Prince William Makes First Public Appearance on New York Trip Without Kate Middleton

The Prince of Wales helped to restore oyster reefs on Monday.

Prince William has big plans during his short trip to New York City. On Monday, the 41-year-old Prince of Wales arrived stateside to attend the second Earthshot Prize Innovation Summit and carry out additional meetings and events linked to The Earthshot Prize.

"I think this is a very positive trip for Prince William, and most importantly, really establishes him as a statesman on the world stage," royal expert Katie Nicholl told ET. "What we're seeing here is William lobbying for something he's passionate about -- protecting and saving the planet -- but also showing off what we call this soft power, the ability of the royals to really lobby politicians and change makers."

William hit the ground running on Monday, visiting the Billion Oyster Project on Governors Island, which is restoring oyster reefs to New York Harbor in collaboration with New York City communities.

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The royal also paid a visit to the United Nations, meeting with U.N. Secretary-General António Guterres.

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While William is busy in the Big Apple, his wife, Kate Middleton, is "carrying out her own engagements" in the U.K., Nicholl said.

"This is a fleeting visit, and the couple tend not to travel abroad together unless they have to, because, of course, they're juggling childcare and schooling for three children," Nicholl said of Prince George, 10, Princess Charlotte, 8, and Prince Louis, 5. "This is William's project... This summit was something that William planned to always do on his own."

Though William's brother, Prince Harry, now calls the U.S. home, the siblings won't be reunited during this trip.

"This is the second time that William's been in America in a year, and, of course, with America being Harry's new home you might expect there to have been some sort of a visit. Alas, it's not going to happen," Nicholl said. "... There are no plans for the brothers to meet while they are in the same country. I think any chance of a reconciliation, for now, is some time off. My understanding is that the brothers are barely speaking."