Millions of people around the world will come together to mark Earth Hour this evening, in a bid to raise awareness and inspire action on climate change and environmental conservation.

People in more than 180 countries will switch off their lights between 8:30pm and 9:30pm to “show their steadfast commitment to protecting nature.”

The World Wildlife Fund (WWF) said this year’s event aims to inspire global action as “nature declines like never before, coupled with the ever-present challenge of climate change.”

Áras an Uachtaráin will go dark as President Higgins and his wife Sabina switch off all non-essential lights to show their support.

Leinster House, Trim Castle, Ross Castle and the Rock of Cashel are also taking part.

The Acropolis of Athens goes dark for Earth Hour, 24-03-2018. Image: Xinhua/Lefteris Partsalis

More than 17,900 landmarks around the world went dark for the occasion last year – and this year some of the world’s most famous monuments are taking part.

The lights will go out at the Eiffel Tower, the Empire State Building, the Pyramids of Egypt, the Colosseum, the Acropolis, Big Ben, Sydney Opera House, the Burj Kalifa and the Kremlin.

WWF Director General Marco Lambertini said: "On one hand we have the moral responsibility to live in harmony with nature, on the other nature is vitally important to everyone’s daily lives.”

“We depend on it for the food we eat, the air we breathe and the water we drink, and so much more.

“But we are pushing the planet to the limit and nature is severely under threat.”

He said this year’s event is a powerful opportunity to “help secure an international commitment to stop and reverse the loss of nature.”

Earth Hour 2018 celebrations in Italy. Image: WWF-Italy

President Higgins said the Presidential "light in the window" for the diaspora will be the only illumination at the Áras for the hour this evening.

“Sabina and I have asked that the lights at Áras an Uachtaráin will be switched off during Earth Hour, to highlight the need for action on climate change and to encourage the generation of hope in mankind’s ability to affect meaningful change,” he said.

“Earth Hour is a symbolic moment, inviting all of the people of our planet to unite in considering our collective impact on planet Earth, and to make a commitment to undertaking simple energy-conserving acts.”

“The darkness of Earth Hour shines a proverbial light on the collective power of our individual actions, and on the importance of urgent action to deliver on the Sustainable Development Goals and the Paris Agreement.”

Earth Hour 2018 celebrations in Mexico. Image: Secretaría de Medio Ambiente CDMX / WWF-Mexico

Earth hour has evolved over the years and organisations all over the world are finding new ways to unite people behind environmental action.

Ecuador is taking the opportunity to push for a ban on single-use plastics in the capital Quito, while Finland will be challenging over a quarter of the country’s population to eat green and take part in a candlelit vegetarian dinner.

Morocco will educate people on the importance of saving water and making every drop count while Indonesia is encouraging five million young people to adopt a greener lifestyle.

The Eiffel Tower goes dark for Earth Hour 2017. Image: Alain Apaydin/ABACAPRESS.COM

The WWF said the event has already inspired critical climate and environmental initiatives around the world – including a 3.5m hectare marine-protected area in Argentina, a 2,700-hectare Earth Hour forest in Uganda, an all-out plastic ban in the Galapagos in 2014 and the planting of 17 million trees in Kazakhstan.

You can find out how to get involved celebrate the diversity of life on earth here.