Half a Kilometer of Ice Gone in Just 7 Years — West Antarctica’s Smith Glacier Points To Nightmare Melt Scenario

The nightmare global warming melt scenario for West Antarctica goes something like this —

First, ocean waters warmed by climate change approach the vast frozen continent. Melt already running out from the continent forms a fresh water lens that pushes these warmer waters toward the ocean bottom. The waters then get caught up in currents surrounding Antarctica that draw them in toward numerous submerged glacial faces. The added ocean heat combines with falling melting points at depth to produce rapid melt along sea fronting glacier bases. Since many of these glaciers sit on below sea level beds that slope downward toward the interior of Antarctica, a small amount of initial melt sets off an inland flood of these warmer waters that then produces a cascade of melt. This glacial melt chain reaction ultimately generates a Heinrich Event in which armadas of icebergs burst out from Antarctica — forcing global sea levels to rapidly rise.

This is Why We Worry So Much About Multi-Meter Sea Level Rise

Ultimately, seas rising by multiple meters this Century are a very real possibility under current warming scenarios in which such a series of cascading melt events occurs in West Antarctica.

(NASA video narrated by Dr. Eric Rignot, a prominent glacial scientist. Concerns about the origin of melt water pulse 1A during the end of the last ice age led to investigation of large Antarctic melt pulses as a potential source. Subsequent investigation identified melt vulnerabilities at the bases of large sea fronting glaciers in West Antarctica to present and predicted levels of ocean warming. At issue was the fact that bottom waters were warming and that because many glaciers rested on sea beds that sloped inland, melt rates had the potential to very rapidly accelerate.)

Though such a nightmare melt scenario was recently theoretical, it represented a very real potential near-future event as global temperatures rose into the 1-2 degrees Celsius above 1880s range during recent years. For times in the geological past around 115,000 years ago also produced large glacial melt pulses and related sea level rises of 15-25 feet during periods of similar warmth.

However, direct evidence of such a powerful melt dynamic had not yet been directly observed in Antarctica’s glaciers. Fresh water lenses were developing, rates of glacial loss were quickening. Basal melt rates looked bad. But the kind of tremendous losses necessary to produce rapid sea level rise were not yet fully in evidence.

Smith Glacier Loses Half a Kilometer of Ice in Seven Years

That situation changed during recent weeks when two scientific papers broke the news that some of West Antarctica’s glaciers had lost upwards of a half a kilometer of ice thickness due to contact with warm ocean waters over the past decade.

The studies, entitled Rapid Submarine Ice Melting in the Grounding Zones of Ice Shelves in West Antarctica and Grounding Line Retreat of Pope, Smith and Kohler Glaciers took a comprehensive look at both surface and underside melt of three major west Antarctic glaciers near the Thwaites and Pine Island Glacier systems. These glaciers included Pope, Smith and Kohler — which have seen increasing instability and rates of seaward movement during recent years. Using multiple instruments, the scientists found evidence of massive ice losses and speeding ice flows.

pope-smith-and-kholer-glacial-flow-velocities

(Surface velocity of Kohler, Smith and Pope Glaciers provided by NASA. More rapid seaward movement of glaciers = faster rates of sea level rise.)

The losses occurred at a time when an influx of warmer water (warming circumpolar deep water) was heating the ice shelves and grounding lines buttressing these three partially submerged glaciers. This warming was found to have produced melt along the grounding zones of these glaciers in the range of 300 to 490 meters from 2002 to 2009. In other words, about 1/3 to 1/2 a kilometer of ice thickness at the grounding line was lost in just seven years. Melted away from below by warming deep ocean conditions at the rate of up to 70 meters or around 230 feet per annum.

The studies found that the Pope and Kohler glaciers, which rested on up-sloping sea beds, produced slower rates of melt. While Smith, which sat on a retrograde (or down-sloping bed) produced very rapid rates of melt. According to the Nature study:

We attribute the different evolution of Smith Glacier to the retreat of its grounding line deeper allowing warmer waters to flood its grounding zone, and increasing ocean thermal forcing due to the lowering of the in situ melting point; as well as to the exposure of the glacier bottom to ocean water as the grounding line retreated rapidly.

A Context of Worsening Risks

Unfortunately, numerous glaciers in the Amundsen Sea region including parts of the Thwaites system and the massive Pine Island Glacier also sit on retrograde slopes. These glaciers are seeing increasing fluxes of warm, deep water. By themselves they represent multiple feet of sea level rise (4-7 feet). Furthermore, Thwaites and Pine Island Glacier currently buttress a number of massive inland glaciers that become vulnerable to melt if inland-running retrograde slopes become flooded with warming ocean waters.

The very real concern is that Smith Glacier serves as a harbinger for near future events to come. As a result, coastal regions around the world are now under a heightened risk of swiftly rising seas and rapid coastal inundation over the coming years and decades.

Links:

Rapid Submarine Ice Melting in the Grounding Zones of Ice Shelves in West Antarctica

Grounding Line Retreat of Pope, Smith and Kholer Glaciers

Heinrich Event

Dr. Eric Rignot

Studies Offer Glimpse of Melting Under Antarctic Glaciers

Thwaites Glacier

Pine Island Glacier

Hat tip to Zack Labe

Hat tip to Miles h

Another Blow to Antarctic Glacial Stability as Larsen C Ice Shelf Cracks Up

Larsen C rift

(Northern edge of Larsen C Ice Shelf is at significant risk of breaking off as a massive rift continues to open within it. The above image shows the rate of rift propagation since November of 2010. Image source: Cryosphere Discussions.)

There’s a 30 kilometer long and hundreds foot deep crack running through West Antarctica’s massive Larsen C ice shelf.

It’s a rift that now stretches from the Weddell Sea — where winds and currents have driven human-warmed ocean waters to up-well along the ocean-contacting faces of the great Antarctic ice sheets — and deep into the interior of this 49,000 square kilometer and 600 to 700 foot tall block of ancient, floating ice.

Over the past few years this rift has been rapidly advancing at a rate of about 2.5 kilometers each year.  Given that the rift has already traversed more than half of the Larsen C ice shelf calving face, a very large break-up could now occur at almost any time.

Larsen C Destabilizing

This evolving situation now threatens to destabilize the entire Larsen C ice shelf — resulting in major losses to a very large block of ice that has been a permanent feature of the Antarctic coastline since at least the last interglacial period 150,000 years ago. Such rapidly evolving risk was the subject of a February 5 communication by a group of glaciologists warning that “significant threats” to “Larsen C ice sheet stability” now existed.

The report notes:

In a change from the usual pattern, a northwards-propagating rift from Gipps Ice Rise has recently penetrated through the suture zone and is now more than halfway towards calving off a large section of the ice shelf (Figs. 1 and 2). The rate of propagation of this rift accelerated during 2014. When the next major calving event occurs, the Larsen C Ice Shelf is likely to lose around 10 % of its area to reach a new minimum both in terms of direct observations, and possibly since the last interglacial period (Hodgson et al.2006)

Connecticut-Sized Break-up Possible

Large ice shelf break-ups have been occurring along the Antarctic Peninsula since the 1970s. As human warming advanced and the heat sink of the southern Ocean increased bottom water temperatures along the Antarctic perimeter, many of the far northern ice shelves and an increasing number of ice bodies closer to the Antarctic interior have lost significant portions of their mass.

Now, Larsen C is at risk of an even worse break-up. For the predicted 10% loss to Larsen C would equate to about 5,000 square kilometers — or an area roughly the size of Connecticut — floating off into the Southern Ocean:

Section of Larsen C vulnerable to break-up

(Larsen C Ice Shelf map with the new rift indicated in red and the potential calving face outlined in blue. Note the previous calving fronts in 1975 and 1988. Image source: Cryosphere Discussions)

It would be yet one more major ice loss for the region, and perhaps a new record loss for an area that has frequently seen Rhode Island sized chunks of ice (around 1,000 square kilometers) break off into the warming world’s seas.

The report goes into further detail about the importance and vulnerability of Larsen C, stating:

The Larsen C Ice Shelf is the most northerly of the remaining major Antarctic Peninsula ice shelves and is vulnerable to changes both to ocean and atmospheric forcing (Holland et al., 2015). It is the largest ice shelf in the region and its loss would lead to a significant drawdown of ice from the Antarctic Peninsula Ice Sheet (APIS). There have been observations of widespread thinning (Shepherd et al., 2003; Pritchard et al., 2012; Holland et al., 2015), melt ponding in the northern inlets (Holland et al., 2011; Luckman et al., 2014), and a speed-up in ice flow (Khazendar et al., 2011), all processes which have been linked to former ice shelf collapses (e.g. van den Broeke, 2005).(Emphasis Added).

Conditions in Context

As mentioned above, during recent years we have seen numerous ice shelves and ice sheets begin to destabilize. In addition, two ice shelves — Larsen A and Larsen B have already completely disintegrated due to human-caused warming.

Larsen C may be most immediately at risk, but the leading edges of the Ronne-Filchner Ice Shelf, The Pine Island Glacier, The Ross Ice Shelf, and the Amery glacier have all shown rapid seaward acceleration. Further, various studies of these increasingly vulnerable ice shelves have shown substantial basal melt coincident with a floating of the ice sheets off grounding lines, leading to a retreat of the anchor points landward.

Major Antarctic Ice Shelves

(Antarctica’s major ice shelves. Image source: Commons.)

Sea-facing ice sheets and ice shelves serve to anchor the great interior glaciers of Antarctica. Loss or destabilization of these anchors would result in more and more rapid flow of land ice into the Southern Ocean. It is for this reason that the destabilization and shattering of ice shelves like Larsen C can have serious implications for the rate of sea level rise over the coming decades.

Overall, nearly 200 feet worth of sea level rise is locked in Antarctica’s glaciers and we are, through a heating of the world’s oceans, ice, and atmosphere, pushing these glaciers to melt and move in an ever-more dramatic and world-altering fashion.

Links:

Newly Developing Rift in Larsen C Ice Shelf Presents Significant Risk to Stability

Shrinking Ice Shelves and The Pine Island Glacier

Commons: The Larsen C Ice Shelf

Hat-tip to Colorado Bob

Nature: Human Warming Now Pushing Entire Greenland Ice Sheet into the Ocean

Leading Edge of the Zacharie Ice Stream meets the ocean

(Leading edge of the accelerating Zachariae Ice Stream meets the warming and increasingly ice free ocean on August 20 of 2013. Satellite image source: Lance-Modis.)

Greenland — a vast store of ice three kilometers tall at its center and the final remnant of the Northern Hemisphere’s great glaciers of the last ice age has now begun what is likely an unstoppable rush to the sea. For according to a new report in Nature Climate Change, the last stable region of glacial ice along the Greenland coastline is now accelerating through one of the ice sheet’s largest and deepest outlets — the Zachariae Ice Stream.

Zachariae, the last domino to fall

The Zachariae Ice Stream is a vast river of ice in the northeast section of Greenland. It terminates in two outlets through a broad and deep ice-choked bay facing the Fram Strait.

Throughout the 1990s and into the early 2000s, both warmer air and ocean water temperatures at the margins of Greenland began to speed up and destabilize glaciers all along Greenland’s southern, eastern and western coasts. But the northern glaciers remained relatively stalwart, continuing the rate of seaward motion observed over previous decades.

Then, starting in 2003, something ominous began to happen. A combination of sea ice loss, warming air and ocean temperatures began to affect the northern edge of the great ice sheet. Its speed of forward motion through its outlet bays began to increase. By 2012, the great glaciers were dumping 10-20 billion tons, or roughly 10-20 cubic kilometers of ice into the ocean every single year. In just nine years the Zachariae Ice Stream had retreated a total of 20 kilometers toward the heart of Greenland. By comparison, the Jakobshavn Ice Stream, known to be Greenland’s fastest and located in South Greenland, has retreated 35 kilometers over the past 150 years.

greenland_velocity-base

(Greenland Ice Sheet velocity map as of 2010. Measures in red are in the range of 1,000+ meters per year. Note that ice sheet velocity is fastest at the glacial outlet face and that rapid ice sheet velocity now extends far into interior Greenland. The Zacharie ice stream, the most recent to show rapid acceleration, is indicated by the letter Z in the upper right hand corner of the image. Note how this ice stream plunges deep into the heart of Northern Greenland and that a rapid flow is now established all the way to the ice sheet’s core. Image credit: Joughin, I., B. Smith, I. Howat, and T. Scambos.)

An ice stream drains an ice sheet the same way a river drains a watershed. So long as ice stream flow and rate of glacial recharge at the top of the glacier remains about equal, the ice sheet retains stability. But if the rate of ice stream flow and surface melt exceeds the rate of recharge, the glacier is said to have begun a difficult to reverse process called destabilization.

The initiation of the great Zachariae Ice Stream’s destabilization is ominous for a number of reasons. First, it means the entire Greenland Ice Sheet has, as of the early 2000s, begun a plunge into the ocean that is likely unstoppable. For once the great and massive glaciers of Greenland start to move, gravitational inertia sets in and even a radical cooling of the climate may not halt the surge. Furthermore, the Zachariae Ice Stream drains 16 percent of the entire Greenland ice sheet alone. And finally, Zachariae stretches deep into the heart of Greenland, extending seven hundred kilometers inland and taking hold of Greenland’s massive central glaciers in its now accelerating ocean-ward draw.

“Northeast Greenland is very cold. It used to be considered the last stable part of the Greenland ice sheet,” explained the study’s lead investigator Michael Bevis of The Ohio State University in a recent press release. “This study shows that ice loss in the northeast is now accelerating. So, now it seems that all of the margins of the Greenland ice sheet are unstable.”

nclimate2161-f1

(Greenland Ice Sheet ice surface elevation change in meters per year from 2003-2006, 2006-2009 and 2009-2012 respectively. Note the elevation loss of greater than 3 meters per year in Northeast Greenland near the Zachariae Ice Stream’s outlet in the final frame. Image source: Nature.)

Margin melt and increasing velocity is an important indicator of overall stability throughout Greenland. For, during much of Greenland’s history, a more solid, less mobile ice margin has kept the central ice locked in. But like the collapsing edge of a plastic swimming pool, Greenland’s drooping margins are starting to let the central ice flows surge toward the coast line. Now the ice margin is destabilized in all the major edge zones leading to the initiation of the ice sheet’s draining.

It is also worth noting that ice sheet motion is just one aspect of Greenland destabilization and a recent NASA paper shows that surface melt since 2009 has also rapidly accelerated. So the ice sheet is now a zone of accelerating glaciers and of annual surface melt all running more frequently and in ever greater volumes toward the swelling seas.

The recent study involved the use of GPS modules scattered over top of the Greenland ice sheet to measure glacial speed, mass and altitude loss. This finding is the most recent study provided by the group’s network dubbed GNET.

Greenland: An Archipelago with an Ice Sheet on Top

In understanding why Greenland’s ice sheets are likely to continue to flow into the ocean, it is useful to look at Greenland in its geological context. For Greenland is essentially an island archipelago with an enormous ice sheet sitting atop it. As such, great channels and fractures run deep into the heart of this frozen plcae. Many of these fractures are below sea level, providing ocean waters access further and further inland as Greenland melts. Furthermore, the high elevation of the ice sheet creates a kind of gravitational inertia that continuously drives glaciers toward the sea. Only friction from the anchoring ground beneath the glaciers, Greenland’s cold climate, and the chill of the surrounding airs and oceans provided Greenland with enough ice recharge while slowing the ice sheets enough to keep it stable during the last interglacial period (Holocene). Now, human warming is pulling that plug by flushing melt water to the ice sheet’s base, creating warmer ocean water invasions at the ice edge and creating conditions by which warm air increasingly both overrides the ice sheet edge and invades into the ice sheet interior.

It is in this context that we should consider the relative positions of ice stream fronts, grounding lines, and co-joining sea level as ice sheets continue their flow toward the ocean:

nclimate2161-f4

(Comparison of Northern Greenland ice face coming into contact with a floating glacier in transect 1 to the deep reaching Zacharie Ice Stream over-riding below sea level land masses in transect 2. Note that sub land elevation beneath the ice surface is below sea level for a stretch more than 150 kilometers inland along the base of the Zacharie Ice Stream. Meanwhile, the ice surface slope and elevation provide seaward momentum even in regions that are near or slightly above sea level. The change in velocity of various sections of ice flow are shown in the colored spaghetti lines. Image source: Nature.)

Conditions in the Context of Human-Caused Climate Change

Current atmospheric conditions now provide enough greenhouse gas forcing to destabilize ice sheets in both Greenland and West Antarctica. These levels, at around 400 ppm CO2 and at around at least 425 CO2e when taking into account all the additional negative and positive forcing from aerosols and other greenhouse gasses, were enough in past climates to send these immense regions of ice plunging into the world ocean and to raise sea levels by between 15 and 115 feet over the course of centuries (Greenland alone contains enough water locked in its ice sheets to raise sea levels by about 23 feet). All of the Greenland ice sheet and large sections of West Antarctica are now undergoing the first stages of a similar destabilization.

Topographic_map_of_Greenland_bedrock

(Topographical map of an archipelago-like Greenland without its overlaying ice sheet. Glacial outflows are likely to be most intense toward the northeast, northwest, southwest and southeast through lower lying zones in the ranging from below sea level to about 100 meters above sea level. From the point of view of surface melt hitting the oceans, it is worth noting that the center of the Greenland ice sheet is currently taller than even the highest surrounding mountains. Image source: Commons.)

Today’s pace of sea level rise is currently 3.2 millimeters each year or a little more than a foot each century. Of this total, fully 1/6th is now being contributed by Greenland. But with inertia and gravitational forces now taking hold as massive ice sheets destabilize, and with human-caused warming continuing to ramp up, it is likely that we can expect both the Greenland ice sheet’s contribution and the pace of sea level rise to rapidly accelerate.

As the great ice sheets sped toward the oceans at the end of the last ice age, the pace of sea level rise hit as high as 10 feet each century. With the pace of human warming now about 30 times faster than at the last ice age’s fall, we may well eventually witness something even outside this difficult to understand context.

Even more ominous is the fact that greenhouse gas forcing levels that are enough to destabilize and then melt all the world’s ice sheets, eventually raising seas by about 250 feet, arrive as soon as the next few decades once CO2 (or equivalent) forcing levels hit between 500 and 600 parts per million value. The current rate of emission gets us there within about 20 years. But, unfortunately, that rate of emission is still rising even as amplifying feedbacks from terrestrial carbon stores in both the Arctic and the tropics loom.

In essence, it looks more and more, from the point of ice sheet stability, like we’ve probably at least locked in a Heinrich type event and will be well on our way to initiating total ice sheet loss over the coming two decades.

Links:

Greenland Ice Impacted Further in Sea Level Rise

Northeast Greenland Ice Sheet Loss

Lance-Modis

Climate Monsters we Want to Keep in the Closet: Heinrich Events, Superstorms, and Warming the Deep Ocean

GNET/PoleNET

An Improvement in Mass Budget for the Greenland Ice Sheet

Hat tip to Colorado Bob

Hat tip to Spike

Climate Monsters We Want to Keep in the Closet: Heinrich Events, Superstorms, and Warming the Deep Ocean

“Think of the climate change issue as a closet, and behind the door are lurking all kinds of monsters — and there’s a long list of them,” — Steve Pacala.

***

It has been said that Nature is a serial killer. Within her vast managerie of life, climate, and the physical world, there are many, many terrible processes that could mortally impact individuals, larger groups, entire species and even families of species. And if you were to look for the means by which Nature performs her worst violence, the mass extinction events, your eyes would almost immediately settle upon the uncomfortable issue of climate change, an issue all too relevant today.

Of twelve major mass extinction events identified in past geological epochs, ten were likely caused by climate change. Marked by layers of rocks almost entirely devoid of complex life, these periods in which Earth became little more than a tomb should serve as a stark warning against our own rapidly increasing insults to Earth’s climate. The very worst of these ‘tomb epochs,’ the Permain or ‘Great Dying’ in which 90 percent of all species went extinct was clearly caused by a series of worsening insults brought on by a terrible switch in climate brought on by a raging global warming nightmare. And though the Permian Extinction raged about 200 million years ago, it has some rather disturbing similarities to today. For one, it was an era in which a cold glacial period emerged into a far warmer period. And secondly, a large greenhouse gas emission source forced warming to drastically accelerate resulting in not one but three major extinction crises over the course of about 165,000 years. It was the worst of the worst of all tomb epochs and it was most likely set off by a massive chain of events brought on by very rapid warming.

Scattered across the wreckage of the Permian and these other tomb epochs are the foot prints of the three climate monsters from Pacala’s horde that we most definitely do not want to unleash. Monsters we are through our current actions and choices, even now, causing to stir.

Three to Keep Behind the Door

Human beings, through their carbon emissions, risk prodding the very worst monsters in Nature’s death brigade to awaken — the ones that set off previous mass extinction events through a combination of terrible weather, unleashing carbon stocks sequestered over millions of years, and, eventually, turning the ocean into an enormous killing machine. These three, worst of the worst, climate monsters which we most certainly want to keep behind Pacala’s door are: Heinrich Events, Rapid CO2 and Methane release, and Anoxic and Canfield Oceans. Though these three are identified here as separate catastrophic events, they are related in that they can set in motion a chain of self-reinforcing effects that may enhance the likelihood for the other events to occur. They also unleash a set of more minor but still terrible associated difficulties.

In this particular blog, I’ll explore the first and arguably mildest of these catastrophes — Heinrich Events.

Pulses of De-glaciation

As Earth moved through its far more milder, nature-caused, phases of glaciation and deglaciation, previous warm phases often resulted in sudden surges of ice burgs and melt flows from the Earth’s ice sheets. Large pulses during warm trends set off armadas of these maritime brutes which flooded the ocean, causing drastic consequences to weather and climate.

The ice bergs unleashed during these warming-induced pulse events were enormous floating collections of rock and ice. As they melted, the glaciers disgorged the rocks frozen in their bellies, leaving layers of pebbles littering the sea floor and creating a record of their passage. Hartmut Heinrich was the first to describe these events. So now they bear his name.

Greenland and West Antarctica: Gateways For the Heinrich Monsters

In the emergence from the last ice age, it is thought that sudden melt pulses from the vast but now entirely melted Laurentide ice sheet resulted in the majority of these events. Since only the ghost of this ice sheet remains in the form of a thin patina of frozen tundra over the Northern Hemisphere’s Arctic regions, there is no longer any risk for Heinrich melt and ice burg pulse events from this now ephemeral source.

But the great Greenland and West Antarctic ice sheets remain. Greenland is a vast store of ice. Nearly two miles high at its center, it contains enough ice to raise the world’s sea levels by 23 feet. West Antarctica is yet one more great pile of ice. In total, if the two were to melt together, they could contribute as much as 75 feet of sea level rise.

But these melt events, as we see the in the geological past, don’t happen neatly. The great glaciers sit mostly still for long, boring periods and then they surge in brief, catastrophic instances unleashing massive flows of both water and ice bergs. Heinrich Events.

Alone or together, Greenland and Antarctica bear more than enough ice to set off this particularly nasty brand of climate induced catastrophe.

The Human Forcing is Far More Brutal

In the past, a slower build up of heat set off by the warm phase of gradual orbital cycles eventually passed tipping points that led to rapid ice sheet disintegration and related melt-pulse Heinrich Events. Today, the human greenhouse gas forcing is far, far more powerful. At the last ice age’s end, a combined forcing of about 100 parts per million of additional CO2 and the steady but ever so slight forcing caused by the warmer orbital cycle was enough to set off these powerful events. Today, CO2 has risen by 120 ppm and continues to rise by 2-3 parts per million each year even as other rising greenhouse gasses, primarily methane, add an additional 28% to this strong and growing forcing.

It could easily be argued that the human forcing surpassed that of a natural forcing powerful enough to end an ice age sometime last century. But the ice age is already done and so we head into mostly uncharted territory only vaguely hinted at in the deep geological past. The current pace and path of increased forcing makes a bad situation worse as a CO2 rise to at least 480 ppm is predicted by mid-century. Business as usual end century estimates come in at the catastrophic level of 800 ppm or more of atmospheric CO2 with an unknown additional amount of methane and related greenhouse gasses.

The Greenland Ice Sheet is Starting to Slip

Unfortunately, it seems we may have already begun to let one Heinrich monster off its leash. For reports coming in over the past decade show that the vast two mile high Greenland ice sheet is starting to slip.

Under the current and ever-rising insult of the human climate change forcing, the Greenland ice sheet is sagging and deforming, filling with melt ponds and flows that flush through to its base, and, most ominously, monstrously grinding toward the ocean at an ever increasing pace. Research conducted by Arctic scientists shows that the ice sheet’s speed is increasing by a rate of about 2-3 percent per year. This speed of increase results in the disgorging of vast volumes of ice burgs and melt waters into the North Atlantic. An average of about 500 cubic kilometers of ice bergs and melt waters are now flowing into the ocean from Greenland alone. But with the pace of ice sheet melt and movement picking up, we are, sadly, only at the beginning of what appears to be a very risky situation.

Flotillas of Icebergs Riding a Tsunami Like Melt Pulse

Let’s step back for a minute from this slow motion disaster that we’re both the cause of and captive audience to and consider, for a moment, the structure of Greenland’s ice and land mass. The Greenland coastline is little more than a honeycomb of semi-frozen channels both coming into contact with the larger water bodies of Baffin Bay and the North Atlantic and drilling deep into the interior of Greenland itself. The two mile high glacier slopes gradually down toward and into these hundreds of channel estuaries, creating a slope defined by tall ice sheets terminating in low, ocean-opening waterways.

Greenland -- where ice meets ocean

Greenland — where ice meets ocean.

(Image source: Lance-Modis)

In the above image, you can see just one section of these ice channels that encompass almost the entire coastline of Greenland. Note the dark ocean water coming into contact with the silver-white of Greenland ice. The small white flecks you can see in this Modis shot are nothing less than immense ice burgs riding the winds and tides out into the North Atlantic. If you accurately imagine the entire coast of Greenland perforated by such outlets, what you come to realize is that Greenland is nothing less than an enormous ice burg dispersal mechanism. One that, if it really cranks up, will disgorge vast flotillas of ice bergs riding out upon tsunami-like melt pulses in every direction.

Inherent to this potential is the fact that Greenland ice is continuously in motion. Pulled by gravity, the towering ice sheets constantly seek the sea. Slowly grinding away, the ice moves gradually, steadily until it, at last, finds water, there it explodes in a riotous calving of the immense and monstrous ice burgs. The more solid and cold Greenland becomes, the slower its ice moves toward the ocean. The ice sheet weight increases, depressing the entire island into the crustal plate and keeping more of its ice locked in the center. The ice forms more solid boundaries to other ice flows and the ice grinding slows as it thickens. But the more wet and warm the ice becomes, the opposite is true. Water flows through the ice sheet to lubricate its base, the large pools of water on top further heat and deform the ice, the crustal plates rebound, pushing the island higher and adding gravity as a more and more powerful force attracting ice to ocean, and increasingly large pulses of melt water flush out from the center of the glaciers, drawing both ice and water along in ever greater volumes toward the ocean.

In a Heinrich Event, the melt forces eventually reach a tipping point. The warmer water has greatly softened the ice sheet. Floods of water flow out beneath the ice. Ice ponds grow into great lakes that may spill out both over top of the ice and underneath it. Large ice dams may or may not start to form. All through this time ice motion and melt is accelerating. Finally, a major tipping point is reached and in a single large event or ongoing series of such events, a massive surge of water and ice flush outward as the ice sheet enters an entirely chaotic state. Tsunamis of melt water rush out bearing their vast flotillas of icebergs, greatly contributing to sea level rise. And that’s when the weather really starts to get nasty. In the case of Greenland, the firing line for such events is the entire North Atlantic and, ultimately the Northern Hemisphere. But the Southern Hemisphere has its own set of troubles to contemplate. For there resides the seemingly endless pile of ice that is Antarctica.

Storms of My Grandchildren

A long time ago, I read a book called “The Coming Global Superstorm.” The book trivialized the potential effects of Heinrich Events by lumping them into a myopic and artificial single instance that the authors referred to as a Superstorm. The book was also chock full of astrological New Age jargon and other unrelated philosophy that greatly discredited the authors’ notion of Superstorm. Even worse, Hollywood jumped onto the trivialization bandwagon by producing the entirely unrealistic movie “The Day After Tomorrow.”

About this New Age book and its related Hollywood film, I have but one thing to say — if only it were so easy. Both the book and the movie boil the risk of human caused global warming into a single, linear event, which ends in single results. Even worse, both the book and the movie produce the false impression that such storms will result in an ice age. Again, if only it were so easy.

If you want to learn about the potential involved in such events, you should become a student of climate scientist James Hansen. You could start by reading the excellent book “Storms of My Grandchildren” and you could continue by reading his papers pertaining to extreme weather caused by West Antarctic and Greenland Ice melt.

What Hansen describes in his later work is the potential for ‘continent sized frontal storms packing the punch of hurricanes’ to rip across vast swaths of the Northern Hemisphere in association with an extreme weather pattern set up by a Heinrich type event acting in combination with a human warming induced heat amplification of the tropics. In vast difference to the “Day After Tomorrow,” these storms are not single instances, but potentially re-occurring catastrophic weather hazards.

How bad could these storms get? As an example, the freak hybrid superstorm Sandy is but a prelude to the main events.

Sandy Arctic Arm

Sandy’s Arctic Arm

Yet Sandy’s somewhat unique hybrid structure and location may well provide us with hints as to the nature of future superstorm events. What we see in the above NOAA satellite shot is a storm that is linked both in the tropics and in the Arctic. The storm derives energy from a cold air mass over Greenland and pulls in another ‘arm’ of energy from the tropical Atlantic.

During the Heinrich event, the ice berg cooling effect mentioned by Hansen in his papers and the human caused heat amplification of the tropics will set up a far more disastrous atmospheric storm potential. And the raking effect of continent sized frontal storm systems would have even more damaging consequences to human infrastructure than the related pulse of sea level rise alone.

Ocean Circulation Change to Open the Door for the Hydrate Monster, Anoxic/Canfield Oceans?

Yet one more ominous result of Heinrich Events is a high-stress shock to ocean temperature and saline circulation systems. Such events are likely to shove the northern termination of larger ocean systems further toward the equator. The cold, fresh water pulses would result in less sinking of water at the poles. Related increased heat at the tropics would begin to set up a system where salty waters begin to sink there.

Even more ominously, a wedge of cold water at the surface spreading out from the poles would push hotter, saltier water toward the ocean bottom. Fresh water is less dense than salty water, so the fresh water pulses from glaciers and melting ice bergs will act as a wedge, driving the denser, warmer, saltier water toward the bottom The net effect of such changes would be a shallower and weaker ocean circulation system as more warm water is averted toward the ocean bottom near the equator and then spreads northward and as warmer surface waters toward the poles and temperature regions are driven toward the sea-bed.

Since vast stores of methane lay locked in hydrates on the sea bed, these stores are at risk of greater forcing and more rapid destabilization. To note, the end of the Permian, in which a partially glaciated world transitioned to a hot house, is estimated to have seen methane levels at around 11 parts per million — almost ten times the current level. Large melt pulses are, therefore, a potential mechanism for ocean bottom heating and increasing rates of methane release.

This event sets in place conditions that increase risk for the two other climate monsters — increasing CO2 and methane release from Earth Systems and the perhaps more ugly anoxic and Canfield Ocean states. And both we will visit in future blogs.

How Soon?

How soon could we see Heinrich type events, Hansen-style superstorms, and dangerous changes to ocean circulation? Hansen, in “Storms of My Grandchildren” indicates a risk for such events emerging by mid-century under business as usual fossil fuel emissions. Jason Box and others have shown an increasing speed and melt of the Greenland Ice Sheet occurring during the first and second decades of the 21rst Century. So it appears we are starting to ramp up to such events even now as an ominous ice sheet response begins to show on the climate radar. So the period of risk appears to be sometime between now (low) through 2070 (moderate to high depending on human CO2 forcing growth or mitigation).

That paleoclimate and modeling performed by Hansen show the potential for such powerful events should be cause for serious concern and reason for ever-greater urgency in reducing human greenhouse gas emissions and our related climate risk to the lowest levels possible. And, in the end, we almost certainly do not want to begin to bring forward conditions that will release the other two ‘monsters behind the door’ — rapid CO2 and methane response from Earth Systems and anoxic and Canfield Oceans.

Links:

Storms of My Grandchildren

Under a Green Sky

Human Climate Change Is Wrecking the Jet Stream; UK Met Office Calls Emergency Meeting

cloverleaf jet stream

(Weather model showing forecast temperature, high and low pressure for April 20. What this clover-leaf pattern roughly represents is the new ‘normal’ shape of the jet stream. Image source: here)

The UK Met recently called an emergency meeting with the world’s top climate scientists to discuss how melting polar ice is radically altering that country’s weather. A permanent blocking high pressure system has formed over Greenland. This high has, effectively, caused the Arctic to invade the UK with increasing ferocity. The state is now so extreme that the Met is calling a meeting of the world’s climate experts to discuss what the future may hold.

Dr. Slingo, Britain’s top climate scientist notes how persistent high pressure systems are blocking the polar wind pattern from moving. What this means is that the weather simply cannot change. Increasingly, the UK has become a part of the Arctic. Slingo noted to ITV News:

If this is how climate change could manifest itself, then we need to understand that as a matter of urgency.

This meeting’s discussion will likely focus on how melting polar ice is dramatically altering the north polar jet stream and what future changes we can expect as sea ice continues to erode. Over the past year, Dr. Jennifer Francis has issued increasingly clear warning about the potential for extreme weather events due to polar sea ice erosion. Her warnings were then punctuated by an amazing and freakish superstorm: Sandy.

This winter, the increasingly powerful blocking high pumped warmer air into the Arctic even as typical Arctic weather was flushed south into the UK and Europe.

The New Clover-Leaf Jet Stream

In understanding this phenomena, it is important, first, to understand what is normal. During the 20th century, the polar jet stream ran swiftly around the northern hemisphere. For the most part, it served as the border between temperate regions of relatively warmer, milder climates and the much colder Arctic environment. This rapid jet served to keep colder air trapped in the Arctic and warmer air confined primarily to the south. Ripples in this jet stream were mild, looking almost like the wavy pattern of a stylized upside down fruit bowl. Invasions of warm air to the north and cold air to the south were rare and often resulted in strong storms that were then noted as ‘extreme’ weather events.

Today, things are radically different. Looking at the image above, we can see that the jet stream looks more like a mangled clover leaf than a gracefully arching bowl. This increasing clover leaf pattern is a result of a number of atmospheric dynamics. The first is that sea ice and Greenland ice are dramatically melting. Sea ice volume is 80 percent lower than it was in 1980 and Greenland is losing water at the rate of 250 cubic kilometers every year. This ice has an amazing ability to keep cold air locked in place, keeping the Arctic colder and, importantly, driving the jet stream to faster speeds. But, with the loss of this ice, the temperature difference between the Arctic and the southern latitudes is lessened. With more warmth in the Arctic, the jet stream has tended to slow down, meandering in these great, clover-like dips and whirls.

As the jet stream dips and whirls it tends to get stuck, staying in the same shape over the same location for long periods of time. This shape change is the result of certain features that push the jet into this new pattern. One is that more cold, reflective ice is in Greenland now than over the north pole. The result is that high pressure systems tend to form over Greenland rather than the north pole itself. The formation of this Greenland high many hundreds of miles to the south has severe weather implications for the UK and the rest of Europe. What it means, primarily, is much colder, stormier winters for Europe.

In other regions, warm air floods northward creating heatwaves. This was particularly true for the US during winter/spring of 2012. But an area not often mentioned is the west coast of Greenland and Baffin Bay which has experienced temperature averages more than 3 degrees Celsius hotter than normal for the entire winter. Last summer was also extraordinarily hot for Greenland, resulting in a record 150 year melt. In the above image, you can see these warm air invasions in the form of yellow and orange fingers pushing into the space of the colder greens and blues.

The new clover-leaf jet stream will not be easy for humans to manage. It will mean more persistent weather in a given region. And, if conditions are extreme, they will stay extreme for longer periods. More heatwaves, more cold snaps. More storms in areas where storms have become more prevalent.

Ironically, the new clover leaf jet stream causes one more self-reinforcing impact. It transports more warmer air into the Arctic. As such, it enhances the melt of ice which was the initial driver of extreme weather patterns in the first place. So, in this case, extreme conditions have the potential to snowball with a mangled jet stream resulting in more ice melt and more ice melt resulting in more extreme weather.

One last word and one last thing to think about. More and more the weather patterns resemble those roughly described by scientists as a Heinrich Event. Such events were characterized by rapid Arctic ice melt and resulting extreme weather and climate shifts. So it might be useful for climate scientists and the UK to discuss these geological events in the context of potential future weather. Because the UK, Europe and the rest of the world appear to be at the start of just such an event. The difference between this event and past events in the geological past is that the human forcing driving it is much greater than the previous natural forces that caused such changes. So it would be naive of us to hope that the current event will not also be more extreme than those seen in the past.

Links:

UK Met Calls Emergency Meeting to Discuss Climate Change

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