Energy System Transformation for a 1.5°C Future

The document argues that while climate and energy scenarios are essential for target setting, they often rely on legacy modeling that can constrain imagination and overlook non-linear transformations. It distinguishes between scenarios (future snapshots), pathways (adaptive courses), and roadmaps (deterministic methods), and advises decision-makers to use a combination of top-down models and bottom-up assessments to identify a broader 'opportunity space'. The author highlights critical gaps in current scenarios, including a lack of stakeholder diversity, neglect of equity and non-emissions benefits, and a failure to account for learning curves in technological innovation and demand-side efficiency.

• The document distinguishes between three distinct tools for climate planning: scenarios provide a 'snapshot of what the future could look like', pathways 'chart a course from what is happening today to the landscape of a future scenario' while remaining adaptive, and roadmaps provide a 'specific outline for how an institution will align with a pathway' and are best for manageable, intermediate goals.
• Climate scenarios generally employ two methodologies: top-down models, which represent 'holistic system interactions' and produce mathematically consistent results but often miss emerging trends, and bottom-up assessments, which are 'narrative-driven scenarios' based on detailed sectoral literature reviews but lack guaranteed quantitative cohesion.
• The rigor of temperature rise claims in scenarios varies; the 'gold standard' involves using an Earth system module or calculating cumulative GHG emissions over the scenario's timespan, whereas less rigorous methods simply compare annual emissions at a few checkpoints to other scenarios.
• Current scenario development often suffers from 'tunnel vision' because it relies on historical data to project the future, neglecting human capacities for innovation, learning, and collective action.
• Scenarios frequently omit critical stakeholders—such as automakers, the steel industry, and subnational governments—and often neglect non-emissions benefits like equity, public health, and poverty reduction, typically relegating these to 'co-benefits'.
• The International Energy Agency (IEA) has historically underestimated solar PV expansion because its methodologies often treat technology cost as a 'function of time' rather than accounting for 'learning curves' driven by cumulative production experience.
• Demand-side efficiency and flexibility are powerful but underutilized levers in scenarios; for example, India's Energy Efficiency Services Limited (EESL) demonstrated the impact of aggregated procurement by deploying over 360 million LED light bulbs through its UJALA program.

APA

Mulvaney, K. (2021). Energy System Transformation for a 1.5°C Future. RMI. https://rmi.org/app/uploads/dlm_uploads/2020/12/rmi_using_climate_energy_scenarios.pdf

Chicago

Mulvaney, Katie. Energy System Transformation for a 1.5°C Future. RMI, 2021. https://rmi.org/app/uploads/dlm_uploads/2020/12/rmi_using_climate_energy_scenarios.pdf.

Wikipedia

{{cite report |last1=Mulvaney |first1=Katie |title=Energy System Transformation for a 1.5°C Future |publisher=RMI |date=February 2021 |url=https://rmi.org/app/uploads/dlm_uploads/2020/12/rmi_using_climate_energy_scenarios.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{mulvaney2021energy, author = {Mulvaney, Katie}, title = {{Energy System Transformation for a 1.5°C Future}}, institution = {RMI}, year = {2021}, month = feb, url = {https://rmi.org/app/uploads/dlm_uploads/2020/12/rmi_using_climate_energy_scenarios.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }