Cleansing the Atmosphere Spurs Global Warming
Volume 12, Number 20: 20 May 2009

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Working with data obtained over the last three decades at 342
meteorological stations scattered throughout Europe, Vautard et al.
(2009) analyzed the frequency of occurrence of low horizontal
visibility conditions at 0300, 0900, 1500 and 2100 Universal Time,
comparing their results with concomitant changes in near-surface air
temperature, as well as with spatial and temporal variations in sulfur
dioxide emissions. Their reason for doing so, of course, was that "by
enabling less energy to be received at the surface during daytime," as
they describe it, "the low-visibility phenomenon inhibits surface
heating, and therefore induces a lower local temperature."
Consequently, since low-visibility conditions were presumed to have
declined over the three-decade period, due to the implementation of
more effective air pollution control measures, it was anticipated that
a temporal warming trend would be evident in the temperature data.

The three researchers state that the major accomplishment of their
study was their documentation of "a massive decline (about 50% in 30
years) of low-visibility occurrence throughout Europe," and they
report that this decline was "spatially and temporally correlated with
trends in sulfur dioxide emissions, suggesting a significant
contribution of air-quality improvements" to the improvement in
visibility. In addition, they did indeed find that by statistically
linking local visibility changes with temperature variations, "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."

A major implication of the three researchers' findings is that the
cleaning-up of European air pollution over the past three decades has
been responsible for much of the significant warming of that part of
the planet over the same time span; and this observation leads to the
uncomfortable conclusion that the cleansing of the continent's air has
exacerbated the many dire consequences that are routinely predicted by
climate alarmists to result from global warming (if one believes what
the world's climate alarmists say in this regard).

There is, however, hope for the future (if one is worried about this
state of affairs), for Vautard et al. write that air quality in Europe
has improved so much over the last two decades, "owing to emission
control policies," that there is now "less hope for further
improvements" in this area, which thus suggests there will be less of
an air-cleansing-induced warming in Europe's future, so that less hope
equals more hope!

Sherwood, Keith and Craig Idso

Reference
Vautard, R., Yiou, P. and van Oldenborgh, G.J. 2009. Decline of fog,
mist and haze in Europe over the past 30 years. Nature Geoscience 2:
115-119.