All equations and parameters in En-ROADS are included in the ~400 page Reference Guide. Some of the key assumptions are listed below.

For the En-ROADS Baseline scenario, we chose to adopt the baseline scenario definition from one of the foundational papers on the Shared Socioeconomic Pathway scenarios, (Riahi et al., 2017): “a description of future developments in absence of new climate policies beyond those in place today” and which “do[es] not consider feedbacks from the climate system on its key drivers such as socioeconomic impacts of climate change.”

Assumptions behind drivers of growth in CO2 emissions:

The drivers of growth in carbon dioxide emissions are explained by the Kaya equation

Global Population x GDP per Capita x Energy Intensity of GDP x Carbon Intensity of Energy = CO2 Emissions from Energy

  • Population growth: United Nations medium growth scenario

  • Economic growth (GDP per capita):

    • Long-term economic growth rate: 1.5%/year

    • Near-term economic growth rate: 2.5%/year

    • Transition time to convert from near-term economic growth rate to long-term economic growth rate: 75 years

  • Energy intensity of GDP

    • Buildings and Industry: 1.2%/year improvement in energy efficiency

    • Transportation: 0.5%/year improvement in energy efficiency

  • Carbon intensity of energy

    • Progress ratio for growth of renewables and new technology: 0.8 (every doubling of cumulative capacity brings a 20% drop in cost)

Other key assumptions in the En-ROADS Baseline:

  • Methane: closely follows SSP2

  • Carbon removal: none

  • Climate system sensitivity (how much global temperature will increase per doubling of atmospheric CO₂ above pre-industrial levels): 3°C

  • Calibration: SSP2 baseline scenarios of a suite of Integrated Assessment Models, specifically, PBL IMAGE, PNNL GCAM4, PIK REMIND-MAGPIE, NIES AIM/CGE, IIASA MESSAGE-GLOBIOM, and EIEE WITCH-GLOBIOM (Riahi et al., 2017Rogelj et al., 2018Gidden et al., 2019)

Currently, the factors below are not included in the En-ROADS Baseline scenario:

  • Climate impacts such as negative economic repercussions of unmitigated climate change

  • Countries’ Nationally Determined Contributions (NDCs) under the Paris Agreement

  • Other future climate policy and associated economic impacts

You can modify many of these assumptions in En-ROADS in the Assumptions menu (under Simulation > Assumptions). Changing these assumptions will affect the current scenario but will not change the Baseline scenario (the black line in the graphs). You cannot modify the Baseline scenario in En-ROADS at this time.