Mrs. Clinton, a Democratic presidential candidate who served in Mr. Obama’s cabinet as secretary of state, has largely stood by the president on policy matters since beginning her campaign this year. While she has remained silent on whether she would support the Keystone XL oil pipeline project, which Mr. Obama has under review and which environmentalists oppose, Arctic drilling was an opportunity for her to accommodate the progressive wing of her party.
“The Arctic is a unique treasure,” Mrs. Clinton wrote in a signed Twitter post. “Given what we know now, it’s not worth the risk of drilling.”
The Obama administration on Monday granted Shell a final permit to begin drilling in the waters of the Chukchi Sea off Alaska’s northwest coast. Oil companies have long sought the rights to explore the region, which scientists estimate could contain up to 15 billion barrels of oil.
But five years after the Deepwater Horizon oil spill in the Gulf of Mexico, environmentalists warn that drilling in the Arctic Ocean will accelerate global warming and that cleaning up a spill in those waters would be especially difficult. Shell acquired leases in 2008 under the George W. Bush administration to gain the rights to drill.
On Tuesday, environmental groups applauded Mrs. Clinton’s stance.
“She’s exactly right: Everything we know about dangerous oil drilling in the Arctic indicates it imperils a national treasure and is guaranteed to make our climate crisis worse,” said Michael Brune, executive director of the Sierra Club.
Mrs. Clinton continues to face pressure to take a position on the Keystone pipeline. She has said she will remain silent on the issue until Mr. Obama makes a decision on the project’s future because she was involved during its early stages of discussion.
But questioned by reporters Tuesday in North Las Vegas, Nev., on why she has not expressed a position, she said she was getting impatient waiting for the administration to act “because I’m not comfortable saying, you know, I have to keep my opinion to myself given the fact that I was involved in it.”
Potential Republican rivals for the presidency seized on Mrs. Clinton’s announcement as an opportunity to express their support for drilling. Former Gov. Jeb Bush of Florida said that Mrs. Clinton was “extreme” in her position.
But speaking in Nevada, Mrs. Clinton said Shell’s history of drilling difficulties raised red flags and that she had concluded after reviewing available data that the Arctic waters should be protected from exploration.
“I think we should not risk the potential catastrophes that could come about from accidents in looking for more oil in one of the few remaining pristine regions of the world,” she said. “Rather we should be focusing on clean renewable energy.”
Mr. Obama has said that Arctic drilling is an inevitability that needs to be carefully managed.