Sunak's office previously said he had to skip the gathering, known as COP27, which start on Sunday. It cited “pressing domestic commitments," including preparations for a major government budget statement scheduled for Nov. 17.
But Sunak tweeted Wednesday that he would attend the two-week gathering because “there is no long-term prosperity without action on climate change."
“There is no energy security without investing in renewables," he wrote.
Sunak's earlier decision to skip the talks were criticized by many, including British government climate adviser Alok Sharma, who will hand over presidency of the Conference of the Parties, or COP, at the summit in the Egyptian resort of Sharm el-Sheikh. The U.K. hosted last year's COP26 climate summit in Glasgow, Scotland.
Sunak's about-face came the day after former Prime Minister Boris Johnson confirmed he will be going to the climate talks at the invitation of the host country. Under Johnson, who left office in September, the U.K. committed to reach net-zero carbon emissions by 2050 and to eliminate coal from its energy mix by 2024.
Environmentalists worry there could be backsliding on those commitments because of the energy crisis triggered by Russia's invasion of Ukraine.
The opposition Labour Party's climate spokesman, Ed Miliband, said Sunak had been “shamed into going to COP27.”
“His initial instinct tells us about all about him: he just doesn’t get it when it comes to the energy bills and climate crisis," Miliband said.
Green Party lawmaker Caroline Lucas said Sunak's initial decision and subsequent U-turn was “an embarrassing misstep on the world stage.”
“Let this be a lesson to him — climate leadership matters,” she tweeted.
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