There aren't enough hours in the year. Turning off the lights everywhere forever would be about 2% of the power used. Your water and sewage still gets pumped, your trucks still deliver your food, supermarkets still run freezers, planes still fly, aircon still blows, foundries still make steel, ...

And the big unspoken: livestock still farts, and methane is about 30 times more potent as a greenhouse gas than carbon dioxide.

Earth Hour probably has a negative effect on the earth overall. How many people turned on the TV for longer than usual to see what was happening, or took an extra car trip downtown for the novelty of seeing how dark it was. How many made extra phone calls and recharged their phones a bit more, or turned on their PCs to email their photos across the world? Or had an extra beer, and flushed the loo an extra time. Or lit a dozen candles - how much useless heat from refined oil, and how little light!

Nice publicity stunt and a warm feeling for the hippiies, but not really going to save the world, is it?