An elephant cools off at a zoo in Karachi, Pakistan, 31 March 2021. Caretakers at Karachi's zoo were working to keep animals cool during a​ heatwave affecting southern Pakistan. (Photo by Shahzaib Akber/EPA/EFE)

People wearing mushroom hats stand in front of the Washington Monument in Washington, D.C., U.S., May 14, 2021. (Photo by Andrew Kelly/Reuters)

A jogger is seen running at Hampstead Heath with London in the background on June 1, 2021. Britain sees temperatures increasing for the second day in a row after the mercury hit 25C (77 Fahrenheit) for the warmest day of the year so far on Bank Holiday Monday. (Photo by Joshua Bratt/London News Pictures)

A spot-billed pelican sits on a street light in Colombo on March 16, 2021. (Photo by Ishara S. Kodikara/AFP Photo)

Flag bearers Bunpichmorakat Kheun and Sokong Pen of Team Cambodia during the Opening Ceremony of the Tokyo 2020 Olympic Games at Olympic Stadium on July 23, 2021 in Tokyo, Japan. (Photo by Kai Pfaffenbach/Reuters)

Nina Betschart of Team Switzerland dives against Germany during the Women's Preliminary - Pool F on day one of the Tokyo 2020 Olympic Games at Shiokaze Park on July 24, 2021 in Tokyo, Japan. (Photo by Sean M. Haffey/Getty Images)

Chinese Taipei's Hsiao-Wen Huang reacts after winning her fight against Serbia's Nina Radovanovic during their women's fly (48-51kg) quarter-final boxing match during the Tokyo 2020 Olympic Games at the Kokugikan Arena in Tokyo on August 1, 2021. (Photo by Ueslei Marcelino/Reuters)

People cling on to a crowded train as it leaves a railway station during the ongoing Coronavirus Disease (COVID-19) outbreak in Ghaziabad, India, September 21, 2021. (Photo by Anushree Fadnavis/Reuters)