A small section of the expanding remains of the Veil Nebula, a massive star that exploded about 8,000 years ago. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan. Image taken by NASA's Hubble Space Telescope. Released September 24, 2015. (Photo by Reuters/NASA/ESA/Hubble Heritage Team)

In this picture made available Thursday July 11, 2013 a zoo-keeper presents three of twelve ferret babies at Eekholt Zoo in Grossenaspe, Germany, Wednesday July 10, 2013. The ferret babies were born May 25, 2013. (Photo by Markus Scholz/AP Photo/Dpa)

Star trails are pictured from a road in Singapore. These astonishing images of night sky are captured by Singapore based photographer Justin Ng. The pictures were taken between November 2013 to January 2014. It show's star trail caused by the earth's rotation and also can be achieved by zooming the DSLR lens inward or outward in small steps using a dedicated motorized zooming device. (Photo by Justin Ng/Barcroft Media)

People on inflatable boats enjoy the weather on the Lake Lucerne in Sisikon, Switzerland, August 5, 2018. (Photo by Denis Balibouse/Reuters)

Ayah, 37, weeps as she is embraced by a police officer during a demonstration against the Danish face veil ban in Copenhagen, Denmark, August 1, 2018. (Photo by Andrew Kelly/Reuters)

A cow is seen on land that used to be under water, at the Aculeo Lagoon in Paine, Chile, May 14, 2018. (Photo by Matias Delacroix/Reuters)

An Iran fan attends the Russia 2018 World Cup Group B football match between Morocco and Iran at the Saint Petersburg Stadium in Saint Petersburg on June 15, 2018. (Photo by Dylan Martinez/Reuters)

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)