Model Comparison – History🔗
The purpose of this section of the En-ROADS Technical Reference is to supplement the historical comparison graphs in the En-ROADS application by sharing multiple comparisons of En-ROADS model behavior compared against measured historical data.
Table of Contents🔗
- Use of Historical Data in En-ROADS
- Primary Energy Demand History
- Final Energy Consumption History
- Electricity Generated by Energy Source History
- Marginal Cost of Wind, Solar, and Geothermal Electricity History
- Emissions History
- Atmospheric Concentrations History
- Radiative Forcing History
- Temperature History
Use of Historical Data in En-ROADS🔗
En-ROADS uses historical data for two purposes: initialization of the simulation and calibration. Certain variables in En-ROADS are initialized with their measured historical values from 1990, and then the model runs. We compare the model output from 1990 through present day to measured historical data to identify opportunities for model improvement.
The graphs below compare the En-ROADS Baseline Scenario to measured historical data for select variables. Not all variables and comparisons to history are included here. The historical data are derived from the following sources:
- Energy Institute. (2024). Statistical Review of World Energy.
- Global Carbon Budget: Friedlingstein, P., et al. (2025). Global carbon budget 2023. Earth System Science Data, 17(3), 965-1039. [CO2 energy emissions only]
- IEA. (2020). Evolution of solar PV module cost by data source, 1970-2020.
- IEA. (2024). World Energy Statistics & Balances.
- IRENA. (2023). Renewable Power Generation Costs in 2022.
- Lazard. (2023). Lazard's Levelized Cost of Energy Analysis - Version 16.0.
- Met Office: Morice, C. P., et al. (2022). An updated assessment of near-surface temperature change from 1850: the HadCRUT5 dataset. Journal of Geophysical Research: Atmospheres, 126, e2019JD032361. Data is from HadCRUT version 5.0.2.0 (2024), available at https://www.metoffice.gov.uk/hadobs/hadcrut5/data/HadCRUT.5.0.2.0/download.html.
- NASA GISS. (2025). GISS Surface Temperature Analysis (GISTEMP), version 4. NASA Goddard Institute for Space Studies.
- NOAA AGGI: NOAA. (2023). Annual Greenhouse Gas Index.
- NOAA ESRL: NOAA. (2025). Trends in Atmospheric Carbon Dioxide.
- PRIMAP: Gütschow, A., Busch, D., & Pflüger, M. (2024). The PRIMAP-hist national historical emissions time series v2.6 (1750-2023). [Non-CO2 greenhouse gas emissions only]
Five historical comparison graphs are also included in the En-ROADS app under Graphs > Model Comparison—Historical and are included and disaggregated here:
- Greenhouse Gas Net Emissions History
- Primary Energy Demand of Coal, Oil, and Gas History
- Primary Energy Demand of Wind and Solar History
- Marginal Cost of Solar Electricity History
- Temperature History
Primary Energy Demand History🔗
Global primary energy demand of energy sources for the En-ROADS Baseline Scenario compared to historical data. This is measured in exajoules per year (joules x 1018/year) for electric and nonelectric sources combined.
Primary energy refers to the total energy from a raw energy source that is converted into consumable energy. For example, primary coal energy demand refers to the total energy in coal that is mined, processed, and consumed. Primary energy is greater than final energy consumption because it accounts for inefficiencies in fuel processing, thermal conversion, and transmission and distribution (T&D).
En-ROADS, as well as many other sources, assumes that nuclear energy has an efficiency of 100% conversion of primary energy into electricity generated. Some sources, like the IEA World Energy Statistics & Balances, assume that the primary energy equivalent from the electricity generation has an efficiency of 33%. To compare En-ROADS output to the IEA World Energy Statistics & Balances, we multiply the primary energy from nuclear in En-ROADS by 3.
Final Energy Consumption History🔗
Global total final consumption of energy sources in exajoules/year (joules x 1018/year) for electric and nonelectric sources combined in the En-ROADS Baseline Scenario compared to historical data.
Final consumption refers to the total energy consumed to meet the demand of all final energy uses plus the use of feedstocks for products like plastics. For example, how much electricity a lightbulb uses or how much fuel a truck burns are measures of final energy consumption. It does not include energy lost through transmission and distribution (T&D) or inefficiencies, which, in contrast, is accounted for in primary energy.
Final energy consumption is divided into two end uses: stationary (buildings and industry) and transport.
Electricity Generated by Energy Source History🔗
Marginal Cost of Wind, Solar, and Geothermal Electricity History🔗
The marginal cost of electricity production from wind, solar, and geothermal energy in dollars ($US 2021) per kilowatt hour (kWh) in the En-ROADS Baseline compared to historical data. This is the marginal cost for energy producers to make electricity from a new solar, wind, or geothermal installation. The cost factors in how much it costs to build new energy generation facilities (the levelized capital costs), how much it costs to operate and maintain new facilities (O&M), and how much it costs to store the energy.
Emissions History🔗
Global greenhouse gas emissions (GHGs) in the En-ROADS Baseline Scenario and historical data, in gigatons of CO2 or CO2 equivalents per year. CO2 equivalents are used to standardize the effect of all greenhouse gases in terms of CO2.
The Greenhouse Gas Net Emissions graph measures the total gross greenhouse gas emissions minus the total net anthropogenic carbon dioxide removal (CDR). Contributions to gross GHGs are from carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and the F-gases (PFCs, SF6, and HFCs).
Atmospheric Concentrations History🔗
Radiative Forcing History🔗
The radiative forcing due to CO2, CH4, N2O, and halocarbons in the atmosphere, in watts per meter squared (W/m2), in the En-ROADS Baseline Scenario compared to historical data. Halocarbons refer to F-gases (PFCs, SF6, and HFCs) and Montreal Protocol gases.
Greenhouse gases absorb infrared radiation and re-radiate it back, causing an increase in surface temperature. Radiative forcing measures the difference between energy absorbed by the Earth and energy radiated back into space. When incoming energy is greater than outgoing energy, RF is positive and the planet will warm.
Temperature History🔗
Temperature change from 1850 in the En-ROADS Baseline Scenario compared to historical data, in degrees Celsius. NASA GISS (GISTEMP v4) includes the average and the lower and upper 95% confidence intervals.