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Early Greenland Melt Spike Possible as Forecast Calls for Temperatures of up to 50 F Above Average

Greenland — a region vulnerable to the slings and arrows of human-forced climate change — appears set to experience both considerable warming and a significant melt spike this week.

Starting on Wednesday, May 3, a sprawling dome of high pressure is expected to begin to extend westward from the far North Atlantic and out over Iceland. As the high pressure dome builds to 1040 mb over the next couple of days, its clockwise flow will thrust abnormally warm and moist air northward out of the Atlantic. This air-mass is expected first to over-ride eastern Greenland, then run up into Baffin Bay, finally encompassing most of the island and its vast, receding glaciers.

(May 5, 2017 GFS model run as shown by Earth Nullschool is predicted to produce widespread above-freezing temperatures over the surface of the Greenland Ice Sheet. Such warming is expected to be accompanied by rainfall over a number of glaciers. Image source: Earth Nullschool.)

Liquid precipitation is then expected to start falling over southern sections of the Greenland Ice Sheet as temperatures rise to 1-6 C (33 to 43 F) or warmer. Since water contains more latent heat energy than air, such rainfall is likely to produce more melt than would otherwise be caused by a simple temperature rise.

For those of us living in more southerly climes, a temperature of 6 C (43 F) may not sound very warm. But for the northeastern region of Greenland shared by the ZachariaeBrittania, Freja, and Violin Glaciers, such temperatures far exceed ordinary expectations for early May. They are anything but normal. In fact, the building influx of heat is more reminiscent to readings Greenland would have tended to experience during summer — if at all — under past climate averages.

(GFS model predictions for May 4 show widespread liquid precipitation falling over southern Greenland. Image source: Climate Reanalyzer.)

Unfortunately, the new climate presented by human-forced warming is now capable of producing some rather extraordinary temperature extremes. And the anomaly ranges that are predicted for the coming week are nothing short of outlandish.

According to climate reanalysis data, by May 5th, temperatures over northern and eastern Greenland are expected to range between 15 C above average over a wide region and between 20 and 28 C above average in the northeast. For the Fahrenheit-minded, that’s 27 to 50 degrees F above normal. Or the equivalent of a 102 F to 125 F May day high in Gaithersburg, MD.

(An amazing temperature spike is expected to ride up and over Greenland on May 3 to May 5. This warming is expected to produce very extreme above average temperatures for this time of year. Image source: Global and Regional Climate Anomalies.)

Overall excessions for Greenland temperature are also predicted to be quite extraordinary for the day — hitting nearly 9 degrees Celsius (16 F) above average for the whole of this large island. So much warmth extending so far inland and combining with liquid precipitation, if it emerges as predicted in these GFS climate models, is likely to produce a significant early season melt spike — especially over southern and eastern Greenland. In places, these temperatures exceed expected normal summer conditions for Greenland’s glaciers. So it is difficult to imagine a situation where a significant surface melt spike does not occur if these predicted temperatures emerge.

Links:

Earth Nullschool

Global and Regional Climate Anomalies

Climate Reanalyzer

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Extensive Dark Snow, Very Large Melt Lakes Visible Over West Slope of Greenland as Late Season Melt Pulse Continues

Late Season Greenland Melt Pulse Continues.

Late Season Greenland Melt Pulse Continues.

(Image source: NSIDC)

A strong, late-season melt pulse continued over the Greenland ice sheet this weekend as melt covered a much greater portion of the ice sheet than is typical for this time of year. As of late July, the area of the Greenland ice sheet subject to melt had spiked to nearly 45%. Soon after, a second melt spike to around 38% followed. Over the past two weeks, melt area coverage has fluctuated between 5 and 25 percentage points above the seasonal average for this time of year, maintaining at or above the typical melt season maximum of around 25% for almost all of this time.

This late-season melt surge was driven by a switch in the polar Jet Stream. A trough which had dominated through much of summer, bringing near average temperatures and melt conditions, had eroded and by late July a broad ridge began to form. This high amplitude wave dredged warm air up from as far south as the south-eastern US, then dumped it on the west facing coast of Greenland. There, last week, a new record all time high temperature of 78.6 degrees (Fahrenheit) shattered Greenland’s previous highest temperature of 77.9 degrees.

And this record heat is beginning to have a very visible affect on the ice. Aqua satellite passes this weekend recorded a visible darkening of ice cover in the region most greatly impacted by high temperatures last week. The snow and ice cover there has taken on a sooty appearance with darker gray tendrils finding their way deep into the ice pack. At the same time, large melt lakes expanded over the region with some of these lakes measuring more than  three kilometers across.

In this first Modis shot we see a broad region of darkened, melt-pond speckled ice forming over a very large swath of Greenland’s western ice sheet:

Greenland west coast melt, August 4.

Greenland west coast melt, August 4.

(Image source: Lance-Modis)

For reference, Baffin Bay is toward the left of the image, the southern tip of Greenland, toward the bottom, and the far right frame of the image runs about down the center-line of the south Greenland ice spur. Note the swatch of dark ice that appears much like dirty snow running down western side of the ice sheet. This major melt region, at its widest, appears to dive as much as 100 miles into the ice sheet. Even at this level of resolution, we can see the large melt lakes speckling the inland border of this darkened region.

Zooming in to a region where melt appears to have penetrated deepest into the ice pack, we find even more dramatic features.

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

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

(Image source: Lance Modis)

The orientation of this particular image is the same as the larger image above, but we have just zoomed in to a large, central melt region. Toward the coast, we can see melt and ice flowing into channels and fjords. Adjacent to this rocky coastal zone is a region of more rapidly mobile and fractured ice flows. Few melt ponds are visible in this region and this is, likely, due to the large fissures and steep vertical faces that cover most of the ice surface in this area. It is beyond this boundary margin and inward toward the ice sheet’s center that we find a second region of very dark snow and ice. This area shows some large melt ponds, but its prominent feature is an almost complete loss of reflective snow cover with lower layers of soot deposition and darker sediment now exposed. Still further in, we find the third, and arguably most dramatic, melt zone. This particular area is coated, not in dark gray, but in blue. It is a feature primarily caused by a very extensive surface melt covering much of this region. In this single picture, we can count over a hundred large melt lakes mostly dominating this region. They range in size from about a half kilometer to over three kilometers across. Connecting these lakes is what appears to be a web of melt rivers, some of which terminate in moulins that core into the glacier’s heart, delivering warm melt water the frigid ice’s center and base. The general bluish color of this region indicates a very high degree of melt with puddles and pools below the 250 meter resolution of this particular satellite shot lending an azure tint to the ice.

Conditions in Context

Over the past two decades, Greenland has shown a very disturbing and rapid melt response to human-caused warming. During the mid 1990s, Greenland began to show a net loss of ice mass. Through the 2000s, this melt rate accelerated, growing generally, but rapidly peaking in rather disturbing melt surges as warm weather conditions grew more extreme during certain years. By 2012, a very extreme melt year had occurred, resulting in ice sheet losses on the order of 700 cubic kilometers in just one year. These peak melt years appeared to re-cur at a rate of once every 2-5 years even as overall average melt from Greenland grew to a disturbing 500 cubic kilometers by the early 2010s.

Even worse, sensors deep within the ice sheet indicated that the ice sheet had become more mobile, increasing in velocity by about 2-3 percent each year since 2010.

Though 2013 does not appear to be a peak melt year, as weather conditions have favored less melt than in 2012, the continued softening of the Greenland ice sheet remains a very disturbing summer feature. This year’s west coast melt has been particularly dramatic, with the most recent shots shown above featuring some of the worst melts I have yet witnessed.

UPDATE:

Prokaryotes (think about the name) was kind enough to produce the following video of this blog on his own platform: Climate State. I’ve linked the YouTube version here:

Links:

Greenland Ice Sheet Slipping Under Hottest Temperatures Ever Recorded

Keep up with Greenland Melt by Reading Jason Box’s Website

The Dark Snow Project

NSIDC’s Review of the Record 2012 Greenland Melt Season

Global Warming Rolls Climate Dice Yet Again: High Amplitude Jet Stream Wave Brings Late July Melt Surge to Greenland

The old cliche is that lightning never strikes twice in the same place. In weather and climate terms, natural variability makes it highly unlikely that record year will follow record year, even when a forcing, such as human global warming, tends to push in that direction.

In the context of Greenland, it was very unlikely that record melt on the order of around 700 gigatons of ice lost during 2012 would repeat in 2013.  That said, even in a year like 2013, where climate attempts a return to the average trend line, it’s entirely clear that conditions are anything but normal.

Throughout late June and much of July, a downward dip in the Jet Stream dominated weather patterns over Greenland. Cold, Arctic air was locked over the massive island, pushing melt rates closer to ‘normal’ for a summer season. The term to use is definitely ‘closer,’ because even during weather conditions that would normally bring colder than average conditions to Greenland, warmth and melt were still above average.

Global warming adds a roll

A metaphor we can use to describe this phenomena of implied variability in a warming system is James Hansen’s climate dice. Imagine that a basic roll of a d10 gives us a typical weather pattern for Greenland. 1 on the dice represents record cold, 10 record warmth, 2 and 3 are colder than average, with 2 being near record lows and 3 being closer to average, 4, 5, 6 and 7 are average, 8 and 9 are hotter than average, and 10 is record heat.

This set of weather and climate possibilities is a basic representation of ‘normal’ for Greenland. But when we add in human climate change and global warming, we are essentially adding a new player to the mix, with its own set of dice. In this case, let’s add a 1d3 to the global warming hand. Now, with the extra dice roll for global warming, the potential for extreme hot, melting years just got far, far more likely and we begin to experience never seen before heat and melt events. But we still end up with colder than average years and normal years, just less of them.

The situation is probably worse than the simulation described above because on the typical 1 to 10 scale we can label 2012 about a 13 (with freakish never seen before record heat and melt) and 2013 through about July 26th a 7.1 — slightly hotter than average with ever so slightly above average melt.

The problem is that June and July were average when they should have been cold. I say this because a high amplitude wave in the Jet Stream flowed down over Greenland, pushing relatively colder air over the sea ice and into the freezer that is still Greenland. Such conditions usually push for colder than average Greenland temperatures and lower than average melt. This period of what should have been colder than average conditions instead resulted only in an abatement of record melt and a return to slightly above average melt.

Mangled Jet Stream switches back to ‘hot’

But now, even this brief respite appears to have evaporated. Over the past couple of weeks, the deep, cooler trough over Greenland eroded, weakening as warmer air pushed into southern Greenland. Now, the trough has completely reversed — becoming a ridge and somewhat mimicking the freakish conditions that occurred during 2012. So slightly above average melt conditions are now starting to swing back toward record melt conditions for this time of year.

You can see the large, high amplitude bulge riding from south to north, carrying air from the south-eastern US all the way north to Baffin Bay and southwestern Greenland, in the Jet Stream map for July 30th below:

Greenland Jet

(Image source: California Regional Weather Service)

This sudden Jet Stream switch brings back a weather pattern that caused such major melt conditions during summer of 2012 and such warm winter conditions for Greenland as 2012 turned to 2013. And the results, as far as ice melt goes, have been almost immediate. Earlier melt peaks at around 34% of the ice sheet during July were obliterated in one fell switch of atmospheric air flow that, once again, drew warm, temperate air into the Arctic.

Over the past two days, this extra warmth has increased Greenland melt area to above 40%, peaking at near 45% just a couple of days ago. This peak, though not as anomalous as the 90% + melt coverage experienced during early July of 2012, is still about 80% higher than the average melt peak observed for the period of 1981-2010 and more than double the average for melt in late July. It also puts Greenland further into above average melt year territory, possibly shifting the 2013 score from 7.1 to around 8.5.

You can see the melt coverages graph, provided by NSIDC, for the current year below:

Greenland Melt 2013 Late July

(Image source: NSIDC)

The warm air pulse that drove these anomalously high late season melt rates in Greenland appears to have settled in for at least the time being. Temperatures along the Greenland coast range from the upper 30s to the lower 60s — quite warm for this time of year — while summit Greenland is experiencing warmer than average temperatures in the lower 20s (Fahrenheit).

Above average melt when it should have been cold

So what is freakish about 2013 when compared to 2012 is not that it matched a major melt event that will likely stand as a record for the next five years or so, but that in a year where weather conditions would have pushed Greenland to be mostly colder than normal, above average warmth and melt were still experienced. In this case, it becomes very clear that we are rolling with loaded climate dice or, as the illustration above shows, human global warming is adding its own wicked set of rolls.

Links:

California Regional Weather Service

NSIDC

James Hansen’s Climate Dice

Learn about Dark Snow

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