Earth Hour is a great example of millions of how people can spontaneously cooperate to achieve a collective good. Unfortunately, while participants succeed in coaxing others to participate, the collective good they create is a fleeting sense of collective accomplishment. As for achieving the primary goal of the activists--reducing greenhouse gases--it completely misses the point. The most efficient way to reduce greenhouse gas emissions is to increase energy efficiency. Fortunately, nearly everyone has a vested interest in energy efficiency--saving money.
Does turning off the lights for an hour have a lasting impact on energy efficiency? Of course not. The real rational behind Earth Hour is to create support for legislation that they believe will reduce carbon emissions. In other words, Earth Hour is a bottom up attempt to use top down means to solve hundreds of billions of problems--namely the multitude of individual energy inefficient decisions each of us make every day. This approach is bound to fail. Declaring that carbon emissions shall be reduced doesn't have an impact unless individuals and businesses do something to reduce their carbon emissions. Diktats have far less ability to change people's behaviour than economic incentives, absent Draconian measures. In short, the best way to convince people to conserve energy is to show them that it will save them money.
So how could we leverage the co-operation of Earth Hour into an increased awareness of the individual benefits of energy conservation? I would suggest that rather than turning off the lights for an hour, the World Wildlife Foundation (organizers of the event) suggest that everyone make one improvement to their household energy efficiency during Earth Hour. This could range from replacing an old refrigerator (or at least purchasing one online during the hour) to installing an energy efficient light bulb, or installing new weatherstripping on a drafty window. Sure, it doesn't have the visual impact of having large swaths of a city fall into darkness, but it would actually have a bigger long term impact. WWF could feature an energy efficiency calculator on their site, and participants could roughly calculate their energy consumption savings, and send them on to WWF to aggregate. This way participants would still get some of the sense of accomplishment that comes along with cloaking their city in darkness. Given that WWF believes energy efficiency to be the most efficient way to reduce greenhouse gas emissions, this would seem like the perfect way for them to get their message across.
So here is the choice: self loathing deprivation, or a celebration of human accomplishment. Given the extremely negative message the first sends to people who aren't hardcore environmentalists--that conservation requires inconvenience and sacrifice--the smart approach would be to send a positive message: energy efficiency saves you money. It lacks the feel good factor of sacrificing for the good of the planet, but at least it could have an actual impact. Like it or not, self interest almost always trumps self sacrifice. The goal should be to harness people's self interest, rather than fighting against it.