How Antarctica is Melting From Above and Below

Upside-down rivers lapping at the bottoms of ice sheets and brilliant blue mini-lakes dotted on top may be speeding up Antarctic melting.

National Geographic

The frozen mountains and icy plains of Antarctica hold enough water to raise global sea levels nearly 200 feet. Thankfully, over three-quarters of the continent is girded by ice shelves, the floating extensions of glaciers that protect the land-bound ice behind them like walls surrounding a vast, icy castle. But scientists are discovering new vulnerabilities that could weaken those walls from above and below.

In the frigid realm of East Antarctica, tens of thousands of brilliant blue lakes are forming across ice shelves in the summertime—far more than scientists previously realized, according to a study published last month in Scientific Reports. Meanwhile, in rapidly-melting parts of West Antarctica, “upside down rivers” of warm water are gnawing away at the ice shelves’ weak spots from below, according to a study published Wednesday in Science Advances.

As the Earth continues to warm, both processes could hasten the demise of Antarctica’s icy armor and the giant glaciers it holds back.

Invasion of the blue lakes

For much of the year, the ice blanketing Earth’s polar regions is locked in a deep freeze. But on mild summer days, the surface of the ice begins to melt, draining into depressions and forming topaz blue lakes.

Beautiful as they are, these lakes are bad news for ice. Because of their dark color, they absorb more of the sun’s energy, triggering further warming. And under certain conditions, clusters of lakes can drain rapidly into the ice below them, causing it to break apart in a process known as “lake-induced hydrofracturing.”

scientists have been intensively studying these meltwater lakes across fast-warming parts of Greenland and the Antarctic Peninsula. Now, a team of researchers has conducted the first systematic survey of meltwater lakes in East Antarctica, the coldest part of the continent and home to its most stable ice.

They found a lot more lakes than they were expecting. In fact, in satellite data from January 2017, the researchers identified a whopping 65,000 lakes and ponds spread across the East Antarctic coastline. Many of them seemed to be clustered in regions of ice shelves that could be vulnerable to collapse via hydrofracturing.

The study only looked at one melt season, and a weird one at that: In late 2016 and early 2017, mild weather and unusual atmospheric circulation patterns gripped Antarctica’s coastlines, causing its sea ice to crash. The scientists are planning to repeat their analysis with additional years of satellite data, Stokes said. But even if 2017 was an outlier, the study suggests some of East Antarctica's ice shelves could be more vulnerable to warm years than we thought.

Upside-down Rivers

As lakes raise concerns about the future of East Antarctica’s ice shelves, to the west an unseen force is attacking ice from below. Blobs of warm water are rising up from the deep, forming river-like channels that eat away at the bottoms of those ice shelves.

Several years back, Karen Alley, a glaciologist at the College of Wooster, began studying these ‘upside down rivers’ via satellite imagery. By examining depressions at the surface of the ice, she could tell that some of them were enormous—up to three miles wide, tens of miles long, and hundreds of feet deep. She also noticed that the rivers frequently formed below what glaciologists call “shear margins,” weak points at the edges of ice shelves.

In their latest research, Alley and her co-authors used satellite imagery to try and understand why that is. As they report in their new paper, the formation of rivers beneath shear margins seems to start on the land, when flowing ice streams are stretched and thinned along their edges. When those stretch zones reach the ocean, they rise up relative to the thicker ice surrounding them, creating what looks like an inverted river bed running across the bottom of the shelf. Rising warm water gets funneled into that bed, forming an upside down river.

The researchers found that the rivers are most likely to form beneath fast-flowing ice, including the ice shelves protecting West Antarctica’s imperiled Pine Island and Thwaites glaciers. “There were a lot more of these ice shelf channels on shear margins than we thought,” Alley says.

Taken together, ephemeral lakes and hidden rivers point to poorly-understood weaknesses in Antarctica’s icy fortress. And the two phenomena could work in tandem to weaken ice. With both the atmosphere and the oceans warming due to climate change, the assault could be heating up on both fronts.

There's something about that mysterious continent that intrigues me, deeply. Visiting it has definitely been on my bucket list, and I guess AirBnB was calling among the public to submit for a chance to be a citizen scientist in Antarctica for a month, working directly for Kirstie Jones-Williams - an environmental scientist, investigating the presence of microplastics in the icy region.

OMG A DREAM COME TRUE!?!
....
crap, no passport.

About 33million years ago Antarctic was allegedly a heavily forested area that became iced over in a few hundred years(pretty short amount of time on the scale we are dealing with here.) Would it be all that strange to thaw out in the same amount of time?

www.geolsoc.org.uk...
a reply to: LtFluffyCakes96

originally posted by: Athetos

(pretty short amount of time on the scale we are dealing with here.)

And we could very well be shortening that amount of time even more. Ive come across one or two papers or articles that talked about finding fossilized trees and plants in Antarctica, the type of trees being tropical in nature. Very interesting stuff!

What the heck is an "upside down river?" Can anyone help me visualize that?

originally posted by: LtFluffyCakes96

originally posted by: Athetos

(pretty short amount of time on the scale we are dealing with here.)

And we could very well be shortening that amount of time even more.

Ahh I see now, this thread is another angle on climate change caused by humans.

But -

Judging by the elites that have transited down there the last few years they've clearly found alot more than just upside down lakes and hidden rivers.

a reply to: Athetos

a heavily forested area that became iced over in a few hundred years

Nice try, but you left a word out. Your source:

At the beginning of the Oligocene Epoch, some 33 million years ago, the South Pole – Antarctica – went from being largely forested – a little like New Zealand, say, to being largely ice-bound in a mere few hundred thousand years.

originally posted by: KansasGirl
What the heck is an "upside down river?" Can anyone help me visualize that?

Do you know how to click a link?
I know you do.

Buoyant plumes of warm ocean water beneath ice shelves can be focused into these basal troughs, localizing melting and weakening the ice-shelf margins.

Warm water flows through troughs in the underside of the ice shelf. Upside down from a river which flows on the topside of a trough in rocks.

originally posted by: CthruU

originally posted by: LtFluffyCakes96

originally posted by: Athetos

(pretty short amount of time on the scale we are dealing with here.)

And we could very well be shortening that amount of time even more.

Ahh I see now, this thread is another angle on climate change caused by humans.

But -

Judging by the elites that have transited down there the last few years they've clearly found alot more than just upside down lakes and hidden rivers.

If that's the way you wanna see it? I mean the proof is in the puddin', that the climate is definitely undergoing some sort of change - be it short or long term, but whether it's nature herself or humans causing/accelerating it - Idc. It's changing and people should know about what's actually occurring and going on around the world, in a means of preparedness and also that more brains = more ideas on how to combat it, if applicable.

Makes me think of Mount Abora and Alph the sacred river... perhaps in a not too distant future. a reply to: Phage

a reply to: LtFluffyCakes96

Its concerning that the poles are warming faster than anywhere else on the planet, big changes are coming.

a reply to: LtFluffyCakes96

Fair enough, nice comeback to.

I'm thinking it's more magnetic - i.e poleshift due to rapidly increasing pole degree migration.

Gr8wrk.

The planet changes. We should do what we can to not accelerate these changes but people must understand we can't "save" the planet. Regardless of our existence, the climate changes.

The world has been hotter than this. The world has been cooler than this.

If we are so accountable, why have things been worse without us?

originally posted by: MrConspiracy
The planet changes. We should do what we can to not accelerate these changes but people must understand we can't "save" the planet. Regardless of our existence, the climate changes.

The world has been hotter than this. The world has been cooler than this.

If we are so accountable, why have things been worse without us?

What matters is our ability to thrive, luckily we humans are adaptable.

originally posted by: hopenotfeariswhatweneed

originally posted by: MrConspiracy
The planet changes. We should do what we can to not accelerate these changes but people must understand we can't "save" the planet. Regardless of our existence, the climate changes.

The world has been hotter than this. The world has been cooler than this.

If we are so accountable, why have things been worse without us?

What matters is our ability to thrive, luckily we humans are adaptable.

We have thrived. Look at the advancements. If it wasn't for our ability to advance (and inadvertently, potentially damage the planet to some extent) we wouldn't have simple things like access to constant clean water, heating, air conditioning, advances in medicine, food and transport. For all the negative things people spout about "industrialization" we certainly wouldn't want to be without it's positives.

If anyone’s been on top of a glacier in the summer, you’ll see little pots or bowls of water with a tiny spec of dirt. The dirt particle soaks up the suns heat and forms a bowl of thawed glacier water, (most likely millions of year old ice), I used to stick my head down and drink directly from those, it’s the best tasting water I’ve ever had in my life, has a unique fresh ozone’ish taste hard to describe. Those pools of water in the OP’s picture has me wanting to bottle it up!

a reply to: MrConspiracy

Agreed, either way the planet will be fine, as far as we humans go well that depends on how fast we can adapt to the change.

I admit defeat...
Good day sir

a reply to: Phage

a reply to: Athetos

Strange or not wouldn't want it to happen in our lifetime.