En-ROADS and C-ROADS June 2023: Baseline Scenario

By Climate Interactive
June 1, 2023

The June 2023 En-ROADS and C-ROADS update introduces numerous improvements, with the change to the Baseline Scenarios being among the most notable. See the video above for a summary of these changes or read more below.

The temperature in 2100 for the En-ROADS and C-ROADS Baseline Scenarios is 0.3 °C lower than what it was previously. This is primarily due to the inclusion of the economic damage function (covered in depth here), in which temperature increase causes lower economic growth, resulting in lower energy demand and CO₂ emissions.

Updates in En-ROADS, aside from the damage function, result in different behavior in the Baseline Scenario from what it was previously:

• Less coal and oil, mostly due to a new carbon price of $5/ton CO₂ in the Baseline
• More renewable energy, from the carbon price, a faster decrease in wind and solar costs than previously expected, and a continuation of historical subsidies for renewables past 2030
• Substantially higher CO₂ emissions from bioenergy and land use emissions because of significant improvements to land use modeling
• Less carbon capture and storage (CCS) because it is now driven in the model only by a carbon price (and the current price of $5/ton CO₂ is low)
• More electrification of transport and less electrification of buildings and industry due to significant improvements in electrification modeling

Understanding the Baseline Scenario

The En-ROADS and C-ROADS Baseline Scenarios are a reasonable starting point for testing climate action and exploring the impact it could have. They are not a forecast of what is likely to happen. The Baseline Scenarios include an approximate, aggregated implementation of current global technological, policy, and investment conditions. Climate policies in place around the world today, such as the United States’ Inflation Reduction Act and China’s “1+N” framework, are promoting renewables, continuing to subsidize oil and gas, and incentivizing energy efficiency and electrification. En-ROADS and C-ROADS do not explicitly represent local, national, international, and corporate policies, but instead estimate the overall effects of the conditions they create. The Baseline Scenarios assume that such conditions will continue, but they do not strengthen or weaken:

Comparison to other modeling teams’ scenarios

A key procedure in testing our simulators involves comparing their results with other models, particularly the Integrated Assessment Models (IAMs) used by the Intergovernmental Panel on Climate Change (IPCC). IAMs aid scientists and policymakers in understanding climate change dynamics and human impact. By comparing against standardized scenarios used by IAMs, we test assumptions and build confidence that the simulator’s results reflect the best understanding of the scientific literature. See the video above for a summary of testing and comparisons or read more below.

Whereas the previous 2022 En-ROADS Baseline Scenario was calibrated to a no-climate-policy scenario from the Shared Socioeconomic Pathways (the SSP2 Baseline), the 2023 version of En-ROADS is now compared to a newer set of standardized scenarios created by the Network for Greening the Financial System (NGFS)¹. The NGFS is an international consortium of central banks and financial institutions, and their scenarios contributed to the most recent IPCC Assessment Report (AR6 2022). The NGFS’s Current Policies Scenario assumes that the only policies that continue into the future are policies that were implemented around the end of 2019. This is similar to the assumptions in the En-ROADS Baseline Scenario, making it a useful comparison. Three different integrated assessment modeling teams contributed to the NGFS scenarios and generated their own versions of the NGFS’s Current Policies Scenario.

The graph below compares greenhouse gas emissions in the 2023 En-ROADS Baseline Scenario to the three IAMs that evaluated the NGFS Current Policies Scenario. The En-ROADS Baseline Scenario uses different assumptions than the IAMs—for example, population in the En-ROADS Baseline Scenario is higher because it follows United Nations population projections, and the carbon prices in the NGFS Current Policies Scenario grow higher than the carbon price in the En-ROADS Baseline Scenario. The variation between the En-ROADS Baseline Scenario and the IAMs producing the NGFS Current Policies Scenario is similar to the variation among the IAMs themselves within the NGFS Current Policies Scenario.

The IPCC’s Sixth Assessment Synthesis Report (2023) gives a range of greenhouse gas emissions for implemented policy scenarios, which include the NGFS Current Policies Scenario (graph below). In terms of global net greenhouse gas emissions, the En-ROADS Baseline Scenario is at the higher end of the range of scenarios in the Implemented Policies category due to differences in assumptions about the cascading effects of policies and model dynamics.

Footnotes

1. Network for Greening the Financial System. (2022). NGFS scenarios for central banks and supervisors. The NGFS scenarios were created to be a “common starting point for analyzing climate risks to the economy and financial system.” Three integrated assessment modeling teams contributed to the NGFS scenarios: PIK REMIND-MAgPIE, JGCRI GCAM, and IIASA MESSAGEix-GLOBIOM. ↩