http://www.bbc.co.uk/sn/tvradio/programmes...imming_qa.shtml
If the 9/11 contrail evidence suggests warmer nights due to the air travel, isn't that global warming rather than dimming?
The 9/11 study showed that removing contrails resulted in a large increase in the daily temperature range - in other words warmer days and cooler nights. The study does not really provide a clear-cut answer to the question of whether the overall effect of the contrails is a net warming or a net cooling averaged over the whole 24 hours. This question is controversial. But what seems clear is that contrails contribute to a reduction in the amount of daytime solar radiation reaching the surface, and that this has significant effects on temperature.
kortom: het 9/11 effect op de ocntrails heeft te kort geduurd om zonder twijfel een koelend effect te kunnen concluderen van door vliegtuigen veroorzaakte bewolking.
http://www.realclimate.org/index.php/archi...ty-and-climate/
The most important recent volcanic impact on climate was that of Mt. Pinatubo in the Phillipines which erupted in June 1991. Prior to that El Chichon (Mexico, in 1982), Mt. Agung (Indonesia, 1963), Santa Maria (Guatemala, 1902) and Krakatoa (Indonesia, 1883) all had noticeable cooling effects.
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One point that is also worth making is that although volcanoes release some CO2 into the atmosphere, this is completely negligable compared to anthropogenic emissions (about 0.15 Gt/year of carbon, compared to about 7 Gt/year of human related sources) .
Echter, elke serieuze vulkaanuitbarsting veroorzaakt een langdurige meetbare temperatuurdip.
Verder mijn leken-inzicht: warmte die niet binnenkomt hoeft er ook niet uit. Dus ligt het voor de hand te veronderstellen dat bewolking een koelend effect heeft.