Fossil records indicate that this early lizard, Megalania (Megalania prisca or Varanus priscus), was a whopping seven metres in length. They were part of a megafaunal assemblage that inhabited southern Australia during the Pleistocene. The youngest fossil remains date to around 50,000 years ago. The first aboriginal settlers of Australia might have encountered them and been a factor in their extinction. (Photo by Sky TV/The Guardian)

The tusk of a woolly mammoth that lived some 18,000 years ago, from which researchers sequenced the extinct mammal's entire genome, is seen in northeastern Siberia in this photo from 2015. (Photo by Love Dalen/Handout via Reuters)

Filipinos cross a swelling river in Las Pinas city, south of Manila, Philippines, 09 July 2015. According to the Philippines State weather forecast, heavy rainfall is expected in Metro Manila and nearby provinces due to an enhanced Southwest Monsoon and Tropical Storm Linfa, Typhoon Chan-hom and Typhoon Nangka which are lining up across the Pacific Ocean. (Photo by Francis R. Malasig/EPA)

A mischievous squirrel chases a turkey in a garden in Medford, Wisconsin in the second decade of January 2024. The garden’s owner, artist Cheryl Plautz, said the squirrels chase the birds “for fun”. (Photo by Cheryl Plautz/Solent News)

A man and his son ride a horse at Tahrir Square in Sanaa, Yemen on January 21, 2021. (Photo by Khaled Abdullah/Reuters)

Women activists wearing veils gather at during a rally organised by the collective #NousToutes against feminicides at Place du Pantheon in Paris on October 9, 2022. (Photo by Julien de Rosa/AFP Photo)

Members of the Prizma Ensemble wearing full solid-coloured bodysuits walk pest ultra orthodox jewish men as they take part in the 6th Jane's walk Jerusalem in Jerusalem, Israel May 6, 2016. Jane's Walk is a global walking tour movement, inspired by US-Canadian author and activist Jane Jacobs. (Photo by Baz Ratner/Reuters)

The Greenland ice sheet is a vast body of ice covering 660,235 sq miles, roughly 80% of the surface of Greenland. It is the second largest ice body in the world, after the Antarctic Ice Sheet. Some scientists predict that climate change may be near a "tipping point" where the entire ice sheet will melt in about 2000 years. If the entire 2,850,000 cubic kilometres (683,751 cu mi) of ice were to melt, it would lead to a global sea level rise of 7.2 m (23.6 ft).