Detecting and attributing recent warming in Europe

Abstract

Europe has warmed faster than the rest of the globe during the last decades, especially when considering trends for each season separately. In addition to warming caused by greenhouse gas emissions, the atmospheric circulation is the key driver of seasonal warming in Europe. For example, westerly airflow tends to bring warmer weather in winter. Of secondary importance are climate feedbacks that may enhance warming locally. For example, snow reflects more sunlight than grass or bare ground. A retreating snow cover reveals a darker ground that allows more sunlight to be absorbed, and leaves more energy available for further melting and warming (the snow albedo feedback). A different feedback, the soil moisture–temperature feedback, mainly acts during warm spells when the soil moisture may decrease to such low levels that evaporation is reduced. Since evaporation requires energy, less evaporation means less cooling, which means that the initial warming is enhanced. The aim of this thesis is to detect recent trends for Europe on the monthly scale, and improve our process understanding of key drivers of change.