MIAMI — For the past three decades, University of Miami geology professor Harold Wanless has tracked the tides as they crept higher, watched oysters head for drier ground and repeatedly warned that the ocean is swelling in ways that could one day put coastal cities like Miami under water.

MIAMI — For the past three decades, University of Miami geology professor Harold Wanless has tracked the tides as they crept higher, watched oysters head for drier ground and repeatedly warned that the ocean is swelling in ways that could one day put coastal cities like Miami under water.

His predictions — punctuated with dire conclusions like “this is going to test the very fibers of civilization” — often drew skepticism or, worse, silence.

But earlier this month, two new studies reported findings that, if they hold up, would confirm what he and other scientists have long suspected: Global warming has triggered an unstoppable melting of polar ice in Antarctica that could raise sea level by 10 feet or more over the next several centuries.

Coming on the heels of international and national assessments that this spring affirmed the effects of climate change, the 72-year-old professor is finding himself in new territory.

“People used to yell at you when you gave talks,” said Wanless, who is not prone to smiling. “They don’t do that anymore.”

The chair of UM’s geology department, he has a 43-page resume listing dozens of publications and accomplishments, including being a lecturer for the National Oceanic and Atmospheric Administration as well as an elementary school science fair judge. He now hopes the long debate over climate change can get to what he sees as the real point: not whether humans are warming the planet, but how fast it is warming.

Wanless was not alone when he sounded the alarm bell on rising seas over the years. But getting the public — and politicians — to pay attention was a struggle, particularly for scientists used to operating in the safety of their laboratories.

“You’re supposed to be sitting in a lab doing really good science, and what’s happening to the rest of the world is not of your concern,” said Orrin Pilkey, a Duke University earth and ocean sciences professor emeritus and expert in coastal erosion.

Then came findings that manmade greenhouse gases were changing the planet’s climate in dangerous ways. Around the world, from growing acidity in warmer oceans to rising water in South Florida, alarming signs began forcing scientists into the public debate, sometimes at their own risk. Michael Mann, a Pennsylvania State University climatologist and geophysicist whose work helped the Intergovernmental Panel on Climate Change (IPCC) win the Nobel Peace Prize with Al Gore in 2007, had his emails hacked and his records subpoenaed by Virginia’s attorney general and wound up in a bitter libel dispute with the National Review.

When it came to sea level rise, Wanless was often at the front of that effort in South Florida, Pilkey said.

“The good thing about Hal is he’s greatly respected by the scientific community,” he said. “I think we’re lucky to have him on patrol.”

But his predictions that put sea level rises in South Florida higher than consensus assessments sometimes triggered skepticism. In its April report, the IPCC predicted a 1-to-3-foot rise over the next century. The Miami-Dade County Climate Change Task Force that Wanless co-chairs predicted a 3-to-5-foot rise. But Wanless believes the starting point for projections should be 4 feet.

“It doesn’t mean we are saying different things about the science,” said Leonard Berry, director of the Florida Center for Environmental Studies at Florida Atlantic University and an author of the National Climate Assessment’s Southeast chapter, published in April. “It means we are making different judgments about the timing of those events. In defense of Hal’s position, every step of the way in the last 10 or 15 years, our projections have moved upwards. So some of the rest of us are where he was 10 years ago.”

Still, Benjamin Kirtman, a UM meteorology and oceanography professor who helped author the April IPCC report, said more studies need to be done to confirm the higher projections for sea rise triggered by melting ice.

Wanless has not ducked the contentious politics of the issue and does not hesitate to call out skeptics of manmade climate change, particularly politicians. He said he twice offered to convene scientists to talk to U.S. Sen. Marco Rubio, but the Miami Republican never took him up on the offers. So when Rubio recently said on ABC News that he was not convinced humans were driving climate change, Wanless called it “horrible.”

Though Rubio later said in an interview with the Miami Herald that he is not denying that climate change is occurring, he also would not answer yes or no when asked whether humans were driving the change.

“I understand, politically, the issue is easier to write as ‘He either supports it or he doesn’t. He either believes it or he doesn’t.’ But these are complex issues. Even the science on this has evolved over the past 20 years,” Rubio said.

Wanless, however, is unequivocal in his response.

“Any elected official who doesn’t understand climate change, who isn’t fully trying to plan for what people and communities are going to have to face,” he said, “shouldn’t be in elected office.”