Earth Hour 2009 is fast approaching. On Saturday March 28th (yes, tomorrow), many people around the world will turn out their lights for one hour, from 8:30 to 9:30 in the evening (local time, wherever you are on the globe). Despite all the gossip about Earth Hour on the web, there seems to be some confusion about what it is actually about in some places.

Earth Hour is not about saving electricity. If you switch off your lights for one hour, you’re not going to save much. One hour every year is about one hundredth of a percent, so in the grand scheme of things that’s a drop in the ocean. No, that’s not what Earth Hour is about at all.

Earth Hour is about raising awareness across the world that people want action on climate change. A global, co-ordinated action to make it clear how strongly people feel that climate change needs to be tackled now.

The organisers of Earth Hour are hoping that 1 billion people will participate this year, which corresponds to about one out of every seven people in the world. That’s a huge number, and would make it one of the largest events in human history. Considering that the first Earth Hour was held only two years ago, in one city, that’s an impressive growth, and a strong statement about how people feel about saving our planet.

So who is that statement for? Well, I guess it’s for everyone, there are still a lot of people with their heads in the sand. With one billion people involved, Earth Hour must surely be difficult to ignore. Even the politicians will have a hard time claiming that nobody cares about climate change. More importantly, world leaders will be shown that it is not just people in rich or poor nations, large or small, developed or not, that care about climate change. Countries like China and India are participating, along with many other developing nations. Hopefully this will encourage leaders of nations everywhere to be more responsible about tackling the problem than they have been in the past.

One thing that intrigues me is, how exactly will the organisers figure out how many people participated, after it’s all over? It’s not like they’re going to have time to go round counting, they’ll only have an hour to check each timezone and I don’t suppose Father Christmas is on the team.

One way is to measure it indirectly from the utility companies. Providers of electricity have become masters of estimating demand to within one or two percent minute by minute, and if one person in 7 turns out the lights for an hour, they should be able to spot that rather easily (Toronto showed nearly a 9% drop last year). That’s still a lot of information to analyse, there are over 80 countries involved. If anyone out there has a clearer idea of how the Earth Hour organisers will make their estimate, please let me know!

However it’s done, the important thing is that people should participate. It’s not just about telling the politicians, it’s also about telling the other 6 out of 7 people, and encouraging them to add their voices too. Maybe there’s something special happening near you. If not, there’s a list of suggestions for things to do during Earth Hour on the Earth Hour site, some of which can definitely be more fun in the dark than with the lights on!

(Possibly) related posts:

1. An hour, a day, a week, for the earth
2. March diary
3. Earth Day 2009, it’s here!
4. How many Physicists does it take to change a light bulb?
5. Why is Copenhagen important?