There have been two Arctic heatwave episodes in 2016: 1.) centered 14-15 November and 2.) 24-25 December. Two more days of data and shortening the time interval to 1 day reveal that the recent heatwave is warmer than that in mid-November. See below…
average (near-surface air) temperature departures from normal, averaged around the world, across east-west belts (2.5 degrees latitude or ~250 km in width north-south) separately for land and ocean areas.
The patterns in the two time periods are similar across the globe. Averaging across latitude is problematic because at the North Pole, the area is much much smaller compared to the equator. Yet, we don’t see large variations at the South Pole as the North Pole. We see a huge Arctic Ocean warm anomaly and a smaller but distinct cold anomaly over land between roughly 50 and 70 deg. N latitude.
Besides being alarmed we’re in uncharted climate territory driven by abrupt human-driven climate change, the concern I have is how the record low Arctic sea ice may be promoting cold-air outbreaks and storminess across the mid-latitudes this cold season.
The image underscores the distinction between ocean and land and thus points to there being something to the pattern: “Warm Arctic, Cold Continents”. What are the impacts? Why should we care? For one, the patterns indicate a system changing state. For two: That change probably affects the frequency and persistence of weather, a hallmark of climate change; changing extremes… more hots and ironically sometimes sharper colds.
Planetary ‘Heat Engine’
Useful to bear in mind that the *normal* excess heating of our planet in the tropics drives all weather and the hydrological system, including polwe-ward oceanic heat transport. Anthropogenic climate heating increases this poleward heat transport, so no surprise the Arctic is heating.
Warm Arctic Cold Continents
Chris Mooney at Washington Post wrote an excellent review, interviewing leading scientists on the issue. Judah Cohen and others published findings that the Warm Arctic Cold Continents pattern is promoted by negative Arctic Oscillation index (AO has been negative in recent weeks) and above average snow cover (recent snow cover is not far under normal for N America and appears above average for Eurasia). Above average Eurasian snow cover favors negative AO (see Cohen et al. 2013). Sea ice decline is shown to moisten Arctic lower atmosphere and promote snow which may reinforce the sea ice decline / cold Eurasia through cold core high pressure over Siberia. James Overland (NOAA, PMEL) found (2009) the normal zonal flow dividing into two, promoting cold air outbreaks to lower latitudes, e.g. what some have called the ‘Siberian Express’ or what can also be a Canadian continental cold air outbreak. see http://www.polarresearch.net/index.php/polar/article/view/15787
By the way
A damping feedback is that thin ice grows fast, provided air temps are sub-freezing, which just isn’t the case around Svalbard where warm air is transported into the Arctic through the main atmospheric and oceanic conduit, the North Atlantic.
I participated in this residency last summer, strongly recommend…
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Master’s student Karina Hansen appeared at the door to my office at GEUS: “something looks strange” at Spalte Glacier connected to the 79 Glacier far northeastern Greenland.
In Danish, Spalte means “split” or “crevassed”.
The ~9 km wide Spalte Glacier is a tributary of the 79 Glacier which today has the Arctic’s largest ice shelf. The ice shelf forms the end of the North East Greenland Ice Stream, the only Greenland ice stream clearly reaching the highest elevations.
2016 aerial of ‘the new rift’ from Nat J. Wilson
7 Sept Sentinel 2 image from Jens Jacobsen of DMI’s Greenland Ice Service
We observed that between 14 Aug., 2015 and 3 September 2016, a marine-terminating tributary of the 79 fjord glacier, the Spalte Glacier flowing into Dijmphna Sound has detached and area (more than 95 km2) roughly the area of Manhattan Is.
The detachment of the ice shelf fragment appears to be nearly 100% complete.
The floating ice shelf fragment appears to have split into more than one piece already. But the main fragment have not floated away yet. I expect that will happen this year or next.
The fracturing and detachment is partly due to glacier dynamics (flow, stress, strain, pre-existing fractures).
Whether the ice shelf detaching is the consequence of the record warm ‘summer’ (June through August) observed at the DMI Danmarkshavn meteorological station (332 km to the south) is an obvious question.
Using Danish Meteorological Institute air temperature data c/o John Cappelen, the absolute summer temperature at Danmarkshavn was +4.9 C, producing a +2.3 C anomaly from the 1981-2010 “normal” period having temperature +2.6 C.
At Station Nord (220 km to the north) July temperatures were +1.9 C above the 1981-2010 period. Absolute July temperature at Station Nord was +5.9 C, producing a +1.9 C anomaly from the 1981-2010 ‘normal’ period having temperature +4.0 C). The Station Nord summer average temperature was +3.1. Normal is +2.3. So the Station Nord summer temperature anomaly was +0.8 C.
With a few exceptions, marine terminating outlets of the Greenland ice sheet have been retreating in recent decades. Box and Hansen (2015) surveyed 45 of the widest Greenland glaciers, which between 1999 and 2015 collectively lost an area of 1799 square km.
A Clear Statistical Pattern
Summer air temperature records at all 11 Danish Meteorological Institute stations around Greenland are correlated with glacier front area change… in warm summers, more ice area is lost. At 4 of the 11 sites, the confidence in that correlation is above 95%. At 7 of the 11 sites, the confidence in that correlation is above 80% (Box and Hansen, 2015). The physical mechanisms at work are probably hydrofracture in which the weight of water, being more than ice, adds force that can disaggregate ice (e.g. Weertman, 1973; Van der Veen, 1998) and forced convection driving more heat exchange between the (overall warming) ocean and the ice underbelly.
USGS Landsat 8 image sequences below prepared by Karina Hansen and myself.
In August 2010, the longest ice shelf connected to the Greenland ice sheet at Petermann Glacier (also then the Arctic’s largest ice shelf) calved 245 km2. Petermann ice shelf disintegration continued with a 140 km2 calving in 2012 (Jensen et al. 2015). The largest and most consistent (year to year) changes in Greenland glacier area are concentrated in the north of the island (Howat and Eddy, 2011; Box and Decker, 2011). The largest Greenland and Arctic ice shelf is now at the front of the North East Greenland Ice Stream.
Box, J.E. and D.T. Decker, 2011: Greenland marine-terminating glacier area changes: 2000–2010, Annals of Glaciology, 52(59) 91-98.
Box, J.E. and K. Hansen, 2015. Survey of Greenland glacier area changes, PROMICE newsletter 8, december 2015, http://promice.org/Newsletter_08.pdf
Jensen, T., J.E. Box, and C.S. Hvidberg, 2016. A sensitivity study of annual area change for Greenland ice sheet marine terminating outlet glaciers: 1999–2013. Journal of Glaciology, 2016 doi:10.1017/ jog.2016.12
Howat, I.M. and A. Eddy. 2011. Multidecadal retreat of Greenland’s marine-terminating glaciers. J. Glaciol., 57(203), 389–396.
Van der Veen, C. J., 1998: Fracture mechanics approach to penetration of surface crevasses on glaciers. Cold Reg. Sci. Technol., 27, 31–47.
Weertman, J., 1973: Can a water-filled crevasse reach the bottom surface of a glacier? IAHS Publ., 95, 139–145.
Our new study reveals that under warm and wet conditions, atmospheric heat can melt the lower 1/3 of the Greenland ice sheet elevations more than under sunny conditions. This was especially so during the 2012 heat wave when a record warm North America loaded the air with heat and moisture that drifted to Greenland.
We recorded the largest ever observed daily and annual surface melt rates on Greenland under PROMICE. The 8-11 July, 2012 heat wave produced 0.9 m (3 ft) of ice melt for a yearly total of 8.5 m (28 ft), actually 9% less than the 2010 annual value of 9.2 m (30 ft). The peak daily melt rate was 0.28 m (11 inches) occurred on 11 July. To capture such high melt rates, we use a 12.4 m (40 ft) long ruler.
A persistent air flow that drove air up and over west Greenland prevailed for 6 summers (2007 to 2012), parts of 2015, and in other years. This is the same kind of “atmospheric river” that can replenish California’s moisture deficit and cause flooding. In the case of Greenland, if it’s summer and air temperatures are high enough, there will be no snow, just rain and atmospheric heat delivered to the ice surface can do untold damage to the surface.
The study decomposes the ice melt energy into contributions. Together, atmospheric heat and condensation delivered more energy to the lower elevations of the ice sheet than absorbed sunlight during pulses in July and August 2012. It’s counterintuitive that under cloudy conditions there can be more melting, especially because the surface is so dark in this lower 1/3 of the ice sheet elevations. It goes to show that the ice sheet melt does not get a break just because the sun is blocked.
Climate models under-represent this effect, by our estimate by a factor of two, and with the frequency of warmer air masses driven over Greenland expected to increase with climate change (Collins et al., 2013), the impact of atmospheric heat and condensation will probably bring Greenland ice melt loss faster than forecast.
Collins, M., R. Knutti, J. Arblaster, J.L. Dufresne, T. Fichefet, P. Friedlingstein, X. Gao, W.J. Gutowski, T. Johns, G. Krinner, M. Shongwe, C. Tebaldi, A.J. Weaver, and M. Wehner, (2013), Long-term Climate Change: Projections, Commitments and Irreversibility. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Fausto, R. S., D. van As, J. E. Box, W. Colgan, P. L. Langen, and R. H. Mottram (2016),The implication of nonradiative energy fluxes dominating Greenland ice sheet exceptional ablation area surface melt in 2012,Geophys. Res. Lett., 43, doi:10.1002/2016GL067720.
Below are some 2-day temperature anomaly (relative to 1981-2010 climate “normal”) maps I made using an observationally-constrained US product indicating peak “green Christmas” American warmth (+17 Celsius temperature anomaly) centered over looks like Kentucky 25-27 Dec.
Isotherms are each 2 C, odd numbers
27-29 (and 28-30) Dec was a +25 Celsius above normal north of the Kara Sea, Russian High Arctic, between island archipelagos of Franz Josef Land and Severnaya Zemlya.
The message of ‘north pole melting’ are irksome seeing how the warm anomaly is centered over northern Kara Sea and part of the Arctic Ocean, barely abutting 90 N latitude.
I made some calculations to address two obvious and important questions regarding CO2 sequestration.
To sequester all of the annual atmospheric increase in CO2 with a citrus forest having a 8.3* tons per hectare per year CO2 uptake, an area equivalent with three times that of Australia would need to be in active cultivation. Using a value of 30 tons per hectare, representative of C4 plants like corn, sorghum, sugar cane , one gets 0.8 x Australia. Yet, as those crop products are consumed and the byproducts decompose, the carbon finds its way back to the atmosphere.
Question: What fraction of Earth’s land area would be needed to sequester the 50 ppm CO2 surplus we currently have in our atmosphere, 50 ppm above the upper safe limit of 350 ppm?
It’s not a fraction, per se. No. Seven times Earth’s land area would need to be in cultivation. I earlier had a more optimistic value based on 30 tons per hectare, half the Earth’s land area would need to be in cultivation. Yet, unfortunately, the associated crops are not suited for long term sequestration.
ps. The calculations are on one of the 9 benefits of the massive scale tree planting I believe we need to increase climate stability and peace globally:
humidification of ground and air
wildlife habitat restoration
human habitat creation
employment in forestry and related industry
sustainable timber production
sustainable economic development modeling
* I had earlier taken 30 tons per hectare from an innacurate source. So I reran the calculation using 8.3 tons per hectare after .
Sometime May, 2014 AirZafari (+299 55 28 19) 13 year old guest photographer Ruben Wernberg-Poulsen captured a new perspective on massive Greenland glacier calving. In addition to the massive scale of the event seen clearly from the air, I think we’ve never seen that basal ice so clearly and so graphically from this birds eye perspective.
The video is from none other than the site than that which grabbed headlines as the world’s fastest glacier calved a giant area (12.4 sq km) and retreated (at least temporarily) to a new record minimum between 14 and 16 August, 2015 .
A rough dimension of the 2014 iceberg in the aerial video suggests a volume of ~180 million cubic meters of ice. If spread out over the Washington DC Mall from the Capitol steps to the Washington Monument (1.8 km x 0.4 km), this ice would have a depth (~375 m) more than twice the 169 m height of the Washington Monument.
Sapphire blue basal ice
Extreme pressure from 500-900 m ice overburden plus extreme strain due to friction between the glacier and its bed, strain heating, all seem to compress air bubbles straining the white ice into denser blue ice. Else, likely pressure melting, possible freeze-on of melt water or sea water may also be at play to produce the curious sapphire blue basal ice on display in this extremely large iceberg calving event.
Commentary on the 12 sq km event 14 to 16 August, 2015 
It’s impressive to see the Jakobshavn glacier retreat further, to a new record position upstream.
I wouldn’t say it’s the largest calving event to occur. The glacier lost a larger area between 2002 and 2004, a floating ice shelf. What’s different now: the ice is grounded or near floatation.
There is an interesting interplay to consider; accelerated forward motion of ice given loss of internal flow resistance on calving that will move the ice front forward quickly to replace the void. So, in not many days, the calving front may be back to the position as in the before image.
The calving front position represents the dynamic interplay between calving, producing front migration upstream and forward flow. Hypotherically, that dynamic could be in balance; no net front position change over time. Or the front could be in imbalance with retreat upstream as is the case in point.
This and most other Greenland glaciers are thinning (vertically), having the effect of un-grounding the ice from the bed at the glacier front. As this is a flooded, underwater system, these glaciers have because of buoyancy forces, what is called ‘marine instability’, allowing the glacier to retreat more quickly as they have fronts near or at floatation. Recent West Antarctic Ice Sheet glacier retreat (e.g. Rignot and others, 2014) suffers from the same marine instability.
This is an inherently unstable system given that the bed of the glacier is underwater several 10s of km upstream.
In this Greenland case, there is an upstream reverse bed slope, the bed gets deeper upstream at some point, not far from where the calving front has retreated to now. Further retreat upstream can be to deeper ice. This is unstable, so an even further retreat will occur given likely continued thinning.
A negative feedback here, something to dampen that instability, is an increase of ice flooding into the void from the sides of the flow, re-jamming it up a bit (regaining internal flow resistance), like partially recorking the flow.
There is a titanic struggle here between accelerated flow [due to loss of flow resistance from calving] and ice flooding into the void, partially re-jamming it up. Given likely continued thinning*, the winner is the loser, of more ice.
* from likely increased surface melting, likely increasing ocean temperatures. However, from year to year (the weather of climate), we may have a cold year that reverses this activity, leading to a short term advance, amid a longer term retreat observed at this an other Greenland glaciers in the past decade.
Rignot, E., J. Mouginot, M. Morlighem, H. Seroussi, and B. Scheuchl (2014), Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011, Geophys. Res. Lett., 41, 3502–3509, doi:10.1002/2014GL060140.
Thanks Ruben Wernberg-Poulsen for capturing and sharing the video with World of Greenland. Thanks to Malik Milfeldt for the tip.
from K. Mankoff …A newish class of algorithms that have been classified under the name “structure from motion” or SfM. While these algorithms have been in use in the robotics / computer science / other domain for over a decade (Microsoft released an implementation titled “PhotoSynth” several years ago), they have not yet been widely used in the Earth Science domain. This is changing.
Three papers have come out in the past few months introducing SfM to Earth Scientists, providing case studies:
1. It is possible to make 3D models using photographs using freely
available software (eg SfM toolkit, bundler, CMVS, PMVS), but packages
like Photoscan (mentioned by Matt) are vastly easier to use and
contain already the tools required to geolocate your point cloud, and
do some error analysis. I’ve built both an implementation of
bundler/CMVS/PMVS in Ubuntu Linux, attempted to install and run
SfMtoolkit in Windows 7, and managed to get my hands on Photoscan for
Linux. I don’t use bundler-> CMVS or SfMtoolkit anymore. One key
reason is that I can give photoscan apriori image coordinates for use
in its bundle adjustment, and get some ideas about predicted vs
adjusted camera positions (error). The other is that I don’t have to
chase *nix libraries for every new build.
2. On the down side, SfM algorithms struggle a little on ice, since
they rely on inhomogeneous imagery to work with. It is very easy to
make models of say, Antarctic stations. It is not very easy to make
great models of sea ice unless there are lots of features and the
light is good. Mountain glaciers or snowpacks on sunny days, however,
should provide great subjects!