Prince William and Kate Middleton on Thursday "celebrated young peoples’ drive and passion to help solve the world’s biggest environmental challenges."
"Young people inspire us every day through their ingenuity to bring about change and their ability to generate collective action," the couple said in their Instagram post on International Youth Day.
The royal couple's popularity has grown online since Prince Harry and his wife Meghan Markle stepped down from their roles as senior members of the British royal family.