Newsday: It’s hard to whip up concern for a creeping threat whose predicted advance can be compared to “being attacked by a giant snail.” That’s how environmental advocate Sarah Newkirk of the Nature Conservancy described sea level rise at a recent forum in Upton. Her phrase was a rueful nod to empty seats at the meeting, convened by state planners to seek public input on rising oceans. Just a few dozen residents had shown up, though the turnout was more than in Nassau the day before, …