h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I watched a programme the other day on BBC2, I think it was Horizon (I always end up regretting wathcing these programmes, they're too depressing) but it was on a topic called global dimming, which is connected to global warming.

Basically, because we're sticking all this rubbish in the air, it lowers the amount of sunlight reaching the surface (as well as what does get through not being ale to get out again, which is global warming). The particles in the air make clouds more reflective and changes the properties of water droplets in the clouds, so it doesn't rain as much, leading to drought.

The two problems are connected - global dimming is bad for human health (asthma etc) but reduces the heating effect of global warming. So if we reduce global dimming, global warming will increase.

There's an article here:

http://news.bbc.co.uk/1/hi/sci/tech/4171591.stm

The major problem with this survey is that it only covers the last 50 years. I think we'd want to see data from prior to the industrialisation of the West (i.e. back to the Eighteenth century and beyond) in order to make a good comparison. 50 years is nothing in terms of climate variation.

RF