Global emissions pathways under different socioeconomic scenarios for use in CMIP6: a dataset of harmonized emissions trajectories through the end of the century

Abstract

Abstract. We present a suite of nine scenarios of future emissions trajectories of anthropogenic sources, a key deliverable of the ScenarioMIP experiment within CMIP6. Integrated Assessment Model results for 14 different emissions species and 13 emissions sectors are provided for each scenario with consistent transitions from the historical data used in CMIP6 to future trajectories using automated harmonization before being downscaled to provide higher emission source spatial detail. We find that the scenarios span a wide range of end-of-century radiative forcing values, thus making this set of scenarios ideal for exploring a variety of warming pathways. The set of scenarios are bounded on the low end by a 1.9 W m-2 scenario, ideal for analyzing a world with end-of-century temperatures well below 2 °C, and on the high-end by a 8.5 W m-2 scenario, resulting in an increase in warming of nearly 5 °C over pre-industrial levels. Between these two extremes, scenarios are provided such that differences between forcing outcomes provide statistically significant regional temperature outcomes to maximize their usefulness for downstream experiments within CMIP6. A wide range of scenario data products are provided for the CMIP6 scientific community including global, regional, and gridded emissions datasets.

Significant climate impacts of aerosol changes driven by growth in energy use and advances in emissions control technology

“…Present-day anthropogenic aerosol emissions are largely influenced by sectors including power generation, industry and transport. However, in some of the future emission pathways, for example the Tier-15 1 Shared Socioeconomic Pathways scenarios (SSP1; Gidden et al (2018)), aerosol emissions are expected to decline drastically worldwide as we transit to non-fossil-fuel-based fields together with rapid implementation of air pollution control measures and new technologies. However, the timing and rate of such transitions are largely uncertain.…”

“…For example, the sign and magnitude of the effect of aerosols on clouds and precipitation can vary substantially depending on emission locations, forcing types as well as meteorological conditions (Rosenfeld et al, 2008;Stevens and Feingold, 2009;Yu et al, 2014;20 Malavelle et al, 2017;Kasoar et al, 2018). Also, there are large uncertainties due to the incomplete knowledge of both historical aerosol emissions and how they will evolve in the future (Gidden et al, 2018). All these uncertainties make it challenging to project future climate and to quantify the associated impacts on a range of sectors.…”

“…Aerosol mitigation, however, may lead to adverse climate impacts, such as the increased risk of climate extremes (Kloster et al, 2010;Samset et al, 2018a;Zhao et al, 2018;Zhao et al, 2019). A 5 number of equally-plausible future emission pathways have been designed to seek a compromise between the impacts of air pollution on environment and climate following aerosol abatement in the near-, medium-, and long-term (Gidden et al, 2018).…”

Gridded Emissions for CMIP6

“…This harmonization process adjusts the native model data to match the 2015 starting year 5 values with a smooth transition forward in time, generally converging to native model results (Gidden et al 2018). The production of the harmonized future emissions data is described in Gidden et al (2019).…”

“…One focal point of that work was 40 the compilation of a year 2000 emissions dataset that was used as the starting point for the future projections. See Hoesly et al (2018) and van Marle et al (2017) for a comparison of the CMIP6 and CMIP5 anthropogenic and open burning datasets respectively, and Gidden et al (2019) for a comparison of the CMIP6 and CMIP5 projections.…”