BBC NEWS | Science/Nature | Why the Sun seems to be 'dimming':
Why the Sun seems to be 'dimming'
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Scientists have been studying solar measurements for decades
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We are all seeing rather less of the Sun, according to scientists who have been looking at five decades of sunlight measurements.They have reached the disturbing conclusion that the amount of solar energy reaching the Earth's surface has been gradually falling.
Paradoxically, the decline in sunlight may mean that global warming is a far greater threat to society than previously thought.
The effect was first spotted by Gerry Stanhill, an English scientist working in Israel.
Cloud changes
Comparing Israeli sunlight records from the 1950s with current ones, Dr Stanhill was astonished to find a large fall in solar radiation.
"There was a staggering 22% drop in the sunlight, and that really amazed me." Intrigued, he searched records from all around the world, and found the same story almost everywhere he looked.
Sunlight was falling by 10% over the USA, nearly 30% in parts of the former Soviet Union, and even by 16% in parts of the British Isles.
Although the effect varied greatly from place to place, overall the decline amounted to one to two per cent globally every decade between the 1950s and the 1990s. |
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