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Sea Level Rise is on the Rise

As our planet warms, sea levels are rising around the world – and are doing so at an accelerating rate. Currently, global sea level is rising about an eighth of an inch every year.

That may seem insignificant, but it’s 30% more than when NASA launched its first satellite mission to measure ocean heights in 1992 – less than 30 years ago. And people already feel the impacts, as seemingly small increments of sea level rise become big problems along coastlines worldwide.

Higher global temperatures cause our seas to rise, but how? And why are seas rising at a faster and faster rate? There are two main reasons: melting ice and warming waters.

 The Ice We See Is Getting Pretty Thin

About two-thirds of global sea level rise comes from melting glaciers and ice sheets, the vast expanses of ice that cover Antarctica and Greenland. In Greenland, most of that ice melt is caused by warmer air temperatures that melt the upper surface of ice sheets, and when giant chunks of ice crack off of the ends of glaciers, adding to the ocean.

In Antarctica – where temperatures stay low year-round – most of the ice loss happens at the edges of glaciers. Warmer ocean water and warmer air meet at the glaciers’ edges, eating away at the floating ice sheets there.

NASA can measure these changes from space. With data from the Ice, Cloud and land Elevation Satellite-2, or ICESat-2, scientists can measure the height of ice sheets to within a fraction of an inch. Since 2006, an average of 318 gigatons of ice per year has melted from Greenland and Antarctica’s ice sheets. To get a sense of how big that is: just one gigaton is enough to cover New York City’s Central Park in ice 1,000 feet deep – almost as tall as the Chrysler Building.

With the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission – a partnership with the German Research Centre for Geosciences – scientists can calculate the mass of ice lost from these vast expanses across Greenland and Antarctica.

It’s not just glaciers in Antarctica and Greenland that are melting, though. Nearly all glaciers have been melting in the last decade, including those in Alaska, High Mountain Asia, South America, and the Canadian Arctic. Because these smaller glaciers are melting quickly, they contribute about the same amount to sea level rise as meltwater from massive ice sheets.

The Water’s Getting Warm

As seawater warms, it takes up more space. When water molecules get warmer, the atoms in those molecules vibrate faster, expanding the volume they take up. This phenomenon is called thermal expansion. It’s an incredibly tiny change in the size of a single water molecule, but added across all the water molecules in all of Earth’s oceans – a single drop contains well over a billion billion molecules – it accounts for about a third of global sea level rise.

So Much to See

While sea level is rising globally, it’s not the same across the planet. Sea levels are rising about an eighth of an inch per year on average worldwide. But some areas may see triple that rate, some may not observe any changes, and some may even experience a drop in sea level. These differences are due to ocean currents, mixing, upwelling of cold water from the deep ocean, winds, movements of heat and freshwater, and Earth’s gravitational pull moving water around. When ice melts from Greenland, for example, the drop in mass decreases the gravitational pull from the ice sheet, causing water to slosh to the shores of South America.

That’s where our view from space comes in. We’re launching Sentinel-6 Michael Freilich, an international partnership satellite, to continue our decades-long record of global sea level rise.

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You’ve Heard “Houston, we’ve had a problem,” But Do You Know The Mission It’s From?

It’s the 50th anniversary of the Apollo 13 mission! NASA’s “successful failure,”Apollo 13 was to be the third lunar landing attempt, but the mission was aborted mid-flight after the rupture of a service module oxygen tank. The crew never landed on the moon, but due to the dedication and ingenuity of Mission Control, made it back to Earth safely. We’ve put some of the most important numbers of the Apollo 13 mission in perspective. Check it out!

Listen to the mission in real time, HERE. 

Follow NASA History on Twitter and Facebook for more interesting information about aerospace history!

Check out the stats of all the Apollo Missions in the free e-book Apollo by the Numbers, HERE.

Earth Facts that Live Rent-Free in Our Heads

Earth is a big weird planet. With so much going on, it’s easy to forget some of the many, many processes happening here. But at the same time, some stuff is so unexpected and just plain strange that it’s impossible to forget. We asked around and found out lots of people here at NASA have this problem.

Here are some facts about Earth that live rent free in our heads:

Earth has a solid inner core that is almost as hot as the surface of the Sun. Earth’s core gets as high as 9,800 degrees Fahrenheit, while the surface of the Sun is about 10,000 degrees Fahrenheit.

Dust from the Sahara fertilizes the Amazon rainforest. 27.7 million tons blow all the way across the Atlantic Ocean to the rainforest each year, where it brings phosphorus – a nutrient plants need to grow.

Ice in Antarctica looks solid and still, but it’s actually flowing – in some places it flows so fast that scientific instruments can move as much as a kilometer (more than half a mile!) a year.

Speaking of Antarctica: Ice shelves (the floating part of ice sheets) can be as big as Texas. Because they float, they rise and fall with the tide. So floating ice as big as Texas, attached to the Antarctic Ice Sheet, can rise and fall up to ~26 feet!

Melting ice on land makes its way to the ocean. As polar glaciers melt, the water sloshes to the equator, and which can actually slow the spin of Earth.

Even though it looks it, the ocean isn’t level. The surface has peaks and valleys and varies due to changes in height of the land below, winds, temperature, saltiness, atmospheric pressure, ocean circulation, and more.

Earth isn’t the only mind-blowing place out there. From here, we look out into the rest of the universe, full of weird planets and galaxies that surprise us.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

感染拡大の防止、医療インフラの整備、人々へのストレス軽減のために私たちそれぞれが自身の役割を果たすように求めています。

“Words are so powerful. They can crush a heart, or heal it. They can shame a soul or liberate it. They can shatter dreams or energize them. They can obstruct connection or invite it. They can create defenses, or melt them. We have to use our words wisely.”

— Jeff Brown

NASA’s View of COVID-19

#COVID19 led to changes in human activities around the globe. We can see some of these changes from space. Some bodies of water have run clearer, emissions of pollutants have temporarily declined, and transportation and shipment of goods have decreased.

Along with our partner agencies – ESA and JAXA – we’re making satellite data available on the COVID-19 Earth Observation Dashboard, where you can explore some of the changes we can see from space.

But it’s not just what we can see. When the pandemic began, NASA engineers sprang into action to build ventilators, oxygen hoods and more to help save lives.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com