President Joe Biden signed sweeping actions to combat climate change just hours after taking the oath of office, moving to rejoin the Paris accord and imposing a moratorium on oil leasing in the Arctic National Wildlife Refuge. Environmentalists said Biden’s actions — some of which could take years to be implemented — renew the U.S. commitment to safeguarding the environment and signal to the world that America has returned to the global fight against climate change.

The moves mark a dramatic rebuke of President Donald Trump’s pro-industry approach to energy and the environment.

On Paris alone, Biden is directly reversing Trump’s decision to yank the U.S. from the accord. Trump labeled the pact “a total disaster” that would harm American competitiveness by enabling “a giant transfer of American wealth to foreign nations that are responsible for most of the world’s pollution.”

Biden notified the United Nations the U.S. is rejoining the Paris climate agreement before day’s end, with the re-entry set to take effect 30 days later.

“While we are grateful for this action, we also know this is only the start. We need our country to be fully powered by clean energy, and we must do it quickly and thoroughly,” said Andrea McGimsey, senior director for Environment America’s Global Warming Solutions campaign. “The days of dirty, fossil fuel-burning, 19th Century technology must be numbered in order to reach a cleaner tomorrow.”

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Some of the moves drew opposition from industry and even one key Democrat. Senator Joe Manchin, a Democrat from coal-rich West Virginia in line to chair the Energy and Natural Resources Committee, called for changes to the Paris accord.

“I agree that President Biden must renew America’s leadership on climate change through innovation,” Manchin said in a statement. “I also uphold my view that the Paris agreement must be improved to set all nations on the same stage and hold each to the same standards of accountability.”

In an executive order Wednesday, Biden directed agencies to review and address Trump-era policies “that were harmful to public health, damaging to the environment, unsupported by the best available science or otherwise not in the national interest,” according to a transition fact sheet.