Regional Evidence of Global Warming

Abstract

This chapter assesses to what extent the factors causing global warming affect the Baltic Sea area. Summertime near-surface warming in northern Europe exceeds natural internal variability of the climate system, and the observed warming cannot be explained without human influence. Regional changes in extreme temperatures, growing-season length and timing of the onset of spring are consistent with the large-scale signal of a human influence (mainly greenhouse gases). Shifts in large-scale circulation in the Northern Hemisphere and precipitation changes in northern Europe and the Arctic have been detected to exceed natural internal variability, but the climate models used to assess these quantities seem to underestimate the observed changes. To what extent this discrepancy between simulated and observed changes also affects the attribution of regional warming to human influence is still a matter of debate. Other aspects of regional climate change including changes in storminess, snow properties, run-off and the changing physical properties of the Baltic Sea have not been formally attributed to human influence yet.