The Malizia II, a zero-carbon yacht, with Swedish climate activist Greta Thunberg, 16, arrives in the US after a 15-day journey crossing the Atlantic in on August 28, 2019 in New York. - "Land!! The lights of Long Island and New York City ahead," she tweeted early Wednesday. She later wrote on Twitter that her yacht had anchored off the entertainment district of Coney Island in Brooklyn to clear customs and immigration. (Photo by Johannes EISELE / AFP) / ALTERNATIVE CROP        (Photo credit should read JOHANNES EISELE/AFP/Getty Images)
JOHANNES EISELE/AFP/AFP/Getty Images
The Malizia II, a zero-carbon yacht, with Swedish climate activist Greta Thunberg, 16, arrives in the US after a 15-day journey crossing the Atlantic in on August 28, 2019 in New York. - "Land!! The lights of Long Island and New York City ahead," she tweeted early Wednesday. She later wrote on Twitter that her yacht had anchored off the entertainment district of Coney Island in Brooklyn to clear customs and immigration. (Photo by Johannes EISELE / AFP) / ALTERNATIVE CROP (Photo credit should read JOHANNES EISELE/AFP/Getty Images)
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Teenage climate activist Greta Thunberg is making landfall in New York after sailing across the Atlantic for the past 15 days.

The 16-year-old tweeted in the early hours of Wednesday morning that she could see the lights of New York City and Long Island.

She had originally been expected to dock her vessel on Tuesday but was held up in rough seas south of Nova Scotia.

Thunberg has been sailing to New York to speak at the UN Climate Action Summit on September 23, and traveled on a zero-emissions sailboat to reduce the environmental impact of her journey, according to a statement from her team.

She set sail on her vessel, the Malizia II, from Plymouth, UK on August 14, and has been documenting her journey on social media.

Hours before reaching land, Thunberg tweeted an image of her final evening on board the boat. She had previously posted a video showing choppy waters lashing the boat as she approached North America.

The Swedish teenager has become the figurehead of a burgeoning movement of youth climate activists after her weekly protests inspired student strikes in more than 100 cities worldwide.

Thunberg doesn’t fly, because of the high levels of emissions from air travel, according to a statement. The Malizia II allowed her to make a zero-emissions journey, thanks to solar panels and underwater turbines that generate electricity, the statement said.

UN Secretary-General António Guterres has called on world leaders to present concrete plans to reduce greenhouse gas emissions at the upcoming summit in New York.