Nature gives us a much closer look not just at how much the ocean is rising, but where the levels will be changing most, using data from gravity-sensing satellites that show where ocean water flows once it’s no longer ice:
Ice sheets and glaciers have a slight gravitational pull on the water that surrounds them, making sea level a little higher at their edges — similar to how the Moon tugs on the ocean to generate tides, but on a fraction of the scale. When a glacier or ice sheet melts, it loses mass; therefore, the gravitational pull it exerts on nearby ocean water weakens and the sea level falls. At the same time, the land rises up because the ice is no longer weighing it down, which causes a further drop in sea level.
The loss of mass changes Earth’s gravitational field causing the fresh meltwater and ocean water to move away towards faraway coastlines; the resulting pattern of sea-level rise is the fingerprint of melting from that particular ice sheet or glacier. For example, the latest study found that ice melt in Antarctica causes sea level to rise 52% faster in California and Florida than it does in other parts of the world, Velicogna says. Much of Earth’s middle and lower latitudes bear the brunt of rising sea levels because they’re sandwiched between Antarctica and Greenland, which are home to massive ice sheets that are shedding mass as meltwater or icebergs.
Velicogna and co-author Chia-Wei Hsu, also at the University of California, Irvine, used gravity data from NASA’s two Gravity Recovery and Climate Experiment (GRACE) satellites, which measure changes in mass on Earth’s surface. The scientists looked at satellite data from April 2002 to October 2014, and matched it with measurements from pressure stations on the ocean floor.