A picture taken on August 25, 2021 shows a view of the Aletsch Glacier. After hiking for hours across the mountain and a vast expanse of white, Swiss glaciologist Matthias Huss crouches down near the middle of the massive glacier and checks the measurements. Analysis of the data gathered from Aletsch, the largest glacier in the Alps, paints a dire picture of the toll that climate change is taking on the behemoth. (Photo by Fabrice Coffrini/AFP Photo)

A model poses with a crocodile at Chinchorro Banks, Mexico on June 21, 2018. These crocs had a lot to smile about – sporting huge toothy grins as they posed with stunning models in incredible underwater snaps. The brave models held their breath as they came face to face with the magnificent predators during the daring shoot. Photographer Ken Kiefer took a two hour boat ride to reach the carnivorous crocs at Chinchorro Banks, Mexico, along with his wife and model, Kimber and model, Melodie Trevino. (Photo by Ken Kiefer/Caters News Agency)

A ring-tailed lemur sunbakes at Melbourne Zoo in Melbourne, Victoria, Australia on December 21 2016. (Photo by Julian Smith/EPA)

An undated handout photo obtained on May 14, 2022, from Khartoum's Marshall Nature Reserve for exotic birds, shows a visitor posing for pictures with some of the protected birds in the capital Khartoum. Tucked away east of Sudan's capital Khartoum, a sanctuary of lush green vegetation has been a haven for dozens of exotic birds from far and wide. (Photo by Khartoum Marshall Nature Reserve/AFP Photo)

A performer from the Imperatriz samba school takes part in the first night of Rio's Carnival at the Sambadrome in Rio de Janeiro on March 4, 2019. (Photo by Carl de Souza/AFP Photo)

“Sniff out the Appenzell Cheese”. Alexander Hunter, 30, of Greenwich, Conn., took this photo in Appenzell, Switzerland, in September 2014. (Photo by Alexander Hunter)

Global wildlife populations will decline by 67% by 2020 unless urgent action is taken to reduce human impact on species and ecosystems, warns the biennial Living Planet Index report from WWF (World Wide Fund for Nature) and ZSL (Zoological Society of London). From elephants to eels, here are some of the wildlife populations most affected by human activity. Here: The maned wolf is among the large mammals in the Brazilian Cerrado that are threatened by the increasing conversion of grasslands into farmland for grazing and growing crops. (Photo by Ben Cranke/Nature Picture Library/Alamy Stock Photo)

The fourth annual BigPicture Natural World Photography Competition aims to celebrate the diversity of life on Earth, and encourages people to protect and conserve it. Here: “The Salmon Catchers”. Terrestrial Wildlife. To capture this view of a mother grizzly bear and her cub, photographer Peter Mather set up a camera trap on a log that he knew the bears tended to traverse while fishing for salmon, in the Yukon River watershed in Canada. (Photo by Peter Mather/BigPicture Natural World Photography Competition 2017)