Abstract
Abstract. The Baltic Sea region is very sensitive to climate change; it is a region with spatially varying climate and diverse ecosystems, but it is also under pressure due to a high population in large parts of the area. Climate change impacts could easily exacerbate other anthropogenic stressors such as biodiversity stress from society and eutrophication of the Baltic Sea considerably. Therefore, there has been a focus on estimations of future climate change and its impacts in recent research. In this overview paper, we will concentrate on a presentation of recent climate projections from 12.5 km horizontal resolution atmosphere-only regional climate models from Coordinated Regional Climate Downscaling Experiment – European domain (EURO-CORDEX). Comparison will also be done with corresponding prior results as well as with coupled atmosphere–ocean regional climate models. The recent regional climate model projections strengthen the conclusions from previous assessments. This includes a strong warming, in particular in the north in winter. Precipitation is projected to increase in the whole region apart from the southern half during summer. Consequently, the new results lend more credibility to estimates of uncertainties and robust features of future climate change. Furthermore, the larger number of scenarios gives opportunities to better address impacts of mitigation measures. In simulations with a coupled atmosphere–ocean model, the climate change signal is locally modified relative to the corresponding stand-alone atmosphere regional climate model. Differences are largest in areas where the coupled system arrives at different sea-surface temperatures and sea-ice conditions.
Highlights
For many years, hundreds of global climate projections have been produced according to various scenarios of future greenhouse gas emissions and other forcing factors including changes in aerosols and land use
Larger warming than the global average is generally expected for land areas, since land heats more quickly than sea areas where enhanced evaporation tends to reduce warming (e.g. Sutton et al, 2007); it is most clearly seen in winter in the eastern part of the area
As only eight general circulation models (GCMs) have been used for these RCP8.5 RCM experiments, the spread between quartiles could be lower than what would have come from an exhaustive downscaling of all Coupled Model Intercomparison Project phase 5 (CMIP5) global simulations; Kjellström et al (2016) compared nine GCMs, including the eight GCMs analysed here, to 25 other CMIP5 GCMs and found the nine-member-ensemble spread over Sweden to be comparable in summer but smaller than that in the larger GCM ensemble in winter
Summary
Hundreds of global climate projections have been produced according to various scenarios of future greenhouse gas emissions and other forcing factors including changes in aerosols and land use. This has been coordinated in model intercomparison projects (MIPs) that have provided fundamental input to the Working Group I assessment reports of the Intergovernmental Panel on Climate Change (IPCC; IPCC, 2001, 2007, 2013, 2021). The most recent, sixth, Assessment Report (IPCC, 2021; AR6) builds on the successor, CMIP6 (Eyring et al, 2016), that involves a new set of Shared Socioeconomic Pathway (SSP) scenarios (O’Neill et al, 2017)
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