Dubai, United Arab Emirates - President Joe Biden will miss the latest UN climate summit in Dubai, after two years of attending the talks in hopes of highlighting US leadership, a US official said Sunday.

Some 70,000 people including national leaders and Pope Francis are expected at COP28 as it opens Thursday, in what could be the largest United Nations climate summit ever.

Schedules released by the White House for Biden and Vice President Kamala Harris showed neither heading to Dubai this week.

Biden's engagements include a trip to Colorado to highlight US investment in wind energy, a meeting with the president of Angola, and the lighting of the national Christmas tree.

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A US official confirmed that Biden was not planning to attend COP28 this week or during a second window close to the end of the talks on December 12.

The official, speaking on condition of anonymity, said the Biden administration was still discussing whether to send a top-level official to Dubai.

John Kerry, the US climate envoy and former secretary of state and senator, will be leading day-to-day negotiations for the United States.

The official did not give a reason for Biden's decision. But the president has been focused for more than a month on Israel's war on Gaza and is also looking to highlight his domestic agenda with less than a year to the US presidential election.

Until Biden, it was not customary for the US president to attend each COP summit.

Biden in 2021 traveled to Glasgow to vow that the United States would again take a global leadership role on climate after his predecessor Donald Trump pulled out of the Paris climate accord.

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Trump, who is seeking the White House again, is a climate skeptic who says that action is too costly to the United States.

Biden again made a brief trip last year to COP27 in Sharm el-Sheikh, Egypt.

Biden has said he places high priority on climate domestically, with the so-called Inflation Reduction Act, his signature legislative achievement, channeling billions of dollars to the green economy including through incentives for electric cars. But he has also made a series of decisions which will ramp up emissions, including green lighting major fossil fuel projects in Alaska and the Gulf of Mexico.

Ahead of COP28, Kerry held extended talks with his Chinese counterpart, Xie Zhenhua, with the two negotiators promising that their countries, the world's two largest greenhouse gas emitters, would work together for progress in Dubai.