database for Global Atmospheric Research” (EDGAR) for CO2 emissions from fossil fuel combustion and industry (FFI), CH4 emissions, N2O emissions as well as the release of fluorinated gases and use a well-established fast-track method to extend this dataset to 2019. We complement this with information on net CO2 emissions from land use, land-use change and forestry (LULUCF) from three available bookkeeping models. We provide an assessment of the uncertainties in global GHG emissions by combining statistical analysis and comparisons of global emissions inventories with an expert judgement of the likelihood of results lying outside a 90% confidence interval (5th-95th percentile) informed by the relevant scientific literature. We identify important data gaps: CH4 and N2O emissions could be 10- 20% higher than reported in EDGAR once all emissions are accounted, respectively. F-gas emissions estimates for individual species in EDGARv5 do not align well with atmospheric measurements and the F-gas aggregate overreports the measured concentrations by about 30%. However, EDGAR and official national emission reports under the UNFCCC do not comprehensively cover all relevant F-gases species. Excluded F-gas species such as chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs) are larger than the sum of the reported species. GHG emissions in 2019 tracked at 59±6.6 GtCO2eq: CO2 emissions from FFI were 38 (±3.0) Gt, CO2 from LULUCF 6.6±4.6 Gt, CH4 11±3.3 GtCO2eq, N2O 2.4±1.5 GtCO2eq and F-gases 1.6±0.49 GtCO2eq. Our analysis of global, anthropogenic GHG emission trends over the past five decades (1970-2019) highlights a pattern of varied, but sustained emissions growth. There is high confidence that global anthropogenic greenhouse gas emissions have increased every decade. Emission growth has been varied, but persistent across different (groups of) gases. While CO2 has accounted for almost 75% of the emission growth since 1970 in terms of CO2eq as reported here, the combined F-gases have grown much faster than other GHGs, albeit starting from very low levels. Today, they make a non-negligible contribution to global warming – even though if CFCs and HCFCs are not considered. There is further high confidence that global anthropogenic GHG emissions levels were higher in 2010-2019 than in any previous decade and GHG emissions levels have grown across the most recent decade. While average annual greenhouse gas emissions growth slowed between 2010-2019 compared to 2000-2009, the absolute increase in average decadal GHG emissions from the 2000s to the 2010s has been the largest since the 1970s – and within all human history as suggested by available long-term data. We note considerably higher rates of change in GHG emissions between 2018 and 2019 than for the entire decade 2010-2019, which is numerically comparable with the period of high GHG emissions growth during the 2000s, but we place low confidence in this value as the majority is driven by highly uncertain increases in CO2-LULUCF emissions as well as the use of preliminary data and extrapolation methodologies for these most recent years. While there is a growing number of countries today on a sustained emission reduction trajectory, our analysis further reveals that there are no global (sub-) sectors that show sustained reductions in GHG emissions. We conclude by highlighting that tracking progress in climate policy requires substantial investments in GHG emission accounting and monitoring as well as the available statistical infrastructure.