NEW ORLEANS, La. — The Obama administration on Thursday laid out a plan to deal with the catastrophic dangers of rising sea levels, hurricanes and erosion on the Gulf Coast, and backed efforts to invest in restoring barriers islands and wetlands in Mississippi and Louisiana.

Experts hailed the policy document as the strongest sign of support for coastal restoration on the Gulf Coast ever endorsed by a White House.

“It’s a terrifically important document if it’s followed through on,” said Mark Davis, the director of the Institute on Water Resources Law and Policy at Tulane University in New Orleans.

The document, called a “roadmap” for the coast, said the nation’s energy supply, crucial ports and waterways, vital habitat for fish and wildlife and the Gulf Coast’s “rich cultural legacy” were at stake.

“Unless we stem the rapid rate of ecosystem loss in the region, the ecosystems and the services they provide will collapse,” the document said.

At risk, the paper said, was “not only the economies of Louisiana and Mississippi, but also the economy of the nation as a whole.”

Tom Strickland, the assistant secretary for fish and wildlife at the Department of the Interior, said the White House understands the problems on the Gulf Coast.

“Finally, this issue has received the highest priority with a White House and a president that has said we are going to take charge of this,” Strickland said. He is one of several high-level Obama officials who crafted the document as part of a working group looking at the Gulf Coast’s unique problems.

Already, there are several multimillion-dollar programs to stem land loss in Louisiana, but they have been unable to keep up with erosion.

Since the 1930s, the Mississippi River delta has been slowly falling apart and eroding due levee construction, oil drilling hurricane damage and other factors. Louisiana has lost about 2,100 square miles of coast and loses about 25 square miles a year, according to the U.S. Geological Survey.

With sea levels on the rise due to global warming, experts warn that much of south Louisiana and Mississippi are at risk of being lost for good.

The administration said it would work with state officials to develop long-term solutions to pay for the massive multibillion-dollar ecosystem restoration project, which would be one of the largest ever undertaken.

Over the next 18 months, the administration said it would cut through red tape, finish critical reports looking at what can and cannot be saved, fill in data gaps to gain a complete scientific understanding of the problem and do a better job of using Mississippi River sediment, most of which washes out to the Gulf of Mexico.

The sediment in the river is important because scientists say it can be diverted into sections of the coast that have been cut off from the Mississippi. The Mississippi’s mud built the Louisiana delta over the past 7,000 years but the delta began falling apart after levees were erected.

The report also said it was vital to protect Mississippi’s barrier islands and coastal wetlands because they “served to absorb or reduce some of the impacts from coastal storms.” Last year, Congress appropriated $439 million for barrier island restoration and other ecosystem repair work on the Mississippi coast.

Louisiana Gov. Bobby Jindal said the report “clearly demonstrates a positive shift in direction, but must be coupled with aggressive action on the ground — turning dirt. There is no time for delay.”

Dan Turner, a spokesman for Mississippi Gov. Haley Barbour, praised the Obama administration and said Mississippi’s barrier islands were “flattened with recent storms” and that the state’s coast will be vulnerable “until they are restored.”

U.S. Sen. Mary Landrieu, D-La., praised the Obama plan as carrying out an “integrated, comprehensive approach that accelerates our work in coastal Louisiana and builds a true partnership with the state.”

King Milling, the head of the Whitney National Bank in New Orleans and chairman of the coastal advocacy group America’s Wetland Foundation, said the White House was “now acting upon what many have long felt were unheard cries in the wilderness.”

Still, there were questions about the administration’s approach, which advocated that restoration of the delta was possible. There are scientists who believe policymakers need to emphasize relocating towns and communities and stop beach-front development because of sea level rise.

“The science is clear that ecosystem restoration — at the level that will be possible — will provide limited storm protection to infrastructure and communities,” said Rob S. Young, a coastal geologist and director of the Program for the Study of Developed Shorelines at Western Carolina University.

He said that the $439 million in Mississippi restoration work was a “waste of money” with uncertain benefits because barrier islands do not do much to stop hurricane storm surge.

Davis, the Tulane professor, said the White House’s document left many questions unanswered about how the restoration work would get done and with what money.

“There are legal and budgetary boundaries that this framework acknowledges, but I don’t see a clear path forward,” he said. “It’s a commitment to seek results, not a commitment to achieve results.”