Evaluation of the Emissions Provided by the RCPs and SSPs Emission Scenarios

Simulations of climate change rely on emissions scenarios, which provide different estimates of the emissions of carbon dioxide and other compounds. These scenarios are designed, based on estimations of demographic patterns, economic development, social and environmental conditions for the next century.

The Representative Concentration Pathways (RCPs) scenarios were developed for the 5th IPCC Assessment (AR5) Report, and a new set of scenarios, the SPPs (Shared Socioeconomic Pathways) was published a few years ago, in support of the 6^th IPCC Assessment Report (AR6). These scenarios provide the emissions of chemically active species, and they have also been used in simulations of the distribution of tropospheric gases and aerosols in the coming decades.

Within Susan Solomon’s group at NOAA/CIRES, we have started to evaluate the emissions of several atmospheric compounds provided by inventories and emission scenarios. We will discuss the most recent results obtained as part of this study. Emissions from RCPs and SSPs since 2005 are compared with current state-of-the-art global and regional emission inventories, as well as with several recent top-down inverse modeling satellite estimates of various chemical species in different world regions. For each region, the SSP lying closest to recent trends in emissions is identified. This analysis allows to evaluate the current emission estimates and trends, bring into light differences and possible inconcistencies, and provide useful guidance in selecting the scenarios to be downscaled for particular regions for air quality, climate projections and regional impact studies.