US President Joe Biden appeared to be the only world leader wearing a mask during a virtual climate summit hosted by the White House.
Leaders who could be seen maskless on the call included Russian president Vladimir Putin, German chancellor Angela Merkel, Turkish president Recep Tayyip Erdoğan, and EU leaders Ursula von der Leyen and Charles Michel.
Mr Biden kicked off the proceedings of the two-day summit on Thursday by unveiling a new pledge to cut US emissions in half by 2030.
Microsoft co-founder Bill Gates thanked Mr Biden during the summit “for re-establishing America’s leading role on climate change”.
“This is a promising moment. Climate activists and young people especially are bringing amazing energy and attention to this issue. They are demanding action and rightly so,” Mr Gates said.
Mr Biden has led a push for Americans to wear masks to stem the spread of Covid-19, instituting a 100-day mask challenge as he entered office. He has dutifully been wearing masks when he appears in public and signed an executive order to mandate mask-wearing on federal properties on his first day in the White House.