The global sea level has been gradually rising over the past century.'The effects and impacts of changing sea level are being felt now, in our country and throughout the world.'Д®mail Sarah Lewin at or follow her Follow us, Facebook and Google+. 'Let there be no doubt: This is relevant science, and it will result in understanding that yields direct societal benefit,' Freilich said. The picture NASA is developing will help predict exactly what shape those changes will take. But the uncertainties are significant, officials said, and the actual increase could wind up being much larger. The United Nations Intergovernmental Panel on Climate Change predicted in 2013 that sea level would rise by 1 to 3 feet (0.3 to 1 m) by the end of the century. They are all connected pieces of research.' What's happening in Greenland is relevant to what's going to happen to Antarctica in the future as well. 'Looking at Alaska's glaciers tells us what Greenland will look like in a century or a few centuries. 'When you look across Alaska, Greenland and Antarctica, you see a whole range of climate variables,' said Eric Rignot, a glaciologist based at the University of California, Irvine and NASA's Jet Propulsion Laboratory in Pasadena, California. Starting in September, NASA will also perform several sweeps over Greenland, with instruments on the HU-25C Guardian Falcon plane for Operation IceBridge. Greenland's ice sheet alone would raise sea levels globally by 20 feet (6 m) if all of it were to melt, researchers said.

A major new effort, called Oceans Melting Greenland (OMG), will begin by mapping the seafloor near Greenland with underwater probes, to see how the huge island's contours are guiding melting. In addition to doing satellite-based research, NASA scientists are venturing out by land and sea to better understand the Earth's changes. In 2014, NASA formed a new sea-level-change research team comprising scientists with expertise in glaciology, hydrology, oceanography, geophysics and a variety of other fields, Nerem said.В 'You need all these fields вЂ¦ to actually understand all the factors that affect future sea level rise,' he noted. And NASA has more satellites in the pipeline for later on, such as the radar-imaging NISAR (Nasa-Isro Synthetic Aperture Radar) and SWOT (Surface Water and Ocean Topography) missions in 2020. Jason 3 was scheduled to launch this month by SpaceX, but it must be rescheduled because of SpaceX's recent failed resupply mission to the International Space Station. ДЄ follow-up to the GRACE mission is expected to launch in 2017, officials said, as is ICESat-2. The distance between the two spacecraft varies as ice and water move around on the planet, Steve Nerem, who leads NASA's Sea Level Change Team at the University of Colorado, Boulder, said at the news conference - and the GRACE duo can measure those changes to within the diameter of a red blood cell. The model also incorporates data from GRACE, twin satellites that are very sensitive to changes in Earth's mass distribution. NASA's ICESat satellite also keeps tabs on ice-sheet height with pulses of laser light. The measurement is extremely precise: Freilich mentioned that such a tool mounted on a jetliner flying at 40,000 feet (12,200 meters) would be able to detect the bump caused by a dime lying flat on the ground. To study sea levels, NASA has used satellite altimetry, which measures the time a radar burst takes to hit Earth's surface and return to orbiting spacecraft such as TOPEX/Poseidon, Jason 1 and then Jason 2. NASA's data reveals that, although the picture is complex, sea levels overall are rising faster than they were 50 years ago - more quickly than expected - and that the speed will likely increase in the future, primarily because of melting ice sheets. UCLA's Laurence Smith deployed this autonomous drifter in a meltwater river on the surface of the Greenland ice sheet in July 2015 as part of an effort to understand the causes of sea level rise around the globe.

Map of the world after sea level rises