(Image source from: World to go dark for an hour tonight})

Today evening, millions across the globe will switch to darkness at 8.30pm for an hour to mark WWF's annual Earth Hour.

Into its eighth year now, the mass participation event is being held to show support for environmental issues, ahead of the Intergovernmental Panel on Climate Change report that will show how global warming will affect wildlife, food supplies, water and the weather.

"It's fortuitous timing that as millions of people take part in WWF's Earth Hour, the world's leading scientists release the latest IPCC report, which highlights the various impacts of climate change," said Colin Butfield, director of public engagement and campaigns at WWF-UK. "The significance of these two events is massive. Climate change is the biggest environmental threat facing our planet – it's real, it's happening right now, and we need to act fast."

Not just homes and residential complexes, but even offices, stores, malls and world's famous landmarks that will dim their lights tonight. Among the famous buildings are the Empire State building in New York, the Brandenburg Gate in Berlin, the Eiffel Tower in Paris, the Kremlin and Red Square in Moscow, the Bosphorus Bridge in Turkey and the Burj Khalifa in Dubai.

In the UK, the Houses of Parliament, Buckingham palace, Tower Bridge and the London Eye will all dim their lights, with an estimated 10 million Britons expected to take part.

AW: Suchorita Choudhury