– Miami Beach became ground zero for climate change when U.S. Sen. Bill Nelson convened a rare field hearing to draw national attention to the dangers posed by rising seas.

“For those who deny sea level rise and climate change, here is the proof,” Nelson, a Democrat, said during the two-hour hearing in Miami Beach.

It was one of several times he pointedly called out his colleagues in Congress who deny that climate change has been scientifically documented.

A half dozen witnesses, including a NASA scientist, a mayor and a county commissioner, forecast a dire future with a 3-foot rise in seas by the beginning of the next century. At that rate, large swaths of Florida’s coast would be inundated, with billions of dollars in damage, even as climate change fuels more severe hurricanes. But the panel also offered hope, saying there’s still plenty of time to plan.

“It’s a slow, steady, persistent creep. But the fact that it’s slow means there’s time,” said Fred Bloetscher, an associate civil engineering professor at Florida Atlantic University.

Nelson, the state’s former insurance commissioner, said he held the hearing to make “part of the official record of the Senate” the federal government’s take on climate change as well as the growing list of sea rise-related problems encountered by Florida residents — including contaminated drinking water and flooded streets.

Over the past 150 years, the Earth’s temperature has risen, said Piers Sellers, deputy director for Sciences and Exploration at the Goddard Space Flight Center in Maryland. At the same time, rising temperatures and warming seas have caused polar ice caps to melt.

He said South Florida will likely see more severe weather and an increase in the frequency of strong hurricanes with warming oceans and a more volatile climate.

In Miami Beach, residents are already seeing changes, Mayor Philip Levine told Nelson. The 7-mile-long island is lowest at its core, so water collects there. And not just during storms. When strong high tides occur, the island regularly floods, he said.

“Sea level rise is our reality in Miami Beach,” he said.

Four counties including Broward and Miami-Dade agreed in 2009 to create a joint action plan. Next week, Miami-Dade’s climate change group is expected to approve its plan.

Bloetscher said the biggest challenge will be what to do with water once it is collected. Urban water can’t be dumped in the ocean or the Everglades. “Quantity is easy,” he said. “Quality is the problem.”