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Melt Expanding into East Antarctica as Nansen Ice Shelf Crack Produces 20 Kilometer Long Iceberg

Ever since 1999 a gigantic crack has been growing in the Nansen Ice Shelf in East Antarctica. By 2014, expansion of the crack accelerated. As of early 2016, the crevice had grown to 40 kilometers in length. Flooded by melt along the Ice Shelf’s warming surface and weakened by the heating of ocean waters from below, on April 7th, according to ESA reports, this East Antarctic Ice Shelf produced an immense 20 kilometer long iceberg. A towering block of ice covering an area larger than Manhattan floating on out toward the world’s shipping lanes.

Nansen Ice Shelf Fracture

(Surface melt water flooding into a great crack along the Nansen Ice Shelf. Large volumes of melt water flooding into ice shelf cracks forces them to widen even as they dive toward union with the warming waters below. Image source. ESA.)

The Nansen Ice Shelf, before this most recent very large iceberg calving event, was a 10 mile wide and 30 mile long ice shelf that buttressed the Presley and Reeve Glaciers of East Antarctica. It abuts the north side of the Drygalski Ice Tongue, and runs out from Mount Nansen just inland of the coast of Victoria Land, Antarctica. And it’s yet another large shelf of ice that appears to be facing severe weakening as global average temperatures are driven above 1 C warmer than those experienced during the late 19th Century by an ongoing and reckless fossil fuel emission.

Nansen occupies a region of the world that has come under increasingly intense observation due to a number of scientific studies highlighting its accelerating rates of melt and a related risk of rapidly rising global sea levels.  Human-forced heating of the world’s ocean has caused waters warm enough to accelerate glacial melt to encroach upon Antarctica from the Southern Ocean. These warmer waters are drawn along beneath the floating ice shelves as fresh melt water flooding out along the ocean surface generates a landward-moving bottom current. These warmer waters eventually push beneath the ice shelves — eating away at their undersides.

Nansen Ice Shelf Fracture

(Massive ice berg breaks away from the Nansen Ice Shelf on April 7th in this ESA satellite shot.)

In West Antarctica, glaciers are seen as especially vulnerable. One region containing the Pine Island and Thwaites glaciers — alone capable of increasing global sea levels by 3-6 feet — is experiencing 3-4 meters of melt along the undersides of ice shelves each year. Meanwhile, the Pine Island Glacier’s grounding line — the point upon which the floating ice shelf is anchored — has retreated more than 31 kilometers further into Antarctica.

As ice shelves and glaciers melt from below, more of the glacial mass is floated away from the main ice mass. And since West Antarctica has a retrograde slope, more warm ocean water comes flooding in beneath the glaciers. As more ice calves off the glacial faces, ice fronts along the ocean become taller. The brittle ice cannot retain structural integrity for long and ever taller ice faces produce swifter and swifter rates of collapse into the ocean. On the surface, warmer conditions cause rivers of melt water to flow into cracks. The extreme weight of the water flooding these cracks serves as a kind of wedge — widening the cracks and shoving sea-facing sections along the cracks into the ocean.

Antarctic glacial melt

(Though the most rapid rates of glacial melt dominate the Antarctic Peninsula and the region near the Pine Island and Thwaites glaciers, increasing rates of volume loss from Antarctic ice shelves have been creeping into a section of East Antarctica near the Nansen Ice Shelf along the coastline of the Ross Sea [just below where the abbreviation DRY for Drygalski Ice Tongue appears on the map]. With global average temperatures now exceeding 1 C above pre-industrial, we can expect melt and net volume loss to expand along the Antarctic coastline. Image source: Science.)

East Antarctica, a region occupied by Nansen, has been seen as less vulnerable to melt from human-forced warming than West Antarctica and the Antarctic Peninsula. That said, increasing melt rates have progressed on into much of the Ross Sea coastal region. Though the current very large calving event at Nansen appears to have taken place within the expected time-frame (once every 30 years), a context of melt is beginning to encroach. For almost all glaciers along this section of East Antarctica show increasing rates of ice loss.

Links:

Nansen Gives Birth to Two Icebergs

Widespread, Rapid Grounding Line Retreat at Pine Island Glacier

Volume Loss From Antarctic Ice Shelves is Accelerating

The Nansen Ice Shelf

The Drygalski Ice Tongue

Hat Tip to Colorado Bob

 

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Warning From Scientists — Halt Fossil Fuel Burning Fast or Age of Superstorms, 3-20 Foot Sea Level Rise is Coming Soon

First the good news. James Hansen, one of the world’s most recognized climate scientists, along with 13 of his well-decorated fellows believe that there’s a way out of this hothouse mess we’re brewing for ourselves. It’s a point that’s often missed in media reports on their most recent paper — Ice Melt, Sea Level Rise, and Superstorms. A paper that focuses on just two of the very serious troubles we’ll be visiting on ourselves in short order if we don’t heed their advice.

The way out? Reduce global carbon emissions by 6% each year and manage the biosphere such that it draws carbon down to 350 ppm levels or below through the early 22nd Century. To Hansen and colleagues this involves a scaling carbon fee and dividend or a similarly ramping carbon tax to rapidly dis-incentivize carbon use on a global scale. Do that and we might be relatively safe. Safe, at least in the sense of not setting off a catastrophe never before seen on the face of the Earth. That’s pretty good news. Pretty good news when we consider that some of the best climate scientists in the world see an exit window to a hothouse nightmare we’re already starting to visit upon ourselves.

The bad news? According to Hansen and colleagues, even if we just continue to burn fossil fuels and dump carbon into the atmosphere at a ‘moderate’ pace some of the terrifically catastrophic impacts of human caused climate change are not too far off.

A Moderate Pace of Burning

The new Hansen paper takes a look into both our geological past and our climate future in an attempt to give us an idea what may be in store. In this scenario, model, and paleoclimate based study, Hansen and colleagues assume two things about global human civilization. The first assumption is that we don’t follow the worst case, business as usual carbon emissions policies that lead to around 1000 ppm CO2 in the atmosphere by 2100. It is instead assumed that some effort is given to reducing coal, oil, and gas consumption. That some renewable energy, increased efficiency and behavior changes replace a significant portion of future fossil fuel emissions. But the most effective solution — a complete transition away from fossil fuel burning over the next few decades — fails.

A1B1

(A1B is a ‘moderate’ emissions scenario that, according to model essays, is likely to see between 2.5 and 3.5 C warming by the end of this Century and around 700 ppm of CO2 accumulation. That is, without the kind of major ice sheet response indicated in the new Hansen study. Image source: Knutti and Sedlacek.)

As a result, we end up with around 700 parts per million carbon dioxide in the atmosphere by 2100. In such a case we’ve followed what the IPCC community terms as the A1B or ‘moderate’ fossil fuel emissions scenario.

A Question of Melt Rate Doubling Time

It is in this context that the Hansen paper attempts to determine a key factor that will have wide-ranging impacts on ocean health, the continued existence and lifespan of coastal cities, and on the severity of the weather itself. That factor is captured by a single simple question — if we continue a moderate pace of fossil fuel burning, then how rapidly will ice sheet and ice shelf melt double?

To Hansen this is a critical question. One he has already done quite a bit of work to answer over recent years. And according to his findings it looks as if land ice melt rates for both Greenland and West Antarctica could now be doubling every 5-20 years. It’s a doubling rate that may find a historical allegory in the milder yet still intense glacial outflows of times long past. And it’s something that, according to Hansen, is being directly driven by an extreme pace of human-based greenhouse gas accumulation.

The Eemian — Significant Sea Level Rise and Terrible Storms Under Far Lower CO2 Forcing

To this point, Hansen’s new paper takes a dive into the paleoclimate study of an ice age interglacial that bears some stunning similarities to our own, human warmed, time period. He looks at the Eemian, a warm period that occurred 130,000 to 115,000 years ago. A period that featured temperatures in the range of 1-2 C above 1880s values (we’re in the process of hitting 1 C above 1880s values this year). A period in which CO2 levels were in the range of 285 parts per million (about 15 parts per million higher than the Holocene average before humans spiked that level to 400 parts per million during recent years). And a period that, according to Hansen’s broad study of past research, included numerous Heinrich type glacial outburst and melt events.

Back then, at 285 parts per million CO2 levels, seas were as much as 5-9 meters (16 to 30 feet) higher than they are today. The global climate, on the other hand, was much stormier. For two Heinrich type events that Hansen investigated were found to have dramatic impacts on severe storms in the North Atlantic during the Eemian. Hansen found large boulders propelled up onto the islands of Bermuda and the Bahamas by what appear to be powerful storm waves. Hansen also noted chevron shaped wave channels carved into the calcified sand beds in the Bahama Island Chain.

Heinrich Event

(Heinrich events included major glacial outflows like the one seen here at Jacobshavn, Greenland. Note the significant ice volume outflow through the channel at center frame. Also note the white dots in Baffin Bay indicating ice berg discharge. For reference, bottom edge of frame is about 100 miles. In past Heinrich Events outflows like the one seen above hit high gear as glaciers released armadas of ice bergs into the oceans which generated ocean and atmospheric changes. As the ice bergs melted, they deposited rocks on the sea bed. These piles of ice raft debris then became a signature geological feature of Heinrich events in the ancient past. Image source: LANCE MODIS.)

It paints an overall picture of very stormy weather in the North Atlantic as a result of these Heinrich ice sheet melt episodes affecting Greenland and West Antarctica. These melt events drove fresh water out into the North Atlantic and the Southern Ocean at the rate of about 0.5 to 1 meters of sea level rise per century. The expanding cold, fresh water along the surface zones in the upper latitude waters shut off heat exchange between the ocean and the atmosphere by generating a stratified ocean state. This fresh water wedge interrupted the plunging of heavier, salt-laden waters in the North Atlantic and the Southern Ocean. A loss of heat exchange that resulted in the cooling of airs directly over the fresh water outflow pools.

Meanwhile, since heavy, saltier waters were no long diving to the ocean bottom in these regions — broader ocean circulation was interrupted. As a result, heat from the equator was no longer traveling poleward. The equator warmed. The cold, fresh water outflow regions cooled. And this high temperature gradient subsequently became a powerful storm generator — providing extreme baroclinic potential energies for the storms that likely reshaped the ocean bottom and deposited massive boulders upon islands throughout the North Atlantic.

It’s worth noting that the 5-9 meter sea level rise during the Eemian occurred in the context of global temperatures that are now similar to our own (1-2 C above 1880s values). But it’s also worth considering that the underlying CO2 and greenhouse gas conditions for the current age are far, far worse. Peak global CO2 during the Eemian never hit higher that 285 parts per million. For the Anthropocene age we are now leaving the 400 parts per million CO2 level in the dust. Meanwhile, the pace at which we are warming is also more than 10 times faster than the pace of warming to peak Eemian heat values. And it’s these two factors — an extreme greenhouse gas overburden combined with a very rapid pace of warming that has Hansen and colleagues very concerned about our climate situation over the next 10-80 years.

Land Ice Below Sea Level — Amplifying Feedback For Melt

Turning to the current day, there’s a growing number of reasons why we should be concerned that rapid land ice melt, large fresh water outflow to oceans, and resulting superstorms could be in our future. First, we’ve learned that the topography of Greenland and Antarctica include numerous channels that tunnel deep into its great glaciers at depths well below sea level. When oceans warm, and they’re warming as you read this, the submerged, sea-facing slopes of glaciers are confronted with more and more heat gnawing away at their under-bellies. Just a 0.1 C increase in water temperature can melt away a meter of ice over the course of a year. Multiply that by glaciers with faces that are submerged hundreds of feet deep whose sea fronting cliffs extend for many miles and you can end up with quite a lot of melt due to very little warming. As more of the undersides of glaciers melt, more of the water tunnels inland and large masses of ice are rafted away from the central ice exposing still more of the land anchored ice to a warming ocean flood.

image

(Image from Hansen Paper shows how land ice melt generates ocean stratification which is an amplifying feedback that enables ocean bottom warming and more land ice melt. Note — AABW stands for Antarctic bottom water, NADW — North Atlantic down welling. Image source: Ice Melt, Sea Level Rise, and Superstorms)

As bad as this dynamic may sound, the process includes one more wrinkle that makes it even worse. As the undersides of ice shelves erode and more fresh water laden ice bergs are pulled out into the ocean, these ice bergs begin to melt en mass. This massive ice melt develops into an enormous and expanding pool of fresh water at the surface. And its this troublesome demon that traps heat in the deeper ocean levels. So, in other words, as the ice from the land glaciers floats away and melts it traps and focuses more heat at the base of these great glaciers. It’s an amplifying feedback. A very serious kind that doesn’t even require the human forced kick to create severe trouble. One that during the Eemian really wrecked the weather and caused massive surges in ocean height.

It’s a process that Hansen and his colleagues believe make both Greenland and West Antarctica very vulnerable. A process that could, when combined with the high velocity human heat forcing, produce melt rates that double every 20, 10 or even every 5 years. But of the two — Greenland or Antarctica — which is worst off?

Greenland topography

(Topographic map of Greenland sans its great ice sheet. Most of central Greenland’s mass is now below sea level. It’s a basin that now holds a miles high ice mountain. Various channels allow ocean water access to the central ice mass should the channel openings melt due to warming oceans. Such an invasion could set off a rapid sea level rise driven by Greenland melt. Image source: Livescience.)

Greenland, for its part, is little more than a great Archipelago held together by its stunning ice mass. Remove the ice and the interior of Greenland would flood, leaving a ring of islands as a final remnant. Though deep, most of these channels run up slope. And this feature, according to the Hansen study, may be one saving grace for potential Greenland ice melt pace. Up slope channels limit the impact of basal melt by serving to check rates of catastrophic destabilization. So though Greenland is certainly vulnerable to ice melt due to the fact that many channels cut hundreds of feet below sea level and into the island’s glacial heart, it is not as vulnerable as West Antarctica.

There, many channels cut deeper beneath the Antarctic ice mass. But not only are they below sea level by hundreds of feet as with Greenland, they slope down. They slope down and not for just a little ways under the ice sheet — some of these ocean heat skids extend in down-sloping fashion for hundreds of miles beneath the Antarctic ice. The result is a kind of skid, that once unlocked by initial melt, can continue to expose larger and large chunks of bottom ice to the warming ocean. Allowing, ultimately, the creation of new warming seas underneath the ice and floating it away in very rapid fashion.

In West Antarctica, ice shelves facing the Weddell and Ross seas both feature these dangerous retrograde slopes. In East Antarctica, the Totten Glacier is likewise vulnerable as are many other glaciers surrounding the vast periphery of Antarctica.

Retrograde slope Ross ice shelf

(Retrograde slopes behind ice sheet grounding lines are just one reason why Antarctic land ice is so unstable. Image source: Ice Sheet Mass Balance and Climate Change.)

Finally, in addition to being surrounded by the warming, deeper waters of the Southern Ocean, in addition to featuring dangerous retrograde slopes that channel warming sea water further and further inland and beneath the ice sheets, West Antarctica itself sits on a geological hot bed. Though not mentioned in the Hansen study, recent work also highlighted that West Antarctica rests atop a geologically active zone that had formed numerous sub-glacial lakes warmed by geological activity. This added geological heat makes West Antarctica that much less stable — an instability that when given the shove of human heated oceans is leading the Larsen B Ice Shelf to completely collapse by 2020. It makes Antarctic land ice that much more vulnerable to the added heat human beings are forcing into the oceans and opens up the ominous possibility that melt rate doubling times for West Antarctica could become quite extreme indeed.

Modeling Land Ice Melt’s Impact in the 21st Century — Facing A Coming Age of Superstorms

So what does all this mean? In the worst case (5-10 year melt rate doubling times), it’s possibly 3 meters of sea level rise by mid Century, perhaps 7 meters by end Century under business as usual fossil fuel emissions. Even in the more moderate cases (10-20 year melt rate doubling times), 1 meter of sea level rise by mid Century and 3 meters or more of sea level rise by end Century is not entirely out of the question, according to Hansen’s new research. These potentials are markedly different than the more conservative rates outlined by IPCC which is still calling for a less than 1 meter sea level rise under even the worst case human carbon emissions scenarios (1000 parts per million CO2, in the range of 1200 ppm CO2e).

So much fresh water hitting the oceans would cause a rapid stratification. A rapid loss of ocean to atmosphere heat exchange in the regions impacted. A train wreck of heat backing up at the equator. Such a train wreck would result in temperature extremes and gradient differences that would make the Eemian Heinrich events (mentioned above) seem moderate and slow by comparison.

Hansen has been working on global atmospheric models for tracking these events for a number of years now. And this new study is an improvement on his earlier, model-driven “Storms of My Grandchildren” work. Hansen’s new model runs are imperfect simulations of what may happen given large melt pulses from Greenland and Antarctica. The models, according to Hansen, mix the ocean water too much, reducing the overall impacts of stratification through the mechanism of the fresh water wedge. However, even with this imperfection, the temperature gradients displayed by these models are absolutely stunning. A clear warning to anyone who still wants to keep burning fossil fuels that they’re really grabbing the dragon by the tail.

image

(A mid range simulation including 10-20 year melt rate doubling times and 6 feet of sea level rise by 2080 — half Greenland, half Antarctica — shows enormous weather impacts in the form of a severe, superstorm generating, temperature gradient. Image source: Ice Melt, Sea Level Rise, Superstorms.)

In the above image we can see just one of these model runs. The model assumes a 10-20 year doubling time for rate of land ice melt. It contributes equal portions of melt from Greenland in the north and Antarctica in the south. Greenhouse gas accumulation is considered to be along the moderate case A1B track. By 2080 we have about six feet of sea level rise globally and about 600 parts per million CO2 in the atmosphere. The more rapid rate of melt has put a temporary damper on the rate of global atmospheric warming which has dipped to 1.11 C above 1880s values (just slightly higher than today). But much of this cooling is localized to the Southern Ocean and to an extreme cold pool in the North Atlantic between Northwestern Europe and Greenland.

There a massive outflow of fresh water has shut down the ocean’s ability to exchange heat with the atmosphere. AMOC has been vastly weakened. The Gulf Stream is backed up along the US East Coast and into the Gulf of Mexico. Heat is building in the Arctic opposite Greenland and all along the Equator. Temperature anomalies in the range of 17 degrees Celsius below average occur over the ocean fresh water pool. This drop is enough to generate year round winter like conditions in the cold pool region even as other sections of the atmosphere around it continue to warm or retain severe excess heat.

Energy imbalance at the top of the atmosphere rockets to between 2 and 4 Watts per meter squared. What this means is that, in failing to ventilate heat to the atmosphere in the North Atlantic and Southern Ocean, the world ocean system has continued to accumulate a massive amount of heat. Heat that is now going to work warming the ocean bottom and hitting the bases of the already rapidly melting land ice.

Sandy

(More superstorms in our future. If Hansen’s new research is correct storms like Sandy will grow both more powerful and more common as Greenland dumps ever increasing volumes of fresh water into the North Atlantic. Image Source: NASA.)

For the North Atlantic, it is the greatest of understatements to say that an area of perpetual winter surrounded by warming airs and sitting atop a warming deep ocean is a major storm generator. Summer time temperature deltas between the center of the cold pool will range from near zero C to 20s, 30s and 40s C over nearby ocean and continental land masses. It’s like taking the High Arctic and shifting it to Scotland while all the adjacent airs warm. Temperature gradient and baroclinic (pressure gradient) energy for storm generation will be on the order of something that modern humans have never experienced. The potential for superstorms in this model simulation will, notably be quite high.

Final Notes — Superstorm Conditions Could Emerge Sooner than Models Indicate

The point to consider here is that large scale land ice melt sets in place forces that result in a weather wip-lash of epic proportion. It’s been the heart of Hansen’s work for many decades and it’s an issue that we really need to consider as time goes forward. A dwindling time for response that may well be much shorter than even Hansen’s models indicate. First, ice sheet vulnerability may well be higher than IPCC officials imagine and we could well be on a slope of melt rate doublings in the range of 5-20 years now.

global sea level change

(Global sea level rise keeps hitting a steeper and steeper slope. Image source: Dr. James Hansen, Columbia University)

Second, Hansen’s models likely capture the atmospheric impact of such large-scale land ice melt later than would happen in the real world. This later capture is due to the fact that his low resolution models mix the ocean heat more with the atmosphere than would occur under the kinds of ocean stratification events that we are likely to see due to these doubling times. Third, and finally we return again to the paleoclimate time of the Eemian where there is ample evidence that a mere 0.5 to 1 meter per century rate of sea level rise due to melting Greenland and West Antarctic ice during that time set in place conditions to generate superstorms with high enough peak intensity to deposit massive boulders upon islands in the Atlantic and to carve the impression of gigantic, long-period waves into the sea bed.

Anyone reading this work and considering the notion that some of the greatest scientific minds this age has birthed could be right is immediately confronted with the realization that the gargantuan forces we are playing with are not to be trifled with. And yet, the trifling continues despite the wise and well considered scientific warning to relent.

Links:

Hansen Paper: Ice Melt, Sea Level Rise and Superstorms

Dr. James Hansen, Columbia University, Former NASA GISS Lead Scientist

Knutti and Sedlacek: Robustness and Uncertainties in Climate Model Projections

The Eemian

LANCE MODIS

Livescience — Topographic Map of Greenland Sans Ice Sheet

Ice Sheet Mass Balance and Climate Change

NASA: 10,000 Year Old Ice Shelf to Collapse by 2020

IPCC Sea Level Change

NASA Earth Data

Storms of My Grandchildren

 

North Pole Web Camera 2 Adrift in Large, Expanding Melt Pool

North Pole Camera 2 in Melt Pool

North Pole Web Camera 2 sits in large and expanding melt puddle.

(Image source: APL)

Last week, a melt puddle began to form near APL’s Camera 2. The pool extended in the near camera field from left to right just beyond the black and white markers. It covered just more than half the field of view and was represented by a thin, though growing, swath of melt water.

As you can see in the image above, last week’s melt pool has greatly increased. It now covers the entire camera field and has turned the ice on which the camera stands into a tiny island. In the distance and to the left-hand side, we can also see a black stretch of open water cutting between the ice flow upon which the camera sits and a far ice flow barely visible in the distance.

Hole at the North Pole

Since early June, a series of storms have consistently worn away at the central ice, resulting in thinning over an area that is usually very resilient to melt. This thinning has resulted in steep losses of sea ice concentration and thickness in a large swath near the North Pole and extending into the Laptev Sea.

The US Navy’s most recent thickness model run shows this expanding swath of thin ice in the animation below:

North Pole Hole

(Image source: US Navy)

In the most recent model prediction, central sea ice melt is shown to continue to expand through next week. So, through direct observations on the ice and through model summaries like the one above, we have clear evidence of expanding ice melt in the Arctic’s most protected regions. As such, it seems North Pole Camera 2 may soon be in even deeper water.

Links:

Melt Ponds, Distant Open Water Visible at North Pole Camera 2

Jet Stream Over US So Weak Weather Systems are Moving Backwards

NOAA Weather Moving Backwards

(Front and associated trough sweep from east to west over Central US. Image source: NOAA)

An extreme US summer that has featured floods and heavy rains in the east and drought and devastating fires in the west boasts yet one more bizarre weather pattern: a backward moving storm system.

As of last week, a strong frontal boundary had swept into the southeastern US bringing with it another dose of heavy rains and storms. Then the system stalled. Over Friday, Saturday and Sunday, the front and associated low pressure systems have backed up, moving from east to west, passing over the Appalachians, then the Tennessee River Valley, then the Mississippi, until today it reached a central region stretching from Texas all the way north to the Dakotas.

This retrograde weather is a very uncommon, but not unheard of, event. In the context of an already strange summer, it adds yet one more anomalous weather pattern to the list. In the AQUA/NASA image below, we can see the position of this retrograde frontal boundary and low pressure system as of yesterday. Note how the eastern front essentially collapsed as it pushed westward forming a bow from Texas to the Dakotas in the image at the top of this post.

Retrograde Low

(Frontal System begins to move in reverse on Saturday, July 13. Image source: NASA)

The cause for this retrograde storm motion is an extraordinarily weak Jet Stream. Over the past two decades, the Northern Hemisphere Jet has continued to weaken as both sea ice and summer time snow cover rapidly eroded. This helped reduce the strong north-south temperature differentials that drove the Jet to move weather systems rapidly from west to east. Now, temperature differences between high and low lattitudes are greatly reduced and, as a result, the Jet proceeds more slowly.

One result is that weather tends to persist much, much longer over a given region. Droughts, heat, and dry weather persist in areas where the Jet is pushed into a south-north configuration. Rain, storms, and cooler weather persist in regions where the Jet is pushed into a north-south configuration.

In the case of this weekend, the Jet became so weak that prevailing local influences overcame a hemisphere wide system to drive weather patterns against its ebbing flow. In this case, though, the result may be a somewhat positive influx of rainfall to drought and fire stricken western regions. Let’s hope this doesn’t turn into too much of a good thing.

UDPATE:

The weather system I reported on earlier today is still moving in its retrograde fashion, east to west, across the United States. It now stretches almost to Utah and appears to be dumping rain in a bow shaped arc from Texas into New Mexico and then re-curving northward back through the Dakotas and all the way through to Quebec. A moist upper level flow issuing from the Atlantic Ocean is still pushing the arching front westward.

You can see the progress of this retrograde storm in the most recent satellite image here:

Retrograde Front US July 14 #2

(Image source: NOAA)

This retrograde action has now spanned 2/3 of the Continental US and is still proceeding westward. May well be something for the record books…

Links:

NOAA

NASA

Where Insolation is King: ‘Blue Ice’ Melt Forming In Northwest Passage

BlueIce

(Image source: Lance Modis)

It’s been rather warm in the Canadian Arctic over the past few days. This day, especially, revealed particularly high temperatures. From the bottom edge of the Canadian Arctic Archipelago southward, 20 degree + Celsius temperatures ran through a wide region on the west side of Hudson Bay.

These high temperatures are having their impact. Hudson Bay itself is riddled with holes and rapidly thinning. Meanwhile, a section of the Northwest Passage in the Canadian Archipelago is turning a characteristic blue color.

Looking down from our satellite perch, this pale shade appears to grace the ice with a flattering color. But closer in we notice that this particular peal is a result of a multiplication of melt ponds on the ice surface. The ponds refract the light, turning them a mesmerizing shade of blue. And as these lakes increase in number to dot the ice, from far away the it appears to take on their color.

This particularly brilliant display comes with an ominous note. Thin ice, vulnerable to accumulated energy from the sun (insolation) tends to melt much faster. And so it is melting faster, about three weeks to a month ahead of schedule in this particular region. Together, warm air plus insolation may be spelling out an early end to winter’s ice here.

Chris Reynolds over at Dosbat and Neven over at the Arctic Ice Blog have been warning of the sea ice’s special vulnerability to insolation this year. This vulnerability is primarily due to the fact that most of the Arctic Ocean and related waterways are covered only by a thin layer of about two meters of ice. Very few regions remain where thick ice dominates. And two meter ice may well not survive the assault of the summer sun.

In the Central Arctic, where much of the remaining thick ice resides, the area is plagued by a powerfully churning storm. This persistent monstrosity is little more than a giant engine of heat exchange. It pulls air in from the surrounding atmosphere, it feeds on heat and moisture, it flings out winds, and it even turns and churns the icy ocean beneath. Such a storm, so long ongoing, poses its own threats to the Arctic’s more vulnerable ice.

But where the air is still, where there is ambient heat, and where the clouds open wide and allow the sun’s rays to plunge down upon the ice surface, insolation is king. And that force, a direct force of sunlight, appears to be spelling an early end to this so seemingly lovely stretch of pale, blue ice.

Links:

Lance-Modis

Arctic Ice Blog

Dosbat

Greenland Melt Speeding Up; Northern Hemisphere Snow Cover Falling Below Average

greenland_melt_area_plot

(Image source: NSIDC)

Greenland ice sheet melt spiked today, moving into above average territory with nearly five percent of the ice sheet showing surface melt. Influx of warmer air from the south combined with ongoing heat absorption by the ice sheet to push melt levels higher over a broad area of southern Greenland. Temperatures rose above freezing for most of southern Greenland while much colder air remained concentrated to the north.

greenland_melt_nomelt

(Image source: NSIDC)

Over much of the Arctic, warmer air is invading northward. Above freezing temperatures are now common around Hudson Bay, in Northwestern Canada, in Northern Alaska, over sections of the Bering, Beaufort and Kara Seas, and are nearing the coast in East Siberia. Higher temperatures pushing northward have not only set off Greenland melt, but overall Northern Hemisphere snow cover continues to push into lower than average territory.

nhtime-4month

This rapid melt is especially worthy of note considering the massive amount of snow dropped by major storms this winter over much of the Northern Hemisphere. Should pace of snow melt continue, we may be on track for another record year.

Last year, both Greenland surface ice melt and Northern Hemisphere snow melt plunged into record low territory. Greenland melt was particularly exceptional with nearly 100% of the surface area of Greenland showing melt on certain days during July. The last time a similar level of melt occurred on Greenland was more than 100 years ago. A repeat of this kind of melt at any time within the next decade would be unprecedented. However, given current levels of Arctic warming, such melt is certainly possible.

Loss of tundra in certain regions appears to be one of the key drivers of enhanced snow melt during summer time. Arctic warming over the past few decades has continued to push the tundra line northward. As a result, snow is less resilient in northern regions come summer.

Links:

NSIDC

NCEP

Though Weather Patterns Would Indicate Re-freeze, Slow Arctic Sea Ice Melt Continues

Sea ice area and extent fell again today by slight amounts. JAXA showed sea ice extent at 3.593 million square kilometers and Cryosphere today showed sea ice area at 2.294 million square kilometers. NSIDC showed a slight bump in extent numbers over the past couple of days. But, in general, most melt values are still slowly ticking lower.

Temperatures for the region above the 80th parallel are about 3 degrees C above the average for 1958-2002. These higher than normal temperatures are likely the primary driver for the continued melt we are seeing.

Weather patterns in the area — a persistent high pressure system over the Siberian coast and a deep low developing near Iceland and reaching all the way to Scandinavia and the UK — would usually herald the melt season’s end and, possibly, promote a re-freeze. As yet, this hasn’t happened. However, the slowing melt over the past couple days may be a sign that this pattern is tipping the balance back toward equilibrium or freezing.

In any case, we have two new record lows — one for JAXA and one for Cryosphere Today — as of today. Departures from previous record lows are as follows (previous record year in parenthesis):

JAXA Extent: -657,000 square kilometers (2007)

Cryosphere Today Area: -611,000 square kilometers (2011)

PIOMAS Volume: -400 cubic kilometers (2011)

NSIDC Extent: -682,000 square kilometers (2007)

Overall, these values are likely to be very close to final records set for the end of this melt season. Any further melting is likely to be less than 100,000 square kilometers. In any case, these values are deep into record low territory and represent severe losses of sea ice for this year alone.

Links:

http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

http://nsidc.org/arcticseaicenews/

http://arctic.atmos.uiuc.edu/cryosphere/

Greenland Ice Sheet on Verge of Rapid Melt

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Greenland is beginning to succumb to amplifying climate feedbacks. In short, what this means, is rising seas and the loss of one of Earth’s key cooling mechanisms.

According to polar researchers, Greenland is poised to break melt records again this year and is fast approaching a dangerous ‘tipping point’ after which the ice sheet will go into rapid decline. These research findings not only show record melt, but also a rapid reduction in the reflectivity of the ice sheet. Loss of reflectivity is critical because the primary reason the ice sheet remains cool is due to its ability to reflect solar radiation. Now, a surface covered with melt lakes and soot is absorbing more of the sun’s light and heat, heralding the beginning of rapid melt.

The primary driver of the Greenland melt, however, is human greenhouse gas emissions. Just this year, some places in the Arctic measured CO2 at records of over 400 ppm. Average CO2 worldwide is currently near 397 ppm. This is well above the safe range recommended by scientists at 350 ppm.

In the geologic past, when CO2 has reached 400 ppm, sea levels have tended to rise anywhere from 15 to 75 feet. Substantial melt in Greenland could contribute massive volumes of water to the world’s oceans, speeding sea level rise as CO2 heats the world. Such an event would likely make current scientific estimates of 1-4 feet of sea level rise by the end of this century seem extremely conservative, especially considering the fact that the same scientists expect CO2 to measure between 600 and 900 ppm CO2 and up to 11 degrees Fahrenheit additional warming by the end of this century.

It is important to note that there is no record of CO2 rise occurring at such a rapid pace in all the Earth’s history. Similar increases in CO2 have tended to occur over the course of a thousand years or more. The current rapid increase in CO2 caused by human greenhouse gas emissions is an order of magnitude faster and, therefore, much more dangerous. Both the oceans and the climate system have little or no time to respond to this rapid forcing. With such an unprecedented increase of such powerful, heat-trapping, gasses we should expect rapid, violent, and unpredictable changes to the world’s climate, oceans, weather, and glaciers.

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Links: http://www.meltfactor.org/blog/?p=476

https://robertscribbler.wordpress.com/2012/03/18/arctic-sea-ice-melt-methane-release-shows-amplifying-feedbacks-from-human-caused-climate-change/

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Arctic Sea Ice Melt, Methane Release Shows Amplifying Feedbacks from Human Caused Climate Change

For years now, scientists have warned that additional atmospheric heat caused by human releases of carbon dioxide (CO2) could result in amplifying feedbacks that cause even more heat. At first, most of these comments were academic, an exercise in predicting what would happen if humans did not curtail greenhouse gas emissions. But as human CO2 emissions continued to increase, global warming amplified and changes accelerated. Now the warnings from scientists are much more direct. Consider NASA scientist James Hansen’s most recent statement:

“We don’t have a substantial cushion between today’s climate and dangerous warming. Earth is poised to experience strong amplifying feedbacks in response to moderate additional global warming.” – James Hansen

Amplifying Feedbacks via Microphone

An amplifying feedback is a rapidly increasing response to an initial forcing. In everyday life, people are generally familiar with what happens when you put a microphone close to a speaker. The microphone picks up ambient noise, and pushes it out through the speaker. This, now louder, noise is picked up again by the microphone and sent back to the speaker as a much louder input. The loop continues until the speaker is pouring out a rapidly rising wail of sound.

Arctic Sea Ice Melt as Amplifying Feedback

In nature, something very similar can happen as a result of an initial climate forcing. In the Arctic, we can see this in the form of sea ice melt over the past few decades. Increases in ocean temperature and stored heat has gradually worn away at both Arctic sea ice area and Arctic sea ice volume.

In 2007, Arctic sea ice area reached the lowest levels ever recorded, a level far below the 1979-2001 average. Sea ice lost area equal to 20% of the total summer coverage of the previous year. More than 20% of Arctic sea ice gone in one year. Since that time, Arctic sea ice area has failed to recover with 2011 showing the second lowest area on record at end of summer, an area very close to the unprecedented 2007 record low.

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The above image shows the difference between 1980 and 2007 Arctic sea ice (Source: Cryosphere Today).

But sea ice area as seen from above only tells half the story. The second half is told by total sea ice volume. Area measures how much surface is covered by ice. Volume measures the total amount of ice by taking into account sea ice thickness. And when looking at volume, there has been a precipitous and unrelenting fall.

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Sea Ice Volume shown above is calculated using data from the Pan-Arctic Ice Ocean Modeling and Assimilation System of the Applied Physics Lab at the Polar Science Center and inserting it into a curve fitting process. And the curve shows a near-ice free Arctic under current trends by or before the summer of 2020. In fact, the model shows that September could see ice-free seas as early as 2013. Not likely, but another couple summers like 2007 could bring us very close.

But even if current trends don’t hold, additional statistical analysis shows nearly ice free summers by or before 2035.

And the, usually guarded, IPCC findings point toward ice-free summers before 2050. So depending on the dynamics of Arctic weather, which can certainly be very dynamic, our best analysis points toward a continuation of rapid collapse or a shift to a more gradual melt down.

Regardless of final melt dates, APL sea ice volume measurements show Arctic sea ice is getting very, very thin.

The reason Arctic sea ice melt is an amplifying feedback is due to the heat reflective nature of ice vs the heat absorption nature of water. Water just by virtue of color alone, absorbs more sunlight than ice. This results in water temperature in ice free seas being as much as 5 degrees C warmer than water beneath sea ice. And this warmer water heats both the air and the entire water column. Loss of sea ice alone is a powerful amplifier of temperatures during the Arctic summer and this extra absorbed heat is on top of the extra heat added by human caused global warming via CO2 emissions.

Arctic Methane Releases as Amplifying Feedback

It is the nature of single amplifying feedbacks that they tend to kick off other feedbacks. And this is exactly what is happening with Arctic methane.

In the Arctic, both methane and ice have been locked together in a chilly marriage ever since the roof of the world began to freeze about 10 million years ago. The reason for this is that the bodies of dead plants and animals have accumulated in the tundra’s frozen soil year after year. Dead and decayed biological matter has also been locked in formations called methane hydrates in the shallow Arctic sea.

When the ice melts, seas warm. This results in warmer winds blowing over the tundra. The tundra’s permfrost soils begin to melt and, when they do, bacteria begin to break down the dead matter locked in these frozen soils for so long. Once the matter breaks down, methane is released.

Now methane is a very powerful greenhouse gas — packing a potency twenty times that of CO2. So Arctic methane releases result in a powerful global warming force adding to the effects of sea ice melt and human CO2 emissions. The result is that the Arctic warms even more, more tundra melts, and more methane is released.

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Often, when heat melts the tundra, new lakes form. These lakes contain large volumes of methane. Sometimes, researchers ignite this methane to demonstrate how much is being emitted from the lakes. Often, these ignitions result in dramatic plumes of fire, illustrating the explosive nature of methane emissions in the Arctic.

But, sometimes, this new methane seeping up from Arctic soils are ignited by nature in the form of lightning strikes. And these lightning strikes can result in vast tundra fires that burn massive swaths of the Arctic. One such tundra fire recently burned an area the size of Cape Cod in Alaska.

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These tundra fires convert massive volumes of biological matter into CO2 which adds another amplifying feedback.

Out Gassing of Submerged Arctic Methane

Even though vast areas of land are now providing amplifying feedbacks as Arctic tundra thaws, some of the thawing tundra isn’t on land, it’s under the water. North of Siberia, the East Siberian Arctic Shelf (ESAS) is a protrusion of tundra now flooded by the Arctic Ocean. As the water above this shallow shelf warmed, the submerged tundra began to thaw, and as it thawed it began to release methane.

These underwater methane releases were only recently discovered. Since their discovery, the rate of methane release has defied all expectations, pouring more methane into the atmosphere than any other natural source. Just this summer, Arctic researchers including Igor Semiletov discovered enormous plumes of methane venting up from the sea bed. According to the researchers, some of these methane plumes were more than 1 kilometer across.

“Earlier we found torch-like structures like this but they were only tens of metres in diameter. This is the first time that we’ve found continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter. It’s amazing,” Dr Semiletov said in a 2011 interview. “I was most impressed by the sheer scale and high density of the plumes. Over a relatively small area we found more than 100, but over a wider area there should be thousands of them.”

Some of this submerged methane comes from the decomposition of submerged tundra, the rest comes in the form of destabilized methane hydrates. As seen on the map below, the ESAS is just one of many areas where high concentrations of methane hydrate are expected.

Overall, 1700 gigatons of carbon are estimated to be locked up in the melting tundra and more than 4400 gigatons of carbon are estimated to be stored in the form of methane hydrates. By comparison, remaining conventional fossil fuel sources are estimated to contain about 1100 gigatons of carbon — about equal to the amount already emitted. So even if a fraction of Arctic Methane destabilizes it could more than double the impacts of human caused climate change.

But there is additional danger. They include loss of oxygen in the world’s oceans, rapidly increasing ocean acidification, the risk of much larger tundra fires, and the risk of very large fires sparked by lightning strikes in the event of sudden, large methane releases. These dangers should be seen as directly related to the risk posed by amplifying feedbacks.

Combined Impacts

When added to the very high volumes of CO2 produced by human activity, a volume 150 times that produced yearly by volcanoes, the increased heating caused by melting sea ice and increased methane release creates a dangerous amplifying feedback to global warming. The effects of these feedbacks are large and growing larger. The valid concern among scientists and those researching climate change is that these feedbacks will only expand exponentially as human forcing increases, eventually creating a cascade of effects whose scale is beyond the ability of humans to reign in.

Sources:

Cryosphere Today: http://arctic.atmos.uiuc.edu/cryosphere/

National Snow and Ice Data Center: http://nsidc.org/arcticseaicenews/

The Polar Science Center: http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/

“Vast Plumes of Methane Seen in Arctic as Sea Ice Retreats” http://www.independent.co.uk/news/science/vast-methane-plumes-seen-in-arctic-ocean-as-sea-ice-retreats-6276278.html

International Arctic Research Center: http://www.iarc.uaf.edu/en/about

The Storms of My Grandchildren by James Hansen, 2008

 

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