Feb 19, 2025

CMIP7 Scenarios endorsed by WCRP

The WCRP announced today that the World Climate Research Programme (WCRP) Joint Scientific Committee (JSC) have formally endorsed the CMIP7 scenarios proposed by ScenarioMIP and the community engagement process used to define them.

In a joint statement between WCRP and the Earth System Modelling and Observations (ESMO) Core Project released on 19th February 2025, the JSC identified that the scenarios are a “scientifically rigorous framework for assessing future climate pathways and offer plausible alternative futures based on coherent assumptions“. The statement goes on to highlight that the scenarios’ experimental design ensures scientific robustness and policy relevance through the four identified key guiding principals:

  1. The scenarios form illustrative descriptions of future emissions and land use.
  2. The scenario set covers a wide and plausible range.
  3. Most scenarios will be emission-driven mode (for CO2).
  4. The scenarios cover the period up to 2100 AD, and long-term extensions are developed beyond that as stylised pathways.

The scenarios are fully outlined in a recent GMD preprint from ScenarioMIP and feature six different future climate scenarios (see Figure 1 below):

  • High Emission Scenario (H): High emission scenario to explore potential high-end impacts 
  • Medium Emission Scenario (M): Medium emission scenario consistent with current policies 
  • Medium-Low Scenario (ML): Scenario with delayed increase in mitigation effort, insufficient to meet Paris Agreement objectives 
  • Low Emission Scenarios: Includes three trajectories aligned with the Paris Agreement:
    • A feasible Low (L) scenario consistent with staying likely below 2 °C 
    • A Very Low with Limited Overshoot (VLLO) consistent with limiting warming to 1.5°C by 2100 AD with limited overshoot (as low as plausible) of 1.5 °C during the 21st century 
    • A Very Low after High Overshoot (VLHO) scenario with similar end of-century temperature impact to VLLO, but with less aggressive near-term mitigation and large reliance on net negative emissions, resulting in a higher overshoot.  
Figure 1: Draft scenarios for CMIP7 ScenarioMIP, showing (a) GHG emissions pathways as a function of time for each of the proposed scenarios (based on GWP-100) and (b) the expected global average temperature outcomes using the probabilistic FaIR ensemble used in IPCC AR6 (IPCC, 2021). Shaded regions for temperature outcomes show the 33-66 percentile range of the distribution while uncertainty bounds for emissions show +/-8 GtCO2 around the median. Scenarios are (H) High, (M) Medium, (ML) Medium-Low, (L) Low, (VLHO) Very Low after High Overshoot and (VLLO) Very Low with Limited Overshoot. Source: Van Vuuren et al., 2025 in review.

The CMIP7 scenarios will form a crucial input to the Intergovernmental Panel on Climate Change 7th Assessment Report (IPCC AR7) and will aid scientific advancements on climate processes, impacts, adaptation, and mitigation research. The endorsement statement concluded:

“WCRP fully endorse this process and proposed scenarios, recognizing their critical role in shaping a science-based response to climate change.”

WCRP JSC, Joint Endorsement Statement on the Process and Proposed Scenarios for CMIP7

To top