According to the International Energy Agency (IEA), setting upon a “well below 2oC” pathway in concert with the Paris Agreement implies “comprehensive, systematic, immediate and ubiquitous implementation of strict energy and material efficiency measures.”6 Given a wide range of uncertainties, no single pathway can be reasonably predicted. As a result, many governments, universities and non-governmental organizations are seeking to analyze potential 2oC scenarios or pathways. Such studies may be useful in helping identify options to address climate risks and ensure energy remains reliable and affordable.
A key uncertainty relates to advances in technology that may influence the cost and potential availability of certain pathways toward a 2oC scenario. Many potential pathways are designed to utilize a full range of technology options, which may have significant benefits for society by minimizing related costs of a dramatic transition process.
Considerable work has been done in the scientific community to explore energy transformation pathways. A recent multi-model study coordinated by the Energy Modeling Forum at Stanford University (EMF 27) brought together many energy-economic models to assess technology and policy pathways associated with various climate stabilization targets (e.g., 450, 550 ppm CO2 equivalent or CO2e), partially in support of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).
The chart above illustrates potential CO2 emission trajectories under EMF 27 full technology scenarios7 targeting a 2oC pathway (Assessed 2oC Scenarios) relative to the 2018 Outlook, and baseline pathways (Assessed Baseline Scenarios) with essentially no policy evolution. The 2018 Outlook incorporates significant efficiency gains and changes in the energy mix, resulting in a projected CO2 emissions trajectory that resides between the pathways illustrated by the baseline and 2oC scenarios.
A key characteristic of the Assessed 2oC Scenarios is that energy-related CO2 emissions go to zero, or potentially negative, by the end of the century. As shown, the 2oC pathways represent a stark and fairly rapid transition from the baseline scenarios, while also illustrating significantly different emission trajectories toward a 2oC ambition.
Many experts developed scenarios to reduce global CO2 emissions consistent with an atmospheric GHG concentration (450 ppm CO2e in 2100) consistent with a 2oC pathway. The chart above shows potential indicative pathways based on results of 13 models.