Nkosi, a critically endangered Eastern Black Rhino is hosed down by its keeper at Folly Farm and Zoo, Begelly, Pembrokeshire, Wales, Britain. July 25, 2019. REUTERS/Rebecca Naden

Nkosi, a critically endangered Eastern Black Rhino is hosed down by its keeper at Folly Farm and Zoo, Begelly, Pembrokeshire, Wales, Britain. July 25, 2019. REUTERS/Rebecca Naden

Pigeon drinks water from a fountain on a hot summer day in Brussels, Belgium, July 25, 2019. REUTERS/Johanna Geron

A dog drinks water at a fountain on a hot summer day in Brussels, Belgium, July 24, 2019. REUTERS/Yves Herman

A dog drinks water at a fountain on a hot summer day in Brussels, Belgium, July 24, 2019. REUTERS/Yves Herman

A dog drinks water at a fountain during a hot summer day in Brussels, Belgium, July 24, 2019. REUTERS/Yves Herman

Birds splash in a fountain on the Rose Kennedy Greenway on the first day of a forecasted summer heatwave in Boston, Massachusetts, U.S., July 19, 2019. REUTERS/Brian Snyder

Large crocodiles are seen in the Tarcoles River, a river with one of the highest crocodile population in the world, in Tarcoles, province of Puntarenas, Costa Rica, July 16, 2019. REUTERS/Juan Carlos Ulate

A large crocodile is seen in the Tarcoles River, a river with one of the highest crocodile population in the world, in Tarcoles, province of Puntarenas, Costa Rica, July 16, 2019. REUTERS/Juan Carlos Ulate

Bear Napa enjoys a bath in a pond at the Arosa Baerenland sanctuary in the mountain resort of Arosa, Switzerland June 25, 2019. Picture taken June 25, 2019. REUTERS/Arnd Wiegmann

A seals swims in the water, as a heatwave is expected to reach the city, at the Berlin Zoo, Germany June 25, 2019. REUTERS/Annegret Hilse TPX IMAGES OF THE DAY

A water buffalo, owned by Anan Chalermlarb, has a shower before a practice session ahead of Chonburi's annual buffalo race festival in Chonburi province, Thailand October 18, 2018. Picture taken October 18, 2018. REUTERS/Athit Perawongmetha TPX IMAGES OF THE DAY

Water buffaloes swim in Lake Manzala, north Nile Delta, northeast of Cairo, Egypt, September 15, 2018. REUTERS/Amr Abdallah Dalsh

Valet, a male tapir, cools down under a stream of water sprayed by an employee on a hot summer day inside its enclosure, with the air temperature at about 30 degrees Celsius (86 degrees Fahrenheit), at the Royev Ruchey Zoo on the suburbs of Krasnoyarsk, Russia August 20, 2018. REUTERS/Ilya Naymushin TPX IMAGES OF THE DAY

Valet, a male tapir, cools down under a stream of water sprayed by an employee on a hot summer day inside its enclosure, with the air temperature at about 30 degrees Celsius (86 degrees Fahrenheit), at the Royev Ruchey Zoo on the suburbs of Krasnoyarsk, Russia August 20, 2018. REUTERS/Ilya Naymushin

A man loses his balance as he gets drenched by a large wave during high tide at a seafront in Mumbai, India, August 13, 2018. REUTERS/Danish Siddiqui TPX IMAGES OF THE DAY

A man loses his balance as he gets drenched by a large wave during high tide at a seafront in Mumbai, India, August 13, 2018. REUTERS/Danish Siddiqui TPX IMAGES OF THE DAY

A man sits under an umbrella as he overlooks the Mediterranean Sea as a heatwave with high temperatures continues in Marseille, France, August 7, 2018.   REUTERS/Philippe Laurenson 

A man cools off under a beach shower as a heatwave with high temperatures continues in Marseille, France, August 7, 2018.   REUTERS/Philippe Laurenson 

Fountains are seen in silhouette as they spray water across from the Eiffel Tower as a heatwave with high temperatures continues in Paris, France, August 7, 2018. REUTERS/Benoit Tessier

People cool off in the fountains across from the Eiffel Tower as a heatwave with high temperatures continues in Paris, France, August 7, 2018. REUTERS/Benoit Tessier

A boy jumps into a public swimming pool to cool off from the heat in Vienna, Austria, August 6, 2018. REUTERS/Lisi Niesner

A boy jumps into the water at the Alte Donau, a former side arm of Danube river, in Vienna, Austria August 6, 2018. REUTERS/Heinz-Peter Bader

A boy jumps into the water at the Alte Donau, a former side arm of Danube river, in Vienna, Austria August 6, 2018. REUTERS/Heinz-Peter Bader

A boy jumps into the water at the Alte Donau, a former side arm of Danube river, in Vienna, Austria August 6, 2018. REUTERS/Heinz-Peter Bader

A man jumps into the water at the Alte Donau, a former side arm of Danube river, in Vienna, Austria August 6, 2018. REUTERS/Heinz-Peter Bader

A western lowland gorilla eats ice cream in its enclosure at Prague Zoo, Czech Republic, August 6, 2018. REUTERS/David W Cerny TPX IMAGES OF THE DAY

A western lowland gorilla eats ice cream in its enclosure at Prague Zoo, Czech Republic, August 6, 2018. REUTERS/David W Cerny

Western lowland gorillas eat ice cream in their enclosure at Prague Zoo, Czech Republic, August 6, 2018. REUTERS/David W Cerny

An aerial view shows people at a beach on the shores of lake Silbersee (Silver Lake) during a long-lasting heatwave over central Europe in Haltern, Germany, August 4, 2018. REUTERS/Wolfgang Rattay TPX IMAGES OF THE DAY

A man cools off as a temperature soars throughout the country, at the Vatican August 4, 2018. REUTERS/Max Rossi

An aerial view shows people at a beach on the shores of lake Silbersee (Silver Lake) during a long-lasting heatwave over central Europe in Haltern, Germany, August 4, 2018. REUTERS/Wolfgang Rattay

An aerial view shows people at a beach on the shores of lake Silbersee (Silver Lake) during a long-lasting heatwave over central Europe in Haltern, Germany, August 4, 2018. REUTERS/Wolfgang Rattay

An aerial view shows people at a beach on the shores of lake Silbersee (Silver Lake) during a long-lasting heatwave over central Europe in Haltern, Germany, August 4, 2018. REUTERS/Wolfgang Rattay

An aerial view shows people at a beach on the shores of lake Silbersee (Silver Lake) during a long-lasting heatwave over central Europe in Haltern, Germany, August 4, 2018. REUTERS/Wolfgang Rattay

A man sunbathes in front of the Vasco da Gama bridge in Lisbon, Portugal August 4, 2018. REUTERS/Rafael Marchante

A dog jumps in a public fountain, as temperatures soar across Europe, in Madrid, Spain August 3, 2018. REUTERS/Javier Barbancho

A child stands in a fountain to cool off as a summer heatwave with high temperatures continues in Paris, France, August 3, 2018. REUTERS/Regis Duvignau

A child cools off in a fountain as a summer heatwave with high temperatures continues in Paris, France, August 3, 2018. REUTERS/Regis Duvignau TPX IMAGES OF THE DAY

People play amongst the fountains outside the Royal Festival Hall in London, Britain, August 3, 2018. REUTERS/Henry Nicholls TPX IMAGES OF THE DAY

A child cools off in a fountain as a summer heatwave with high temperatures continues in Paris, France, August 3, 2018. REUTERS/Regis Duvignau

A beachgoer enjoys the hot weather at Brighton in southern Britain, August 3, 2018. REUTERS/Toby Melville

Children cool off in fountains as a summer heatwave with high temperatures continues in Paris, France, August 3, 2018. REUTERS/Regis Duvignau

A boy plays in a fountain to cool down at a park during a hot summer day in Tokyo, Japan, August 1, 2018. REUTERS/Toru Hanai

A boy plays in a fountain to cool down at a park during a hot summer day in Tokyo, Japan, August 1, 2018. REUTERS/Toru Hanai

A boy plays in a fountain to cool down at a park during a hot summer day in Tokyo, Japan, August 1, 2018. REUTERS/Toru Hanai

Hamish the first polar bear bear cub to be born in the UK for 25 years cools down in the pond in his enclosure at The Highland Wildlife Park near Kingussie, Scotland, Britain July 26, 2018. REUTERS/Russell Cheyne

Hamish the first polar bear bear cub to be born in the UK for 25 years cools down in the pond in his enclosure at The Highland Wildlife Park near Kingussie, Scotland, Britain July 26, 2018. REUTERS/Russell Cheyne

Hamish the first polar bear bear cub to be born in the UK for 25 years cools down in the pond in his enclosure at The Highland Wildlife Park near Kingussie, Scotland, Britain July 26, 2018. REUTERS/Russell Cheyne

Hamish the first polar bear bear cub to be born in the UK for 25 years cools down in the pond in his enclosure at The Highland Wildlife Park near Kingussie, Scotland, Britain July 26, 2018. REUTERS/Russell Cheyne

Hamish the first polar bear bear cub to be born in the UK for 25 years cools down in the pond in his enclosure at The Highland Wildlife Park near Kingussie, Scotland, Britain July 26, 2018. REUTERS/Russell Cheyne

A man jumps into a sprinkler in Berlin, Germany, July 25, 2018. REUTERS/Hannibal Hanschke

A volunteer, for recovery work, uses emergency water supply to cool down as he takes a break in a heat wave at a flood affected area in Kurashiki, Okayama Prefecture, Japan, July 14, 2018. REUTERS/Issei Kato

A girl plays in a water fountain on a hot summer day in Tbilisi, Georgia, July 2, 2018. REUTERS/David Mdzinarishvili

Pamir, an 11-year-old Tien Shan White Claw bear, is sprayed with water to cool down on a hot summer day with the air temperature at about 35 degrees Celsius (95 degrees Fahrenheit) at the Royev Ruchey zoo in the suburb of Krasnoyarsk, Russia June 26, 2018. REUTERS/Ilya Naymushin TPX IMAGES OF THE DAY

Aurora, an eight-year-old female polar bear, eats a trout in a pool during a hot summer day at the Royev Ruchey zoo in Krasnoyarsk, Russia June 21, 2018. REUTERS/Ilya Naymushin

A polar bear plays with a ice block filled with apples on a hot day at an amusement park in Yongin, South Korea, June 21, 2018. REUTERS/Kim Hong-Ji