Representative Concentration Pathways

Representative Concentration Pathways
Efbrazil · CC BY-SA 4.0 · source
Name	Representative Concentration Pathways
Abbreviation	RCPs
Developed by	Intergovernmental Panel on Climate Change
First published	2011
Succeeded by	Shared Socioeconomic Pathways
Purpose	radiative forcing scenarios for climate modelling

Representative Concentration Pathways are a set of greenhouse gas concentration scenarios used to project future climate change, designed to provide standardized forcing trajectories for climate models and impact studies. They were prepared for the Intergovernmental Panel on Climate Change assessment process and have been widely used by research groups, national agencies, and international bodies to compare outcomes across models and policies.

Overview

The RCP framework was developed to link atmospheric concentration trajectories with radiative forcing targets for the years 2100 and beyond, enabling coordinated experiments across climate centres such as Hadley Centre, GFDL, MPI-M and NASA Goddard Institute for Space Studies while informing assessments by organizations including United Nations Framework Convention on Climate Change, World Meteorological Organization and International Energy Agency. Each RCP specifies a pathway of radiative forcing measured in watts per square metre, which climate modelling groups use to drive coupled atmosphere–ocean general circulation models like CMIP5 and to assess impacts in disciplines represented by institutions such as IPCC working groups and national laboratories like Lawrence Berkeley National Laboratory. The RCPs were adopted in major assessments and policy analyses alongside scenarios from agencies such as OECD and World Bank.

Development and Methodology

Creation involved climate scientists, integrated assessment modelers, and chemistry–climate experts from centres including Potsdam Institute for Climate Impact Research, IIASA, MIT and Stanford University who combined emissions inventories, concentration pathways, and radiative forcing calculations using codes from groups like MAGICC and IMAGE. The methodology translated emissions scenarios from teams such as MESSAGE, GCAM, EPPA and AIM into concentration trajectories using carbon cycle models and atmospheric chemistry schemes developed at NCAR and Met Office Hadley Centre, with subsequent calculation of effective radiative forcing following protocols from IPCC reports and peer-reviewed literature in journals like Nature and Science. Quality control and harmonization were overseen by coordination among editorial committees that included contributors from NOAA, CSIRO, NASA, and university consortia such as University of Oxford and Columbia University.

Individual RCP Scenarios

The four canonical pathways—commonly cited as RCP2.6, RCP4.5, RCP6.0 and RCP8.5—represent distinct long-term radiative forcing levels; these trajectories were derived from scenario families produced by modeling teams including IMAGE for low forcing, AIM and MESSAGE for intermediate forcing, and fossil-fuel–intensive narratives associated with groups such as IIASA and MIT. RCP2.6 corresponds to strong mitigation assumptions akin to policy targets discussed at Paris Agreement negotiations and analyses by UNFCCC; RCP4.5 and RCP6.0 represent stabilization without overshoot explored by EPA and academic assessments; RCP8.5 reflects high-emission pathways used in studies by IPCC authors and climate impact teams at Scripps Institution of Oceanography and University of Washington. Each scenario was paired with concentration inputs for greenhouse gases, aerosols, and land-use change derived from datasets maintained by institutions like Purdue University and Carnegie Institution for Science.

Climate Model Applications and Projections

RCPs served as inputs to multi-model intercomparison projects such as CMIP5 and influenced projections of temperature, precipitation, sea level, and extreme events generated by modelling centres including NOAA's Geophysical Fluid Dynamics Laboratory, Met Office, and IPSL. Results informed assessments in sectoral studies by organizations such as IPCC and World Health Organization and underpinned national climate assessments by agencies like USGCRP and European Environment Agency. The RCP-driven outputs were used in impact analyses for regions and cities including studies by C40 Cities and national institutes like Australian Bureau of Meteorology to evaluate risks to sectors overseen by bodies such as FAO and IMO.

Socioeconomic Assumptions and Emissions Pathways

Although RCPs specify concentrations and radiative forcing, the underlying socioeconomic narratives were provided by integrated assessment models from teams like IIASA, Potsdam Institute, GCAM and MESSAGE that incorporated assumptions about population trends from United Nations Department of Economic and Social Affairs, economic growth patterns studied at World Bank and technology deployment scenarios evaluated by IEA. Land-use pathways linked to datasets from FAO and modelling at Max Planck Institute for Meteorology defined emissions from agriculture, forestry, and other sectors, while energy system transitions reflected assumptions appearing in analyses by McKinsey & Company and academic groups at Imperial College London.

Criticisms and Limitations

Critiques arose from researchers at institutions like University of Exeter, Princeton University, and Stockholm Resilience Centre who argued that RCPs conflated concentration targets with socioeconomic narratives, that high-end scenarios such as RCP8.5 were mischaracterized in policy debates involving UNFCCC negotiators, and that aerosol forcing and regional climate responses remained uncertain in studies published in Nature Climate Change and Proceedings of the National Academy of Sciences. Others at NOAA and European Space Agency noted limitations in representing extreme technological pathways, and modelling centres including GFDL highlighted uncertainties in carbon cycle feedbacks and permafrost thaw addressed in follow-up work.

Legacy and Successors (SSPs)

The RCP framework directly informed the development of the Shared Socioeconomic Pathways by teams at IIASA, Potsdam Institute, IIASA, OECD and universities such as IIASA and University of Maryland, which combined Representative Concentration Pathways with standardized socioeconomic narratives to produce SSP-RCP combinations used in CMIP6 and assessments by IPCC Working Groups; successor scenarios integrate demographic projections from United Nations, technology pathways studied at MIT and policy analyses by IEA to address many criticisms of the original RCPs and to support a new generation of climate, impact, adaptation and mitigation research.

Category:Climate scenarios