Posts Tagged ‘Grounding Line’

West Antarctica Melting, Amazon Not Helping

March 21, 2015

A curious fact has baffled those who observe Earth: the Antarctic sea ice has been augmenting, year after year (whereas it has been shrinking year after year around the North Pole, as expected). How could the former fact, increasing sea ice, be compatible with global warming?

Scientists have been baffled. Some meekly suggested that stronger winds spread the cold water, and sea ice, further out. Winds have increased in the Antarctic Ocean, indeed. The latter point is straight from what one would expect of global warming: heat is motion on the smallest scale, resulting in density differentials, thus pressure differentials, hence winds, from high to low pressures.

The continent of Antarctica seems to be a solid mass, but the reality below all that ice is different. If one melted all the ice, Antarctica, at this point is more like an archipelago.

All Antarctica That Is Blue Will Be Under Water Soon

All Antarctica That Is Blue Will Be Under Water Soon. So Will Be Most Coastal Areas Around the Continents.

(However, if the ice melted, the continent would raise by hundreds of meters… I would guess, taking into account that rock is about three times the density of ice. But that would take millennia. Many quakes, as still experienced in Scandinavia, which is still rising at the pace of one meter per century.)

Notice that it is often much deeper inland than along the continental margins. The West Antarctic Ice Shield (WAIS; drained by the Pine, and other glaciers mentioned below) is on the left. To the bottom of the page, one sees the Wilkes Subglacial Basin I mentioned in 2009. Right of it is the Totten catchment and Aurora Subglacial basin.

The Wilkes Subglacial Basin Was Part of the Ocean In the Pliocene, 5 Million Years Ago

The Wilkes Subglacial Basin Was Part of the Ocean In the Pliocene, 5 Million Years Ago

Most of these three giant basins have up to 4 kilometers of ice any of these If the three of them melted, sea level would go back to conditions 5 million years ago (when CO2 levels were the same as today). The ocean would be up to 40 meters higher.

I will suggest a much more sinister explanation for the spreading of the sea ice around Antarctica (sinister explanations are my specialty).

The dynamics of water in the ocean is dominated by its density, and friction of atmospheric winds on its surface (the latter creating trade winds and storms heading east below the two main temperate jet streams centered around 45 degrees, plus upwelling; all of this consequences of Earth’s mighty rotation and the Coriolis force).

Denser water sinks, less dense water rises. Water density itself is a two-dimensional quantity: it depends upon temperature, and salinity. The more salt, the more dense, the more the water sinks. The dependence on temperature is subtle: pure water is denser at 4 Centigrade, not zero Centigrade (when it freezes, by definition of the Centigrade scale). Thus the water which sinks the most, and thus wiggles the most below ice, the 4C water, is plenty warm enough to melt ice.

The warm water comes from below, dragged by the current melting creates, and its higher density (caused both by its salt content, and the fact warmer water is denser, close to the freezing point, a weird fact of H2O). When it rubs along the ice shelf, it gets colder, hence less dense, all the more as it mixes with glacial sweet (thus less dense) water. (By the way, this creates inverted water channels scouring the ice sheets from below, and they can even be seen from the air.)

The Melting Of The Grounding Line Creates Surface Cold Water That Spreads Out

The Melting Of The Grounding Line Creates Surface Cold Water That Spreads Out

Thus, the more extended the sea ice is around Antarctica, at this point, the greater the evidence that the ice continent is losing cold, so to speak: it loses cold by spreading out at the surface of the ocean.

Something similar, on a much larger scale, caused a massive cooling of Europe 18,000 years ago (so-called Younger Dryas). Right in the middle of global warming, Europe froze for a millennium (due to the spread of cold water from Greenland melting, plus the subsequent short-cut of the Gulf Stream).

Here is a related fact. My friend Paul Handover called my attention on the following opinion I used to have:

“The melting of the ice sheet over Greenland is now a given. The ice sheets of West and East Antarctica a hair’s breadth from being a given.”

This is what I thought, say ten years ago. However I do not believe this opinion anymore: Antarctica will melt before Greenland. And nobody expects this.

Reason: it is easier to melt ice with warm water than with warm air, because the caloric capacity of water is much higher. Much of Antarctica, East and West is below sea level.

All the continental margin of Greenland is mountainous, and extends for hundreds of kilometers (mostly, although very long deep canyon have been found, lurking below the ice, in the last couple of years). In the case of Antarctica, the mountainous margins are either perfunctory and thin (WAIS), or inexistent (East Antarctica). This is why what was supposed to melt last, big time, East Antarctica may well melt first, big time.

Another factor, also overlooked, is that a lot of Antarctica’s coast is at pretty high latitude (hugging the polar circle), especially in East Antarctica, whereas only the mountainous tip of Greenland is south of the polar circle.

Here is the Geophysical Research Letters on 27 May 2014 about the catastrophic situation in West Antarctica: Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011.

The grounding line retreat of glaciers draining the Amundsen Sea sector of West Antarctica was documented, using Earth Remote Sensing from European satellites (which went many times over their lifespans).

(ERS-1/2) satellite radar interferometry from 1992 to 2011 showed the following:

Pine Island Glacier retreated 31 km at its center, with most of the retreat in 2005–2009 when the glacier ungrounded from its ice plain. Thwaites Glacier retreated 14 km along its fast flow core and 1 to 9 km along the sides. Haynes Glacier retreated 10 km along its flanks. Smith/Kohler glaciers retreated the most, 35 km along its ice plain, and its ice shelf pinning points are vanishing. These rapid retreats proceed along regions of retrograde bed elevation (this means that, the further inland, the lower the ice plain below the glaciers; so warm water has a potential to fall DOWN towards the INTERIOR of the continent, as the future sea floor is crushed by the mass of the ice).

The team concluded: “Upstream of the 2011 grounding line positions, we find no major bed obstacle that would prevent the glaciers from further retreat and draw down the entire basin.”

A similar situation holds under the Ronnie Ice Shelf, east of the base of the Antarctica Peninsula. There again the Ice Shield rests mightily on an old ocean floor, sloping down towards the interior, to a depth of at least a mile. I don’t see why this sort of contraption cannot melt, and disintegrate, in a few years. I really don’t. Actually, I fully expect it. I don’t see how it could be otherwise.

This is the ultimate sucking sound… And something nobody very seriously employed as a “climate scientist” can afford to believe, lest she/he, wants to go live under a bridge.

Lest some will conclude that this is just a matter of a few billion people moving out of the way, please be reminded that the littoral is often where the best lands are.

But not just this. The assault of humanity against the biosphere are many, and some of these attacks are directed at the CO2 absorbing system. For example the Amazon absorbs only half the CO2 that it did, twenty years ago.

We need much more advanced technology, just to save the biosphere. Now.

Patrice Ayme’

East Antarctica Melting

March 20, 2015

SHALLOW SEAS COMING ALL OVER:

East Antarctica Melting Could be Explained by Oceanic Gateways

Antarctica is very cold. Most of it is always frozen. So why are some country-sized glaciers there, thinning by six meters per year? Enquiring minds want to know.

This thinning was not anticipated, by common scientists. Apocalyptic considerations do not advance academic careers. However it looked ineluctable to yours truly, long ago:

https://patriceayme.wordpress.com/2009/05/31/sun-cooling-ice-melting/

The naïve had bellowed that East Antarctica would not melt for thousands of years. I pointed out that vast swathes of the ice continent were below sea level, and would melt in a geological instant, if warm water got below. This is exactly was is happening.

Let me have the pleasure to present to you the outlet of the Totten Glacier, hundreds of kilometers long, and fifty kilometers wide:

Warm Water Flowing Through Narrow Red Marks (5 Kms Wide). I Melt, You Drown.

Warm Water Flowing Through Narrow Red Marks (5 Kms Wide). I Melt, You Drown.

As I said, this is just the outlet of the Totten Glacier. As the picture below shows, most of the glacier is in the interior, and it is hundreds of time greater in area… And volume. More troubling, its bottom is miles… under water. Many glaciers of Antarctica, East or West, rest kilometers below sea level. (Much of the interior of Greenland is also below sea level; it is entirely possible that the sea could enter, too; a grand canyon was just discovered there.)

The reason is the weight of the ice. Two miles of ice press down with 3,000 tons per square meter. Over a square kilometer, that’s three billion tons. As continents float on a liquid layer which rests on something viscous, continental masses sink under the ice (“isostasis”). Conversely, 10,000 years after the disappearance of the ice, Scandinavia is still lifting up.

The euphemistically named “climate change” see even a drying California’s Sierra Nevada, going up: a drying Sierra is lighter than a wet Sierra.

So what is going on with these East Antarctica glaciers? Let’s consider Totten.

The “catchment basin” of the Totten glacier is larger than California. It firmly rests on the continent with depths as great as more than two miles below sea level (nearly four (4) kilometers!). I warned explicitly, six years ago, that it would melt soon, with the exact mechanism now revealed as being in full swing.

This Will All Melt. Map Above, The Entrance of Totten, Is The Red Rectangle

This Will All Melt. Map Above, The Entrance of Totten, Is The Red Rectangle

The coast of East Antarctica hugs the Polar Circle. Thus, it is not that far south. It is potentially exposed to warm waters. It is roughly at the same latitude as Iceland, a place where forests are growing again.

All this ice is protected by, or used to be protected by thick frozen lips, next to the Antarctic Ocean. (Reason: on the margin of the continent, there is no more ice, or then floating ices shelves; thus, there is no more weight pressing down, and the continent flexes back up, forming the lips; I made up the word “lip”, by the way).

The frozen lips used to be stuck with giant ice plugs. Those are melting, or, in the case of Totten, have melted, and relatively warmish water is increasingly circulating below. (The reason is that warm salted is denser than colder sweeter water; so warm water passes below.)

If the warm water passes the threshold, the lip, it will fall on the other side, below the giant glacier, or, as it called, the icecap.

The warm water has advanced below the Totten Glacier by hundreds of kilometers, and has lifted the glacier. The line where the glacier is still resting on the continent is called the “Grounding Line”.

The study published in Nature was the result of cooperation from NASA, ESA, USA, France, UK, Australia, and more than 100 scientists. East Antarctica Melting Could be Explained by Oceanic Gateways

 

The Grounding Line can be picked up on ice penetrating radar. Such radar can distinguish the polished ice lifted and melting, and the grounded ice.

It is known that the entire Totten basin has melted in the past. One has to understand the human species evolved in the last two million years or so, roughly coincident with the freezing of Antarctica.

Why, when did Antarctica freeze? When the CO2 density fell below 450 PPM. Now it’s 400 PPM, if restricted to CO2.

However, in truth, we are well above 450 PPM, because one has to count the other man-made greenhouse gases (which did not exist when Antarctica started to freeze three million years ago).

So now Antarctica is unstable. As a frozen continent.

The warm water is not just lifting the glacier, but melting it. From below. When the glacier is entirely melted, all the ancient water molecules frozen above sea level in the past will rejoin the oceans. And the oceans, in turn, will rise.

A secondary effect is that, as the sea level rises, the ice shelves will get pushed up. As this happen, they will fracture, and melt even faster than expected. This will have an effect especially on West Antarctica, much of it been anchored by giant ice shelves.

Antarctica, and Greenland, if they thoroughly melted, would stay melted. Forests would grow (they started to, in Greenland).

Scientists are reassuring: if the Totten glacier melts completely, it will take centuries. They look at each other, and opine. I can hear them bleat from here. They have to be reassuring, because they are Very Serious People, on whom plutocracy leans.

It is the same crowd who, six years ago, was absolutely sure East Antarctica would never melt.

Yet, it is melting.

I will not bother to roll out mathematics and compute. Take California, cover it with two miles of ice. Then direct at it cold water, with a hose, five miles wide, half a mile deep. How long? Ah, a detail that may not be a detail: it’s coming from below. With ice shelves, lifting from below induces their brutal disintegration. The same happens with flowing glaciers. The spectacle is nearly incomprehensible in its violence and gigantism.

So watch this video, of the largest calving event ever filmed:

https://www.youtube.com/watch?v=hC3VTgIPoGU

This is the future of the Totten glacier, soon, and on a wide, getting ever wider, front.

No, it will not take centuries.

Decades, at most.

Melting Totten will change human civilization, forever. And of course, it will not melt alone. As I showed in detail, six years ago, there is an ever larger catchment basin in East Antarctica, with its bottom miles under sea level

Patrice Ayme’