After decades advocating for action on climate change as a U.S. senator and then secretary of state, John Kerry has been tapped for a newly created post — special presidential envoy for climate, based on the National Security Council.

"America will soon have a government that treats the climate crisis as the urgent national security threat it is," Kerry said on Twitter shortly after the announcement by President-elect Joe Biden's transition team. "The climate crisis demands nothing less than all hands on deck."

Defense leaders have warned for years that warming temperatures and rising seas pose an array of national security challenges, including mass displacement, political instability and food scarcity.

Kerry helped negotiate the Paris climate agreement, signing it in 2016 with his granddaughter on his lap. Biden has pledged to rejoin the pact after Trump withdrew from it. But Kerry could face skepticism as he seeks to reassert U.S. leadership and gain the trust of other countries for more aggressive climate action.

Environmental groups praised the Kerry appointment. Fred Krupp, president of the Environmental Defense Fund, called him "one of the world's most effective climate champions."

Varshini Prakash, executive director of the progressive Sunrise Movement, said Kerry "is committed to engaging and listening to young voices — even when we might not always agree — and ensuring we have a seat at the table."

Prakash and Kerry served together on a joint task force to help shape Biden's ambitious climate plan.

But she added that this new role "is not enough." Her group and others want Biden to appoint a domestic counterpart to Kerry, to push for deep cuts in climate warming emissions at home, not just abroad.

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