Pedestrians cover their face as they walk along the dusty road in Kathmandu, Nepal February 27, 2017. Nepal has forced 2,500 old vehicles off roads in its capital city of Kathmandu, part of a fight against alarming air pollution levels that have hit nine times World Health Organisation (WHO) limits. Air pollution has been a chronic problem in rapidly growing Kathmandu, which sits in a Himalayan valley and is home to more than 3mn people. (Photo by Navesh Chitrakar/Reuters)

Cuban migrant Yamilen Arbelo, 40, walks down a hill as she crosses the border from Colombia through the jungle into La Miel, in the province of Guna Yala, Panama November 29, 2015. According to local authorities in La Miel, some 100 to 150 Cubans have been entering Panama from Colombia every day for the last three months. Scores of Cubans have come to Panama as they seek overland passage towards the United States fearing a recent detente between Washington and Havana could end their preferential treatment. (Photo by Carlos Jasso/Reuters)

People wearing face masks walk through Ginza area on December 27, 2020 in Tokyo, Japan. Japan announced it will close its borders to non-resident foreign nationals from tomorrow until the end of January after two people were discovered to be infected with a new strain of Covid-19 coronavirus that has begun spreading around the world. The country is also grappling with a surge in coronavirus infections, with Tokyo reporting 708 cases today. To date, Japan has recorded 218,453 infections, 3,052 deaths and 3,052 recoveries from the virus. (Photo by Yuichi Yamazaki/Getty Images)

Montegut fire chief Toby Henry walks back to his fire truck in the rain as firefighters cut through trees on the road in Bourg, Louisiana as Hurricane Ida passes on August 29, 2021. Hurricane Ida struck the coast of Louisiana on August 29 as a powerful Category 4 storm, 16 years to the day after deadly Hurricane Katrina devastated the southern US city of New Orleans. “Extremely dangerous Category 4 Hurricane Ida makes landfall near Port Fourchon, Louisiana”, the National Hurricane Center wrote in an advisory. (Photo by Mark Felix/AFP Photo)

A golden huddle by Minqiang Lu, China. Two females and a male golden snub-nosed monkey huddle together to keep warm in the extreme cold. Threatened by forest loss and fragmentation, this endangered species is confined to central China. Restricted to living high up in the temperate forests, these monkeys – here in the Qinling mountains in Shaanxi province – feed mostly in the trees, on leaves, bark, buds and lichen. In heavy wind and snow, Minqiang walked up the mountain carrying his equipment. He stayed for half an hour in temperatures of –10C opposite the tree where the group was huddled before achieving this eye-level composition. (Photo by Minqiang Lu/Wildlife Photographer of the Year)

Environmental activist Rob Greenfield walks around Beverly Hills, California on May 16, 2022 wearing a suit filled with every piece of trash he has generated living and consuming like a typical American for one month to raise awareness about how much garbage just one person generates. (Photo by Robyn Beck/AFP Photo)

In this March 7, 1991 file photo, a U.S. Marine patrol walks across the charred oil landscape near a burning well during perimeter security patrol near Kuwait City. Twenty five years after the first U.S. Marines swept across the border into Kuwait in the 1991 Gulf War, American forces find themselves battling the extremist Islamic State group, born out of al-Qaida, in the splintered territories of Iraq and Syria. The Arab allies that joined the 1991 coalition are fighting their own conflicts both at home and abroad, as Iran vies for greater regional power following a nuclear deal with world powers. (Photo by John Gaps III/AP Photo)

“Lofoten Glow”. I was desperately searching a good sunrise spot this particular morning. Normally Storvatnet Lake is completely covered in snow, so you can only imagine my surprise when I saw these crazy ice formations almost being shot out of the frozen lake. I put my crampons on and took a big risk walking out. I could hear the ice cracking underneath my feet, and when you’re all alone in a fjord/canyon like this – the cracks are echoed and sound really frightening. Was it worth it? I sure think so! Photo location: Storvatnet, Lofoten Islands in Northern Norway. (Photo and caption by Stian Klo/National Geographic Photo Contest)