Shabtai Cohen, who works at the Vocani Centre in Israel, said: "The cloudy times are getting darker. If it's cloudy then it's darker, but when it's sunny things have not changed much." Experts say the impact of reduced solar radiance may be greater in overcast areas of the northern hemisphere, such as Britain and Europe.
"Black Carbon Is Plunging The World Into Darkness," Western Daily Press, December 19, 2003
The finding went against all scientific thinking. By the mid-80s there was undeniable evidence that our planet was getting hotter, so the idea of reduced solar radiation the Earth's only external source of heat just didn't fit. And a massive 10% shift in only 30 years? Ohmura himself had a hard time accepting it. "I was shocked. The difference was so big that I just could not believe it," he says. Neither could anyone else. When Ohmura eventually published his discovery in 1989 the science world was distinctly unimpressed. "It was ignored," he says.
It turns out that Ohmura was the first to document a dramatic effect that scientists are now calling "global dimming". Records show that over the past 50 years the average amount of sunlight reaching the ground has gone down by almost 3% a decade.
David Adam, "Earth is 20% darker, say experts," The Guardian (London, England), December 18, 2003
Gerald Stanhill and Shabtai Cohen, "Global dimming: a review of the evidence for a widespread and significant reduction in global radiation with discussion of its probable causes and possible agricultural consequences," Agricultural and Forest Meteorology, April 19, 2001