Learn more about climate scenarios
After reading this article, you will learn:
What are climate scenarios?
Climate scenarios are projections of future greenhouse gas (GHG) emissions, used to explore the potential impacts of climate change under different socioeconomic conditions. They describe plausible climate futures rather than predict future outcomes, taking into account climate science, social science and economics to project how the evolution of human activity may interact with and drive changes in our climate system - positively or negatively.
Why should I use climate scenarios?
Climate scenarios provide critical information for decision makers. Due to the uncertainty of how policy decisions and human activity will impact future GHG emissions, experts advise using a range of scenarios to assess climate risk. This is because climate scenarios are designed to take into account uncertainties around both future human activity and policy decisions. By examining multiple scenarios simultaneously, decision makers can account for multiple possible outcomes.
The purpose of climate scenarios is to support and inform decisions that anticipate climate change impacts. They are an important part of the creation and adoption of strategies to mitigate, and to adapt, to climate risk. Each climate scenario in EarthScan™ represents a potential climate future and can be used to support strategic planning and decision-making, as well as to inform risk-mitigation and adaptation planning.
Learn more about each of the Climate Scenarios in EarthScan.
How have EarthScan Climate Scenarios been constructed?
The EarthScan Climate Scenarios are based on climate scenarios developed by the Scenario Model Intercomparison Project (ScenarioMIP).
ScenarioMIP has established a common set of climate simulations based on alternative socioeconomic scenarios to be used to make more robust assessments of climate. ScenarioMIP climate scenarios are part of the Coupled Model Intercomparison Project (CMIP6) and inform the basis of the Paris Climate Agreement by the UN Framework Convention on Climate Change (UNFCCC), as well as the Sixth Assessment Report published in 2021 by the Intergovernmental Panel on Climate Change (IPCC).
These scenarios combine Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs):
- SSPs are scenarios that describe possible social and economic development between now and 2100.
- RCPs describe, based on climate science and atmospheric physics, how greenhouse gas emissions interact with the climate system.
The climate scenarios that underpin the latest IPCC assessment incorporate both SSPs and RCPs.
Please note: the riverine flooding signal for all three Climate Scenarios in EarthScan is based on RCP scenarios. For all other signals, the Climate Scenarios are based on SSP scenarios.
Future riverine discharge scenarios were derived from the latest ISIMIP climate forcing scenarios, which provide daily discharge maps at global scale under RCP2.6 (Paris Aligned), 6.0 and 8.5 (Business as Usual) scenarios. As ISIMIP data do not cover RCP4.5, we use RCP6.0 data to emulate the RCP4.5 (emissions peak at 40) scenario using a time-shift approach.
The ISIMIP data includes the most recent scientific understanding of the full range of processes that may contribute to future changes in riverine discharge. ISIMIP discharge models are driven by climate models from the CMIP5 generation, rather than CMIP6., and ISIMIP has not yet incorporated CMIP6 and SSP scenarios into their datasets. The modelling capability for the riverine signal future projections is limited to the capability of CMIP5, however ISIMIP is currently developing an update to their discharge models that utilises CMIP6 models. Once this is published, we will update the riverine flooding dataset to ISIMIP discharge maps constructed using CMIP6.