More than 100 climate simulations show the future climate

Researchers at SMHI have completed over 100 regional climate simulations for Europe, Africa, the Arctic, the Middle East and South Asia within the framework of the CORDEX project. The result is detailed regional material that is unique in its size. It can be used for further research, in studies into climate effects and for climate adaptation.

Material from nine global climate models has been processed at SMHI’s climate research centre, Rossby Centre. The climate researchers have used Rossby Centre’s regional climate model RCA and three different scenarios for how the greenhouse effect will intensifiy in the future. The result is regional material in varying detail, indicating how the climate may change in the different regions. The extensive material is now available to researchers to analyse, to use in studies of climate effects and for climate adaptation.

“To have more than 100 simulations with the same regional climate model increases the usability of the material. These regional results are more comparable than if the global information had been processed with several different regional models”, says Gustav Strandberg, climate researcher at SMHI Rossby Centre.

Details appear regionally

The global climate scenarios show the climate development with large brush strokes, but usually they incorporate too few details to be useful in effect studies and for climate adaptation. More detailed patterns emerge by performing regional simulations. This becomes especially apparent in areas with varying terrain.

“Coast lines and mountain ranges indicate clear patterns in regional simulations as we “zoom in” more and then see more detail. This is visible in the precipitation patterns over the Alps and in Italy”, exemplifies Gustav Strandberg.

Examples of future temperature and precipitation

“We can see that the models agree in how the temperature and precipitation can develop in Europe during the winter at the end of the century”, says Grigory Nikulin, climate researcher at SMHI Rossby Centre.

Example CORDEX Precipitation
Examples of how changes in precipitation can be shown in a climate scenario for the winter season (December-January-February) 2071-2100, compared to the reference period 1971-2000. In this calculation over future development, RCP 8.5 is used, the scenario that corresponds to the strongest intensification of the greenhouse effect of the four RCPs. The top row shows the mean value of the regional processing of the nine global climate models. The bottom row shows the mean values of the nine global models in the lower resolution, i.e. each calculation box is larger. In the first column we see reference values for winter precipitation, expressed in mm/month for the period 1971-2000. In the second column we see the change in one scenario for the years 2071-2100, i.e. how the amount of precipitation changes compared to the period 1971-2000, expressed in per cent. The regional processing shows that in parts of northern Sweden the amount of precipitation will increase in the winter by about 30 % in the period 2071-2100 compared to 100 years earlier. Column three shows the distribution between the different models (the standard deviation) expressed in mm/month. A smaller distribution shows that the models are in agreement about the amount of future precipitation. The fourth column shows the number of models that indicate an increased amount of precipitation. Over large parts of Europe most models show that the amount of precipitation will increase (green area), while the models are in agreement that precipitation will not increase over northern Africa (brown area).
Example CORDEX Temperature
Examples of how changes in temperature can be shown in a climate scenario for the winter season (December-January-February) 2071-2100, compared to the reference period 1971-2000. In this calculation over future development, RCP 8.5 is used, the scenario that corresponds to the strongest intensification of the greenhouse effect of the four RCPs. The top row of pictures show the regional processing of the nine global climate models. The bottom row shows the mean values of the nine global climate models in the lower resolution, i.e. each calculation box is larger. In the first column we see reference values for winter temperature, expressed in degrees C for the period 1971-2000. In the second column we see the change in one scenario for the years 2071-2100, i.e. how much the mean temperature has changed compared to the period 1971-2000, also here in degrees C. In the largest part of Sweden the temperature in the winter has increased by more than 4 degrees C in the period 2071-2100 compared to 100 years earlier. Column three shows the distribution between the different models (the standard deviation) expressed in degrees C. A smaller distribution shows that the models are in agreement about the future temperature. The fourth column shows the number of models that indicate an increased temperature. All models show that over the whole of Europe’s land mass the temperature will increase.

Part of the CORDEX project

The new regional climate simulations are a part of CORDEX, a project within the World Climate Research Programme. The regional climate simulations are based on the new RCPs (Representative Concentration Pathways) and data from CMIP5, which also forms the basis of IPCC’s fifth climate report.

After IPCC’s fourth climate report in 2007 it became evident that there was a lack of detailed regional information concerning climate development in the world. In response to this CORD was created, a collaboration to compare the ability of different climate models to describe the climate and to produce climate projections to use in effect and adaptation studies.

Initially CORDEX focused on Africa, but simulations have now been made over a large part of the world’s land mass.

SMHI is one of the main partners in CORDEX. CORDEX stands for Coordinated Regional Climate Downscaling Experiment.

CMIP5 stands for Coupled Model Intercomparison Project Phase 5 and is a global collaboration concerning climate calculations. CMIP5 was established by the World Climate Research Programme.

Facts: SRES and RCP scenarios

There are two different types of scenarios, emissions scenarios and radiation scenarios.

Emissions scenarios are assumptions about the future discharge of greenhouse gases. The emissions scenarios are based on assumptions concerning the future development of the world’s economy, population growth, globalisation, a change to eco-friendly technologies, etc. The amount of greenhouse gases discharged depends on how the world develops. These scenarios are called SRES scenarios (Special Report on Emission Scenarios (Nakićenović, 2000)).

Radiation scenarios are based on assumptions about how the greenhouse effect will intensify in the future, known as radiative forcing (measured in W/m²). The greater the discharge of greenhouse gases, the greater the radiative forcing. Such scenarios are called RCP scenarios (Representative Concentration Pathways (Moss et al., 2010)).