Climate Indicators are calculated from two well trusted and globally known climate scientific communities:

  • Global Climate Models (GCM) used in the Coupled Model Intercomparison project (CMIP) Phase 5
  • Coordinated Regional Downscaling experiment (CORDEX) Regional Climate Models

The climate indicators are calculated for different Representative Concentration Pathways (RCP), 2.6, 4.5, and 8.5.

Indicators are calculated from raw (non-bias adjusted) GCM and RCM daily precipitation and daily mean, maximum and minimum temperature (see the grey arrows in the figure below). The data are retrieved from Earth System Grid Federation (ESGF). ESGF is where climate modelling teams make climate simulations available, following quality standards defined by the CMIP5 and CORDEX communities. The spatial resolution for indicators from GCM is 2 degrees (200 km), and for indicators from RCM, the resolution is 0.5 degrees (about 50km).

Indicators produced for
Indicators produced based on CMIP5 and CMIP5-CORDEX.

Daily precipitation and temperature variables from both GCM and RCM are bias adjusted using the Distribution-Based Scaling method (DBS , Yang et al., 2010) with HydroGFD, a global gridded reference dataset (Berg et al., 2018). The bias adjusted variables are then used as forcing input for the global hydrological model World-Wide-HYPE  (WW-Hype, Arheimer et. al., 2020) to calculate water related indicators at catchment resolution.

Bias adjusted variables from RCM are used to calculate the climate indicators at a 0.5 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).

An ensemble of model results is provided to indicate confidence in the estimates.

Expert Teams (ET) such as the ETCCDI (ET on Climate Change Detection and Indices) and ET-SCI (ET on Sector-specific Climate Indices) define the different climate indicators and how they are calculated. Indicators from water variables are defined by experts in the Hydrological Research and Development unit at SMHI. All indicators are calculated and quality checked by SMHI.

Read more:  Quality assurance procedure