No president in 35 years has made as sweeping a conservation proposal as President Barack Obama did today by urging Congress to transform the oil-laden coastal plain of Alaska’s Arctic National Wildlife Refuge into what would be the largest wilderness area in the nation’s history.

The president’s move to designate 12.3 million acres of new wilderness would block decades of efforts to drill for oil on a 1.5-million-acre portion of the refuge. That coastal region is thought to contain up to 10.3 billion barrels of petroleum—roughly as much as the nation’s largest oil field, nearby Prudhoe Bay, has produced since 1968.

It would also protect a stunning, diverse ecosystem that includes 36 types of fish, calving grounds and a migration corridor for a troubled caribou herd, and nesting grounds for bird species that travel to the Arctic from all 50 states. It is the only refuge in the United States that is home to grizzly bears, black bears, and denning sites for polar bears, and it provides a wildlife corridor that stretches from the Canadian border across Alaska to the Chukchi Sea.

The refuge—often referred to simply by its acronym, ANWR—has long been a powerful symbol, a litmus test, about how Americans view the nation’s vast expanse of untracked wild country.

That’s been particularly true since 1980, when President Jimmy Carter was burned in effigy in Fairbanks, Alaska, in part for doubling protections along this vast expanse of tundra and birch and spruce forest that stretches from the Brooks Range north to the Beaufort Sea.

Is sacrificing a small slice of this obscure, rarely visited landscape a small price to pay to meet our energy needs? Or is this a one-of-a-kind environment that should be protected at all costs, a place to start to make a transformation to a cleaner energy future?

It is all but certain Congress will not take the Obama administration’s advice. Just last week, Senator Lisa Murkowski (R-Alaska) moved to propose yet again that the ANWR be open to drilling. On Twitter, Representative Don Young (R-Alaska) compared Obama’s proposal to “spitting in our faces and telling us it’s raining.”

Regardless, the very audacity of the proposal may well force the nation’s leaders into a more direct and open debate that for years has largely been relegated to the sidelines: How should the nation balance its energy needs with wildland conservation and the risks posed by climate change?

While oil drilling can be done safely, the Obama administration insisted in a statement, accidents can happen, and sometimes do.

“The Coastal Plain of the Arctic Refuge, one of the few remaining places in the country as pristine today as it was when the oldest Alaska Native communities first set eyes on it, is too precious to put at risk,” the White House said.

Still, the lines are not always so clearly drawn. For conservatives and liberals, environmentalists and energy companies, there has never been much room for compromise. But for the Native communities residing on Alaska’s North Slope, many of which hold mineral interests in the ANWR, the debate over the future of the refuge has often seemed beside the point.

For many the risk to Alaska’s wetlands and tundra ecosystems is overshadowed by the risk of drilling for oil in the adjacent Arctic Ocean, home to the bowhead whale that is the mainstay of Inupiat culture. Rightly or wrongly, many of those communities have viewed the battle over the ANWR and offshore oil as an either-or proposition.

Some time in the next several days, the Obama administration is expected to unveil its five-year plan for oil exploration in Arctic seas, as well. And the administration already is proceeding with environmental reviews for at least some additional offshore lease sales.

But no matter what larger position the administration takes, that decision—especially when combined with the move on the ANWR—will mark a turning point in the debate about America’s conservation and energy future.