Earth is getting fatter

Jul 28, 2011 By Katharine Gammon, ISNS Contributor
Earth is getting fatter
From the thinning of ice sheets to the flow of water through aquifers and the slow currents of magma inside Earth, measurements of the amount of mass involved provided by GRACE help scientists better understand these important natural processes. Credit: NASA

Like many of its inhabitants, the Earth is getting thicker around the middle -- that's what a new study out this week says. The increased bulge is due to the melting of the Greenland and Antarctic ice sheets.

The Earth was never perfectly round to begin with, due to its spin. Just as an ice skater's skirt flutters up and away from her skates during her pirouette, water on Earth is more concentrated at the equator than at the poles.

As recently as 22,000 years ago, several miles of ice covered much of the . Since the downward pressure of land-based ice has reduced as the ice melted, the land underneath has "rebounded" causing the Earth to become more spherical, said Steve Nerem, an aerospace engineer at the University of Colorado at Boulder and coauthor of a new analysis of the Earth's bulge.

"It's a bit like a sponge, and it takes a while to come back to its original shape," Nerem said.

Scientists had observed the bulge shrinking for years, but then something changed. Around the middle of the 1990s, they noticed that the trend reversed and the Earth was getting fatter, like a ball squeezed at the top and bottom -- but until recently they didn't have the tools to understand why.

Gravity depends on mass, so any changes to the Earth's shape changes the distribution of mass, and therefore its gravity field. Data from GRACE, the Gravity Recovery and Climate Experiment -- twin satellites launched in 2002 that make exacting measurements of Earth's to monitor changes in ice mass, the amount of water in the ocean and losses in continental water -- enabled the researchers to test a theory that the ice loss was changing the shape of the planet. GRACE took snapshots of the surface of the every 30 days, allowing researchers to monitor changes in ice mass from the changes in the gravitational fields.

They found that Greenland and Antarctica were indeed the biggest contributors to the Earth's growing spare tire, as the huge amount of water was pulled to the equator. According to the researchers, the two regions are losing a combined 382 billion tons of a year. While the reduced mass on the continents will allow the land to spring back and make the planet more round, that process takes thousands of years. And in the meantime, the bulge is growing at about .28 inches per decade.

The planet's radius is about 13 miles bigger at the equator than at the poles right now, says Nerem. This means that the point on the Earth's surface furthest away from its center is not the summit of Everest but rather the top of an Ecuadorian volcano.

All this adds up to a strong signal that the planet is changing.

"This is another strong indicator of what's going on in the climate," said Byron Tapley, director for space research at the University of Texas at Austin, who was not involved in the current study. "How mass works in the Earth's system is a very dynamic process, and with a record of almost ten years [with GRACE] we're able to get a much better picture of what's going on."

Nerem says that one danger in the future of the research is that the GRACE satellites will fail sometime soon, probably within the year. While NASA is planning another satellite launch, the technology won't go up until 2016, leaving gaps in the timeline of scientific data.

"We're going to lose our eye in the sky," Nerem said.

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User comments : 18

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greenish
4.5 / 5 (4) Jul 28, 2011
Globesity, perhaps...(o:

Fluid retention centrally.
el_gramador
4.7 / 5 (3) Jul 28, 2011
Insert fat joke here or weird al song, I'm fat *here*.
Kedas
not rated yet Jul 28, 2011
That should read "fLatter"
dogbert
1.5 / 5 (8) Jul 28, 2011
How is a variation in the height of the ocean of .028 inches measured when the surface is in constant vertical motion from waves?
Husky
4.3 / 5 (6) Jul 28, 2011
the average of thousands of radar measurements of a large surface for instance
Sancho
1 / 5 (6) Jul 28, 2011
Prediction: Earth is adding mass at its center directly from the zero-point plenum, as do all celestrial bodies greater than a certain qualifying mass.
Y8Q412VBZP21010
4.5 / 5 (8) Jul 28, 2011
Prediction: Earth is adding mass at its center directly from the zero-point plenum, as do all celestrial bodies greater than a certain qualifying mass.


"Gimme a hit off that bong, Sancho!"
Isaacsname
1 / 5 (3) Jul 28, 2011
So when it slows down enough it'll fly apart ? Or we will just experience a slow downgrade in gravity ?

Isaacsname
1 / 5 (1) Jul 28, 2011
Another question/s:

If the Earth were to slowly lose rotational velocity, this means that surface area would gradually recieve more energy per a given area than what we find today ? This would contribute to an increase in melt rates , in turn leading to faster redistribution of mass at the equator ?

Yes/no ?
SteveL
5 / 5 (1) Jul 28, 2011
Won't fly apart. The earth has been through far more extreme changes than this one. Gravity shouldn't chance any discernable amount either as the mass will be the same - just slightly redistributed. The only change that I can think of is a very miniscule slowing of the earth's rotation around its axis due to the shift in mass away from the poles towards the equator.
SteveL
3 / 5 (2) Jul 28, 2011
It'll be a slower rotation at night also. So there will be less energy at night. We may simply find a slightly larger variance between day and night temperatures.

The surface reflectivity should also make a difference. If the surface is highly reflective such as ice or snow - the extra daylight hours would make little difference because most of the energy should just be reflected back into the atmosphere.
TopherTO
1 / 5 (2) Jul 28, 2011
Maybe a naive question here.

But at any point could the combustion of petroleum and other fuels derived from the Earth from liquid into gaseous state have geological (or other) implications?

I know the mass of the Earth dwarfs that of the liquids we extract, but after a century of doing so, could the cumulative effect mean anything?

Just curious...
Callippo
not rated yet Jul 28, 2011
The Earth may really expand as such. If the planet will pass through dense cloud of neutrinos, its environment will swell in more dense vacuum like sponge in wet.

http://www.physor...s64.html

This swelling can be revealed, if we use the distance measure based on the interference of light at vacuum, instead of material measure.
ArkavianX
1 / 5 (1) Jul 28, 2011
We Americans are allowed to travel again?
Cave_Man
5 / 5 (1) Jul 28, 2011
So wouldn't this, over time, slightly affect the length of rotation on earths axis. Way to go global warming you just fucked up my 10,000 year calendar.
Isaacsname
not rated yet Jul 28, 2011
Funny that in a 100 or 200 hundred years we might be looking for somebody to cast the blame on...I am hoping not, regardless of whether I am still here or not,..but...

...I'm just sayin'
Shelgeyr
not rated yet Jul 28, 2011
Before I even clicked on the link, I knew there'd be a fat joke. I just didn't expect it right up front.

Like many of its inhabitants...


Of the entire global human population, I wonder what percentage is currently facing famine? I know the number isn't zero...
_nigmatic10
not rated yet Jul 31, 2011

Of the entire global human population, I wonder what percentage is currently facing famine? I know the number isn't zero...


Does it matter? Famine isn't a disease. Obesity is. One is much easier to cure than the other.