Living in Miami in 2015 and harboring any doubts about sea level rise is roughly equivalent to being a volcano truther in Pompeii circa 79 AD. The catastrophe is happening. The only question is just how quickly climate change will sink parts of South Florida.

The answer, according to new work by a University of Miami researcher: even more quickly than we thought.

See also: Rolling Stone Predicts Miami Will Be Underwater by 2030

"People ask me all the time: 'When is it going to happen? When will we start seeing sea level rise?'" says Brian McNoldy, a senior research associate at UM's Rosenstiel School of Marine and Atmospheric Sciences. "We've already passed that. It's happening."

To chart that rise, McNoldy recently crunched nearly two decades' worth of data from a tidal monitoring station on Virginia Key. First, he looked at the heights of high, low, and mean sea level measured at the station from 1996, when it was set up, until today.

In research posted last week, he reported that in 2014, the linear trend in all three was more than three inches higher than in 1996.

Even more worrying, though, the data suggests the trend is accelerating. By charting just the highest tide each day and breaking that info into five-year chunks, McNoldy found that the high-water mark rose by an average of 0.3 inches per year overall -- but a much higher 1.27 inches per year over the past five years.

"It was surprising," McNoldy says. "I didn't realize that over such a short time, going back to only 1996, you'd see that much of a trend."

One challenge of convincing people to take the threat of rising seas seriously is that the change is incremental; it's not a sudden Pompeiian eruption but a slow-motion disaster.

But McNoldy says he hopes his data adds more fuel to the growing conversation about what to do in Miami, where the risks include not only billions of dollars' worth of property along the coastline but also a fresh-water table -- the drinking water source for millions -- that could soon be infiltrated by rising seawater.

McNoldy doesn't have any answers about how to address those problems, but he's glad we're talking about them. "That's one good thing about Miami," he says. "Here, people do recognize what's happening and they are trying to do things, while other parts of our country are turning their backs."

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