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The Present Threat to Coastal Cities From Antarctic and Greenland Melt

Seas around the world are rising now at a rate of about 3.3 millimeters per year. This rate of rise is faster than at any time in the last 2,800 years. It’s accelerating. And already the impacts are being felt in the world’s most vulnerable coastal regions.

(Rates of global sea level rise continue to quicken. This has resulted in worsening tidal flooding for coastal cities like Miami, Charleston, New Orleans and Virginia Beach. Image source: Ice Melt, Sea Level Rise, and Superstorms.)

Sea Level Rise and Worsening Extreme Rainfall are Already Causing Serious Problems

Last week, New Orleans saw pumps fail as a heavy thunderstorm inundated the city. This caused both serious concern and consternation among residents. Begging the question — if New Orleans pumps can’t handle the nascient variety of more powerful thunderstorms in the age of human-caused climate change, then what happens when a hurricane barrels in? The pumps, designed to handle 1.5 inch per hour rainfall amounts in the first hour and 1 inch per hour rainfall amounts thereafter were greatly over-matched when sections of the city received more than 2 inches of rainfall per hour over multiple hours.

Higher rates of precipitation from thunderstorms are becoming a more common event the world over as the hydrological cycle is amped up by the more than 1 degree Celsius of temperature increase that has already occurred since 1880. And when these heavy rainfall amounts hit coastal cities that are already facing rising seas, then pumps and drainage systems can be stressed well beyond their original design limits. The result, inevitably, is more flooding.

(Dr Eric Rignot, one of the world’s foremost glacial scientists, discusses the potential for multimeter sea level rise due to presently projected levels of warming in the range of 1.5 to 2 C by mid to late Century.)

New Orleans itself is already below sea level. And the land there is steadily subsiding into the Gulf of Mexico. Add sea level rise and worsening storms on top of that trend and the crisis New Orleans faces is greatly amplified.

All up and down the U.S. East and Gulf Coasts, climate change driven sea level rise and a weakening Gulf Stream are combining with other natural factors that can seriously amplify an ever-worsening trend toward more tidal flooding. It’s a situation that will continue to worsen as global rates of sea level rise keep ramping higher. And how fast seas rise will depend both on the amount of carbon that human beings ultimately dump into the Earth’s atmosphere and on how rapidly various glacial systems around the world respond to that insult (see discussion by Dr. Eric Rignot above).

Presently High and Rising Atmospheric Carbon Levels Imply Ultimately Catastrophic Sea Level Rise — How Soon? How Fast? Can We Mitigate Swiftly Enough to Prevent the Worst?

Presently, atmospheric carbon forcing is in the range of 490 parts per million CO2 equivalent. This heat forcing, using paleoclimate proxies from 5 to 30 million years ago, implies approximately 2 degrees Celsius of warming this Century and about 4 degrees Celsisus of warming long term. It also implies an ultimate sea level rise of between 60 and 180 feet over the long term. In other words, if atmospheric carbon levels are similar to those seen during the Miocene, then temperatures are also ultimately headed for those ranges. Soon to be followed by a similar range of sea level rise. In the nearer term, 1.5 to 2 C warming from the 2030s to late Century is enough to result in 20 to 30 feet of sea level rise.

Of course, various climate change mitigation actions could ultimately reduce that larger heat forcing and final related loss of glacial ice. But with carbon still accumulating in the atmosphere and with Trump and other politicians around the world seeking to slow or sabotage a transition away from fossil fuels, then it goes to follow that enacting such an aggressive mitigation will be very difficult to manage without an overwhelming resistance to such harmful policy stances.

(Antarctic ice loss through 2016. Video source: NASA.)

That said, warming and related sea level rise will tend to take some time to elapse. And the real question on many scientists’ minds is — how fast? Presently, we do see serious signs of glacial destabilization in both Greenland and West Antartica. These two very large piles of ice alone could contribute 34 feet of sea level rise if both were to melt entirely.

Meanwhile, East Antarctica has also recently shown some signs of movement toward glacial destabilization. Especially in the region of the Totten Glacier and the Cook Ice Shelf. But rates of progress toward glacial destabilization in these zones has, thus far, been slower than that seen in Greenland and West Antarctica. Present mass loss hot spots are in the area of the Thwaites Glacier of West Antarctica and around the western and southern margins of Greenland.

(Greenland ice loss through 2016. Video source: NASA.)

With global temperatures now exceeding 1 C and with these temperatures likely to exceed 1.5 C within the next two decades, it is certain that broader heat-based stresses to these various glacial systems will increase. And we are likely to see coincident melt rate acceleration as more glaciers become less stable. The result is that coastal flooding conditions will tend to follow a worsening trend — with the most vulnerable regions like the U.S. Gulf and East Coasts feeling the impact first. Unfortunately, there is risk that this trend will include the sudden acceleration of various glaciers into the ocean, which will coincide with rapid increases in global rates of sea level rise. In other words, the trend for sea level rise is less likely to be smooth and more likely to include a number of melt pulse spikes.

Such an overall trend including outlier risks paints a relatively rough picture for coastal city planners in the 1-3 decade timeframe. But on the multi-decade horizon there is a rising risk that sudden glacial destabilization — first in Greenland and West Antarctica and later in East Antarctica will put an increasing number of coastal cities permanently under water.

Rapid Mitigation Required to Reduce Risks

The only way to lower this risk is to rapidly reduce to zero the amount of carbon hitting the atmosphere from human sources while ultimately learning how to pull carbon out of the atmosphere. The present most rapid pathway for carbon emissions reductions involves an urgent build-out of renewable and non-carbon based energy systems to replace all fossil fuels with a focus on wind, solar, and electrical vehicle economies of scale and production chains. Added to various drives for sustainable cities and increasing efficiency, such a push could achieve an 80 percent or greater reduction in carbon emissions on the 2-3 decade timescale with net negative carbon emissions by mid Century. For cities on the coast, choosing whether or not to support such a set of actions is ultimately an existential one.

Links:

Fragmenting Prospects For Avoiding 2 C Warming

NASA Antarctic Ice Loss

Scientists Just Uncovered Another Troubling Fact About Antarctica’s Melting Ice

It Wasn’t Even a Hurricane, But Heavy Rains Flooded New Orleans as Pumps Faltered

Why Seas are Rising Faster in Miami

Miocene Relative Sea Level

Temperature on Planet Earth

Ice Melt, Sea Level Rise, and Superstorms

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At Least 20-75 Feet of Sea Level Rise Already Locked In? Putting Climate Central’s Surging Seas Into Context

“There are some recent modeling efforts that now show you could get a section of the Antarctic ice sheet, several meters worth of sea level rise, to go in a decade. We used to think it was centuries.” — Andrea Dutton Geochemist at the University of Florida.

*  *  *  *  *

Recent reports out from Climate Central and supported by the work of experts show that a sea level rise of at least 6 meters could already be locked in. And as bad as that sounds, a six meter sea level rise from the warming already set in motion by high atmospheric greenhouse gas levels and likely to come from further human emissions could be a best-case or even unrealistic scenario.

To get an understanding as to why so much water may be heading toward the coastal cities of the world, enough water in a 6 meter rise to set off a mass migration of hundreds of millions away from the world’s coasts (just 1.1 meters is enough to flood out 150 million people), it helps to take a good, hard look at paleoclimate. In studying past, warmer, climate states, we can get an idea how much additional sea level rise might be in store. When looking at these past climates for comparison, the key readings to keep in mind are — temperature, greenhouse gas level, and related sea level.

A Question of Whether We Lock in Greenhouse Gas Levels Comparable to Past Climates

Starting with the current climate that is now being rapidly warmed by human fossil fuel burning, we find that this year peak monthly CO2 levels hit near 404 parts per million. It’s a value fast approaching the top of this key greenhouse gas’s range during the Pliocene around 3.5 million years ago. A time when temperatures were 2-3 degrees Celsius hotter and sea levels were between 25 and 75 feet higher than they are today.

Virginia Beach 6 meter sea level rise

(What Virginia Beach looks like after 6 meters of sea level rise. Notably, about everyone I knew as a child or who still lives in VB now is under water in this scenario. Image source: Climate Central.)

Looking at the climate situation in this way tends to elicit a bit of an ‘oh crap’ response. And it should. For all other things being equal, if CO2 levels were to remain so high over the course of a few Centuries, that’s where we’re headed. Toward a world with 2-3 C hotter temperature and 25 to 75 foot higher seas.

But the atmosphere of today is only a rough allegory to that of Pliocene times. In addition to CO2, our airs now host expanding volumes of other greenhouse gasses — exotic and common. A vast majority of which are emitted as a result of fossil fuel burning, extraction, and industrial processes. So to compare our atmosphere to that of the period around 3.5 million years ago and expect the same results with regards to temperature and sea level would be unrealistic. Current methane readings alone — in excess of 1800 parts per billion — now hit levels likely twice that of the Pliocene. And methane is a greenhouse gas with a global warming potential equal to 20 to 120 times that of CO2 over timescales relevant to current human civilization.

As a result of this additional accumulation of methane and other gasses, this year’s atmosphere is a closer allegory to past atmospheres containing an equivalent of about 484 parts per million CO2 (CO2e). Such times, occurring 15-25 million years ago, hosted sea levels that were more than 100 feet (and possibly as much as 200 feet) higher than today.

It is for this reason that we should view Climate Central’s recent and excellent report on sea level rise — based on Paleoclimate and predicting that at least 20 feet of sea level rise could already be locked in — with a bit of concern. At issue with the report are two factors. The first is that the study bases its findings on predicted temperature increases for the 21st Century only. A process established by IPCC-based studies in which it is assumed that 2 degrees Celsius warming over the course of this Century is, perhaps, the best possible target we can hit through a pretty rapid transition to a zero or near-zero carbon civilization. Implied in this IPCC approach is limiting global CO2 accumulation to 450 parts per million or less. A level that also implies a 530 to 550 parts per million CO2e when other gasses are added in unless all the methane overburden falls out due to its short atmospheric lifetime (about 8 years). A dicey assumption at best considering that at least some and possibly all of that overburden could be maintained by feedbacks now at play in the Arctic and in the world’s land and ocean systems.

Miami submerged 6 meters

(At six meters of sea level rise, Miami is completely submerged. Image source: Climate Central.)

In worse cases, we could see the methane overburden expand in the event that the Arctic carbon stores are less stable than we’d hoped. So while 450 parts per million CO2 might limit us to between 2 and 2.3 C warming this Century, 530 to 550 parts per million CO2e gets us to 2.2 to 2.9 C.

The second issue is that we are only looking at warming for the 21st Century. Due to the long term warming impact of CO2 and other greenhouse gasses on the climate system in total, each 1 C worth of warming this Century implies about 2 C worth of warming long term (ESS sensitivity). So hitting the 2 C target by 2100 gets you to 4 C after many Centuries. And hitting a 550 parts per million CO2e threshold means about 2.7 to 2.9 C 21st Century warming and 5.5 to 5.8 C long term warming. An upper range that is nearly enough to melt all the land ice on Earth and raise sea levels by nearly 240 feet.

How Fast Could Sea Levels Rise?

At least 6 meters indeed! In the 550 parts per million CO2e case, we have one of the better global human carbon emissions scenarios meeting with one of the somewhat more pessimistic Earth Systems response scenarios (but not the worst case) for an absolutely terribly catastrophic outcome. An outcome made even more terrifying by the fact that it is in the mid-to-low range of overall projected greenhouse gas forcings for this Century. In other words, 2 C warming this Century can start to look like a pretty bad outcome for the long haul and we’d probably best be trying to hit well below the implied 450 ppm CO2 target (as Hansen and others have warned). And to this point, we had better move very fast on emissions reductions, because the longer even current greenhouse gas levels are maintained the more likely we hit ice sheet destabilizations that push world ocean levels closer and closer to the Pliocene’s or Miocene’s swollen seas.

Post-Glacial_Sea_LevelTemperature Change End of Last Ice Age

(Just 1 C worth of global warming from 22,000 years BP to 15,000 years BP was enough to set off rapid sea level rise during the end of the last ice age. We are fast approaching the 1 C warmer than 1880s thresholds now. Image source: Commons and Livescience.)

Which brings us to a final question hinted at in the header — how fast could sea levels rise if human forced warming approaches 2 C or more this Century? The modelling efforts Dutton hinted at shows that West Antarctica alone can contribute meters of sea level rise over the course of just decades. And going back to paleoclimate studies of the end of the last ice age we find hints that somewhere between 1 and 2 C worth of warming can trigger very large and rapid glacial outbursts (that then increased sea levels by as much as 16 feet per Century). Finally, recent glacier surveys from Antarctica to Greenland have found extensive and expanding destabilization. Efforts and evidence that imply the 39 inches of sea level rise predicted by IPCC this Century may be quite conservative, even under the better case emissions scenarios.

Links:

Surging Seas

Sea Level Could Rise at Least 6 Meters

Commons

Livescience

Antarctica and Greenland’s Simultaneous Destabilization

Concern Over Catastrophic Methane Release

A Faustian Bargain on the Short Road to Hell

The Keeling Curve

Greenland Ice Loss Increases Fivefold From Late 1990s, West Antarctica Not Far Behind

In the early 1990s, it would have been hard to imagine the rates of glacial ice loss we are seeing now.

There were few ways to accurately measure the Greenland Ice Sheet’s mass. Snow fell, glaciers calved. But observations seemed to show that the great, cold ice pile over Greenland was in balance. Snow gathered at the top, glaciers calved at the edges, but human heating of the atmosphere had yet to show plainly visible effects.

At that time, climate scientists believed that changes to the ice, as a result of human caused heating, would be slow and gradual, and would probably not begin to appear in force until later in the 21st Century.

Greenland Jacobshavn July 30 2014

(Extensive surface melt ponding, dark snow near the rapidly melt Jakobshavn Glacier on the West Coast of Greenland in early August of 2014. Image source: LANCE MODIS.)

Ice Sheet Response Starts Too Soon

By the late 1990s, various satellites had been lofted to measure the gravity, mass and volume of structures on the Earth’s surface. These sensors, when aimed at the great ice sheets, found that Greenland, during a period of 1997 to 2003 was losing mass at a rate of about 83 cubic kilometers each year.

This rate of ice loss was somewhat small when compared to the vastness of the ice sheet. But the appearance of loss was early and, therefore, some cause for concern. More monitoring of the ice sheet took place as scientists continued their investigation, for it appeared that the ice sheet was more responsive to human warming than initially believed.

A Doubling After Just Six Years

By 2009 another set of measures was in and it found that the six year period from 2003 to 2009 showed a near doubling of ice mass loss from the Greenland Ice Sheet. Rates of loss had jumped from 83 cubic kilometers each year to around 153 cubic kilometers. The doubling caused consternation and speculation among climate scientists. Greenhouse gas heat forcing was rapidly on the rise and the world’s oceans were warming faster than expected as human emissions continued along a worst case scenario path. It appeared that the ocean was delivering heat to the ice sheet bases even as atmospheric warming was melting larger areas upon the ice sheet surface.

These changes to the massive ice sheets were occurring far more rapidly than previously considered.

Edge of Greenland Ice Sheet

(Hundreds foot high edge of the Greenland Ice Sheet in Kangerlussuaq as seen at the end of a long valley and across a cold estuary. Image source: EISCAT Scientific Association.)

The potential for a 3, 6, or even 9 foot or more sea level rise by the end of the 21st Century was raised. Perhaps even more ominous, global climate models were showing that rapid ice melt in Greenland and West Antarctica, should it occur, would play havoc with world weather systems. It was this jump in ice loss, in part, that spurred climate scientist and then head of NASA GISS, Dr. James Hansen to write his book The Storms of My Grandchildren as a warning that rapid mitigation in human greenhouse gas emissions along with a stabilization of atmospheric CO2 at 350 ppm would probably be needed to prevent severe consequences from human-caused warming.

But humans kept emitting at a break-neck pace, spending far more money to build coal, gas and oil based technology, than to reduce energy consumption through efficiencies or behavioral change or to invest in alternatives like wind and solar.

Melt Rates Surge Yet Again

And so, by January of 2014, heat forcing had continued to accumulate at a very rapid pace. CO2e heat forcing had spiked to 481 ppm, enough to melt the entire Greenland Ice Sheet and much of Antarctica as well, if maintained or increased over a long period.

And the Greenland Ice sheet was, indeed, melting at an ever faster clip. For the most recent assessment found that the loss rate from Greenland had again more than doubled — hitting a 375 cubic kilometer per year average during the period of January 2011 through January of 2014.

Greenland Ice Sheet Elevation Change

(Greenland Ice Sheet elevation change in meters as found in a recent report by the Alfred Wegner Institute. Note that all Greenland edge zones are now experience elevation losses. Due to higher elevations at the center of the ice sheet, elevation loss at the edge has an effect that speeds ice sheet motion toward the sea. The effect is similar to pushing down the edge of a plastic swimming pool, but on a much larger scale and with somewhat slower moving ice.)

It was an extraordinary rate of melt now 4.7 times faster than in the period from 1997 to 2003 and 2.5 times faster than during 2003 to 2009. But, likely, it is but one more milestone on the path to even faster melt.

The same study that found the Greenland melt acceleration also saw a tripling of the melt rate of West Antarctic since 2003 to 2009. Together, the ice sheets were found to contribute a combined mass loss of 503 cubic kilometers per year between Greenland and West Antarctic. This vast, and still apparently rising, loss now meant that the two great ice sheets were contributing at least one millimeter per year to sea level rise.

Likely Grim Future For Sea Level Rise

It is likely that mass rate losses will continue to increase until some kind of break or negative feedback comes into play. Similar rates of melt increase would mean an annual 5-8 millimeter sea level rise by 2035 due to Greenland and Antarctic melt on top of a 2-3 millimeter sea level rise from thermal expansion of the oceans and from other melt sources. But even taking into account the cooling effect at the ocean surface from ice melt and fresh water floods, one could easily envision the feared 1-3 foot sea level rise by sometime near mid century and the even more concerning 3-9 foot sea level rise amidst a very intense battle between hot and cold weather systems through to century’s end.

As of 2014, it appears the conditions leading up to the warned of “Storms of My Grandchildren” are well in play and rapidly building.

Links:

Alfred Wegner Institute: Elevation Change of the Greenland Ice Sheet

Greenland Ice Loss Doubles From Late 2000s

LANCE MODIS

The Storms of My Grandchildren

EISCAT Scientific Association

Hat Tip to TodaysGuestIs

On Death Ground: Bangladesh is Fighting for its Life by Installing Solar Panels — Why Every Coastal City, State and Country Should Follow Suit

Apparently tired of waiting for the rest of the world while its fragile coastlines and mangrove wetlands are devoured by rising seas, Bangladesh has recently kicked its pace of solar panel installation into high gear.

Reports from the International Renewable Energy Agency found that Bangladeshis were installing small, rooftop solar photovoltaic generators at the stunningly rapid rate of 80,000 units each month in early 2014. In a country as financially strapped as Bangladesh, where only 47% of households have access to electricity, this is an extraordinary achievement, especially when one considers that the 2.8 million solar rooftops already gathering clean sunlight in Bangladesh will expand to challenge the 6 million threshold in just a few years.

Low Lying Coastal Bangladesh

(On the front lines of climate change low-lying coastal Bangladesh is one of an increasing number of regions vulnerable to sea level rise from rapidly destabilizing glaciers. Image source: LANCE-MODIS.)

While fossil fuel special interests twist the arms of politicians in an attempt to stymie solar development in Western countries like Britain, Australia, and the US, employing underhanded political tactics and pumping Orwellian terms like ‘solar blight‘ and ‘sea ice contamination‘ into the mainstream presses, Bangladeshis are charging ahead. And the reason couldn’t be more clear — the seas are rising.

The Gift of Fear

In the media analysis of human response to climate change, we often encounter the analogy of the frog in a pot of slowly heating water. As the analogy goes, the frog stays in the pot as it grows ever-warmer. The slow rise of temperature disables the frog’s pain and fear responses. Eventually, the frog’s muscles shut down and the frog boils.

Admittedly, this is a flawed analogy. Put a frog in a heating pot and it is wise enough to jump out once the water gets too warm — about 25-30 C. Why does the frog escape? Simple: the gift of fear. Eventually, the frog becomes uncomfortable about its situation in a slowly heating pot. The water is just a little too warm and it continues to head in the wrong direction. Rational survival instinct, at this point, intervenes to remove the hazard. The frog jumps out.

Now, keeping the frog in mind, let’s consider Bangladesh’s situation for a moment. They can see the storms that take more and more of their vulnerable lowlands with each passing year. They can see the ever-increasing advance of the tides. They know their land is in danger. To their west, their nearest neighbor, India, is building a wall to keep them out, should they have need of a refuge. And when the tides rise, as they will due to the vicious force that is human-caused climate change, they will most certainly need a refuge.

Last week’s announcement by NASA that six key glaciers in West Antarctica are now in irreversible collapse hammers the fact further home — the entire nation of Bangladesh is standing on what Sun Tzu used to refer to as death ground. In short, if the nation of Bangladesh does not decisively act, it will perish. And the only difference between Bangladesh and every coastal city, state, and country is this — Bangladesh is aware of its plight and is fighting to do something about it.

In essence, this is the gift of fear: the rational ability to fight for one’s survival — be it frog, person, city or nation.

Every Coastal Region is Now on Death Ground

greenland_velocity-base

(Greenland ice sheet velocity map as of 2010 shows numerous high-speed glacial flows toward the ocean. In the above map, blue is slow motion, red is fast motion. In the upper right hand corner of the map, the Zacharie Glacier, indicated by the letter Z, features a high speed flow that reaches all the way to the center of the Greenland ice mass. As of early 2014, scientific reports found that the recently confirmed destabilization of the Zacharie Glacier meant the entire circumference of Greenland was destabilized and moving at an ever more rapid pace toward the ocean. Image credit: Joughin, I., B. Smith, I. Howat, and T. Scambos.)

With at least 15 feet of sea level rise now locked in by the world’s destabilized glaciers and with potentially far worse sea level rise on the way if fossil fuel burning continues, one cannot hammer home the point enough — every coastal region in the world and every person living in these regions is now living on death ground. They are all in Bangladesh, even though most aren’t yet aware.

Survival action is as required of them as it is of the frog, as it is of the Bangladeshi. Swift and sure action. And even then survival is not guaranteed.

Miami, a city living in the state of climate change denial that is Florida is certainly on death ground. It is a place that will be severely challenged by another foot or two of sea level rise, much less 15 or more. The Outer Banks of North Carolina — a thin and beautiful strip of land, a redoubt between ocean and sound — bound to be swept away. Virginia Beach — a city surrounded on three and a half sides by water. Washington DC — built on a low-lying swamp at the mouth of the tidal Potomac. New York City — a place whose vulnerability to the rising seas and storms of human warming became all too real two years ago.

The list is almost endless. For wherever there are coastlines, seas, harbors, tidal rivers, mudflats, estuaries, oceans, there are human beings. We are nothing if not a water and ocean loving species — ever drawn to the life-giving edge of the sea.

According to the UN Atlas of the Oceans, about 3.1 billion people live within 150 miles of a coastline. My parents, my sister, my grandmother, my grandfather and a majority of my other friends and relatives are among them.

How many of your friends and family live on or near the coast? Or is it you who is also standing with the Bangladeshis on death ground?

Links:

International Renewable Energy Agency’s 2014 Annual Report

NASA: West Antarctica’s Entire Flank is Collapsing, Fifteen Feet of Sea Level Rise Locked-in

Marco Rubio: I don’t believe in Climate Change

The UN Atlas of the Oceans

Nature: Human Warming Now Pushing Entire Greenland Ice Sheet Into Ocean

 

 

 

 

 

 

 

 

 

 

Grim News From NASA: West Antarctica’s Entire Flank Collapsing Toward Southern Ocean, At Least 15 Feet of Sea Level Rise Already Locked-in Worldwide

(Must-watch NASA presentation finding six Antarctic Glaciers in irreversible collapse.)

Human-caused heat forcing. From the top of the atmosphere to the bottom of the world’s oceans, there’s no safe place to put it. For where-ever it goes it sets in place conditions with the potential to unleash gargantuan forces.

481. Minus aerosols, that’s the equivalent CO2 heat forcing humans have now built up in the atmosphere due to a constant and rapidly rising greenhouse gas emission. By itself, this heat forcing, were it to remain in the world’s atmosphere and ocean system, is enough to melt all of West Antarctica, all of Greenland, and part of East Antarctica pushing sea levels higher by between 30 and 120 feet or more.

Inertia. Namely, the massive inertia in the Earth climate system creating a perceived ability to resist rapid destabilization due to the human insult. It’s the one hope scientists and policy-makers alike pinned on the possibility of bringing human greenhouse gas emissions down in time to prevent radical and damaging change.

Rapid glacier and ice sheet destabilization. What, by 2014, became understood as the new reality, as an ever-increasing number of the world’s glaciers displayed far less resilience than previously anticipated and were set in motion to an unstoppable and catastrophic reunion with the world’s oceans by human warming.

Now, a new NASA study finds that six of West Antarctica’s largest glaciers are in a state of irreversible collapse. These add to a growing tally of destabilized glaciers from Greenland to Svalbard to Baffin Island to Antarctica and beyond which, all together, show that at least a 15 foot sea level rise from human-spurred glacial release is now inevitable.

Their names were Pine Island, Thwaites, Haynes, Pope, Smith and Kohler

antarctica_screen_grab1_2

(The locations of West Antarctica’s ‘butcher board’ glaciers — those that are doomed to an inevitable embrace with the Amundsen Sea. Image source: NASA.)

At issue are six massive glaciers representing more than 1/3 of total the ice mass of West Antarctica and what could well be called its entire weak flank.

As early as 1968, this massive section of West Antarctica was listed as unstable. Since that time, human heat forcing has pumped higher and higher volumes of warmth deep into the Pacific Ocean. The warmth pooled in the depths, building, even as it rose up beneath Antarctica. Ocean circulation and Ekman pumping along the coast of Antarctica brought this warm water up from the depths where it traveled along the continental shelf zone to encounter Antarctica’s mile-high glaciers. The warm water did its work, unseen, for a time. Eating away at the bottoms of these glaciers and speeding their slide to the sea. The increased glacial melt and related fresh water outflow put a kind of cold water cap on the Southern Ocean around Antarctica. This cold cap gave the ever-warming bottom waters no outlet to the surface and so the heat concentrated where it was needed least — at the bases of massive ocean-fronting glaciers.

One section of West Antarctica, composed of the six glaciers now listed as undergoing irreversible collapse, was particularly vulnerable to this basalt melt and ocean upwelling heat forcing. For the glaciers there rested on a section of continental shelf well below sea level — extending scores of miles beneath the ice and on into interior Antarctica. As a result, newly undercut glaciers are flooded until they float, creating lift, reducing friction and rapidly speeding the glacier’s plunge seaward. Even worse, few sub-glacier ridges — speed bumps that glaciologists call grounding points — interrupt the more rapid flow of these glaciers once initiated.

(NASA slide-show illustrating the process of basal melt and grounding line retreat)

By earlier this year, a separate NASA study found that the Pine Island Glacier (PIG), one of the world’s largest glaciers and the most vulnerable ice sheet in West Antarctica, had entered a state of irreversible collapse. Now, the most recent study, led by glaciologist Eric Rignot at NASA’s Jet Propulsion Laboratory, finds that five of its fellows — Thwaites, Haynes, Pope, Smith, and Kohler — are following PIG’s lead.

Rignot’s findings could not be more stark:

“The collapse of this sector of West Antarctica appears to be unstoppable. The fact that the retreat is happening simultaneously over a large sector suggests it was triggered by a common cause, such as an increase in the amount of ocean heat beneath the floating sections of the glaciers. At this point, the end of this sector appears to be inevitable.”

In other words, over the course of decades-to-centuries, these glaciers will disintegrate and slide into the sea until they are no more. Years from now, their names will be a distant memory, reminders of a faded and far better time.

At Least 15 Feet of Sea Level Rise From Glacial Melt Now Locked-in

This year, the pace of new announcements for massive glaciers undergoing destabilization or irreversible collapse could best be described as terrifying and unprecedented. And each new announcement brings with it starker implications for both the ultimate pace and scope of global sea level rise.

Global sea level rise

(Current pace of global sea level rise at 3.26 mm per year is likely now set to rapidly accelerate coincident with the rapid acceleration and melt of an ever-increasing number of the world’s glaciers. Image source: AVISO.)

The amount of sea level rise to result from just the loss of the disintegrating section of West Antarctica described in the most recent NASA study amounts to at least four feet. But looking around the world we also find rapid destabilization of more than 13 glaciers encircling all of Greenland with one, the Zacharie Glacier, featuring an ice flow that stretches all the way to the center of the Greenland ice mass. Recent studies also find that the massive glaciers of Baffin Island and the world’s largest ice cap — the Austfonna glacier on Svalbard’s island of Nordaustlandet — are all locked in an inevitable seaward rush.

The total water composed in the moving and destabilized glaciers worldwide is now at least enough to raise world ocean levels by a total of 15 feet. But the inevitable loss of these glaciers tells a darker tale, one that hints that the 23 feet worth of sea level rise in all of Greenland’s ice and the 11-13 feet of sea level rise in all of West Antarctica’s ice may well be locked in to what is a growing daisy chain of explosive destabilization if human greenhouse gas levels aren’t radically drawn down.

In continuing to emit greenhouse gasses, we make the situation ever worse by imposing a heightening heat pressure on glacial systems that will both speed their release and ensure that an ever growing portion of the Earth’s ice ultimately melts. The current forcing though both extreme and dangerous is small compared to the potential forcing should we not rapidly reign in the human emission.

Links:

Must-Read NASA Study Showing Six of West Antarctica’s Glaciers in Irreversible Collapse

NASA Video: Antarctic Collapse Explained

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

Constant Arctic Heatwave Sends World’s Largest Ice Cap Hurtling Seaward

Doomed Pine Island Glacier Releases Guam-Sized Iceberg into Southern Ocean

Scientists: Warming Ocean, Upwelling to Make an End to Antarctica’s Vast Pine Island Glacier

NASA/UC Study: Warming Ocean Found to Melt Ice Sheets From Below

A Faustian Bargain on the Short Road to Hell: Living in a World at 480 CO2e

Hat tip to Peter Sinclair and Colorado Bob

 

Doomed Pine Island Glacier Releases Guam-Sized Iceberg into Southern Ocean

Science has confirmed it. Human-caused warming is killing Antarctica’s massive Pine Island Glacier (PIG). And this week’s release of a chunk of ice larger than Guam into the southern ocean is just one of the many major losses that will occur as part of what is now an inevitable demise of one of the world’s greatest glaciers.

(CNN provides this stunning NASA imagery sequence of the break-off of B-31, a 12×24 mile iceberg from the, now doomed, Pine Island Glacier.)

Heat-Charged Blow to The Soft Underbelly of Antarctic Ice Shelves

As human greenhouse gas emissions caused the world’s oceans to warm, upwelling currents delivered a portion of that heat to the continental shelf zone surrounding Antarctica. A fortress of ice, numerous glacial ice shelves thrust out from this frozen land and drove deep into the sea floor. Ocean-fronting glaciers featured submerged sections hundreds of feet below the sea surface.

The warming currents encountered these massive ice faces, eroding their undersides and providing pathways for ocean waters to invade many miles beneath the glaciers. These invasions subjected the vulnerable ice shelves not only to the heat forcing of an ever-warming ocean, but also to wave and tidal stresses. The reduction in grounding and the constant variable stresses set the glaciers into a rapid seaward motion.

Antarctica’s most vulnerable glaciers lie along its western out-thrust. Two, Thwaites and the Pine Island Glacier, have recently seen very rapid increases in forward speed. Of these, the Pine Island Glacier, according to a recent study, is undergoing the process of an irreversible collapse. What this means is that the glacier’s speed of forward motion is now too great to be halted. Inevitably, even if the climate were to cool, the entire giant glacier will be launched into the world’s oceans where it will entirely melt out.

PIG basal melt

(Pine Island Glacier underwater melt dynamics. Image source: Nature)

Guam-Sized Chunk of Ice to be One of Many

The Pine Island Glacier is massive, covering a total area of 68,000 square miles and, in some locations, rising to over 2,000 feet in height. It represents 10% of all the ice in the West Antarctic Ice Sheet, holding enough liquid water to raise sea levels by between 1 and 2.5 feet all on its own. And the now destabilized PIG is bound to put added stresses on the adjacent Thwaites glacier together with almost the entire West Antarctic ice system.

Over recent years, PIG’s forward speed has accelerated. Increasing forward velocity by 73 percent from 1974 to 2007. Surveys made since that time show an even more rapid pace. By January of this year, studies were finding that PIG had entered a sate of irreversible collapse. So it is little wonder that enormous chunks of ice are breaking off from this massive glacier and drifting on out into the Southern Ocean.

As of early this week, the immense ice island dubbed B31 measuring 12×24 miles in size (nearly 290 square miles), slid off its temporary grounding on the sea bottom and began its journey out into the Southern Ocean. There it will remain for years, plaguing the world’s shipping lanes as it slowly disintegrates into a flotilla of icebergs. It is just the most recent event in the now ongoing decline of PIG. And we can expect many, many more major ice releases as this vast Antarctic glacier continues its dive to the sea.

Links:

Humongous Iceberg Slowly Drifts Away From Antarctica

Scientists: Warming Ocean, Upwelling Make an End to Antarctica’s Vast Pine Island Glacier

Nature

Retreat of Pine Island Glacier Controlled by Marine Ice Sheet Instability

The Pine Island Glacier

The Thwaites Glacier

Hat tip to Colorado Bob who’s been tracking PIG since 1994

 

 

Scientists: Warming Ocean, Upwelling to Make an End to Antarctica’s Vast Pine Island Glacier

Southern Ocean Interface With Pine Island Glacier

(Southern Ocean interface with Pine Island Glacier as seen during the second week of January, 2014. Note the ocean has already invaded substantially land-ward pushing the glacial coastline back by between seven and ten miles. Image source: Lance-Modis)

Among Antarctica’s most vulnerable ice shelves, the Pine Island Glacier (PIG) is a massive feature. It rests on sloped terrain that is mostly below sea level even as it spills out into the southern ocean through a nearby bay, calving great icebergs that then slowly ride out, like floating ice faerie castles, into the stormy seas. In total, the shelf covers 160,000 square miles, an area two thirds the size of Great Britain.

The Pine Island Glacier is vulnerable for many reasons. It rests on sloped land that tilts it toward the warming seas. Much of it rests below sea level, making its underbelly open to the assaults of the upwelling currents of a rapidly warming ocean. As portions of the under-structure melt, the glacier becomes buoyant, floating on surface waters subject to waves, winds and currents which adds further stress to inland structures.

A few anchors held the great glacier in place over the millenia. The great pressure of ice pushing down shoved the glacier deep into the underlying Earth, for the most part, sticking it in place as it only slowly ground toward the sea.

But now these anchoring features are disintegrating, the warming waters rushing in from underneath, lubricating the ice bottom. The slope, the gravity, the long tongues of ice entering the ocean are all coming into play. The great ice sheet is in motion. A motion that scientists now conclude will not stop until the entire glacier collapses into the heating waters.

Rumors of Glacial Demise

That the Pine Island Glacier was one of Antarctica’s most sensitive to human warming has long been well known to scientists. The geographic features surrounding the glacier, the relatively high angle of slope tipping the glacier toward the ocean, and the large section of the ice shelf below sea level all attracted interest, questions and research.

By the mid 1990s, records of massive melt coming from the Pine Island Glacier began, with upwards of 10 cubic kilometers of ice observed to be lost each year. With ice loss rates continuing to increase, more efforts focused on determining the glacier’s ultimate fate. By the mid to late 2000s, average net ice loss rates were over 20 cubic kilometers per year.

Calving Pine Island

(The July 2013 calving of the Pine Island Glacier as shown in a Lance-Modis satellite shot.)

At about the same time, in 2001, 2007, and 2013, three great icebergs calved off of Pine Island. These were massive bergs, averaging over 2000 square kilometers in size. Though large iceberg calving from the Pine Island Glacier was historically typical, the size and frequency of these amazing events were enough to raise eyebrows and add to already rampant speculation that the Glacier may well be headed toward an inexorable collapse.

Ocean’s Impact on Basal Melt Discovered

By 2010, studies were beginning to come in showing that the Pine Island Glacier was experiencing a rapid melt from underneath. Warming deep ocean currents were upwelling from the Amundsen Sea to erode the glacier’s base. Ice loss from this basal melt was estimated to be even greater than that observed through the increasingly rapid motion of the glacier and related large ocean calving events.

PIG basal melt

(Image source: Nature)

Basal melt was also shown to be undermining the glacier, pushing deeper and deeper beneath the ice shelf and driving ocean water further into the continent. The mechanism for this increased basal melt came directly from a human warming of the deep ocean surrounding Antarctica. Accelerated deep ocean warming was coming more and more into play as human atmospheric heating transferred through the ocean surface and into the depths.

In the Antarctic, a massive pool of warm water developed in the depths surrounding the continent. The warmer water gathered beneath a fresher, colder layer that kept a lid on the warmth, forcing it toward the bottom. But near the continents, the dynamics of ocean currents and coastal mixing brought this warm water up to contact the coast and, in this case, the base of the Pine Island Glacier.

A Nature Geoscience study led by Dr. Adrian Jenkins found progressive basal melt due to the action and heat transfer of this warm, upwelling water (see image above). The evidence collected seemed grim. It appeared that the Pine Island Glacier may well be in the first stages of disintegration. But more comprehensive study was needed before conclusions could be drawn.

Prognosis: Irreversible Collapse

By 2013, enough information had been collected to start making model runs to determine the ice sheet’s ultimate fate. And, recently, three teams of scientists took up the task. The results of these model runs were stark. They showed that, no matter what, Pine Island’s Glacier was probably suffering from the early stages of an irreversible collapse.

Antarctica glacial velocity map

(Glacial velocity map of Antarctica. Note the very high velocity of the Pine Island and adjacent Thwaites glaciers. Image source: Antarctic Glaciers)

In the new Nature study entitled “Retreat of Pine Island Glacier Controlled by Marine Ice Sheet Instability” the authors applying these models found that the glacier had “been kicked and it’s just going to keep on rolling for the foreseeable future.”

Dr Hilmar Gudmundsson, one of the study’s authors in a recent interview with BBC noted:

“Even if you were to reduce melt rates, you would not stop the retreat. We did a number of model runs where we allowed PIG to retreat some distance back, and then we lowered the melt rates in our models. And despite doing that, the grounding line continued to retreat. You can talk about external forcing factors, such climate and ocean effects, and then there are internal factors which are the flow dynamics. What we find is that the internal dynamics of flow are such that the retreat is now self-sustaining.”

In other words, even if the climate somehow miraculously cooled or if the warming ocean somehow managed to melt less ice at the base of the Pine Island Glacier, the glacier would still ultimately destabilize and collapse.

This is hard news, as it has implications for the rest of West Antarctica and, ultimately, about 25 feet worth of sea level rise now locked in the ice. As noted above, the Pine Island Glacier is a massive section of West Antarctica. It is responsible for the draining of about 20% of this section of the continent’s Ice and is one of the primary barriers preventing rapid sea level rise. It is the first domino to start falling. But other dominoes sit in series behind it.

The beginning of PIG’s catastrophic collapse will also likely have major implications for Antarctica’s net ice loss. Gudmundsson’s group found that average melt rates from the Pine Island Glacier are expected to more than quadruple over the next 20 years, increasing to over 100 cubic kilometers of ice loss each year. Total sea level contribution from the Pine Island Glacier alone could be as much as 10 millimeters over the same period, according to model assessments.

This is a large contribution from just one ice sheet. A contribution that is not yet accounted for in global climate simulations for sea level rise. And we have yet to take into account potential additions from other Antarctic melt sources like the adjacent Thwaites glacier or the large glaciers that drain into the Ross Ice Shelf.

In short, if Pine Island has reached the point of no return, then the rest of West Antarctica may well be soon to follow.

Links:

Retreat of Pine Island Glacier Controlled by Marine Ice Sheet Instability

Observations Beneath Pine Island Glacier in West Antarctica and Implications for its Retreat

Pine Island Glacier Retreat “Irreversible”

Ocean Warming Shown to Melt Ice Sheets From Below

Lance-Modis

The Glacial Megaflood: Global Warming Poses Growing Glacial Outburst Flood Hazard From Himalayas to Greenland and West Antarctica

Large Melt Lake, Greenland

Large Melt Lake, Greenland

(Image source: Marco Tedesco)

It’s been yet one more summer of anomalous weather events resulting from human-caused warming. Massive floods have spanned the globe, shattering records that have stood for 50, 100, or even 500 years. In other regions, record droughts and heatwaves have resulted in thousands of heat injuries and hundreds of deaths with the southeast Asian heat dome alone reported to have hospitalized tens of thousands and resulted in at least 100 deaths in China, Japan and Korea. These droughts and heatwaves created hazardous water shortages putting communities from the American Southwest to Eastern China at risk of severe damage and loss of ability to supply growing water demands. They also sparked massive and freakish wildfire complexes that damaged or destroyed hundreds of buildings or left enormous burn scars over landscapes from tropical regions to the Arctic tundra — some of which have now born the excessive insults of major fires for ten years running. The term Arctic heatwave has become common parlance. And the combination of extreme weather has resulted in widespread damage to crops and related livestock industries.

All these extreme events, in concert, are visible proofs of a climate emergency that is just starting to ramp up. Few have received the attention they warrant in the mainstream press — either singly, or together as an overall dangerous alteration to the world’s climate and weather.

But of all these, rather ominous, events, one stands out as a warning of a new, out of context, threat — a set of freakish floods in the Himalayan highlands. Floods set off by a combination of high altitude rainfall and the collapse of damns formed around growing glacial melt lakes in a region undergoing very rapid melt and warming.

(Aftermath of Glacial Outburst Flood at Kedarnath, India)

Glacial Outburst Flooding in Kedarnath

Since the early 2000s, average temperatures in the Himalayan Mountains in northern India have increased by about 1 degree Celsius, around 4 times the global average. This steady temperature rise has resulted in a gradually increasing melt of the massive glaciers along this major mountain chain featuring the tallest peaks in the world.

Over the past decade, immense glaciers along this range have witnessed unprecedented melt with many glaciers losing up to 30% of their mass. Predictions show total melt for most glaciers likely to occur under current rates of warming and fossil fuel emission by around the end of this century. The massive and unprecedented rate of melt has fueled the formation of numerous very large and growing glacial melt lakes throughout the Himalayan region. So far, about 200 of these amazing 20,000 melt lakes have outburst in flood events that are a direct result of human caused warming and related glacial melt in the Himalayas.

One such melt lake developed and filled over the past few years in a region just 4 kilometers to the north of the Indian village of Kedarnath. It was just one of the hundreds of newly formed lakes that developed and steadily grew in size over the past five years. By June of 2013, the lake had filled to capacity. Its high altitude waters held back only by a thin damn of sediment pushed out by the now, mostly melted, glacier. Then came the rains.

In the days leading up to June 17, a massive rainfall event inundated the Kedarnath region, spilling waters into an already over-filled glacial melt lake north of Kedarnath. By June 17, a tipping point was reached and the sediment damn holding back the brimming glacial melt waters erupted, unleashing what amounted to a mountain tidal wave upon Kedarnath and a massive area stretching 40 miles downstream from the glacial outburst.

This immense flood swept away more than 6,000 people who are now presumed dead after one of the worst flood events in Indian history, an event that would almost certainly have never happened without human-caused warming.

From India Today:

“The Kedarnath floods may be only a small precursor to never-seen-before mega floods,” says Maharaj K. Pandit, director, Centre for Inter-disciplinary Studies of Mountain & Hill Environment, Delhi University. Scientists like him believe that the high precipitation on June 16 rapidly filled up Chorabari Tal, a glacial lake less than 4 km upstream from Kedarnath, and the continuing downpour the next morning caused the lake to overflow and possibly burst out from its loosely packed rim of moraines (glacial sediments).

Increasing Rainfall Over Himalayan Glaciers and Growing Risk of Megafloods

Himalayas Melting

Himalayas Melting

(Image source: India Today)

According to reports by Indian scientists, rainfall rates over the Himalayan mountain chain are increasing even as rates of snowfall events are falling. Overall, precipitation is increasing by 30 percent, but more and more of this greater volume of precipitation is coming down as rain. The rain provides a double stress to glaciers in that it delivers more heat to already rapidly melting ice masses and the added run-off creates large pulses that both erode ice sheets and sediment deposits that keep both ice and water locked in. Eventually, water erosion and heat stress is too great, melt rates are too high and sediment and ice damns can no longer hold. The result is a massive and very dangerous flood event called a Glacial Outburst Flood (GLOF).

The Himalayans have seen increasingly severe GLOFS since 1929 when the first major such event emerged. Overall, 200 GLOFS have inundated various regions surrounding the Himalayans with major resultant damage to infrastructure and loss of human life. But with hundreds of new lakes forming over the past five years and with rates of glacial melt spiking, the risk for increasingly catastrophic GLOFS is growing.

As noted above, there are currently 20,000 large melt lakes throughout the Himalayan chain and, with temperatures in the region expected to increase by another 1-2 degrees Celsius before 2050, the number and size of glacial melt lakes is bound to grow. More rainfall will occur at higher and higher elevations, pushing glacial melt lake levels higher and higher. In the end, millions of downstream residents are at increasing risk of Glacial Outburst Floods.

With human climate change pushing warming at such a rapid and unprecedented rate, it is only a matter of time before more of these amazingly dangerous events take place. Global carbon emissions hit a new high in 2012 and a start to global greenhouse gas reductions, without serious and immediate global policy measures, is years to decades away. So it is highly likely that risks for large GLOFS will continue to increase in India and in other nations bordering the Himalayan mountain chain.

Stark Implications for Greenland, West Antarctica

Anywhere in the world where major ice sheets and glaciers exist, the threat of large Glacial Outburst Floods is growing. Perhaps the starkest manifestation of this risk is visible upon the now, rapidly melting, ice sheet of Greenland.

Since the mid 2000s, Greenland has been melting at a rate of 500 cubic kilometers every year. And due to polar amplification, rates of temperature increase over the Greenland ice sheet have been about double the global average. A recent report published in Nature found that just another .8 degree Celsius rise in global temperature would be enough to push the Greenland ice sheet to the point of no return. In this case, a long-term melting of all the Greenland ice sheet will have been set off by human warming.

But with very rapid melt starting to occur now, it is likely that we are already at the point of large-scale destabilization of the Greenland ice sheet even as we stare down the face of setting in place a total melt scenario over the next few decades (setting off a chain of chaotic events that would likely take centuries to complete). With temperatures continuing to rise over Greenland and with human greenhouse gas forcing and Earth System feedbacks also on the increase, it is highly likely that pace of ice sheet destabilization will continue to accelerate.

Greenland melt lakes, dark snow, August 4, 2013.

Greenland melt lakes, dark snow, August 4, 2013.

(Image source: NASA/Lance-Modis)

The problem with Greenland melt, however, is in many ways far worse than the melt of the massive, though comparatively smaller, Himalayan Glaciers. The Greenland ice sheet is entirely contiguous and has massive depth and a towering elevation of two miles at its center. Glacial Outburst Flood events from such a large source will, therefore, be far, far more catastrophic.

In the Greenland melt dynamic, multiple glacial melt lakes will increasingly form over the surface of the Greenland ice sheet. We can already see such events beginning during current summers. The above shot provided by NASA shows numerous melt lakes forming in the western border of the Greenland Ice Sheet on August 4 of 2013. These melt lakes are many times larger than those seen in the Himalayas with some of them stretching six kilometers in length. In the future, we can expect the size and number of the glacial melt lakes to greatly increase.

Risk of a Greenland Megaflood Arises

With such a large region of ice covered by numerous melt lakes, a kind of ominous tipping point may be reached. During warm summer months, weather systems may pull warmth and moisture over a large section of the Greenland Ice Sheet which is already covered with numerous melt ponds. Temperatures above freezing and a constant flow of moisture emerging from the southern latitudes through a locked in place Jet Stream pattern may ensure that the rain event over these Greenland melt lakes lasts for days or weeks.

Eventually, some of these melt lakes begin to over-top, spilling waters into the already filled lakes lower down on the ice sheet. These lakes then also over-top, contributing ever greater volumes of water to the growing flood.

Depending on how far melt lakes penetrate into the ice sheet, this chain reaction over-topping can proceed for tens or even hundreds of kilometers. By the time the massive flood has reached the lower ice sheet edge, perhaps a kilometer or more below the initial flood source, a massive glacier-originating wave has developed, one that is, perhaps, tens or hundreds of feet in height and with a front covering tens or even hundreds of miles.

Such a powerful outburst megaflood would contain both freezing water and large fragments of ice ripped from the ice sheet as the outburst wave proceeded down the ice sheet. And, like the Kedarnath megaflood, it will also likely contain boulders pulled from adjacent mountains and lands. But this particular event would be far, far worse than any Himalayan outburst flood. It would proceed for hundreds and, perhaps, thousands of miles from the outburst site, leaving a swath of destruction similar to that seen in the worst global ocean tsunami events of recent years.

Melt Lakes Forming Among Terrace-Like Structures on the Greenland Ice Sheet

Melt Lakes Forming Among Terrace-Like Structures on the Greenland Ice Sheet. Set up for Future Large Outburst Megaflood?

We see evidence of such events occurring at the end of the last ice age, with petrified trees imbedded in rock strata up to 500 feet above sea level in the cliffs and mountainsides of Pacific Islands bordering the Arctic. It is thought that these trees were carried by massive glacial outburst floods from the melting Laurentide Ice Sheet which, at the end of the last Ice Age, was thousands of miles away from this tree deposition. The trees found in these deposits are natives to Canada and Alaska and the character of their deposition is indicative of a catastrophic outburst flood event or series of events.

Glacial Outburst Megafloods are among the most dangerous risks posed by rapid Greenland and West Antarctic Ice Sheet melting, warming and destabilization. And Greenland is most likely to see its first manifestations, though Antarctica may follow soon after, over the course of years or decades. Such ice sheet decline will be both chaotic and destructive — with moments of almost unthinkable outburst events proceeding once certain tipping points are reached. Some of these events may already be locked in due to current human forcing and related natural feedbacks. Let us hope that it is possible to prevent their very worst manifestations.

Greenland Outburst Flood of 2012 to be Seen as Minor by Comparison

Should such events occur, a massive outflow of water near the Greenland Ice Sheet during 2012 that washed out a bridge and threatened a local airport will be seen as minor. For comparison, I’ve added the following video:

A major outburst flood issuing from a large section of the Greenland ice sheet would render miniscule even this, very energetic event.

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