The second was that of melting ice flowing into the oceans from places such as Greenland and Antarctica.
Lead scientist Professor Steve Nerem, from the University of Colorado Boulder, in the U.S., said: "This acceleration, driven mainly by accelerated melting in Greenland and Antarctica, has the potential to double the total sea level rise by 2100".
Sea ice as seen from NASA's Operation IceBridge research aircraft in the Antarctic Peninsula region, on November 4, 2017, above Antarctica.
Scientists analysing 25 years of satellite data discovered that global sea level is not rising at a steady 3mm per year, as previously thought.
"This acceleration, driven mainly by accelerated melting in Greenland and Antarctica, has the potential to double the total sea level rise by 2100 as compared to projections that assume a constant rate - to more than 60cm instead of about 30", said study author Steve Nerem. Secondly, warmer temperatures melt land ice which then flows into the ocean, adding to the increase. Storm surges and salt water intrusion into aquifers where some communities get their drinking water are just two examples. But, that number "is nearly certainly a conservative estimate of future sea level change", Nerem said. "There may be abrupt changes in the ice sheets", he said.
A couple waits for the sunset by the tetrapods on November 6, 2016, in Male, Maldives.
Another day, another delay for Shiffrin, other Alpine skiers
Men and women shared race days at the 2006 Turin Olympics and 1998 Nagano Olympics, for example. So hoping for the best. "It is a very heavy load", said Shiffrin's coach, Mike Day.
"So far, the difficulty in measuring sea level has made detecting acceleration very hard", said Joseph Majkut, climate scientist at the Niskanen Center, a pro-climate action libertarian think tank. (Volcanic eruptions have a mild cooling effect that can, in turn, affect sea levels).
It also shows how climate models are important in interpreting satellite records, such as in this study where it allows the study group to estimate the background effects of the 1991 eruption of Mount Pinatubo on global sea level.
Consider the record set in Boston Harbor during January's "bomb cyclone" or the inundation regularly experienced in Miami during the King tides; these are occurring with sea levels that have risen about a foot in the past 100 years.
Before this study was published Monday in the Proceedings of the National Academy of Sciences, scientists had suspected sea level rise was accelerating but didn't have the data yet to prove it. That assessment, which Nerem said some describe as a conservative estimate, has been organized by the United Nations since 1988. Nerem's models show the sea rising 26 inches by 2100. Warming seas expand and water from melting glaciers and ice sheets have had nowhere to go but into the oceans.
"[Our study] is much more simplistic, but it's kind of providing a check on those model projections", he explained. They say the accelerating sea level rise is due to ocean warming and melting ice sheets.
"The tide gauge measurements are essential for determining the uncertainty in the global mean sea level acceleration estimate", said co-author Gary Mitchum, University of South Florida College of Marine Science.