What Does CMIP6 Stand For?
CMIP6 stands for Coupled Model Intercomparison Project Phase 6. The project is coordinated by the World Climate Research Programme (WCRP). Its main purpose is to organize international efforts to compare and evaluate global climate models.
The “coupled” part of the name refers to the fact that these models link together different parts of the Earth system: atmosphere, oceans, land, and ice. By coupling them, scientists can simulate how changes in one system (like ocean temperatures) affect others (like rainfall patterns).
A Brief History of CMIP
CMIP has been running since the 1990s. Each phase has introduced improvements as computing power, data collection, and scientific understanding advanced:
- CMIP3 (2000s): Provided the backbone for the IPCC’s Fourth Assessment Report.
- CMIP5 (2010s): Introduced more detailed scenarios and was used for the IPCC’s Fifth Assessment Report. This was also where the METAFOR project’s metadata work played a key role in standardization.
- CMIP6 (2016–present): Expanded the scope with new experiments, more detailed scenarios, and higher-resolution models.
What Makes CMIP6 Different?
CMIP6 introduced several important updates that make it more powerful than earlier phases:
- Shared Socioeconomic Pathways (SSPs): These scenarios combine greenhouse gas projections with socioeconomic trends, like population growth and energy use. SSPs allow policymakers to explore how choices today shape the climate future.
- Higher-resolution models: Advances in computing power mean many CMIP6 models can simulate the Earth at finer spatial scales, making regional projections more reliable.
- More experiments: CMIP6 includes dozens of “Model Intercomparison Projects” (MIPs) that study specific aspects of the climate system, from Arctic ice loss to air quality.
- Improved metadata standards: Building on earlier efforts, CMIP6 datasets include standardized metadata, making it easier for scientists worldwide to share and compare results.
Why CMIP6 Matters
CMIP6 is not just an academic exercise—it directly shapes global climate policy and risk planning. Its significance comes from several areas:
- IPCC Reports: The Sixth Assessment Report (AR6), published between 2021 and 2023, drew heavily on CMIP6 results.
- National policy: Governments use CMIP6 scenarios to guide emissions targets, adaptation strategies, and infrastructure planning.
- Business and finance: Energy companies, insurers, and financial institutions rely on CMIP6 data for climate risk assessments.
- Public understanding: Media stories about “worst-case” and “best-case” climate futures often originate from CMIP6 scenario runs.
Examples of CMIP6 in Action
Here are a few concrete examples of how CMIP6 data is applied:
- Sea-level rise projections: CMIP6 helps estimate how melting ice sheets and thermal expansion will affect coastal cities.
- Extreme weather: Researchers use CMIP6 to assess how the likelihood of heatwaves, droughts, and heavy rainfall events changes with different emissions scenarios.
- Regional climate planning: CMIP6’s higher resolution makes it more useful for cities and regions that need localized information.
Challenges and Limitations
Despite its importance, CMIP6 is not perfect. Key challenges include:
- Computational cost: High-resolution models are expensive to run, limiting how many experiments can be completed.
- Uncertainty: Even with improved models, uncertainty remains, especially for regional projections.
- Complex metadata management: While progress has been made, ensuring consistent metadata across hundreds of models remains a major task.
- Communication: Translating CMIP6 outputs into information that non-experts can understand is still a challenge for scientists and policymakers.
What Comes After CMIP6?
Work is already starting on CMIP7, which will build on the lessons learned from CMIP6. Expectations include even higher-resolution models, integration of new Earth system components, and stronger links between climate science and socioeconomic research. Metadata will remain central, ensuring that vast and complex datasets stay usable and transparent.
Why You Should Care About CMIP6
CMIP6 may sound technical, but its influence reaches far beyond the research community. Every projection of future warming, sea-level rise, or extreme weather risk that enters public debate relies on this global collaboration. By providing a standardized, transparent framework for comparing models, CMIP6 builds the foundation of trust that policymakers, businesses, and citizens depend on.
Whether you’re a researcher, a student, or simply someone following the climate conversation, understanding CMIP6 helps you see where the numbers and headlines come from—and why they matter.