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Why a 15 Percent Slow-Down in North Atlantic Ocean Circulation is Seriously Bad News

“We know somewhere out there is a tipping point where this current system is likely to break down. We still don’t know how far away or close to this tipping point we might be. … This is uncharted territory.” — Stefan Rahmstorf

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The North Atlantic ocean circulation (often called AMOC or the Great Ocean Conveyor) is now the weakest its been in sixteen centuries.

Increasing melt from Greenland due to human-forced warming of the atmosphere through the deep ocean is freshening the ocean surface of the far North Atlantic. To the south, higher ocean temperatures are increasing surface salt content through greater rates of evaporation. Fresh water prevents ocean water from sinking in the north and rising salt content generates increased sinking in the south. As a result, the rate at which waters move from the Equator toward the Pole is slowing down. Since the mid 20th Century, this critical ocean circulation has reduced in strength by 15 percent on decadal time-scales.

(Deep water formation in the North Atlantic is driven by the sinking of cold, salty water. Over recent years, this formation, which drives larger ocean circulation and atmospheric weather patterns, has been weakening due to increasing fresh water flows coming from a melting Greenland. Image source: Commons and the NASA Earth Observatory.)

Movement of warm Equatorial waters northward and their subsequent overturning and sinking in the North Atlantic drives a number of key weather and climate features. The first is that it tends to keep Europe warm during winter and to moderate European temperatures during summer. The second impact is that a fast moving current off the U.S. East Coast pulls water away from the shore keeping sea levels lower. The third is that warm water in the North Atlantic during winter time tends to keep the regional jet stream relatively flat. And the fourth is that a more rapid circulation keeps the ocean more highly oxygenated — allowing it to support more life.

A slowing down of ocean circulation in the North Atlantic therefore means that Europe will tend to cool during winter even as it heats up during summer. Sea level rise will accelerate faster for the U.S. East Coast relative to the rest of the world due to a slowing Gulf Stream combined with the effects of melting land glaciers and thermal ocean expansion. The North Atlantic jet stream will tend to become wavier — with deep troughs tending to form over Eastern North America and through parts of Europe. These trough zones will tend to generate far more intense fall and winter weather. Finally, a slowing ocean circulation will tend to increase the number of low-oxygen dead zones.

(Cool pool formation near Greenland juxtaposed by a warming and slowing of the Gulf Stream as it is forced southward is an early indication of ocean circulation slow-down. During recent years, this phenomena — which is related to larger human-forced climate change — has become a prevalent feature of North Atlantic Ocean climate and weather patterns. An indicator that climate change and ocean system changes for this region are already under way. Image source: Earth Nullschool.)

A 15 percent slow down in ocean circulation is not yet a catastrophic event. It is, however, enough to produce odd weather and climate signals. We have tended to see higher rates of sea level rise off the U.S. East Coast, we have tended to see more extreme winter weather across the North Atlantic basin. The long term trend for increasing ocean dead zones is well established. And European weather has become more and more extreme — with hot summers and severe winters.

With rates of Greenland melt increasing, there is a risk that the historic observed North Atlantic circulation weakening will increase further and more radically — producing still more profound results than we see today. In the event of large melt outflows coming from Greenland during abnormally warm summers or due to warming deep water melting glaciers from below — a possibility that rises with each 0.1 C of global temperature increase — we could see a very rapid weakening of ocean circulation above and beyond that which has already been recorded.

(Like Antarctica, Greenland features a number of below sea level locations directly beneath its largest ice masses. This feature makes Greenland more vulnerable to rapid ice loss and large melt outflows. Image source: NASA JPL.)

If such a tipping point event is breached — and there is increased risk for it as global temperatures enter a range of 1.5 to 2.5 C above 1880s averages during the 2020s through the 2040s — then we can expect far more profound weather and climate disruptions than those we have already experienced.

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The Increasingly Fragile Pine Island Glacier Just Calved Again

The point where the Pine Island and Thwaites glaciers meet the sea serve as a back-stop restraining most of the great ice flows of West Antarctica. If those backstops were to fail, ocean water would flood inland along a reverse slope and generate a massive and swift out-rush of ice that would ultimately raise the world’s oceans by about 3 meters. And, lately, the evidence is mounting that the backstops are failing.

At Thwaites, just south of the neighboring Pine Island Glacier (PIG), recent research found that the ocean was flooding inland beneath that enormous ice sheet at a rate of up to 400 meters per year. But to the north, there is indication of trouble at the ice surface.

Back to Back Calving Events

Just last September, a massive 100 square mile ice berg calved off the Pine Island Glacier. The event was significant in that it marked the first major retreat of the glacial front in the face of an advancing ocean. Pine Island had already sped up. But the calving face withdrawal inland appeared to mark a new phase for the large glacier.

(Sentinel 1 satellite observations show a rapidly moving Pine Island Glacier calving off another large ice berg. Meanwhile, considerable damage appears to have been done to the glacial front.)

Now, just 7 months later, PIG is calving again. A large, approximately 6 kilometer long, 1 kilometer wide, chunk appears to have broken off into the Southern Ocean and shattered. Meanwhile, to the north and south along the glacial front, rifts appear to have formed.

This recent calving event is significant for a number of reasons. The first is that it’s happening just months after a recent large break-off during 2017. Other recent calving events at Pine Island occurred during 2001, 2007, and 2013. The present 2017-2018 events are back-to-back. The second reason is that the splintering appears to indicate a more fragile ice face. An impression reinforced by the concordant formation of rifts spreading away from the calving zone. The third is that the satellite imagery suggests Pine Island Glacier is moving quite rapidly (Recently, this rate of motion has been 1-2 km per year. However, it’s reasonable to question whether the glacier is continuing to speed up).

Conditions in Context

Present global warming due to fossil fuel burning has now forced the world into a range of temperatures between 1.0 and 1.21 degrees Celsius above 1880s averages. This boundary is similar to that of the lower range of the Eemian 120,000 years ago when oceans where 10-20 feet higher than they are today.

(The tall ice cliffs composing the Pine Island Glacial front have become increasingly fragile and fast moving as they enter the warming Southern Ocean and as that warming water continues to invade inland. Image source: Commons, Pine Island Glacier Calving Front, NASA.)

Under present greenhouse gas forcing and planned emissions, additional warming is in store. Climate models produced by Dr. Michael E Mann indicate that we are likely to hit the 1.5 C global temperature boundary some time between 2027 and 2031 on the current emissions pathway. This predicted warming is significant because analysis of past climates appears to indicate a risk of more rapid rates of sea level rise when global temperatures rise to a range between 1.5 to 2.5 C above past base line averages (see meltwater pulse 1 A).

Since the 1990s, the global rate of sea level rise has proceeded at roughly 3.3 mm per year with an apparent acceleration to around 3.6 to 4.1 mm per year during the 2010 to present time period. Given observed ice sheet instability in West Antarctica, in East Antartica, and in Greenland, there is a serious risk that this rate of rise will continue to accelerate over the coming years and decades. The key question of concern is how much and how soon.

Rapid Sea Level Rise Possible as Ocean Floods into Antarctica at up to 400 Meters Per Year

From west to east and in a growing number of places, a warming ocean is cutting its way deep into Antarctica. Grounding lines — the bases upon which mile-high glaciers come to rest as they meet the water — are in rapid retreat. And this ocean, heated by human fossil fuel burning, is beginning to flood chasms that tunnel for hundreds of miles beneath great mountains of ice.

Such an immense flood has the effect of speeding up glaciers as far away as 500 miles from the point of invasion. It does this by generating a kind of abyssal pit that the glacier more swiftly falls into. And as these watery pits widen, they risk pumping sea level rise to catastrophic levels of ten feet or more by the end of this Century.

(A new study in Nature is the first to survey the rate of grounding line movement around Antarctica’s entire perimeter. What it found was disturbing. A large number of major glaciers are seeing historically rapid rates of grounding line retreat [red arrows] as only a few glaciers show very slow rates of grounding line advance [blue arrows]. Image source: Hannes Konrad et al, Nature, University of Leeds.)

The great ocean invasion is clearly on the march. Not yet proceeding everywhere, the advance is happening in enough places to cause major worry. In West Antarctica, 22 percent of its glaciers are seeing their grounding lines move inland by more than 25 meters per year. In the Antarctic Peninsula, 10 percent of glaciers are experiencing this retreat. And in East Antarctica, where the ice is piled thickest, 3 percent of glaciers are affected by the swift invasion.

The most rapid retreat — at up to 400 meters per year — is presently happening at Thwaites Glacier in West Antarctica. Thwaites alone encompasses enough ice to lift the world’s oceans by 3 meters. And the rate of inland ocean water invasion at this single location is a very serious concern.

(Grounding line retreat is just one of many factors that increase the risk of rapid sea level rise. Ice cliff instability, increased rainfall over glaciers, large floods of water into glaciers from melt ponds that then refreeze and fracture the ice, and a number of other factors all compound as the Earth is heated up by fossil fuel burning. Video source: International Business Times.)

But the issue is not one of single glaciers. It’s one where many very large mounds of ice all around Antarctica are under threat. And in much the same way that a dike risks breaking apart when it is punched through by a growing number of holes, Antarctica’s own flood gates to rapid sea level rise are threatened by each grounding line in quickening retreat. Another such ‘hole’ has formed at the Totten Glacier where the grounding line is retreating at around 150 to 175 meters per year. And Totten could produce another 3.4 meters of sea level rise if it collapsed into the Southern Ocean.

Continuing the dike anology, Antarctica holds back enough water as ice, in total, to lift the world’s ocean levels by an average of 200 feet. By greater or lesser degrees, each retreating glacier contains a portion of the potentially massive flood. And the overall rate of loss in the form of new glaciers going into retreat together with the pace of inland ocean invasion is speeding up.

This new set of research provides a more complete if fearsome picture of Antarctic melt. And though models aren’t yet able to pinpoint how fast sea level rise will be, a growing body of evidence points to greater than previously expected risk for rapid sea level rise this Century. So for the sake of our coastlines and of so many cities around the world, the time to act as swiftly as possible to reduce carbon emissions and their terrible related impacts is now.

Big Oil Says You’re to Blame For Climate Change, Not Them

“Global increases in CO2 concentrations are due primarily to fossil fuel use…” — IPCC.

“Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2).”NASA.

“The IPCC does not say it’s the extraction and production of oil that is driving these emissions. It’s economic activity that creates the demand for energy, and that leads to emissions.”Chevron’s attorney in an ongoing California climate change liability suit.

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After years of encountering this argument in the chat forum below, we could well have seen it going mainstream from a mile away.

To bring everyone up to speed, Big Oil and other fossil fuel giants are being put on trial for their role in producing climate harming carbon emissions. Low lying coastal cities like San Francisco are claiming that impacts like sea level rise caused by those carbon emissions are going to be costly to deal with. They’ll have to build coastal defenses with price tags at least in the tens of millions (and probably more) to protect valuable neighborhoods and industries in the very near future.

(Big oil says they just sell the products that cause climate change. The fact that people in captive energy markets have little choice but to use them is not their fault, they say.Image source: Inside Climate News.)

But Big Oil which for years denied that climate change was happening (after they did the science that proved it was), and for still more years denied that it would be damaging, has now added a new deflection to their arsenal of distraction. They’ve come up with a perfect scape goat for the problem they’ve contributed so much to over the years. Who’s that? Well it’s you. Yes — YOU.

The argument goes something like this — climate change is happening, the IPCC proves it, it’s caused by human economic activity and energy use, so it’s not our fault.

We could well call this climate change denial argument # 5,000 — deny responsibility for harms done by blaming the victim which is humankind and related human civilization itself. Never mind the fact that fossil fuel companies have lobbied for decades to prevent government policy that would actually reduce climate harms by cutting carbon emissions. Never mind the fact that monopolistic fossil fuel companies did everything they could since their inception to corner the energy market and keep humans like you and me captive to fossil fuel use. Never mind that these corporations have fought alternative, clean, non-carbon emitting energy sources like wind and solar tooth and nail — going so far as to produce public relations campaigns that demonize these non-carbon energy sources.

(An expose on just one of many fossil fuel based industry attacks on non-carbon emitting sources during recent years. Video source: The Young Turks.)

Now they want to blame you for the damage they fought so long to ensure.

We’ll see how that argument flies in court. Because it’s likely that a growing list of oil, coal, and gas companies are going to be asked to pay for the damage they’ve caused. The damage that they’ve fought and lobbied for over the course of years and decades in the political sphere. They were both the author of the damage and the authors of denial. And I think there will be many more legal and social bills for their various wrongs and excesses that start coming due.

The Great Totten Glacier is Floating on More Warming Water Than We Thought

It’s well known now that massive glaciers in Greenland and Antarctica are contributing to an accelerating global sea level rise. And while we first thought Greenland was primarily at risk of producing ocean-lifting melt this Century, we have now learned that both West and East Antarctica are becoming involved.

(A massive glacier the size of France is floating on more of a warming ocean than previously thought. Taking into account past reports of thinning along the glacier’s underside, and this is a rather concerning finding. Image source: Australian Antarctic Division.)

How much and how soon and under how much warming pressure is still a matter of some debate in the sciences. But the situation is now looking a bit worse for the Totten Glacier — an enormous sea-fronting slab of ice as big as France that if it melted in total would, by itself, raise sea levels by about 10-13 feet globally.

Previously thought to be more resilient to melt as a result of human-caused climate change and related fossil fuel burning, the Totten was once considered to be stable. However, over recent years, concerns were raised first when plumes of warm water were identified approaching the glacier’s base and later when it was confirmed that Totten was melting from below. Concerns that were heightened by new research identifying how winds associated with climate change were driving warmer waters closer and closer to the huge ice slab.

(Winds heated by climate change drove warmer waters toward Totten and accelerated the glacier during recent years. Video source: Science News.)

After follow-on expeditions to Totten, scientists (over the past two years) discovered that the glacier’s floating underside was losing about 10 meters of thickness annually even as its seaward motion was speeding up. Now, new research has found that more of the Totten Glacier is floating upon this warming flood of ocean water than previously thought. According to Professor Paul Winberry, from Central Washington University, who spent the austral summer of 2018 with a Tasmania-funded team of scientists taking measurements of Totten:

“A hammer-generated seismic wave was used to ‘see’ through a couple of kilometres of ice. In some locations we thought were grounded, we detected the ocean below indicating that the glacier is in fact floating (emphasis added).”

Beneath Totten lies a large ridge upon which most of the glacier is grounded as it flows toward the sea. But penetrating this ridge are numerous gateways that, if melted through, provide sea water access to the glacier’s interior. And recent studies have found that a number of these gateways have been thawed open, allowing warming ocean waters access to sections of the glacier that are hundreds of miles inland.

(Warm water invasion pathways have opened along Totten’s previous grounding line. These openings have allowed water to flood far inland beneath the glacier. The result is a less stable, more rapidly moving ice sheet. Image source: Jamin Greenbaum/University of Texas-Austin.)

This warm water breakthrough has contributed to Totten’s seaward movement. And the new study was aimed at discovering the extent of the inland water melt flood. According to lead researcher Dr Galton-Fenzi:

“These precise measurements of Totten Glacier are vital to monitoring changes and understanding them in the context of natural variations and the research is an important step in assessing the potential impact on sea-level under various future scenarios.”

The fact that the extent of inland flooding along Totten’s underside runs further than previously thought is a concern in light of recent findings that the glacier is losing a considerable amount of underbelly ice each year. In addition, the fact that we haven’t yet pinpointed the grounding line should add another note of worry. How much we should worry is unclear at this time. But the fact is that the scientific signs coming in from Totten continue to indicate that the glacier is suffering warming impacts that pose risks to its historic stability.

Sea Level Rise in the United States — From Nuisance to Trouble

As fossil fuel companies fight to keep cities and nations captive to harmful emissions, the effects of rising greenhouse gas concentrations are growing more and more pronounced.

A new study from NOAA finds that the incidence of flooding along U.S. coasts (primarily driven by fossil fuel burning) has increased considerably. This already-damaging situation, under present emissions scenarios, is expected to become much worse over the coming decades.

In the Southeast, high tide flooding days since 2000 have increased from an average of 1.5 per year to 3 per year. In the Northeast, similar flooding days have increased from about 3.5 per year to 6. Flooding is also becoming more common on the U.S. West Coast, though at a slower rate of growth. But hotspots for this region include San Francisco — which is seeing both land subsidence and rising oceans.

(New NOAA study reveals a staggering future for U.S. coastal flooding.)

For all coasts of the U.S. the future is looking increasingly grim. According to William Sweet, an oceanographer at the National Oceanic and Atmospheric Administration:

“The numbers are staggering. Today’s storm will be tomorrow’s high tide.”

By mid-Century the Western Gulf of Mexico is expected to face between 80 to 185 days of flooding per year, the coastal Northeast expects 45 to 130 days, and the Southeast and Eastern Gulf of Mexico is likely to see between 25 and 85 flooding days per year. By 2100, under expected fossil fuel burning scenarios, many locations will see at least minor flooding on most days.

In other words, already widespread flooding is about to get much worse. And the increasingly powerful storms we now see roaring out of an ocean riled by climate change will push their more intense storm surges up over already higher seas. Eventually, there will be no U.S. coastal zone that is untouched by this combined impact.

East Coast Still Experiencing Heavy Seas as Another Storm Looms

Large swells and high tides continued to batter the U.S. East Coast today as a storm that is predicted to become yet another nor’easter began to gather over the Central U.S.

A broad low pressure system that slammed the mid-Atlantic and Northeastern U.S. this weekend with flooding, massive waves, and wind gusts of up to 93 mph was still hurling rough seas and storm tides at the U.S. East Coast on Monday. Such widely-varied locations as coastal Florida and New Jersey were experiencing high water, beach erosion, raging surf and minor coastal flooding. Officials were warning people to stay off the beach and away from riled seas as crews rushed to clear debris.

The storm gained extreme intensity that was likely peaked by a number of climate change related factors including warmer than normal sea surface temperatures, a blocking high over Greenland that was likely impacted by a recent polar warming event, and higher sea levels resulting increasingly severe tidal flooding during the storm’s peak.

(A massive low pressure system that knocked out power to hundreds of thousands and flooded the Northeast coastline this weekend still churned off the U.S. East Coast on Monday — lashing shores with rough surf and minor flooding. Image source: Earth Nullschool.)

Inland, nearly a quarter million people were still without power from Virginia through Maine — down from a high of around two million at the weekend storm’s peak. However, utilities are saying that it may take days to fully restore power to some locations. As repair crews were scrambling, another major storm was starting to gather over the Great Plains — with a high pressure system across Florida drawing very moist air from over a much warmer than normal Gulf of Mexico and into the developing storm’s circulation.

Over the next 24 hours, the new storm is projected to track eastward — crossing to the Ohio River Valley region by late Tuesday. On Wednesday, the low will transition energy into a developing storm off Virginia and the Outer Banks. This low is then expected to rapidly intensify as it moves northward — developing strong onshore winds with gusts of 45-65 mph crossing coastal Delaware, New Jersey, Long Island, Connecticut, Rhode Island and Massachusetts by late Wednesday and into early Thursday.

(Models show another powerful low pressure system battering the Northeast Coast with 45-65 mph winds by early Thursday. Image source: Tropical Tidbits.)

The storm is also predicted to bring heavy coastal rains and up to 1-2 feet of snow across parts of the Northeast.

Presently, the storm is not expected to be as strong as the massive system that slammed the Northeast and Mid-Atlantic this weekend. However, gale force to storm force gusts are presently predicted, and forecast storm strength has been trending toward higher intensity in recent model runs.

In addition, climate change related factors like a warmer than normal Gulf of Mexico, much warmer than normal sea surface temperatures in the Gulf Stream, higher sea levels, and a large blocking high over Greenland are contributing to this most recent storm’s expected intensity. With hundreds of thousands still recovering from this weekend’s historic storm, and with so many factors now in play that could serve to further spike a new storm’s intensity above those presently expected, this is a developing situation that bears watching.

Coastlines in Danger: The Rate of Global Sea Level Rise is Accelerating

A new NASA study published just yesterday confirms long-held warnings about rising oceans from IPCC and other climate change watch dog bodies. What it found, looking back over the last 25 years, was not only that seas were rising, but that they were rising at an ever-increasing annual rate.

If we took a snap shot of the present day, we’d find that oceans are rising at a rate of around 3.3 mm per year. If that rate were to hold steady, it would translate to a 33 centimeter rise per century. Or about 1.1 feet. This is global average rise, of course. In more vulnerable places like Tidewater, VA, or New Orleans, or Miami, such a larger swelling of the world’s ocean could translate to 2-3 feet due to local conditions like subsidence or ocean current change.

That’s bad enough. But it’s not the whole story.

(NASA study shows that sea level rise rates are accelerating due to the melting of large glaciers in Greenland and Antarctica. The key driver of this melt is human fossil fuel burning and related accumulation of heat-trapping carbon dioxide in the Earth’s atmosphere. Carbon dioxide levels this year will hit near 412 ppm in April-May, a level not seen in 10-15 million years. Video Source: NASA.)

According to NASA, that annual rate of sea level rise is also rising. In other words, it’s accelerating like a car when you slowly but inexorably increase pressure on the peddle.

The present annual increase measured by NASA’s satellites shows a 0.08 mm rate of acceleration averaged over the past 25 years. What this means is that if the rate of increase remains steady, next year seas will rise by 3.38 mm, and the following year seas will rise by 3.46 mm. Extrapolate that to the end of this Century and you’d get an annual rate of rise of around 10 mm per year — or about 3.3 feet every 100 years.

This translates to roughly 26 inches of additional sea level rise from now to 2100 globally — or about 3-5 feet in more locally vulnerable places like Tidewater, New Orleans, and Miami.

(Over the past 25 years, the rate of sea level rise has been accelerating by 0.08 mm per year. A backwards extrapolation by NASA of satellite data is a broad confirmation of sea level observations and predictions by IPCC. However, increasing ice sheet instability in Greenland and Antarctica could further spike rates of acceleration, endangering coastal cities even more. This serious global risk is amplified by continued fossil fuel burning, and moderated by more rapid transitions to clean energy. Image source: AVISO.)

Of course, given the fact that we continue to burn fossil fuels, that the necessary renewable energy transition continues to be delayed by predatory industries and their proxy politicians (primarily republicans like Trump in the United States), there is no guarantee that the rate of annual increase in sea level won’t accelerate faster than it already is. So, for this reason, the new NASA, IPCC-confirming, report should be viewed under a caveat (Dr Eric Rignot points toward sea level rise of greater than 1 meter by 2100).

In other words, if we don’t respond soon, the glaciers in Greenland and Antarctica that are already speeding the rate of global sea level rise could start to really let loose and get us into even more trouble than we already are.

(UPDATED)

Gigantic Iceberg Disintegrates as Concern Grows Over Glacier Stability, Sea Level Rise

The stability of a key Antarctic glacier appears to have taken a turn for the worse as a large iceberg that broke off during September has swiftly shattered. Meanwhile, scientists are concerned that the rate of sea level rise could further accelerate in a world forced to rapidly warm by human fossil fuel burning.

(Iceberg drifting away from the Pine Island Glacier rapidly shatters. Image source: European Space Agency.)

This week, a large iceberg that recently calved from West Antarctica’s Pine Island Glacier rapidly and unexpectedly disintegrated as it drifted away from the frozen continent. The iceberg, which covers 103 square miles, was predicted to drift out into the Southern Ocean before breaking up. But just a little more than two months after calving in September, the massive chunk of ice is already falling apart.

The break-off and disintegration of this large berg has caused Pine Island Glacier’s ice front to significantly retreat. From 1947 up until about 2015, the glacier’s leading edge had remained relatively stable despite significant thinning as warmer water began to cut beneath it. But since 2015, this key West Antarctic glacier has begun to rapidly withdraw. And it now dumps 45 billion tons of ice into the world ocean each year.

(Glaciers like Pine Island balance on a geological razor’s edge. Because they sit on a reverse slope, it only takes a relatively moderate amount of ocean warming to precipitate a rapid collapse. These collapses have happened numerous times in the past when the Earth warmed. Now, human-forced climate change is driving a similar process that is threatening the world’s coastal cities. Image source: Antarctic Glaciers.)

The present rate of melt is enough to raise sea levels by around 1 millimeter per year. That’s not too alarming. But there’s concern that Pine Island Glacier will speed up, dump more ice into the ocean and lift seas by a faster and faster rate.

Pine Island Glacier and its sister glacier Thwaites together contain enough water to raise seas by around 3-7 feet. The glacier sits on a reverse slope that allows more water to flood inland, exposing higher and less stable ice cliffs as the glacier melts inland. If the glacier melts too far back and the ice cliffs grow too high, they could rapidly collapse — spilling a very large volume of ice into the ocean over a rather brief period of time. As a result, scientists are very concerned that Pine Island could swiftly destabilize and push the world’s oceans significantly higher during the coming years and decades.

No one is presently predicting an immediate catastrophe coming from the melt of glaciers like Pine Island. However, though seemingly stable and slow moving, glacial stability can change quite rapidly. Already, sea level rise due to melt from places like Greenland and Antarctica is threatening many low-lying communities and nations around the world. So the issue is one of present and growing crisis. And there is very real risk that the next few decades could see considerable further acceleration of Antarctica’s glaciers as a result of human-forced warming due to fossil fuel burning.

Dr Robert Larter, a marine geophysicist at British Antarctic Survey, who has researched Pine Island Glacier in his work with the Alfred Wegener Institute, recently noted to Phys.org:

“If the ice shelf continues to thin and the ice front continues to retreat, its buttressing effect on PIG will diminish, which is likely to lead to further dynamic thinning and retreat of the glacier. PIG already makes the largest contribution to  of any single Antarctic glacier and the fact that its bed increases in depth upstream for more than 200 km means there is the possibility of runway retreat that would result in an even bigger contribution to sea level.”

CREDITS:

Hat tip to Colorado Bob

Hat tip to Erik Friedrickson

From Ice Apocalypse to Mega-Thunderstorms, Continuing to Burn Fossil Fuels Makes the World Scary as all Hell

So I’ve got to say I feel for Eric Holthaus.

Here’s a smart guy. Probably a few years younger than me. A meteorologist by degree and a climate journalist by trade. A guy with two kids that, as is clear from his twitter comments, mean all the world to him. And he’s finally gotten to that point in his study of climate change where he’s thrown his hands up and said — this stuff scares the crap out of me, can we please all just do something about it?

(The calving front of the Pine Island Glacier as seen by a NASA DC-8 aircraft. Image source: Commons.)

For him, as with any of us, the point of existential realization can come through overexposure to a wide range of worsening climate problems. Declining ocean health, rising extreme weather, how much faster we are warming the world up than during the worst hothouse extinction, can all weigh heavily on the heart and mind of any compassionate, feeling person who takes these subjects seriously enough to actually read the science. For Eric, the big deal, and it is a very, very big deal, was sea level rise.

Ice Apocalypse

Yesterday, Eric penned this seminal article on the issue of ice cliff stability as explored by glacier scientist Robert DeConto entitled Ice Apocalypse.

Ice cliff stability is a pretty technical term. One that may make the eyes of your typical reader gloss over. But when we consider that the glaciers of Greenland and Antarctica can be upwards of two miles high, then the question of whether or not the cliffs of those great ice mountains are stable may start to generate a flicker of warning. May conjure up a phantom of the titanic roar set off when such ice giants tumble away into the sea as has happened throughout the deep history of Earth whenever the world warmed up by a certain amount.

When I think of the words ice cliff stability, my mind’s eye pictures a vast wall of numbing white-blue stretching hundreds of feet high. It expands both left and right as far as I can see. And it looms over an endless warming ocean. Waiting for a colossal fall if just that right amount of extra heat is applied.

Ice is fragile. It’s not like stone. It doesn’t flex much. It doesn’t give much. And even minor stresses are enough to make it shatter. We see this with ice cubes in a cup of water at home. Put an ice cube into relatively warmer water, and that little 1×2 inch block will snap and crack. Now just compound that fragility. Set it on the massive scale of a mile-high glacier. Not too hard to image what can happen.

(2012 filming of massive calving event at Jakobshavn Glacier.)

It’s happened already at Jakobshavn Glacier in Greenland. The ocean warmed. The ice shelf protecting the glacier dissolved. And the front of the gigantic glacier fell like great, enormous, white dominoes. We’ve seen it happening in films like Chasing Ice. And we’ve struggled to grasp the enormous scale of it.

Our burning of fossil fuels did this.

Jakobshavn is, even now, contributing to a more rapid rate of global sea level rise. But the amount of ice held back by Jakobshavn is small when compared to the vast volumes kept in check by the Pine Island and Thwaites Glaciers of West Antarctica. What Robert DeConto did, and what has apparently scared Eric Holthaus so much, was apply a computer model based on observations of Jakobshavn ice sheet collapse to these larger Antarctic ice masses.

The DeConto study unearthed results that, indeed, looked apocalyptic. From Grist:

A wholesale collapse of Pine Island and Thwaites would set off a catastrophe. Giant icebergs would stream away from Antarctica like a parade of frozen soldiers. All over the world, high tides would creep higher, slowly burying every shoreline on the planet, flooding coastal cities and creating hundreds of millions of climate refugees.

All this could play out in a mere 20 to 50 years — much too quickly for humanity to adapt…

Instead of a three-foot increase in ocean levels by the end of the century, six feet was more likely, according to DeConto and Pollard’s findings. But if carbon emissions continue to track on something resembling a worst-case scenario, the full 11 feet of ice locked in West Antarctica might be freed up, their study showed.

The DeConto study is just one scientific exploration of what could happen in West Antarctica this Century. And, already, reassurances to a worried Eric Holthaus are forthcoming.

But the problem with the DeConto study, as with any other form of serious climate risk, is that there are plausible scenarios in which terrible catastrophic events are possible even if their degree of likelihood is still somewhat debatable. And reasonable precaution would dictate that even if there were just a 10-20 percent chance of DeConto like events coming to pass, we would do everything we could to avoid them. The risk of this scenario emerging, however, is probably a bit higher. As numerous studies have identified the potential for 6, 8, or even 12 feet of sea level rise by as early as 2100.

The Future of Mega-Thunderstorms Looks Grim if We Continue to Burn Fossil Fuels

Eric’s appeals to his Twitter friends related to his article were touching to me in that I feel like I go through similar shocks with each passing week. And what should be a time of national thanksgiving even as more than half of Puerto Rico’s population is still in the dark 63 days after the climate change amplified blow of Hurricane Maria is no exception.

For a model study recently produced by Nature Climate Change and explored by Bob Henson at Weather Underground has found that the rate of rainfall in large thunderstorm clusters could increase by 80 percent this Century if fossil fuel burning proceeds along a business as usual pathway.

To put this in context, an 80 percent increase in the amount of rain that fell in the Ellicott City Flood in Maryland last year would have produced nearly ten inches of rain in an hour and a half.

(The rainfall intensity in large thunderstorm clusters was found to be greatly enhanced under worst case fossil fuel burning scenarios [RCP 8.5] according to a recent Nature Study. Image source: NCAR, Nature, and Weather Underground.)

As with ice cliff instability, we find ourselves faced with another scientific term in the new study — mesoscale convective systems (MCS). And to translate this term we can simply say that MCSs are gigantic clusters of thunderstorms. The study found that rainfall amounts in the largest of thunderstorm complexes were greatly enhanced as warming proceeded along a business as usual track.

From the Study author’s statement to Weather Underground:

“These new simulations of future MCS rainfall are concerning, because they show very large increases in the amount of rain that a given MCS is likely to produce. The MCSs that we would today consider to be ‘extreme’ in terms of precipitation would become more commonplace in the future. There are also some regions that currently don’t see a lot of MCS activity that might start seeing some of these heavily raining MCSs in the future.”

These increases are on top of already elevated rates of rainfall intensity we presently see today in destructive events that our infrastructure and disaster planning is clearly not prepared for (as seen during Harvey). So as we take the time to give thanks for the great bounty that many of us still have, perhaps we should also take the time to think of the things we can do to keep safe what we have worked so hard for and care so much about and to do our best to help those who are less fortunate. Who have already fallen casualty to a time of troubles.

Sleeping Ice Giants Stir — East Antarctica’s Totten Glacier Accelerates Toward Southern Ocean

“Up till now, we basically had a stationary [East Antarctic] ice sheet, and now it’s started to move,” — Catherine Walker, NASA post-doctoral fellow.

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East Antarctica. Home to most of the world’s remaining land ice. Scientists previously thought that this last bastion of somewhat stable ice in the world would only slowly succumb to the slings and arrows of human-caused climate change. That its ice giants would still sleep for some time — giving the world more time to stave off or avoid worsening rates of sea level rise. Unfortunately, new evidence reveals that this is not the case. That the best time to act on sea level rise was 20+ years ago, and that the second best time to act, in cutting fossil fuel based CO2 emissions, is now.

(Warm water upwelling near East Antarctica’s Totten Glacier threatens to accelerate global sea level rise. Image source: Texas Institute for Geophysics.)

Extreme warming now periodically besets this frozen land. Massive ice bergs are breaking off from West Antarctica, rainfall is now observed, at times, all around the frozen continent’s perimeter from west to east, and the vast Pine Island glacier is being undermined by warm water currents — causing it to crack up from the inside out.

Now, according to new research, one of East Antarctica’s largest glaciers — the Totten — is accelerating toward the Southern Ocean. It’s a situation that we warned about in an earlier post as an indicator of worsening risks of speeding sea level rise due to human caused climate change. Unfortunately, new studies by scientists have now confirmed that warm waters encroaching on Totten have already had an impact.

Researchers found that combined warm winds and encroaching warmer ocean currents had caused the glacier to speed up by 5 percent during the period of 2000 to 2006. This acceleration means that the vast glacier — home to enough ice to raise seas by 11-13 feet — is melting faster. It also means that the glacier is starting to succumb to the tremendous global heat forcing provided by human fossil fuel burning around the world. We should caution that this report covers a period from more than a decade ago. And since that time, human-forced global warming has considerably advanced.

(The Totten Glacier itself contains enough ice to raise seas by 11-13 feet, which is comparable to all of West Antarctica. Its glacial catchment, however, is larger. Image source:  Australian Antarctic Division.)

The primary cause of Totten’s melt acceleration is wind-diven warm ocean currents starting to encroach upon the glacier. These warm currents dive deep and then upwell near the glacier faces and along their weak underbellies. What the new research shows is that CO2-based warming from fossil fuel emissions is increasing the heat content of the waters even as it drives the strengthening of winds that bring these waters into more frequent direct contact with glaciers like Totten.

Chad Greene, one of the study’s lead authors recently noted to Scientific American:

“Upwelling is driven not purely by the broad-scale magnitude of wind, but by the gradient in wind—how strong the wind is at one latitude versus how strong it is at a different latitude. And CO2 in the atmosphere is modeled to increase the wind gradient around Antarctica, and then therefore increase upwelling around Antarctica.”

Glaciers are very difficult to move when sitting still. But once they get moving, it’s very difficult to stop what amounts to a moving mountain of ice. Forces now encroaching upon Antarctica are now conspiring to trigger the seaward movement of various gigantic glaciers. Once that happens, a certain amount of sea level rise gets locked in. This new research indicates that Greenland and West Antarctica aren’t the only systems that are capable of seeing glaciers released in this fashion. With the new research from Totten, East Antarctica is starting to come into play as well. And that means that multi-meter sea level rise this Century is not out of the question.

Links:

Wind Causes Totten Melt Acceleration

A Flood of Warm Waters the Size of 30 Amazon Rivers is Melting One of East Antarctica’s Largest Glaciers

East Antarctica’s Biggest Glacier Lost Ice

How Wind Might Nudge a Sleeping Giant in Antarctica

Hidden Channels Beneath Antarctica Could Cause Massive Melt

Hat tip to Colorado Bob

 

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

New Study Finds that Present CO2 Levels are Capable of Melting Large Portions of East and West Antarctica

If you’re a regular reader of this blog and its comments section, you’re probably more than a little worried about two bits of climate science in particular:

Our understanding of past climates (paleoclimate) and 5-6 C long term climate sensitivity.

And if you’re a frequent returner, you’ve probably figured out by now that the two go hand in glove.

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Looking back to a period of time called the Pliocene climate epoch of 2.6 to 5.3 million years ago, we find that atmospheric carbon dioxide levels were somewhat lower than they are at present — ranging from 390 to 400 parts per million. We also find that global temperatures were between 2 to 3 degrees Celsius warmer than 1880s ranges, that glaciers in Antarctica and Greenland were significantly reduced, and that sea levels were about 25 meters (82 feet) higher than they are today.

(The Totten Glacier is one of many Antarctic land ice systems that are under threat of melt due to human-forced warming. A new paleoclimate study has recently found that levels of atmospheric greenhouse gasses that are below those presently in our atmosphere caused substantial Antarctic melt 4.23 million years ago. Image source: antarctica.gov.)

Given that atmospheric CO2 levels during 2017 will average around 407 parts per million, given that these levels are above those when sea levels were considerably higher than today, and given that these levels of heat trapping gasses are rapidly rising due to continued fossil fuel burning, both the present level of greenhouse gasses in the Earth’s atmosphere and our understanding of past climates should give us substantial cause for concern.

This past week, even more fuel was thrown onto the fire as a paleoclimate-based model study led by Nick Golledge has found that under 400 parts per million CO2 heat forcing during the Pliocene, substantial portions of Antarctica melted over a rather brief period of decades and centuries.

Notably, the model found that the West Antarctic Ice Sheet collapsed in just 100-300 years under the steady 400 ppm CO2 forcing at 4.23 million years ago. In addition, the Wilkes Basin section of Antarctica collapsed within 1-2 thousand years under a similar heat forcing. In total, the study found that Antarctica contributed to 8.6 meters of sea level rise at the time due to the loss of these large formations of land ice.

From the study:

We conclude that the Antarctic ice sheet contributed 8.6 ± 2.8 m to global sea level at this time, under an atmospheric CO2concentration identical to present (400 ppm). Warmer-than-present ocean temperatures led to the collapse of West Antarctica over centuries, whereas higher air temperatures initiated surface melting in parts of East Antarctica that over one to two millennia led to lowering of the ice-sheet surface, flotation of grounded margins in some areas, and retreat of the ice sheet into the Wilkes Subglacial Basin. The results show that regional variations in climate, ice-sheet geometry, and topography produce long-term sea-level contributions that are non-linear with respect to the applied forcings, and which under certain conditions exhibit threshold behaviour associated with behavioural tipping points (emphasis added).

This study began the publication process in 2016 when year-end atmospheric CO2 averages hit around 405 parts per million. By end 2017, those averages will be in the range of 407 parts per million. Even more worrying is the fact that CO2 equivalent forcing from all the various greenhouse gasses that fossil fuel burning and related industrial activity has pumped into the atmosphere (methane, nitrogen oxides, CFCs and others) will, by end 2017 hit around 492 ppm.

As a result, though conditions in Antarctica are presently cooler than during 4.23 million years ago, the considerably higher atmospheric greenhouse gas loading implies that there’s quite a lot more warming in store for both Antarctica and the rest of the world. A warming that, even if atmospheric greenhouse gasses remain at present highly elevated levels and do not continue to rise, could bring about a substantially more significant and rapid melt than during the Pliocene.

Links:

Antarctic Climate and Ice Sheet Configuration During Early Pliocene Interglacial at 4.23 Ma

NOAA ESRL CO2 Trends

NOAA’s Greenhouse Gas Index

East Antarctic Ice Sheet More Vulnerable to Melting than We Thought

Pliocene Climate

antarctica.gov

Hat tip to Spike

100 Fossil Fuel Companies Responsible for 71 Percent of Carbon Emissions Since 1988 — And They’re Being Sued For it

According to research from the Carbon Disclosure Project, since 1988, 100 fossil fuel producers have been responsible for 635 billion tons of greenhouse gas emissions. This total represents 71 percent of human carbon emissions that have occurred over the past 29 years.

Companies involved in this massive carbon emission included such giants as ExxonMobil, Shell, BHP Billiton and Gazprom. The report also found that these 100 companies were responsible for fully 52 percent of all emissions since the industrial revolution began in 1751.

Report authors went on to point out that this relatively small group of companies is likely to have an outsized influence on responses to climate change — hopefully adding that positive action by such corporations could produce significant positive change. However, historically, such companies have tended to fight against global climate treaties, misinform the public on dangers related to human-caused climate change, and work to delay responses to climate change within their host nations. Due to this past bad-economic-actor behavior combined with rising climate change related damages, these corporations also are exposed to what may well be a historic and unprecedented corporate liability.

(If you were born in 2015, the estimate for your lifetime lost wealth from climate change, according to DEMOS, is between 581,000 and 764,000 dollars. With 100 companies responsible for 50 percent of that loss, it’s pretty obvious that liability will become a more and more serious impact as climate harms ramp up throughout the coming decades.)

A far-reaching liability that could well include various harms related to climate change coming from such diverse dangers as sea level rise, loss of water and food security, loss of habitability due to heat, and damage to valuable natural resources like forests, glaciers and reefs.

Already, a number of lawsuits are testing the legal waters in this regard. For example, in California this week, Imperial Beach, San Mateo and Marin counties are filing lawsuits to get some of the world’s largest fossil fuel producers to pay for sea level rise related damages. And if Imperial Beach and the two counties prevail, large corporations like Chevron, ExxonMobil, ConocoPhillips, BP and Royal Dutch Shell could be liable for billions of dollars in mitigation costs and punitive damages in coming decades even as direct damages from climate change ramp up.

According to the San Diego Union Tribune:

Attorneys for the plaintiffs said they modeled their legal tactics after past efforts to hold accountable cigarette businesses, makers of cancer-causing agents and gas and chemical companies that used methyl tertiary butyl ether (MTBE), a gasoline additive that has contaminated groundwater across the country.

And though not all liability related lawsuits against major tobacco and chemical companies were successful, those that stuck resulted in major awards even as the lawsuits themselves produced a very harmful public relations impact for the companies involved.

Antarctica’s 4th Largest Ice Shelf is About to Melt Back to its Smallest Area Ever Recorded

These days, there’s a big debate raging in the sciences over the issue of Antarctic melt. On the one side, you have a growing flood of data indicating that many ice shelves are thinning, that surface melt is more prevalent than previously thought, and that glaciers are threatening to destabilize at faster than previously expected rates. On the other side, we still have a number of hold-outs who rightly claim that ice shelves have always calved and that many of the processes we now observe have always been in place.

The scientific messengers sending these various indicators of Antarctic destabilization are cautious not to draw too many conclusions. But the data itself is pretty stark — which has been enough to produce some qualified, if very appropriate, warnings that Antarctica could be tipping toward instability far faster than previously imagined.

(The northern end of a massive rift in the Larsen C Ice Shelf is spawning numerous smaller ice bergs off a larger, Delaware-sized monstrosity. Now, only 3 miles of ice connect this emerging berg to the Larsen C ice mass. Once the berg separates, Larsen C will break back to its smallest area ever recorded. Image source: Project MIDAS.)

Of course the ice shelves named Larsen A and Larsen B existed throughout human times until they were only recently melted by warmth creeping up the along the Antarctic Peninsula in both the air and the water. Meanwhile, the Larsen C ice shelf is about to shatter off a very large 5,800 square kilometer ice berg even as several smaller ice bergs also appear ready to form. This event, which is now imminent in the coming days, weeks, or at most, months, will break the Larsen C ice shelf back to its smallest area ever recorded even as it marks a period of increased instability and risk of ice shelf loss.

For recent scientific assessments show that Larsen C is lowering in the water — an indication that the shelf is thinning. Furthermore, when the gigantic, Delaware-sized, ice berg and its smaller siblings break off they will take with them outer sections of a stabilizing compression arch. The compression arch, somewhat like the arch of a flying buttress, helps to balance structural stresses for the ice shelf. If it were to be compromised in total, according to glacier scientists like Dr. Eric Rignot, Larsen C would soon be adding its name to the list of various ice shelves around the world that have already fallen due to the warming airs and waters produced by human-caused climate change.

(The large ice berg that is presently breaking away from Larsen C appears to have bisected both southern and northern sections of the ice shelf’s stabilizing compression arch [indicated in the upper images by a solid gray line]. Loss of parts of the compression arch are an indication that Larsen C could become considerably less stable in the near future. However, some science indicates that the ice berg presently breaking off from Larsen C does not compromise key stability features. The nearer term future for the greatly reduced Larsen C Ice Shelf is therefore uncertain. Image source: Marine Ice Regulates Future Stability of Large Antarctic Ice Shelf.)

As with most predictive measures, however, the present trend isn’t perfectly clear with regards to the ultimate fate of Larsen C in the near future. Some studies have indicated that the section of ice breaking off is not crucial to the ice shelf’s stability. And the sections of the compression arch that are being taken out are closer to the outer edge of the ice shelf — not representing the key central arch region.

Overall, however, this story for Larsen C isn’t a good one. The shelf is thinning, it is about to reach its smallest area ever recorded, and even the loss of some outer sections of the compression arch are enough for a number scientists to express qualified concern. Larsen C didn’t show this level of instability back in the 90s or 2000s, so the overall trend here is more toward melt and instability for this 4th largest ice shelf in Antarctica.

UPDATE:

As of 7/10/2017 through 7/12/2017, rift formation had finally met open water and the large ice berg breaking away from Larsen C had finally calved. From the Project MIDAS website:

A one trillion tonne iceberg – one of the biggest ever recorded – has calved away from the Larsen C Ice Shelf in Antarctica. The calving occurred sometime between Monday 10th July and Wednesday 12th July 2017, when a 5,800 square km section of Larsen C finally broke away. The iceberg, which is likely to be named A68, weighs more than a trillion tonnes.  Its volume is twice that of Lake Erie, one of the Great Lakes.

Links:

Project MIDAS (and associated scientists)

Antarctica is About to Lose an Enormous Piece of Ice

Marine Ice Regulates Future Stability of a Large Antarctic Ice Shelf

Maximum Buttressing of Larsen C Ice Shelf

Antarctica’s Ice Shelves Thin — Threaten Significant Sea Level Rise

Scientific Hat tip to Dr. Eric Rignot

Scientific Hat tip to Dr. Richard Alley

A Delaware-Sized Iceberg is About to Enter the Southern Ocean — Loss of Larsen C Ice Shelf Possible in Near Future

A rift in West Antarctica’s Larsen C Ice Shelf is about to expel a 1,000 foot tall, Delaware-sized iceberg into the Southern Ocean. The crack began to form in 2011. But over the past year, it has expanded rapidly. Now this massive, newly-forming iceberg hangs by just a thin 13 kilometer wide thread.

As you can see from the above Sentinel 1 animation posted by Adrian Luckman, rift progression has occurred in large leaps as pressure on the shelf reached various breaking points. New additions to the rift have often been in jumps of 20 kilometers or more of rift length in numerous instances over the past year. With just 13 kilometers of connecting ice remaining, the entire state-sized iceberg could now break off at any time.

According to Project Midas, late June observations show the crack continuing to widen at the rate of about 2 meters per day. So the larger section of the newly-forming berg is progressing toward the Southern Ocean at a rather rapid rate. And this movement is increasing strain on the small remaining ice bridge to the larger Larsen C Shelf.

Once the massive berg breaks off, researchers are concerned that it could precipitate a larger collapse of the Larsen C Ice Shelf itself. Such an event would be the third ice shelf loss along the Antarctic Peninsula during recent decades. A series of ice shelf collapses precipitated by warming oceans and atmospheres induced primarily by fossil fuel burning.

(Many cities are already suffering from rising ocean levels. However, future rates of sea level rise can increase considerably over present rates depending on how rapidly glaciers and ice shelves are taken down by human-forced warming. Image source: Tamino.)

Such ice shelf losses are a rather serious affair as they release the glaciers behind them — allowing these massive ice forms to enter the world ocean more rapidly and thus increasing the rate of global sea level rise. Already, numerous cities, islands and nations are under threat from oceans presently rising at the rate of 3.3 millimeters per year globally. But loss of buttressing ice shelves like Larsen C and others around Antarctica and Greenland may double the present rate of rise many times over.

At a recent meeting of over 250 U.S. Mayors in Miami to discuss how climate change is presenting a serious threat to cities, New York’s Bill de Blasio told reporters: “Miami Beach is facing, literally, an existential crisis.” But it’s not just Miami that’s under the gun. It’s pretty much every coastal town, city, state and nation around the world. And Larsen C is just one of the most recent sea level rise canaries to begin to show signs of ailing in the global warming coal mine.

Links:

Project Midas

A New Crack in One of Antarctica’s Largest Ice Shelves Could Mean a Major Break is Near

Miami Beach Mayors Talk Global Warming

Tamino

Hat tip to Abel

Note: 1,000 foot tall reference includes freeboard + below water line measure.

Featured Comment:

Featured Comment Colin Wright

The Rains of Antarctica are Coming — Warm Summer Storms Melted Texas-Sized Section of Ross Ice Shelf Surface During 2016

“In West Antarctica, we have a tug-of-war going on between the influence of El Niños and the westerly winds, and it looks like the El Niños are winning. It’s a pattern that is emerging. And because we expect stronger, more frequent El Niños in the future with a warming climate, we can expect more major surface melt events in West Antarctica (emphasis added).” — David Bromwhich, co-author of a recent study identifying massive summer surface melt in West Antarctica during 2016.

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If you’re concerned about human-caused global warming, then you should also be concerned about ice. In particular — how warming might melt a miles-high pile of the frozen stuff covering the massive continent of Antarctica.

During recent years, scientists have become more and more worried as they’ve observed warming oceans eating away at the undersides of floating ice sheets. This particular process threatens numerous cities and coastal regions with swiftening sea level rise as ice margins melt and glaciers the size of mountain ranges clamor for release into the world’s oceans.

Major Antarctic Surface Melt Event During 2016

But another potential process in a still warmer world threatens to compound the impact of the heating waters that are already melting so many of the world’s glaciers from the bottom up — large scale surface melt.

(A major warming event during January of 2016 turned a Texas-sized section of Antarctica’s surface into slush. This occurred as a storm running in from the Southern Ocean delivered warm air and rainfall to sections of West Antarctica. Scientists are concerned that more major surface melt is on the way for Antarctica as the Earth’s climate heats up and that repeated warming and rainfall events in this typically-frozen region may further quicken rates of sea level rise. Image source: Earth Nullschool.)

During January of 2016, as a very strong El Nino was combining with human-caused global warming to spike atmospheric temperatures to 1.2 C above 1880s levels, something pretty strange and concerning happened. Over the course of about 15 days, a 300,000 square mile section of the Ross Ice Shelf surface and nearby lands over West Antarctica experienced melting. This mass slushing across Antarctica’s surface occurred as a warm storm swept in from the Southern Ocean (see image above) to deliver an unheard of rainfall event to the region.

West Antarctica is typically too cold for such weather. It is also often too dry. The region is well know by climate researchers as a frozen desert. But as human-forced climate change has warmed the nearby ocean, warm, moist winds blowing in from these heating waters have become more frequent.

Westerlies Interrupted by Warming Ocean

Antarctica is typically protected by strong westerly winds that keep both heat and moisture out. But a warming ocean environment, according to Ohio State researchers, is enabling El Nino to interrupt these westerlies and hurl increasing volumes of heat and moisture over the glaciers of Antarctica. In 2016, countervailing winds pushing against the typically prevailing westerlies bore with them an odd rainstorm that set off a massive surface melt event.

(Surface melt over a large section of West Antarctica lasted for as much as 15 days as heat and moisture from the surrounding ocean beat back a protective barrier of westerly winds and invaded the frozen continent. According to scientists, these events are likely to become more frequent and long-lasting as the climate warms. Image source: Ohio State University.)

When combined with already-active melt from ocean warming, surface melt could further serve to destabilize ice sheets and swiften sea level rise. This was exactly the concern that David Bromwich, an Antarctic researcher at Ohio State and co-author of the paper that identified this strange event highlighted in this statement (please see related Washington Post article here):

“It provides us with a possible glimpse of the future. You probably have read these analyses of West Antarctica, many people think it’s slowly disintegrating right now, and it’s mostly thought to be from the warm water eating away at the bottom of critical ice shelves. Well, that’s today. In the future, we could see action at the surface of these ice shelves as well from surface melting. So that makes them potentially much more unstable (emphasis added).”

It’s worth noting that this particular storm, though unusual and noteworthy, did not produce too much in the way of surface melt ponding. Instead, the storm turned a large section of the Antarctic surface to a slurpee-like slush. But this event did deliver a considerable amount of heat to the Ross Ice Shelf region. And repeated instances could serve to seriously soften this massive ice formation.

Eventually, as warming worsens, significant surface melt and flooding could help to shatter large buttressing ice shelves like Ross or even generate risks of surface glacial outburst flooding in instances where permanent surface melt lakes form behind an ice dam. But the primary concern at this time is that these warm rain events provide a compounding melt influence that adds to risks for more rapid sea level rise this Century.

Links:

Widespread Snowmelt in Antarctica During Unusually Warm Summer

Scientists Stunned by Antarctic Rainfall and Melt Area Bigger Than Texas

Scientists Report Large Scale Surface Melting Event in Antarctica During 2015-2016 El Nino

The Ross Ice Shelf

Earth Nullschool

Hat tip to TodaysGuestIs

New Crack Found in Delaware-Sized Chunk of Larsen C Ice Shelf as it Heads Toward Southern Ocean

A 2,000 square mile section of the Larsen C Ice Shelf is hanging by a thread as it continues to drift toward the Weddell Sea.

(A second crack develops in Larsen C Ice Shelf. Image source: Project MIDAS.)

The break-off section represents fully 10 percent of all the ice contained in the Larsen C system. It has been divided from the larger ice shelf by a 180 kilometer long crack that began to develop in 2009 and that swiftly lengthened during recent years. Now only a 10 kilometer wide bridge links the breaking section to the larger ice shelf. And considering the enormous stresses now being placed on this break-off section it is expected to go at any time.

Since January, according to researchers at Project MIDAS, the large crack has been widening but its length growth has stalled. However, recent reports out this week from MIDAS found that a new crack had developed at the ice-bridge end of the break-off section. The new crack appears to be rounding the corner of the bridge to begin a quicker path to segmenting the massive ice berg away from Larsen C. A testament to the powerful forces that are inevitably forcing this enormous section of ice to relinquish its hold.

(Large section of Larsen C is moving far faster than the rest of the ice shelf toward the Southern Ocean. Image source: Project MIDAS.)

At issue is the fact that the break-off section is moving toward the Weddell Sea considerably faster than the rest of the Larsen C ice shelf. Much of this large section of ice is proceeding away from the Antarctic mainland at 3 meters per day. Surrounding sections of Larsen C are moving at only 1-2 meters per day. As a result, the toe end of the break-off mass is tipping out into Weddell’s waters and the crack separating it from Larsen C is widening.

It’s not really a question of if this massive block of ice will separate from Larsen C. More an issue of how soon.

Loss of so large a section of ice from Larsen C threatens the entire ice shelf’s stability. And some scientists are questioning whether the whole ice shelf will destabilize and eventually splinter — as happened to Larsen A and Larsen B during recent years.

(Rapid loss of buttressing ice shelves like Larsen C lock in higher and higher ranges for sea level rise. A worrying risk for rapid sea level rise occurs as global temperatures warm to between 1.5 and 2.5 C. A level we are fast approaching. Scientists like James Hansen identify a significant risk for multi-meter sea level rise this Century if 2 C warming thresholds are breached. Video Source: Carbon Freeze.)

Warming ocean waters due to human-forced climate change are the primary driver for loss of ice shelves around the world. These ice shelves hold back land glaciers — preventing them from more rapidly sliding into the world’s oceans. Larsen C alone holds back glaciers capable of lifting global ocean levels by 4 inches. But there are numerous such ice shelves and many are now facing thinning and increasing instability due to warming ocean waters. As a result, a growing number of scientists are concerned about the possibility for multi-meter sea level rise this Century if fossil fuel burning is not swiftly halted.

Links:

Project MIDAS

Carbon Freeze

Second Giant Crack Appears on Larsen C

Crack in Larsen C Forks

Larsen C Destabilization Could Trigger 4 Inch Sea Level Rise

Hat tip to June

Hat tip to Andy in San Diego

In Defense of Our Earth — A People’s Climate March

I think it can be fairly said that we are a people who believe in a better future. That the ideals of America are founded on building prosperity and expanding prospects — not only for ourselves, but for our fellows and for those generations that are to follow.

Americans have often been described as a ‘can-do’ kind of people. A people who will undertake any challenge to advance or protect our nation and to graciously extend her kind virtues to the huddled masses of a troubled world. Be it the freeing of slaves, the emancipation of women, the facing down of tyrannical dictators, the liberation of scientific inquiry, or the exploration of our Earth and the vast realm of space we have doggedly decided to march forward and on.

But today we are confronted by a new trouble. A trouble that was, in many ways, an unintended consequence of past progress. For as we industrialized, as a nation and as a global society, we also burned ancient carbon deposits long buried beneath the Earth. And so we expelled a great cloud of the most dangerous of gasses into the Earth’s atmosphere.

We didn’t know it so well at the time. But the carbon dioxide spewing from William Blake’s dark Satanic Mills was the same gas that in excess produced the worst and most horrific global die-offs in the great and deep, deep history of our Earth. Times of great mass extinction due to rising global heat that bear the infamous names — Permian, Triassic, Paleocene, Devonian and Ordovician. Blake, living today, would be terrified how right he was to call those mills Satanic. To learn what our scientists now have told us. But even then, he surely had an inkling. For the Bible itself warns — those who destroy the Earth shall be destroyed. And in 1808 the wanton destruction of the Earth and its airs by the pollution caused by fossil fuel burning was visibly evident if not so scientifically proven and explored as it is today.

Today, if we continue to burn fossil fuels as we have for the past 200 years or so, the world will again surely experience another such extinction. We already see the outliers of this crisis now — in the growing number of people bereft of land and home and livelihood as seas rose, or crops were destroyed by worsening storms and droughts, or lands and animals were lost to wildfires, or as reefs and fisheries were killed off by the warming, acidifying waters of our oceans. But what will come over the years and decades and centuries if we do not turn back from this horrid burning of fossil fuels and the dumping of their carbon into the atmosphere will be far, far worse.

What kind of world is this to make for our fellow human beings? What kind of future to leave for the generations that follow? Surely not the better one that we all work and hope for. Surely not one that honors the can-do, make the world a better place spirit of America.

But despite our worsening prospects and the dark and heavy clouds that now hang over the global climate, we have a window of opportunity in which to act. Our tools to confront climate change in the form of renewable energy systems like wind and solar and electrified transportation are growing more capable. And further innovation and change in our actions as people and nations can yet enable us to draw down the awful pall of heat trapping gasses that now hangs above us. These are things we can and must do if we are a moral people with any kind of vision, foresight and compassion.

This is our moment. The moment when we decide to make the choice to act and to save so many of the very precious things we all hold dear or to turn away from action and condemn each and every person and being now living or that will live to an age of terror and darkness the likes of which Earth has not seen in all of half a billion years.

So I’m asking you for your help. I’m asking you to make the choice to act. To join the People in their march for climate justice tomorrow. To support all the voices that are now speaking out. To lift your own voice to our growing chorus.

For the love of life and of all good things — we simply must act now.

Antarctica is About to Lose a 2,000 Square Mile Chunk of Ice — And it Could Mean the End of the Larsen C Ice Shelf

It’s happened before. Ice shelves on the northern Antarctic Peninsula released large chunks of ice into the Southern Ocean as the world warmed up. They developed a concave shape which became unstable. Then they collapsed.

The ultimate collapse of Larsen A occurred in 1995. In 2002, further up the Antarctic Peninsula, the larger Larsen B Ice Shelf succumbed to the same fate. And it is thought that such losses haven’t happened to this section of Antarctica in at least 11,000 years and possibly as long ago as 100,000 years.

(NASA’s Jet Propulsion Laboratory provides this narrative describing the collapse of the Larsen B Ice Shelf in 2002. Video source: JPL.)

But in the present world, one where human fossil fuel emissions have forced global temperatures above 1 C hotter than 1880s averages, the stability of many of the great great ice shelves is now endangered.

Larsen C Ice Shelf to Calve 2,000 Square Mile Ice Berg

Today, a huge rift has nearly bisected a large frontal section of the Larsen C Ice shelf — an ice system many times the size of its now deceased companions Larsen A and Larsen B. And during December — a period when Antarctica was warming into Austral Summer — this massive crack grew by 18 kilometers.

When, and not if, the crack reaches the ocean, a 2,000 square mile ice berg will float away from Larsen C. It will be one of the largest ice bergs ever to form in human memory. One the size of the state of Delaware. It will tower hundreds of feet above the ocean surface. And it will last for years before ultimately melting.

larsen-c-ice-rift-length-and-width

(The Larsen C is rift grew considerably — both lengthening and widening during December of 2016. It was an indication that a massive ice berg was about to break off. Image source: MIDAS.)

This event will change the geography of our world. And for this alteration alone, it has great consequence. But, as Chris Mooney notes in this excellent Washington Post article on the subject, it’s what happens afterward that really counts.

Event Could Presage Total Collapse

Of concern is the fact that once this massive ice berg calves off of Larsen C, the great ice sheet may become unstable. It will take on a concave form. This form will make it more vulnerable to further melt by warming waters running in toward the shelf. Furthermore, the large ice berg will take a chunk of Larsen C’s compressive arch with it. Such a compressive arch — like the arch of a flying buttress — helps to bear the weight of the shelf and keep it from smashing into thousands of tiny pieces. If too much of the arc is lost, the shelf can’t survive for long.

larsen-c-ice-rift-midas

(Researchers at The MIDAS Project have projected that a 2,000 square mile section of the Larsen C Ice Shelf is about to break off. This section represents 10 percent of the Larsen C system. Its loss risks destabilization of the entire ice shelf. If Larsen C does disintegrate, it will release glaciers capable of increasing global sea level by another 4 inches. Image source: MIDAS.)

Glaciologist Eric Rignot notes in The Washington Post:

“We studied the current rift in the past few years, it has been progressing rather ‘normally,’ the recent acceleration in the rift progression is ‘expected’ in my opinion. The consequences on the rest of the ice shelf are not clear at this point. If the calving continues and goes past the compressive arch … then the ice shelf will break up.”

Scientists are currently divided over the issue of whether or not Larsen C’s near-term demise is imminent. However, the loss of such a massive ice berg from Larsen C, the present human-forced warming of the Antarctic land and ocean environment, and the presently observed thinning of the ice shelf all point toward a rising risk of destabilization or disintegration.

As with most things geological, you can’t really say that such an event is certain until after the fact. But as for Larsen C’s prospects of long term survival, things aren’t looking too great at the moment.

Links/Credits

The MIDAS Project

Antarctica is Set to Lose an Enormous Piece of Ice

An Ice Berg the Size of Delaware is About to Break off From Antarctica

NASA’s Jet Propulsion Laboratory

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