Yes, you read that correctly. The volcanic ash cloud over Europe might be expected to block sunlight and lower continental temperatures in a sort of nuclear winter scenario à la The Road, but according to this report in the Daily Mail the opposite may be true:
Temperatures in Europe could rise as a result of planes being grounded across the continent, according to research.
A study conducted after commercial flights were grounded for three days following the September 11 terror attacks found the average daily temperature range in the U.S. rose markedly – exceeding the three-day periods before and after by 1.8c.
Scientists claimed this showed that clouds formed by the water vapour in the exhaust from jet planes have a small but significant effect on daily temperatures. The unprecedented study suggests the UK and Europe will experience a similar pattern…
The grounding of flights in 2001 gave scientists a ‘tarnished but golden opportunity’ to study the impact that jet planes have on the climate.
The team behind the 2002 research, from the University of Wisconsin-Whitewater, compared the average daily high and low temperatures over North America from 11 to 14 September 2001, with climatic records from 1977 to 2000.
They matched the weather over those three days with similar weather in September over that period, and found that the difference in daily high and nightly low temperatures in the absence of planes’ contrails was more than 1c greater. The researchers said that in regions with crowded skies, the clouds formed by the planes’ water vapour worked like cirrus clouds to prevent days from getting too hot and trapping the Earth’s heat at night.
Meteorologists also warned however that volcanic ash could also decrease the temperature, by blowing immense amounts of material into the sky…
[continues in the Daily Mail]