GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L19809, doi:10.1029/2005GL023624, 2005

Anthropogenic greenhouse forcing and strong water vapor feedback increase temperature in Europe

Rolf Philipona

PhysikalischMeteorologisches Observatorium Davos, World Radiation Center, Davos Dorf, Switzerland
 

Bruno Dürr

MeteoSwiss, Zürich, Switzerland
 

Atsumu Ohmura

Institute for Atmospheric and Climate Science, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
 

Christian Ruckstuhl

Institute for Atmospheric and Climate Science, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
 

Abstract

Europe's temperature increases considerably faster than the northern hemisphere average. Detailed monthbymonth analyses show temperature and humidity changes for individual months that are similar for all Europe, indicating largescale weather patterns uniformly influencing temperature. However, superimposed to these changes a strong westeast gradient is observed for all months. The gradual temperature and humidity increases from west to east are not related to circulation but must be due to nonuniform water vapour feedback. Surface radiation measurements in central Europe manifest anthropogenic greenhouse forcing and strong water vapor feedback, enhancing the forcing and temperature rise by about a factor of three. Solar radiation decreases and changing cloud amounts show small net radiative effects. However, high correlation of increasing cloudfree longwave downward radiation with temperature (r = 0.99) and absolute humidity (r = 0.89), and high correlation between ERA40 integrated water vapor and CRU surface temperature changes (r = 0.84), demonstrates greenhouse forcing with strong water vapor feedback.

Received 25 May 2005; accepted 17 August 2005; published 8 October 2005.

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