Earth Hour 2009 was its first year as a global event and a huge success with over 4,000 cities and towns in 88 countries participating.

On March 27, 2010, individuals, businesses and governments around the world are being asked again to turn off their lights for one hour to make a statement against climate change.

It's quite amazing how big the event has grown. Earth Hour begain in Sydney in 2007, when 2 million people switched off their lights. In 2008, more than 50 million people around the world participated. In 2009, participation came to hundreds of millions.

What good does just one hour do?

In itself, not a lot - I have no idea how much energy it saves or greenhouse gas emissions it avoids; but it gets plenty of media attention which helps raise awareness of climate change and gets people thinking about more longer term changes they can make in their life to lessen their carbon footprint.

This year, many iconic landmarks will switch off for Earth Hour; including the CN Tower in Toronto, Golden Gate Bridge in San Francisco, Grand Palace in Bangkok, the Las Vegas Strip, Table Mountain in Cape Town, the London Eye, Mount Rushmore, Hiroshima Peace Memorial, Empire State Building and the world’s second tallest building, Tapei 101.

Even if you're not particularly fond of joining groups or participating in such events, there's nothing stopping you from observing your own Earth Hour whenever you like and under your own steam :). You could make it a regular event in your household. Without all the distractions of TV, video games and the Internet, it could be a way of gaining some quality time with your family while perhaps discussing environmental issues.

If you're going to use candles for lighting during Earth Hour, bear in mind that common household candles are usually made of paraffin, which is a fossil fuel product. For an even greener Earth Hour, consider earth-friendly candles.

You can learn more about Earth Hour events and register here.