Prince William spoke to world leaders gathered at the United Nations in New York in a video message about the “most pressing existential threat we face” – just hours after estranged brother Prince Harry appeared in the city where he gave a passionate speech

Prince William has warned of the most “pressing existential threat we face” at a New York event – hours after a fiery speech by Prince Harry in the same city.

The Prince of Wales called for action to save the world’s wildlife, habitat and natural resources “buckling under the pressure of our actions”. He made the comments in a video message screened during a UN General Assembly event, a few hours after his estranged brother the Duke of Sussex spoke in person in the city.

Harry delivered a passionate speech at the Clinton Global Initiative on Tuesday and urged the world to tackle the “pervasive threat” the online world poses for children, warning: “Our kids can’t wait”.

New York was the setting for the third annual Earthshot Innovation Summit on Tuesday where, by video message, William announced the finalist in his Earthshot Prize environmental award. He attended the event in the Big Apple last year but did not fly to America this week, while his brother chose UN General Assembly week to carry out a series of events in New York.

William told a reception of world and indigenous leaders gathered to discuss biodiversity: “Thankfully, in 2022 the world adopted the Biodiversity Plan in Montreal and committed to transformative action to halt and reverse biodiversity loss by 2030. But, we now have just five years to deliver on our collective promise.”

He added: “We must act to save our rivers, oceans, savannas, mangroves and forests, as well as the communities that protect and live alongside them. We must act with urgency to protect at least 30% of our land, inland waters, and ocean by 2030.”

The prince called for a halt in the “unsustainable production and consumption of natural resources”, greater working with indigenous and local communities and “traditional custodians of biodiversity”, and redirecting “harmful subsidies” that are “wreaking havoc on our natural world” as well as investing in “alternative solutions”.

The video message came as Harry was carrying out two days of engagements in the Big Apple on the East Coast trip without the Duchess of Sussex during UN General Assembly High-Level Week and Climate Week.

Harry’s other events in New York on Tuesday saw him focus on Lesotho – the impoverished southern African country where he set up his Sentebale charity to support Aids orphans – at a UN General Assembly side event, and gathered with the Travalyst organisation, which he founded to encourage the tourism sector to become more sustainable.

He also spoke at an event for the Diana Award on Monday as well as the Halo Trust anti-landmines charity. Harry is estranged from his older brother William and has a strained relationship with his father the King. The duke is set to briefly return to the UK to attend the WellChild annual awards next Monday.