Tourists kissing front of Malaysia's landmark Petronas Twin Towers with lights on before turned off to mark Earth Hour 2016 in Kuala Lumpur, Malaysia, 19 March 2016. Earth Hour takes place worldwide at 8.30 p.m. local time and is a global call to turn off lights for 60 minutes to raise awareness of the danger of global climatic change (Photo by Fazry Ismail/EPA)

In northwest Russia, in a small village called Alekhovshchina, Nadia Sablin's aunts spend the warmer months together in the family home and live as the family has always lived, chopping wood to heat the house and making their own clothes. Sablin's book of photographs, “Aunties: The Seven Summers of Alevtina and Ludmila”, is published by Duke University Press. Here: “Two-Handed Saw, 2014”. (Photo by Nadia Sablin)

Model Heide Lindgren attends Heidi Klum's 12th annual Halloween party at the PH-D Rooftop Lounge at Dream Downtown on October 31, 2011 in New York City. (Photo by Jemal Countess/Getty Images)

Model Adriana Lima attends the 2011 Victoria's Secret Fashion Show After Party at Dream Downtown on November 9, 2011 in New York City. (Photo by Andy Kropa/Getty Images)

Photographer Jamie McCarthy and Lori Levine attend Moto X presents Heidi Klum's 15th Annual Halloween Party sponsored by SVEDKA Vodka at TAO Downtown on October 31, 2014 in New York City. (Photo by Mike Coppola/Getty Images for Heidi Klum)

A group of around 400 demonstrators participate in a protest by burying their heads in the sand at Sydney's Bondi Beach November 13, 2014. Hundreds of protesters participated in the event, held ahead of Saturday's G20 summit in Brisbane, which was being promoted as a message to Australian Prime Minister Tony Abbott's government that, “You have your head in the sand on climate change”. (Photo by David Gray/Reuters)