An interesting BBC documentary tonight is discussing the “Global Dimming” phenomenom, after new data suggests that the amount of solar energy reaching the earth’s surface has fallen by 10-30% since the 1950s.
The culprit is pollution, of course, which (scientists suspect) was implicated in serious famines in Africa in the 1980s and 1990s. So we should simply cut out pollution, right? We already are doing a lot about pollution, and surely we should do more? Can we guess how much difference this would make? After September 11, 2001, all aircraft in the USA were grounded, and a few researchers noticed the immediate difference it made to the air quality and the colour of the sky. (A year later, on September 11, 2002, few planes were in the air, as a mark of respect. I personally noticed how clear the sky was over Dublin, and took a few photographs for my sky portfolio – see the image gallery. )
What researchers found was: from September 11-13, 2001, the absence of aircraft, and the cleaner air that resulted, meant an increase in average temperature of over 1°C; a huge difference to see from a change to one factor over so short a period. In Europe, thanks to regulations, pollution levels have fallen, and temperatures have risen. This documentary paints an alarming picture, one in which the only way to avoid an environmental catastrophe is to stop the use of all carbon-based fuels, pretty much immediately. In other words: we’re all screwed.