Baltic Sea wave conditions under climate change scenarios

Anthropogenic climate change can alter the wind- and sea-ice climate and thus the wave conditions in the Baltic Sea. Here, transient simulations with the 3rd generation wave model WAM under two IPCC AR4 emission scenarios (A1B and B1) and two initial conditions of the forcing atmospheric fields are analyzed for the period 1961–2100. Future changes in the wave climate comprise higher significant wave height for most regions and simulations. Median waves show temporal and spatial consistent changes, whereas extreme waves (99th percentile and maximum) show much more variability in space and among the simulations. These changes in the wave fields result from not only higher wind speeds but also from a shift to more westerly winds, which leads to different fetch and thus to different significant wave height and direction. The multi-decadal and the inter-simulation variability illustrate the uncertainty in the estimation of the climate change signal.