Much of this country’s barrier islands will be under water in 50 years because of climate change, according to a University of Miami professor and expert on sea-level rise.

On the Jersey Shore, not only would places like Long Beach Island and Seaside Heights be partially covered by sea water, but so would flood-prone coastal communities from Bay Head to Tuckerton. These areas also would face more flooding and greater risk from storm surges, according to Harold Wanless, chairman of the university’s Department of Geological Sciences.

“Most of the barrier islands of the world will become largely inhabitable” within 50 years, he said, using the U.S. government’s official projections.

Wanless, whom some in the media have dubbed “Dr. Doom,” believes the National Oceanic and Atmospheric Administration is underestimating the onset of “a rapid pulse of sea level rise” — perhaps as much as 30 feet by the end of century, or 4.5 times the official projection.

“I think by the middle of the century people are going to become afraid of the (Jersey) Shore,” he said during a November conference by the Institute on Science for Global Policy here. “Right now, it’s where we all want to live.”

New Jersey Gov. Chris Christie, who’s running for the Republican presidential nomination, has said he believes human activity contributes to climate change but described it as “not a crisis.” He has implied that if he were elected president he would not spend his time and energy fighting it.

“I wish (Obama) would focus on America first and the issues that are of most concern to the American people right now,” Christie said during a December campaign stop in New Hampshire. “And believe me, in a list of those climate change would not make the top 10, I suspect.”

That sounds close to the opinion of Brick Wenzel, a property and business owner from Lavallette, N.J., who is worried that basing policy on Wanless’ “alarmist ideology” will only result in bad laws and regulations.

To be clear, Wenzel, a commercial fisherman and owner of a restaurant and ice cream parlor in the half-mile wide borough on the Barnegat Peninsula, said he believes climate change is real. Yet he thinks that scientists like Wanless are blowing its effects of it out of proportion to attract attention.

“He is taking facts and using them to benefit himself,” he said.

Wanless admits that his forecast deviates from the center of academic discussion on rising sea levels, but he’s not the only one who thinks official projections are too low.

“All I’ve recommended people do is to use the U.S. projections and incorporate accelerating ice melt because that’s what’s happening,” he said. “If we’re blindsided by this, … then we’re going to see a mass migration away from the shore and low-lying areas.

“And if we haven’t planned for that, we’re going to (create) a challenge for society,” Wanless said. “If you want to call that alarmist, go ahead.”

Wanless had three main points in his presentation:

1. Stop thinking you have time

“(Sea level rise) is not something that is going to be stoppable at 2 feet or 3 feet or 5 feet. There are some people who go around saying, ‘Well, if we start behaving, it’s going to get better.’ It’s not. We warmed the ocean,” he said. “This is going to keep happening through this century and well beyond.”

Warm water in the North Atlantic and Arctic has been thawing polar ice around Greenland since about 1995, Wanless said.

“Even if we stopped burning fossil fuels tomorrow, the greenhouse gases in the atmosphere will keep warming the atmosphere for at least another 30 years,” he wrote in a policy paper.

2. Stop spending money on sand and sea walls

“It’s really throwing money in the ocean when we do beach renourishment with accelerated sea level rising,” Wanless said

Earlier this year, federal tax dollars paid to transport nearly 10 million cubic yards of sand onto beaches in separate projects in New Jersey’s Monmouth and Ocean counties. The combined bill was about $168 million. That’s money Wanless said could be better spent preparing for the inevitable.

“At what point when you realize that the sea level is going to be rising at an accelerated rate do you say, ‘Maybe we should put aside money to help people relocate,” he said. “People are going to lose everything at some point.”

3. Set — and stick to — rules on new development and rebuilding

“We have to strengthen our regulations for rebuilding after storms,” Wanless said.

A seemingly never-ending debate surrounds flood insurance on the Jersey Shore and other areas subject to tidal flooding and storm surges. Congress passed the Biggert-Waters Flood Insurance Reform Act in 2012 to push premiums up by as much as 25% or more to more accurately reflect risk.

“Then the bills came in, and everybody got on the phone with their senators and congressmen, and guess what, they reversed it,” Wanless said, referring to the Homeowner Flood Insurance Affordability Act of 2014 which considerably softened the reforms.

He contends that politicians need hold firm on raising flood-insurance premiums, designating hazard zones and not encouraging development in areas that essentially are already lost.

“There are areas that will be unlivable and properties that will be unsalable within a 30-year mortgage cycle all along the Atlantic coast,” he wrote.