All climate indicators available on the Climate Information Portal are calculated based on climate projections from a well trusted and globally known climate scientific community. The World Climate Research Programme (WCRP) runs the Coupled Model Intercomparison Project (CMIP) that sets quality standards for the Global Climate Model (GCM) projections accepted to be included in the CMIP for a particular phase. Climate indicators have been calculated for each of a selected number of models from CMIP Phase 6 (CMIP6) and are available on the Climate Information Portal. An ensemble of model results is provided to indicate confidence in the estimates. Different combinations of Shared Socioeconomic Pathways (SSP) and Representative Concentration Pathways (RCP) can be used for projecting potential future scenarios for CMIP6. Climate indicators available on the Climate Information Portal include the following three scenarios: SSP1-RCP2.6, SSP2-RCP4.5, and SSP5-RCP8.5.
A number of different types of climate indicators have been produced and are available for download through the Data Access Platform.
Expert Teams (ET) such as the ETCCDI (ET on Climate Change Detection and Indices) and ET-SCI (ET on Sector-specific Climate Indices) define standards for different climate indicators and how they are calculated. All indicators are calculated and quality checked by SMHI according to these standards. Read more: Quality assurance procedure
The indicators are calculated from GCM daily precipitation and daily mean, maximum and minimum temperature. The data are retrieved from Earth System Grid Federation (ESGF). ESGF is where climate modelling teams make climate simulations available, for models in CMIP. The GCM data comes at varying native spatial resolution and has been interpolated to regular latitude-longitude grids of 2 degrees (about 200 km) and 0.25 degrees (about 25km) for the indicators without and with bias-adjustment, respectively.
Both bias adjusted as well as non-bias adjusted indicators are available on the portal. Bias adjustments are performed because GCMs have systematic errors in their output and by applying bias-adjustment, the projections can look more similar to reality. While the non-bias adjusted indicators available on the platform are calculated directly from the non-adjusted GCM data, production of bias adjusted indicators involves additional processing.
Daily precipitation and temperature variables from GCMs are first interpolated to the spatial resolution of the reference data at 0.25 degrees, and then bias adjusted using the MultI-scale bias AdjuStment tool (MIdAS, Berg et al. 2022) with HydroGFD 3.2, a global gridded reference dataset (Berg et al., 2021). Bias adjusted variables from GCM are used to calculate the climate indicators at a 0.25 degree spatial resolution.
To help make assessments for the future, indicators are provided for different time periods:
- a reference period (1981-2010, absolute values)
- early century (2011-2040, expected future change values)
- mid-century (2041-2070, expected future change values)
- end-century (2071-2100, expected future change values).
Each of the future time periods are available for the different SSP-scenarios described above. In the visualisation tools, some regions show no data for change in precipitation. No change data occurs when there is too little precipitation in the reference period, which leads to very high and unreliable percentage changes.