How much can you save during Earth Hour? If you completely stop using electricity in your house, by my rough but generous estimate, you'd saved about 2,800Wh and reduce your greenhouse gas emissions by 420g.
If you change a 75W incandescent lightbulb to an energy efficient equivalent, you'd save 65,700Wh per year (assuming it's on for 3 hours a day). That works out to 9,950g of greenhouse gases. That's one lightbulb.
(Ridiculous? I know. Every time I re-read this I have to re-check the calculations. 60W saving x 3 hours a day x 365 days a year.)
Blacking out the entire house for one hour every year = 420g reduction per year.
Replacing one lightbulb with an energy saving equivalent = 9,950g reduction per year.
To put it indelicately: Fuck Earth Hour.
Go buy an energy efficient lightbulb and spend Earth Hour with the lights on watching TV - you'd come out ahead by a long, long way. Better still, take an hour's wages and buy energy efficient bulbs for people who don't have them. That'd actually be worthwhile.
Earth Hour supporters retort that even if it doesn't do anything, that's okay, because Earth Hour sends a dramatic message (visible from space!) to our politicians that the citizens of Earth really care and want them to do something.
Earth to Earth Hour: Our politicians, despite their best efforts, do not live in space."
not to mention that earth hour was sponsored by coca-cola, a company that not only cares very little for the environment but is also notoriously anti-union.
those people who argue that earth hour is just about a message, about "consciousness raising", should really consider the implications of ignoring the main sponsors politics and what kind of message that sends.