Countries around the world have been switching off their lights for Earth Hour, a global call for international unity on the importance of climate change.
Since beginning in Sydney in 2007, Earth Hour has spread to more than 180 countries, with tens of millions of people joining in.
From the Empire State Building to the Palace of Westminster, thousands of landmarks switched off their lights for one hour in solidarity for the planet.
Co-Leader of the Green Party Caroline Lucas, urged her Twitter followers to switch off their lights "to send strong message that we demand urgent action to protect our precious natural world".
Marco Lambertini, director general of WWF International, the charity that organises Earth Hour, said: "This Earth Hour, we want to shine a light on the importance of biodiversity and nature.
"Together, as individuals, businesses and governments, we must show the same determination to halt biodiversity and nature loss as we have shown on climate action to secure a healthy, thriving and living planet for all.”
Cristiana Paşca Palmer, executive secretary of the Convention on Biological Diversity said it is "imperative to take action, today and every day, to help safeguard biodiversity."
She added: "The totality of forms of life on the planet, what we call biodiversity, provides the infrastructure for the healthy functioning of natural systems.
"This is critical not only to safeguarding life on Earth but also to the wellbeing and development of the human species."
Images from Earth Hour events around the world will be uploaded as they happen on the WWF website.