CMIP6

1. Overview of CMIP6 Climate Scenarios

  • Purpose: Provides global climate projections based on state-of-the-art climate models.

  • Developed by: Program for Climate Model Diagnosis and Intercomparison (PCMDI)

  • Geographic Coverage: Global, with specific projections for Canada.

  • Time Coverage:

    • Historical data: 1900–2014

    • Future projections: 2015–2100

  • Resolution: 1° x 1° global grid (~110 km)

  • Emissions Scenarios (Shared Socioeconomic Pathways - SSPs):

    • SSP1-2.6 (Low emissions, strong mitigation - Paris Agreement target)

    • SSP2-4.5 (Intermediate stabilization pathway)

    • SSP3-7.0 (High-end emissions, fossil-fuel dominated)

    • SSP5-8.5 (Worst-case scenario, high fossil-fuel use and no mitigation)

Key Climate Variables Modeled

Variable

Unit

Projected Change Metrics

Mean Temperature

°C

Absolute temperature change

Precipitation

mm/day

% change relative to 1995-2014

Wind Speed

m/s

% change in wind intensity

Snow Depth

m

% change in snow accumulation

Sea Ice Thickness

m

Reduction in Arctic ice thickness

Sea Ice Concentration

%

% of grid cell covered by sea ice


2. CMIP6 Data and Processing

2.1 Data Collection and Interpolation

  • Data Source:

    • Monthly CMIP6 datasets downloaded from the Earth System Grid Federation (ESGF) database.

  • Data Format:

    • Processed in NetCDF format and interpolated to a common 1° x 1° global grid.

  • Ensemble Weighting:

    • Only one realization per model is included, giving each model equal weight.

2.2 Calculation of Climate Anomalies

  • Baseline Period: 1995-2014 (reference period for calculating anomalies).

  • Projected Anomalies: Future values minus the historical mean from 1995-2014.

  • Uncertainty Representation: Percentile projections (5th, 25th, 50th, 75th, 95th) to capture spread.

2.3 Future Time Periods Analyzed

  • 2021-2040 (Near-term)

  • 2041-2060 (Mid-century)

  • 2061-2080 (Late 21st century)

  • 2081-2100 (End-of-century)


3. List of Climate Models Used

The CMIP6 dataset includes over 30 global climate models, each contributing to the multi-model ensemble.

Model Name

Institution

CanESM5

Environment Canada

GFDL-CM4

NOAA-GFDL (USA)

HadGEM3-GC31-LL

UK Met Office

CESM2-WACCM

NCAR (USA)

IPSL-CM6A-LR

IPSL (France)

NorESM2-LM

Norwegian Climate Centre

MPI-ESM1-2-HR

MPI (Germany)

MIROC6

JAMSTEC (Japan)

BCC-CSM2-MR

Beijing Climate Center (China)

CMCC-CM2-SR5

CMCC (Italy)

(Full model list available in Table 2 of the CMIP6 documentation.)


4. Differences Between CMIP6 and CMIP5

Feature

CMIP5

CMIP6

Emission Pathways

RCPs (RCP2.6, RCP4.5, RCP8.5)

SSPs (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5)

Model Resolution

~1.5° to 2°

~1°

Historical Baseline

1986-2005

1995-2014

Ocean & Ice Modeling

Coarser resolution

Higher resolution, better sea-ice representation

Aerosols & Carbon Cycle

Simplified feedbacks

Interactive carbon cycle and aerosols


5. Applications of CMIP6 Data

CMIP6 data is widely used for climate impact assessments, adaptation planning, and policymaking.

5.1 Scientific Research & Climate Modeling

  • Studying regional temperature and precipitation changes.

  • Analyzing Arctic sea ice loss and ocean circulation shifts.

  • Modeling extreme weather patterns and climate variability.

5.2 Government Policy & Adaptation Planning

  • Guiding Canada’s climate adaptation strategies.

  • Providing data for IPCC AR6 assessments.

  • Developing resilient infrastructure based on projected climate risks.

5.3 Industry Applications

  • Energy Sector: Planning for hydropower variability and extreme weather risks.

  • Agriculture: Evaluating drought risk, heat stress, and precipitation trends.

  • Insurance & Risk Management: Assessing financial risks due to climate change.


6. Best Practices for Using CMIP6 Data

  • Use a multi-model approach to reduce bias and uncertainty.

  • Analyze different SSP scenarios to assess climate risks.

  • Focus on ensemble median and percentiles (5th-95th) rather than individual models.

  • Downscaling may be needed for localized impact studies.

Use Limitations

  • CMIP6 projections are not forecasts but scenario-based simulations.

  • Regional biases exist in some models, especially for precipitation.

  • Short-term weather variability (e.g., seasonal forecasts) requires additional data sources.


7. Future Considerations: Transition to CMIP7

  • CMIP7 is expected to further refine models, improve high-resolution projections, and update emission scenarios based on post-2025 climate policy trends.

  • Future enhancements will likely include improved cloud representation, aerosol interactions, and better simulation of extreme events.


8. Data Access & References

8.1 Where to Access CMIP6 Data


9. Conclusion

The CMIP6 dataset represents the most advanced and comprehensive climate projection resource, supporting scientific research, government policy, and industry adaptation planning.

With higher-resolution models, improved physics, and new socio-economic pathways (SSPs), CMIP6 provides more accurate and actionable climate insights than its predecessor, CMIP5.

As climate science evolves, CMIP6 will play a critical role in guiding climate resilience efforts worldwide, supporting data-driven decision-making for a more sustainable future.

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