NASA Is Fully Prepared to Watch the Oceans Swallow Earth

NASA already has numerous missions devoted to mapping sea level rise, and more on the way.

Aug 27 2015, 12:00pm

Scientists study melting ice sheets. Image: NASA/Goddard

At this point, there is unanimous scientific consensus that sea levels are globally rising as a result of climate change. But how fast are oceans advancing? How much damage can rising sea levels do? And most importantly, what can we do to slow this literal tide?

This week NASA addressed its approach to these questions, with particular emphasis on monitoring and responding to Earth's rising oceans. Here's the rundown of what the panelists said.

Sea levels are currently rising more rapidly than they were 50 years ago, at about three millimeters a year on average.

Michael Freilich, director of NASA's Earth Science Division, pointed out that this trend has already disrupted millions of people, and will continue to pose significant problems for low-lying cities like Miami, San Francisco, and Tokyo.

A few millimeters may not seem like a lot, but when you consider the sheer volume of new water it represents around the world, the effects quickly add up. For example, rising seas have already intensified coastal flooding in the United States, and will wipe out entire island nations over the coming decades.

Since NASA began monitoring sea levels in 1993, global oceans have risen by six centimeters, though this is not a uniform figure.

This video collates the last 22 years of NASA's satellite observations of sea levels into an animation. It demonstrates why some regions experience falling sea levels, in spite of the the general trend of advancing seas.

For example, sea levels off the southwest coast of North America have been falling due to a phenomenon known as the Pacific decadal oscillation, which cools waters across the mid-latitude ocean, causing levels to drop. But these exceptions are only regional—the global picture of Earth's seas confirms that levels are steadily rising.

NASA already has numerous missions devoted to mapping sea level rise, and more on the way.

This graph summarizes the observations of the current fleet of satellites monitoring sea levels.

Image: Steve Nerem, University of Colorado

Over the next decade, NASA will launch at least three new satellites to provide sharper measurements and monitoring of sea level rise: SWOT, GRACE-FO, and IceSat-2. On top of that, critical ice sheets will be monitored by plane-based missions like Operation IceBridge and the newly minted OMG (Oceans Melting Greenland) program.

September 2015 flight paths of Operation IceBridge. Image: Operation IceBridge

Studying sea level rise may help to predict flooding and emergencies, but for the time being, there is no way to stop the oceans from rising at least three feet in the future.

"Given what we know now about how the ocean expands as it warms and how ice sheets and glaciers are adding water to the seas, it's pretty certain we are locked into at least three feet of sea level rise, and probably more," said Steve Nerem, who heads NASA's Sea Level Change Team.

"But we don't know whether it will happen within a century or somewhat longer," he said.

If you are feeling apocalyptic today, you can test out just how much damage a rise of three feet would do to the coastal American locations of your choosing on this adjustable map from Climate Central. All told, scientists expect this three foot rise to force a global total of almost 200 million people to relocate, with property damage estimated in the trillions.

The global floodgates are opening, and it's too late to prevent the seas from rising at least a few feet. Whether or not we are content to let it rise to even more disastrous levels for future generations, however, depends on us.