Even if fossil fuels were phased out, the seas would likely mount between 0.8 and two feet by century's end, it said.
Average global temperature today is about 1.8 degrees Fahrenheit (one degree Celsius) higher than it was in the late 19th century.
The Rutgers-led study - with co-authors from Harvard University, the Woods Hole Oceanographic Institution and the Potsdam Institute for Climate Impact Research in Germany - was based on a database that included records from 24 locations around the world, and 66 tide-gauge records from the last 300 years.
Scientists say the planet is incredibly sensitive to small changes in temperature, with today's average climate about 1.8 degrees Fahrenheit (one degree Celsius) warmer than it was in the 19th century.
"During the past millennia sea-level has never risen nearly as fast as during the last century," said co-author Stefan Rahmstorf, co-Chair of the Potsdam-Institute for Climate Impact Research's (PIK) research domain Earth System Analysis.
"The new sea-level data confirm once again just how unusual the age of modern global warming due to our greenhouse gas emissions is - and they demonstrate that one of the most dangerous impacts of global warming, rising seas, is well underway."