Tonight at 20:30, all over the world, individuals, companies, government organisations, and possibly even Her Majesty the Queen, will switch off their lights.
162 countries and territories worldwide now take part in Earth Hour.
You can get involved and help to raise awareness about climate change by switching off your lights at 20:30 local time for one hour. You can share your thoughts on the climate change challenge on Twitter using #YourPower.
I recently came across the story of one country, Costa Rica, whose citizens are prepared to go much further in the battle against climate change. Since the beginning of the year, Costa Rica has avoided the use of fossil fuels altogether.
The Costa Rican government recently issued a press release announcing that during the first quarter of 2015, they relied on renewables for 100 per cent of their power generation.