An employee of the National Park Service takes a selfie with President Barack Obama, left, in the background meeting with the crowd after a tour of Everglades National Park on Earth Day, Wednesday, April 22, 2015, in Florida. Obama used the visit to warn of the damage that climate change is already inflicting on the nation's environmental treasures. (Photo by Lynne Sladky/AP Photo)

A Haka is performed before the ceremonial departure of the 'vaka' or traditional canoes ahead of their cross-Pacific voyage from Viaduct Harbour on April 13, 2011 in Auckland, New Zealand. Powered by sun and wind only, the 15,000 nautical mile journey to Hawaii via French Polynesia will set off on April 15, aiming to raise awareness of environmental issues such as ocean noise pollution, acidification and anoxic waters, whilst recapturing traditional Pacific voyaging. The votyage is named “Te Mana o Te Moana” meaning “The Spirit of the Sea”. (Photo by Phil Walter/Getty Images)

A dead wild boar is seen during a hunt in Castell'Azzara, Tuscany, central Italy, October 23, 2015. Extinct across much of the country by the end of the 1800s, the number of wild boar in Italy has almost doubled over the past decade and there are now about a million roaming the country, environmental and agricultural associations say. (Photo by Max Rossi/Reuters)

The photography of Art Wolfe covers the globe, capturing landscapes, wildlife, and cultures from every continent; here he talks through a selection of his favourite images. Art Wolfe is an American photographer and conservationist. His photographs have been noted by environmental advocacy groups for their “stunning” visual impact. Here: Snowy owlets (Bubo scandiacus), Arctic National Wildlife Refuge, Alaska, USA. (Photo by Art Wolfe/Art Wolfe Stock)

Max Gold, 20, of NYC, cruises on his skateboard as thousands gather on the National Mall for the March for Science on Saturday, April 22, 2017, in Washington, DC. Activists and scientists descend on the nation's capital to rally for environmental causes and government policies rooted in scientific research as part of the Earth Day and March for Science rallies. (Photo by Jahi Chikwendiu/The Washington Post)

A butterfly flies into the jaws of a crocodile inhabiting the Tarcoles River, the most polluted basin in Central America and one of the most polluted in Latin America, in the place of Tarcoles, province of Puntarenas, Costa Rica, 05 June 2018. Costa Rica, a country recognized worldwide for its environmental policies, seeks to be a leader in the replacement of single-use plastic with renewable and compostable alternatives, despite its lag in terms of recycling and integrated waste management. (Photo by Jeffrey Arguedas/EPA/EFE)

In this Friday, December 4, 2018 photo, a half sunken cruise ship lays on its side, in the Gulf of Elefsina, west of Athens. Dozens of abandoned cargo and passenger ships lie semi-submerged or completely sunken around the Gulf of Elefsina, near Greece’s major port of Piraeus. Now authorities are beginning to remove the dilapidated ships. Some of them have been there for decades, leaking hazards like oil into the environment and creating a danger to modern shipping. One expert calls the abandoned ships “an environmental bomb”. (Photo by Thanassis Stavrakis/AP Photo)

Villagers from the Medio Jurua nature reserve of Brazil's Amazon rainforest arrive with their catch of pirarucus, the largest freshwater fish in South America, after a night of fishing in Manaria Lake, Carauari municipality, September 3, 2012. Catching the pirarucu, a fish that is sought after for its meat and is considered by biologists to be a living fossil, is only allowed once a year by Brazil's environmental protection agency. (Photo by Bruno Kelly/Reuters)