UN Climate Week on Tuesday, September 24, was a tale of two princes. While Prince Harry made the rounds of various charities in New York, his brother Prince William also spoke at the UN, hours after Harry showed up in person.

The Prince of Wales, 42, spoke via video call from the UK at an event for The Campaign for Nature, which aims to protect the world's oceans and natural lands.

Like his father, King Charles III, Prince William has long been an advocate for environmental protection. In his speech, Prince William called on world leaders to “act urgently” to protect the planet before it is too late.

Referring to the campaign's promise to “reverse biodiversity loss by 2030,” he said, “We now have only five years to deliver on our collective promise.

The prince noted that currently “one million species face extinction.” He said, “We live in conflict with the natural world, and the natural world is bowing to the pressure of our actions.”

William also called on leaders to “stop the unsustainable production and consumption of natural resources” in order to “maintain a livable planet for our children and grandchildren.”

The Crown Prince's speech came on the same day that the finalists for the Earthshot Prize were announced. In a video posted on social media, William congratulated this year's environmental change makers from around the world, including three from the United States.

Each year, the Earthshot Prize awards grants to projects that save the planet, and this year's winners will be announced at an awards ceremony in Cape Town, South Africa, on November 6, where $1.3 million will be awarded.

Meanwhile, Prince Harry, another nature lover, gave a powerful speech about online safety at a Clinton Global Initiative UN event hours before his brother's video message on Tuesday.

Prince Harry also made several in-person visits during UN Climate Week on Monday and Tuesday, including addressing the legacy of his late mother, Princess Diana, at a HALO Trust reception.