More than 350 of the world's most iconic landmarks will switch off their lights at 8:30pm tonight.

The Eiffel Tower, the Empire State Building and the Sydney Opera House - and millions of homes around the world - are all taking part in Earth Hour.

The campaign, which encourages people to plunge their homes into darkness for one hour, is part of a united global effort to raise awareness of climate change.

Here at home, all non-essential lights at Áras an Uachtaráin will be switched off to mark the event.

Leader of the Green Party, Eamon Ryan, has said it is one small way of highlighting the effects of global warming; “If we look at what’s working, look at the like of the Luas system in Dublin, if you look at the green bins we put in they work.

“If you look at the amount of renewable power we have had, it is working, we can do this we just need to do more of what is working, and we should focus on that in a positive way rather than thinking of it as a negative story then we can do more and do better and we can be good at this.”