A grandmother sits in the grass with her grandson on a hill overlooking the Euphrates River as families picnic on May Day, Wednesday, May 1, 2019, in Ein Diwar, Derik, Syria. (Photo by AP)

Melting ice on the Kuskokwim River near the town of Bethel on the Yukon Delta in Alaska on April 12, 2019. (Photo by AFP)

Teams compete in the 29th annual dhow sailing race, known as The Gaffal, near Sir Bu Nuayr Island, UAE May 3, 2019. (Photo by Reuters)

Schoolchildren play on melting ice at Yupik Eskimo village of Napakiak on the Yukon Delta in Alaska on April 19, 2019. (Photo by AFP)

Royal Thai police stand guard near the Grand Palace in Bangkok on May 3, 2019, ahead of Thailand’s King Maha Vajiralongkorn’s coronation which will take place from May 4 to 6. (Photo by AFP)

Crowds queue up outside the Imperial Palace in the hope of seeing the new emperor make an appearance in Tokyo on May 4, 2019. (Photo by AFP)

High-school teachers, medical doctors and university students celebrate with firecrackers as they march towards the Congress building against education and healthcare reforms in Tegucigalpa on April 30, 2019, after a law approved last week was repealed. (Photo by AFP)

Competitors ride their bikes during Stage 4 of the 14th edition of Titan Desert 2019 mountain biking race between Merzouga and M’ssici, in Morocco, on May 1, 2019. (Photo by AFP)

Manny Franco loses Positive Spirit during the 145th running of the Kentucky Oaks horse race at Churchill Downs Friday, May 3, 2019, in Louisville, Kentucky. (Photo by AP)

A Belgian Shepherd jumps while passing through an obstacle course during the Dog Agility championship of the Siberian Federal District in Krasnoyarsk, Russia May 3, 2019. (Photo by Reuters)