Since observational data for barely accessible regions is hard to come by, scientists reconstruct the climate and potential changes with the help of computer models. They generally use global models, which offer information on various parameters like snow cover or air temperature – for the entire surface of the Earth and for longer timeframes. Though this provides researchers with data describing the climate and changes to it, and even for remote regions, the low resolution leaves out many details.
In order to identify small-scale changes, my colleagues at the Cluster of Excellence CliSAP and I have now for the first time applied a regional climate model for Siberia. This approach allows us to see regional and local differences in far more detail than with a global model, even those between adjacent mountain valleys. But it also involves more work and computing power – and raises the question whether the extra effort is justified.
Nevertheless it is still important to know about the global climate, because it serves as a framework of sorts for detailed reconstructions. Accordingly, I embedded the regional model in the global one – the former is essentially a magnifying glass I can use to zoom in on the latter. For instance, I used this approach to calculate the snow cover for the last sixty years, a parameter that provides key insights in a region like Siberia. Snow reflects back 90 percent of incoming solar energy, while dark patches of land only bounce back 20 to 40 percent. This difference affects the air, soil and water temperature – and therefore the entire climate system.
The calculations for my research were performed by the German Climate Computing Center’s Blizzard supercomputer. After analyzing the results, I came to the following conclusion: using the regional model to more precisely simulate Siberia’s climate was a worthwhile endeavor. We now have more detailed and realistic data on snow cover in Siberia – covering the whole region and for every day of the last 60 years.
My findings show that the changes in snow cover vary to a far greater extent, both regionally and over time, than indicated by previous models. Especially in parts of northwestern Siberia, the amount of snow cover in the six winter months has declined. Climate change is apparent, and could have serious consequences: If Siberia’s permafrost thaws, additional greenhouse gases will be released – and could intensify global warming. The amount and extent of sea ice could also change and affect the shipping routes if temperatures in Siberia rise permanently.