There had been a consensus that sea levels would rise between 30 and 90 centimeters (one to three feet) by the end of the century. That was in 2013. Now, with even more data to work with, researchers suggest that the rise is more likely to be at the higher end of that range.
This prediction has come from new visualizations of sea level variations all over the globe. You can see the changes in the following video from NASA, compiled using 23 years of sea level data. While some regions, such as the west coast of the U.S., have seen a decrease (due in part to shifting ocean currents), the majority of the globe is experiencing sea level rise.
Josh Willis explains why sea levels have changed, using sea level data from the last 23 years. NASA/JPL.
Josh Willis, an oceanographer at NASA, explains why in a statement, and warns residents on the west coast of the U.S. not to get comfortable. “Sea level along the west coast has actually fallen over the past 20 years because long-term natural cycles there are hiding the impact of global warming.
“However, there are signs this pattern is changing. We can expect accelerated rates of sea level rise along this coast over the next decade as the region recovers from its temporary sea level ‘deficit.’”
One of the contributors to sea level rise is the melting of ice sheets. The biggest is the Antarctic ice sheet, which covers an area of almost 14 million square kilometers (5.4 million square miles) and is larger than the United States and India combined. Over the last decade, it has shed an average of 118 gigatons of ice a year – no small amount of water.
Smaller, but by no means less important, is the Greenland ice sheet. Covering a more modest 1.7 million square kilometers (660,000 square miles), it has actually shed almost three times as much ice over the last decade as the Antarctica sheet – 303 gigatons a year on average. The changes since 2002 can be seen in this NASA video, taken from the GRACE project's continuous monitoring of the ice sheet's mass.
The mass of ice loss of Greenland's ice sheet. NASA.
In order to learn everything they can about the melting caps, NASA started the Oceans Melting Greenland (OMG) project. (Willis, the project leader, confessed that this acronym was "barely squeezed past the censors.") The project is analyzing how warm ocean water is speeding up the loss of Greenland's glaciers.
It is too soon to confirm whether this fast rate of ice loss is here to stay. “We’ve seen from the paleoclimate record that sea level rise of as much as 3 meters (10 feet) in a century or two is possible, if the ice sheets fall apart rapidly,” said Tom Wagner, the cryosphere scientist at NASA's headquarters in Washington. “We’re seeing evidence that the ice sheets are waking up, but we need to understand them better before we can say we’re in a new era of rapid ice loss.”
With the global population growth not showing any signs of slowing down, and a lot of inhabited space at risk of being submerged by the end of the century, it is more important than ever to figure out how exactly the ocean levels are going to rise. The data NASA is collecting may help nations predict how their populations will likely be affected and assist plans to counteract the effects of rising sea levels.