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Saturday, January 24, 2009

R. Vautard, P. Yiou & G. J. v. Oldenborgh: Decline of fog, mist and haze in Europe over the past 30 years (global dimming)

Letter abstract

Nature Geoscience, published online: 18 January 2009 | doi:10.1038/ngeo414

Decline of fog, mist and haze in Europe over the past 30 years

Robert Vautard¹, Pascal Yiou¹ and Geert Jan van Oldenborgh²


Surface solar radiation has undergone decadal variations since the middle of the twentieth century, producing global 'dimming' and 'brightening' effects [1, 2.] These variations presumably result from changes in aerosol burden and clouds[3], but the detailed processes involved have yet to be determined. Over Europe, the marked solar radiation increase since the 1980s is thought to have contributed to the observed large continental warming[4], but this contribution has not been quantified. Here we analyse multidecadal data of horizontal visibility, and find that the frequency of low-visibility conditions such as fog, mist and haze has declined in Europe over the past 30 years, for all seasons and all visibility ranges between distances of 0 and 8 km. This decline is spatially and temporally correlated with trends in sulphur dioxide emissions, suggesting a significant contribution of air-quality improvements. Statistically linking local visibility changes with temperature variations, we estimate that the reduction in low-visibility conditions could have contributed on average to about 10–20% of Europe's recent daytime warming and to about 50% of eastern European warming. Large improvements in air quality and visibility already achieved in Europe over the past decades may mean that future reductions in the frequency of low-visibility events will be limited, possibly leading to less rapid regional warming.

1. LSCE/IPSL, laboratoire CEA/CNRS/UVSQ, 91191 Gif sur Yvette Cedex, France
2. KNMI, PO Box 201, 3730 AE De Bilt, The Netherlands

Correspondence to: Robert Vautard¹ e-mail:

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