A family take a souvenir picture next to giant male panda Xiao Liwu, who was born at the San Diego Zoo and will be repatriated to China with his mother Bai Yun, bringing an end to a 23-year-long panda research program in San Diego, California, U.S., April 18, 2019. (Photo by Mike Blake/Reuters)

A mural signed by “TV Boy” and depicting Pope Francis and U.S. President Donald Trump kissing, is seen on a wall in downtown Rome, Italy on May 11, 2017. (Photo by Tony Gentile/Reuters)

A young boy plugs his ears as his sister (C) and nanny (L) watch from Gravelly Point Park as planes land at Reagan National Airport in Arlington, Virginia on June 29, 2017. President Donald Trump' s travel ban on people from six mostly Muslim countries will come into force late Thursday, as controversy swirls over who qualifies for an exemption based on family ties. (Photo by Jim Watson/AFP Photo)

Former Olympic gymnast Nastia Liukin performs a flip while throwing the ceremonial first pitch during a baseball game between the Los Angeles Angels and the Tampa Bay Rays, Friday, July 14, 2017, in Anaheim, Calif. (Photo by Jae C. Hong/AP Photo)

A reef shell lies on a beach as the sun sets on Lady Elliot Island located north-east of the town of Bundaberg in Queensland, Australia, June 10, 2015. UNESCO World Heritage delegates recently snorkelled on Australia’s Great Barrier Reef, thousands of coral reefs, which stretch over 2,000 km off the northeast coast. Surrounded by manta rays, dolphins and reef sharks, their mission was to check the health of the world's largest living ecosystem, which brings in billions of dollars a year in tourism. Some coral has been badly damaged and animal species, including dugong and large green turtles, are threatened. UNESCO will say on Wednesday whether it will place the reef on a list of endangered World Heritage sites, a move the Australian government wants to avoid at all costs, having lobbied hard overseas. Earlier this year, UNESCO said the reef's outlook was “poor”. (Photo by David Gray/Reuters)

Fires approach a home near Lower Lake, Calif., Friday, July 31, 2015. A series of wildfires were intensified by dry vegetation, triple-digit temperatures and gusting winds. The golden hills of California were being blackened Friday by a series of wildfires egged on by bone-dry vegetation, triple-digit temperatures and gusting winds. (Photo by Jeff Chiu/AP Photo)

Children eat watermelons to meet the “beginning of autumn” at a kindergarten in Handan, China on August 7, 2015. Chinese tradition to eat watermelons or peaches before that day symbolises “biting away summer”. The solar term ‘beginning of autumn’ falls on 8 August this year. (Photo by Xinhua/REX Shutterstock)

A chicken seller carries his chickens on his head in the market in Peshawar, Pakistan, August 20, 2015. (Photo by Khuram Parvez/Reuters)