RCP4.5: a pathway for stabilization of radiative forcing by 2100

TLDR

RCP4.5 is a scenario that stabilizes radiative forcing at 4.5 W m⁻² by 2100, offering a common platform for climate models to study the climate system response to stabilizing anthropogenic forcing. The purpose is to provide a common platform for climate models to explore the climate system response to stabilizing anthropogenic radiative forcing. Simulated with GCAM, RCP4.5 incorporates long‑term global emissions of greenhouse gases, short‑lived species, and land‑use changes within a cost‑minimizing global economic framework, updated with historical emissions and land cover, and downscaled to a grid for climate model use. Under RCP4.5, the emissions price applied to land‑use emissions leads to an expansion of forest lands from their current extent.

Abstract

Representative Concentration Pathway (RCP) 4.5 is a scenario that stabilizes radiative forcing at 4.5 W m−2 in the year 2100 without ever exceeding that value. Simulated with the Global Change Assessment Model (GCAM), RCP4.5 includes long-term, global emissions of greenhouse gases, short-lived species, and land-use-land-cover in a global economic framework. RCP4.5 was updated from earlier GCAM scenarios to incorporate historical emissions and land cover information common to the RCP process and follows a cost-minimizing pathway to reach the target radiative forcing. The imperative to limit emissions in order to reach this target drives changes in the energy system, including shifts to electricity, to lower emissions energy technologies and to the deployment of carbon capture and geologic storage technology. In addition, the RCP4.5 emissions price also applies to land use emissions; as a result, forest lands expand from their present day extent. The simulated future emissions and land use were downscaled from the regional simulation to a grid to facilitate transfer to climate models. While there are many alternative pathways to achieve a radiative forcing level of 4.5 W m−2, the application of the RCP4.5 provides a common platform for climate models to explore the climate system response to stabilizing the anthropogenic components of radiative forcing.