People cool off in a fountain outside the Southbank Centre on June 30, 2015 in London, England. The UK is currently experiencing a heatwave, with temperatures of 35 degree celsius forecast tomorrow in some parts of the country. The extreme heat has already seen train cancellations and a health warning has been issued. (Photo by Rob Stothard/Getty Images)

Galapagos – Rocking the Cradle: Four major ocean currents converge along the Galapagos archipelago, creating the conditions for an extraordinary diversity of animal life, April 25, 2016. The islands are home to at least 7,000 flora and fauna species, of which 97 percent of the reptiles, 80 percent of the land birds, 50 percent of the insects and 30 percent of the plants are endemic. (Photo by Thomas P. Peschak for National Geographic/World Press Photo)

Crowds watch surfers as the first big swell of the year arrives in Nazaré, Portugal on October 28, 2015. (Photo by Pedro Miranda/Demotix/Corbis)

Bjorn, aged 5, smiles as he poses with a Owl butterfly during an event to launch the Sensational Butterflies exhibition at the Natural History Museum in London, Britain March 23, 2016. The exhibition opens to the public on March 24 and runs until September 11. (Photo by Dylan Martinez/Reuters)

A woman takes a selfie in front of a Lunar New Year display featuring sheep at a shopping mall in Hong Kong, February 13, 2015. (Photo by Bobby Yip/Reuters)

Alisa, 10, gets a kiss from one of the wolves her family tamed in the village of Zacherevye, Belarus, on August 17, 2014. (Photo by Sergei Gapon/AFP Photo)

A giant size figure of the United States' goalkeeper Tim Howard is displayed outside a shopping mall in Hong Kong, Thursday, June 12, 2014, to promote the upcoming 2014 World Cup in Brazil. A total of seven 3.5 meters to 4 meters (11 feet 6 inch to 13 feet one inch) tall figures of famous players attract many soccer fans. (Photo by Vincent Yu/AP Photo)

A Femen activist, Sarah Constantin, is hanged from a noose-like rope from a Paris bridge to call attention to the large number of executions in Iran as she stages a protest against visiting Iranian President Hassan Rouhani in Paris, Thursday, January 28, 2016. A near-naked woman hanging from a noose-like rope from a Paris bridge has sent a message to visiting Iranian President Hassan Rouhani. (Photo by Zacharie Scheurer/AP Photo)