Hot Climate Conjures Trio of Nasty Halloween Tricks — Heatwaves, Record-Low Sea Ice, Fall Greenland Melt

With each passing year, the effects of human-caused climate change become more and more visible. But for some reason, Halloween appears to be a preferred time for the emergence of various hothouse hobgoblins. In 2012, the Atlantic seaboard was reeling after a vicious strike from Hurricane Sandy. Over the past three years, powerful North Atlantic storms had begun to build at this time of year, setting sights on the UK and Europe. This year, as a hurricane-force low roars toward the Aleutians, the nastiness comes in the form of weird heatwaves, record-low global sea ice coverage, and hints of odd late-fall Greenland melt.

Record Heat Strikes Arctic, U.S.

NASA’s Gavin Schmidt has been warning for months that 2016 will be a global scorcher for the record books. Nowhere has this heat been more apparent than in the Arctic. Halloween only serves to reinforce the rule as today’s temperature departure for the entire region above 66 degrees north latitude hit 5.94 degrees Celsius above average:

global-anomaly-map-halloween

(The extreme Arctic warmth that has already caused so much in the way of climate disruption remains firmly entrenched on Halloween. Image source: Climate Reanalyzer.)

Yesterday, those temperatures exceeded the 6-C-above-normal mark. And later this week, temperatures for the region could approach 6.3 to 6.5 C above average.

These are the average departure ranges for the entire area above the Arctic Circle. Localities within that broader region are hitting as much as 20 C (36 Fahrenheit) or more above average on an almost daily basis, bringing temperatures more typical of the Arctic during late summer than in the middle of fall.

In Barrow, Alaska, Jonathan Erdman reports that Saturday saw the proverbial mercury hit 41 F. This temperature, at about 26 degrees above average, smashed the previous daily high and pushed the latest day Barrow has ever seen a reading above 40 F fully one week forward.

record-temperatures-us

(Daily high and high min temperature records for the U.S. were broken at an alarming rate over the past week, producing a Halloween heatwave. Image source:  NOAA.)

Farther south, the lower 48 is experiencing what Bob Henson over at Weather Underground is calling the Halloween Heatwave. Over the past week alone, nearly 300 daytime high marks were broken. But the measure of record-high minimum temperatures — a key indicator of human-forced warming — is off the charts with 639 total records smashed over the past seven days.

What’s even more odd is a near-total lack of cool temperatures. Bob Henson finds that:

Even more noteworthy than the degree of warmth is the lack of widespread autumn chill. For example, Minneapolis has yet to dip below 36°F as of Friday, October 28. That doesn’t look likely to happen before at least next weekend (November 5 – 6). In records going back to 1873, the latest Minneapolis has ever gone before seeing its first 35°F of the autumn is November 1, way back in 1931. The city’s latest first freeze was on Nov. 7, 1900.

Reinforcing this point, NOAA finds that over the past week just 40 record low high temperatures were achieved (about one-seventh the number of record highs). Meanwhile, record low nighttime temperatures were only achieved in six instances, about one-one-hundredth the rate of record high minimum temperatures! Furthermore, at no location in the U.S. for this week, this month, or even this past year has snow depth achieved a new record high. That’s a pretty ridiculous indicator that the U.S. has reached a rather disturbing climate threshold for heat overall.

Record Low Global Sea Ice Coverage

Even as new warm temperature records were being set with amazing frequency across parts of the Northern Hemisphere, another duo of worrisome indicators were popping up in the Arctic and Antarctic. In the Arctic, the ocean has been loaded up with a ridiculous amount of heat. This heat is preventing the ocean from refreezing, creating various regional barriers to ice formation as the waters ventilate this excess heat into the atmosphere. As a result, Arctic sea-ice extent record lows continue to deepen.

Fall 2016 sea ice extent values — which have consistently lagged behind average daily refreeze rates for most of the season — are now more than 600,000 square kilometers below the previous record set during 2012. It’s, quite frankly, an insane shattering of the previous record low value; a warming-spurred melt that has erased an area of sea ice coverage nearly the size of Texas in just four years.

arctic-sea-ice-jaxa

(Current Arctic sea ice extent values are 6.92 million square kilometers [October 30]. This is 600,000 square kilometers below the previous record low set on the same day during 2012. It is also about 3 million square kilometers below average values seen for this day back during the 1980s. Image source: JAXA.)

The Washington Post this past Friday provided a good article explaining the dynamics involved and highlighted predictions by prominent Arctic researchers that ice-free summers could occur by the 2030s. This is a marked departure from earlier estimates that had put off ice-free summers until the 2050s or even the 2080s. However, it’s worth noting that there’s a decent risk that even these more advanced predictions may prove conservative in the end. Under current trends, ice-free periods for the Arctic Ocean during summer become statistically possible as soon as the early to mid 2020s, and a strong outlier year — where an abnormally warm winter is followed by an abnormally warm summer — could produce such a result even sooner.

On the other side of the world, the Antarctic is also experiencing record-low ranges for sea ice extents. There, regional temperatures are near 4 C above average for the entire Antarctic. Though these departures are not as extreme as those currently seen in the Arctic, they are certainly enough to impact sea ice. Now, sea ice extent values there are at their second lowest ever recorded in the daily measure.

Over recent years, storminess in the Southern Ocean and an expanding fresh water lens running out from Antarctica due to glacial melt have generated a seemingly contradictory expansion of sea ice near Antarctica. This happens because fresh water at the ocean’s surface acts to deflect heat toward the ocean bottom, a feature that has enabled the melting of various glacier undersides in Antarctica. But as the global ocean and atmosphere warm in general, larger melt outflows are necessary to reinforce this surface freshwater lens effect. As a result, we appear to be experiencing a seesaw in Antarctic sea ice extent as a pulse of atmospheric and ocean warming overrides the impact of initial fresh water lensing.

global_sea_ice_extent_zoomed_2016_day_301_1981-2010

(MASIE global sea ice extent shows a severe negative departure through October 28, 2016. Image source: Sunshine Hours.)

The combination of significant sea ice losses in the north and second-lowest sea ice extents in the south has resulted in a global sea-ice measure that is well below anything seen in the past for this time of year. It is also one of the largest global negative sea-ice departures seen for any part of the record for any time of year — even when compared to the extreme period of Arctic sea ice loss during September of 2012.

Halloween Greenland Melt?

In addition to producing heatwaves, new temperature records, and ever more extreme sea ice melt, the odd Halloween warmth appears to also be generating flashes of surface melt over parts of northeastern Greenland. There, over the past few days, temperatures have approached or even exceeded the freezing point as warm winds have blown in from the heating Greenland Strait.

(A warm front crosses over northeastern Greenland on October 27, 2016. The associated warm winds blowing off the heating waters of the Greenland Strait produced near or above freezing temperatures for isolated parts of this section of Greenland. This abnormal warmth appears to have tripped NSIDC’s melt sensor, producing a possible odd late-season melt event for sections of this frozen island. Image source: Earth Nullschool.)

This heat has been enough to trip NSIDC’s Greenland melt indicators for the region of the Zachariæ Isstrøm glacier. These indicators, over the past couple of days, have shown relatively extensive melt in this sector of Greenland. During summer 2016, northeastern Greenland was one of the regions that saw strongest indications of surface melt. Typically isolated by sea ice from warm ocean breezes, northeast Greenland does not usually see such long-lasting periods of surface melt. This is especially true for late October as melt during this time for any portion of the Greenland Ice Sheet is practically unheard of. However, as warm ocean water has advanced further and further north, this region has become more vulnerable to invasions of warm air. And it appears that the melt-forcing effect of this ocean warming for nearby Greenland glaciers may well be extending into fall.

Though unconfirmed by NSIDC, these periods of possible melt have occurred coincident with temperature departures in the range of 10-20 degrees C above average. However, since near or above freezing temperatures have mostly been isolated to the very far northeastern sections of Zachariæ Isstrøm near the coast, it’s likely that any potential and brief periods of melt were located in a more limited band than what has shown up on the NSIDC melt maps for October 27, 28, and 29. That said, as noted above, any surface melt over glaicers in Greenland for this time of year would be very odd and concerning — no matter how isolated.

Nasty Global Warming Tricks for Halloween

Halloween heatwaves, record-low sea ice extents and possible periods of fall Greenland melt are all indicators that human-forced climate change is starting to generate more and more obvious effects. Though the most extreme impacts are hitting remote regions like Greenland, the Arctic and the Antarctic, the related abnormal warmth has filtered into the middle latitudes and is now affecting millions of people across the U.S. And what’s happening in the U.S. is linked to these related warming events on a global scale.

So happy Halloween, everyone. Enjoy the holiday. But remember that if it’s oddly warm where you are, it’s not just a freak warm weather treat, but one of the many and worsening tricks conjured up by global climate change.

Links:

NOAA

The Climate of Gavin

Climate Reanalyzer

Jonathan Erdman

Zack Labe

Earth Nullschool

NSIDC

Sunshine Hours

Half a Kilometer of Ice Gone in Just 7 Years

JAXA

Hat tip to Colorado Bob

Hat tip to DT Lange

Hat tip to June

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Big Arctic Warm-Up Predicted For This Week: Melt to Speed Up, Or Sea Ice to Show Resiliency Due to Variability, Strength of Negative Feedbacks?

Rate of Sea ice volume decline for all months

(Rate of Arctic sea ice volume decline with trend lines for all months in the PIOMAS measure. Updated through June of 2014. Image source: Wipneus.)

What it really all comes down to is heat energy balance. Beneath a warming, moistening Arctic atmosphere, sea ice loses resiliency due to slow attrition of the ice surface, due to loss of albedo as ice melts, and due to slower rates of refreeze during winter. Atop a warming Arctic Ocean, sea ice loses bottom resiliency, tends to be thinner and more broken, and shows greater vulnerability to anything that churns the ocean surface to mix it with the warming deeper layers — storms, strong winds, powerful high pressure systems.

It is this powerful set of dynamics under human caused climate change that has dragged the Arctic sea ice into what has been called a ‘Death Spiral.’ A seemingly inexorable plunge to zero or near zero ice coverage far sooner than was previously anticipated.

But in the backdrop of what are obviously massive Arctic sea ice declines and a trend line, that if followed, leads to near zero ice coverage sometime between next year and 2030, lurk a few little details throwing a bit of chaos into an otherwise clear and, rather chilling, picture of Arctic sea ice decline.

The Fresh Water Negative Feedback

One of these details involves the greatly increasing flow of fresh water into the Arctic Ocean. For as the Arctic heats, it moistens and rainfall rates over Arctic rivers increase. This results in much greater volumes of fresh river water flushing into the Arctic Ocean and freshening its surface. Another source of new fresh water flow for the Arctic is an increasing rate of Greenland melt outflow. The volumes, that in recent years, ranged from 300 to 600 cubic kilometers, can, year-on-year, add 1-2% to the total fresh water coverage in the Arctic Basin and North Atlantic. These combined flows mean that fresh water accumulates more rapidly at the surface, resulting in an overall increase in fresh water volume.

Change in salinity

(Change in Arctic Ocean Salinity between the mid 1990s and mid 2000s. Image source: Benjamin Rabe, Alfred Wegener Institute via Science Daily.)

Since 1990, we have observed just such an accumulation. For a recent study in 2011 showed that since 1992, Arctic Ocean surface fresh water content had increased by 20%. A remarkable increase due to the changing conditions that included greatly increased river outflows into the Arctic Ocean as well as a ramping ice melt from Greenland and the Canadian Archipelago Islands.

Fresh water is less dense than salt water and will tend to float at the surface. The physical properties of fresh water are such that it acts as a heat insulator, deflecting warmer, saltier ocean water toward the bottom. As such, it interrupts the heat flow from deeper, warmer Arctic Ocean waters to the sea surface and into the atmosphere.

As an added benefit to the ice, fresher water freezes at higher temperatures. So as the Arctic Ocean freshens, it creates a bit of wiggle room for the sea ice, giving it about a 0.5 to 1 C boost so it can sometimes even form during conditions that were warmer than those seen in the past.

In this manner, an expanding fresh water zone acts as a kind of last refuge for sea ice in a warming world. A zone in which sea ice may even periodically stage comebacks in the backdrop of rampant human warming. We may be seeing such a comeback in the Antarctic sea ice, which has shown anomalous growth and even contributed to an expanding cool atmospheric zone in the Southern Ocean, despite ongoing global warming. The freshwater and iceberg feeds from the vast Antarctic ice sheets have grown powerful indeed due to warm water rising up to melt the ice sheets from below, letting loose an expanding surface zone of ice and fresh water. This process will necessarily strengthen as more and more human heating hits the deep ocean and the submerged bases of ice sheets. An effect that will dramatically and dangerously reverberate through the ocean layers, setting the stage for a horrible stratification.

But today, we won’t talk about that. Today is for negative feedbacks due to fresh water flows from increasing polar precipitation and through ice sheet melt.

In the end, human warming dooms Arctic sea ice to an eventual final melt. But before that happens the increasing volume of fresh water from river flows and the potentially more powerful negative feedback coming from a growing ice and fresh water release from Greenland and the Canadian Archipelago will inevitably play their hands.

The Slower Than Terrible 2014 Melt Season

And so we arrive at the 2014 sea ice melt season for the Arctic. As with 2013, the melt got off to a relatively rapid start and then slowed through July as weather conditions grew less favorable for ice melt. Above freezing temperatures hit the ice above 80 degrees North about one week later than average, also providing some resiliency to the central ice — a condition that historically leads to higher end-season sea ice values in about 80 percent of the record.

The high pressure systems of early June gave way to weak storms and overall cloudy conditions. This shut down the cycle of strong melt, compaction, and transport of ice out of the Arctic that may have put 2014 on track for new records and another horrible slide down the Arctic sea ice death spiral. Instead, conditions set up for slower melt. Ice was retained and backed up through the Fram Strait, and the ice spread out, taking advantage of the thickened fresh water layer to slow its summer decline.

This is in marked contrast to the terrible 2007 and 2012 melt seasons which severely damaged the ice, making a total Arctic Basin ice melt all more likely in the near future. And it was also cutting against the 2010 to 2012 trend in which sea ice volume measures continued to plunge despite ambiguous numbers in sea ice area and extent (no new record lows) during 2010 and 2011. For this year, sea ice volume is now, merely, ‘only’ 4th lowest on record, according to the PIOMAS measure.

The fact that we are looking at a 4th lowest year as another bounce-back year is a clear indication of how terrible things became since 2010. And so far, this year’s melt has, like 2013, simply not been so terrible and terrifying. A wag back toward 2000s levels that is likely due to the inherent negative feedback of freshening surface water and to a swing in natural weather variability that, during any other year and in any other climate, would have pushed summer ice levels quite high indeed.

If the storms had been strong enough to draw a large enough pulse of warm water to the surface, the story might have been different. But, as it stands, this summer of weak Arctic weather hasn’t activated any major melt mechanism to push the ice into new record low territory. And so in many major monitors we are now above 2013 melt levels for this day.

Cryosphere Today shows sea ice area at 5.22 million square kilometers, above 2013 and just slightly above 2011 while ranging below 2008 for the date. Overall, the area measure is at 6th lowest on record for the date. Meanwhile, NSIDC shows sea ice extent at 7.74 million square kilometers or just above 2013 values for the same day but remaining below 2008 and 2009 by a substantial margin. Overall, also a sixth lowest value for the date:

Sea ice july 2014 v2

(NSIDC chart comparing sea ice melt years 2012 [dashed green line], 2008 [maroon line], the 1981 to 2010 average [solid line] and 2013 [pink line]. Image source NSIDC.)

So in the sea ice butcher board tally, with the negative feedback of fresh water floods and glacial melt moderately in play and with weather that is highly unfavorable for melt, we currently stand at 4th lowest in the volume record, 6th lowest in the extent record, and 6th lowest in the area record.

And now, things may just be about to get interesting…

Forecast Shows Arctic Heatwaves on the Way

GFS and ECMWF model runs show two warm ridges of high pressure developing over the Arctic this week. And the emergence of these warm and moist air flows into the Arctic may well have an impact by pushing the Arctic back toward melt-favorable conditions.

The first ridge is already expanding across the Canadian Archipelago. Yesterday it brought 80 degree temperatures to Victoria Island which still sits between wide channels clogged with sea ice. Smoke from wildfires is being entrained in this ridge and swept north and east over the remaining Archipelago sea ice and, today, the Greenland Ice Sheet.

While the smoke aerosol from fires blocks some of the incoming solar short wave radiation, it absorbs and re-radiates it as long-wave radiation. Many studies have shown this albedo-reducing darkening of the cloud layer by black and brown carbon aerosols has a net positive warming effect. In addition, the soot falls over both land and sea ice where it reduces reflectivity medium to long-term (Dark Snow).

Smoke streaming over Canadian Archipelago and Northwestern Greenland

(Smoke associated with record wildfires in the Northwest Territory streaming over the Canadian Archipelago, Northern Baffin Bay, and Northwestern Greenland beneath a dome of record heat. Image source: LANCE-MODIS.)

The ridge is expected to expand east over the next few days until it finally settles in as a moderate-strength high pressure system over Greenland. There it is predicted to juxtapose a set of low pressure systems that will slowly slide south and east over Svalbard. The conjoined counterclockwise cyclonic wind pattern of the lows and the clockwise anti-cyclone of the high over Greenland in the models runs over the Fram Strait. And so, for at least 4-5 days, the models predict a situation where sea ice transport out of the Arctic may be enhanced.

Meanwhile, on the other side of the Arctic, a series of high pressure systems are predicted to back up over the Pacific Ocean section of Irkutsk and Northeast Siberia. This ridge is expected to dominate coastal Siberia along the Laptev and East Siberian Seas. Temperatures along the coast are expected to reach 15-20 C above average, while temperatures over the waters are expected to rise to melt enhancing levels of 1 to 5 C.

Ahead of the ridge runs a warm frontal boundary that is heavily laden with moisture and storms. So a liquid and mixed precipitation band is likely to form over the East Siberian and Beaufort Sea ice as the ridge advances.

The ridge is projected to drive surface winds running from the south over the East Siberian Sea, across the polar region, and into the Greenland and Barents Seas. This cross-polar flow of warm, moist air will also enhance the potential for ice transport.

Melt Pattern

(Pattern more favorable for sea ice melt and transport emerging over the next seven days. This Climate Reanalyzer snapshot is at the 120 hour mark. Note Arctic positive temperature anomalies at +1.18 C. Will the pattern override potential negative feedbacks such as high fresh water content in the Arctic and unfavorable weather likely produced by the late emergence of temperatures above 0 C in the 80 North Latitude zone? Image source: University of Maine.)

Overall, it is a weather pattern that shows promise to increase melt, especially in the regions of the Canadian Archipelago and the East Siberia Sea, and to speed ice mobility and transport. Persistent lows near the central Arctic for the first half of this period and shifting toward Svalbard during the latter half will continue to disperse sea ice which may lend one potential ice resiliency feature to a pattern that is, otherwise, favorable for ice loss.

Negative Feedbacks and Weather Unfavorable For Melt

If the melt pattern described above comes to impact the ice and push greater rates of sea ice loss over the coming days and weeks, it’s likely that end season 2014 will end up with sea ice measures below those of 2013, but above the previous record lows seen during past years. This would likely put 2014 well within the range of the post 2007 era at 3rd to 5th lowest on record for most monitors. Not a new record year, but still well within the grips of the death spiral.

If, however, the weather predicted does not emerge or the sea ice retains resiliency through it, then 2014 stands a chance of pushing above final levels seen in 2013. In such an event, end season area and extent measures may challenge levels last seen during 2005 while sea ice volume maintains between 4th and 5th lowest.

If this happens, we may need to start asking this question:

Are negative feedbacks, in the form of greatly increased freshwater flows from rivers and glaciers, starting to pull the Arctic sea ice out of a high angle nose dive and are they beginning to soften the rate of decline? Or is this just a year when weather again wagged the dog as natural variability played a trump card for the summer of 2014 but further drives for new records will follow come 2015, 2016, or 2017?

In any case, near-term sea ice forecasts remain somewhat murky, as they should given the high instability of the current situation.

Links:

Science Daily

Now Melts the Arctic

The Arctic Ice Blog

NSIDC

LANCE-MODIS

University of Maine

PIOMAS

Cryosphere Today

Dark Snow

 

 

 

 

How Global Warming Enhanced Glacial Melt to Expand Sea Ice in Antarctica

antarctica

Overall, worldwide sea ice totals have been declining over the past few decades. This trend has been led by a massive summer collapse of sea ice in the Arctic. But, on the other side of the world, in Antarctica, sea ice area and extent have been slowly expanding. This seeming contradiction recently spurred researchers to take a closer look at Antarctica to determine why sea ice would be expanding even though worldwide atmospheric and ocean temperatures are on the rise.

What they found was an amazing and complex combination of forces driving a moderate sea ice expansion in the southern hemisphere. Warmer waters coming into contact with submerged glaciers slowly melts the ice. In addition, a warming Antarctic continent disgorges large volumes of water each year. This fresh melt water, flushing into the ocean at a rate of 250 gigatons each year, then expands, covering the ocean surface in a thin layer surrounding Antarctica. Not only does this fresher water freeze at higher temperatures, it keeps warmer waters from rising up to melt the sea ice from below. The result is that sea ice is both insulated and made of fresher water. So until atmospheric and ocean temperatures rise enough to overwhelm this dynamic, Antarctic sea ice will remain protected by insulating processes coming from melting glaciers.

Warmer water trapped in the ocean depths surrounding Antarctica has also played a role in heating the world’s deep oceans. This heating was recently detected in a new study conducted by Kevin Trenberth and colleagues. The study found that a significant portion of the last decade’s heating had been sequestered in the deep ocean. Now it’s apparent that glacial melt in Antarctica may have played a role.

The Arctic sea ice, thus far, hasn’t benefited from a similar insulating process. The result was an 80 percent sea ice volume loss since 1979 and a high risk that sea ice will completely melt one summer between now and 2020. It’s possible that Greenland melt may continue to increase, freshening the Arctic’s waters, and providing a similar benefit at the cost of enhanced sea level rise and more extreme weather. But ocean currents, geography, and salinity dynamics for the Arctic are different from that of the Antarctic. So it is uncertain if melt will play as large a role in insulating northern hemisphere sea ice as it has in the southern hemisphere.

It is worth noting that rapid glacial melt, though it drives more extreme weather events even as it more rapidly increases sea level, tends to put a powerful damper on global temperature increases once glacial melt reaches the 1 meter mark. The heat energy goes more into melting the ice and less into warming the atmosphere and oceans. The negative feedback of fresher ocean waters in the polar regions as well as iceburgs floating in rapid glacial melt zones also has a net cooling effect. The result is that a degree or more of global temperature increases may be ‘held in check’ as the ice melts. Rapid ice melt decades may result in brief periods of relative cooling (where temperature increases back off from 1.5 or 2 degrees above average to around .9 to 1.3 degrees above average).

It’s a balancing effect and trade-off where you end up with more changes to the Earth’s environment and less overall heating in the short-term. This delayed heating effect of ice melt should not be seen as a good sign, however. As mentioned above, it comes at the severe cost of increased weather extremes and more rapid ocean level increases. In the end, once the messy transition decades are passed, a more liquid ocean results in more water vapor in the atmosphere, warmer Arctic and Antarctic environments that pump more greenhouse gasses into the atmosphere, receding glaciers and snow cover reducing the Earth’s reflectivity and adding further warming, and a warmer deep ocean resulting in more ocean methane release.

To get an idea how Greenland and Antarctic melt might dramatically impact world weather while putting a short-term dampening on global warming over the coming decades, take a look at this paper by James Hansen:

Update of Greenland Ice Sheet Mass Loss: Exponential?

It is worth noting that the scenarios examined in the paper come as a result of a relatively moderate increase in human greenhouse gas emissions: the A1B scenario. However, current emissions have increased more along the A1FI scenario which would likely result in even more climate volatility than the Hansen paper suggests.

The thing to take away from this new study is that both the Arctic sea ice collapse and the slower expansion of Antarctic sea ice are caused by the same forcing — human caused global warming — and that the glacial melt now resulting in localized cooling is also driving enhanced sea level rise and more extreme weather.

Please find more information on these new, ground-breaking studies here:

Global Warming Expands Antarctic Sea Ice

Oceans Continue to Warm, Especially in the Deeps

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