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Greenland snow survey #MarchForScience

This April, I’m returning to Greenland for two weeks to make a 40 km ski-based snow survey. Myself and two Swiss scientists have a simple goal: to measure how much snow fell since the end of the last summer. The measurements allow us to check satellite, aircraft and modeled snowfall estimates. Our fundamental question: how much snow nourishes Greenland ice? While ice losses have received lots of attention, what about the gains??

snow profile kit

snow profile kit care of M. Jäggi and M. Schneebelli of SLF Davos, Switzerland

While camping on the southern Greenland ice sheet for 8 days, we’ll be taking roughly 20 snow cores down through the 1 to 4 m (3 to 12 feet) of snow that has accumulated since the end of summer 2016. We’ll measure snow density, grain size and liquid water content. The survey is supported by the Danish PROMICE monitoring programme this year celebrating 10 years in operation. NASA’s operation IceBridge is in the loop to overfly our survey line with an ultra high frequency radar we can then calibrate to precisely map snowfall rates across the region.

A fourth person joining us is operating camera equipment for a IMAX and undergroundchannel.dk videos. This way, our efforts have another kind of impact, to inspire people to appreciate environment.

Our expedition coincides with two global climate mobilizations; 1.) a 22 April March For Science (endorsed by both American and European Geophysical Unions and some 100 other science organizations) and 2.) a 29 April People’s Climate March.

It’s meaningful to march (on Greenland ice) in solidarity with these causes, for climate change is a defining issue of our time, whether or not one accepts what science tells us. And unfortunately, the US is now confounded from Washington DC by a brand of deeply cynical politics that threatens our species tackling climate change soon enough. Historically, the largest source of climate changing pollution, the US and DC is turning its back on the Paris Agreement, a global treaty enforcing the ambition to keep climate warming under +1.5 C above pre-industrial. Our species is acting late on this crisis. Already today at +1C above pre-industrial, we’re beginning to see profound damaging effects including increased storm severity, the drying of continental interiors, and melting ice sheets. All of these climate change effects have overall strongly negative impacts, primarily on reducing food and water security for humans and nature that surrounds.

through feb 2017

image via Stefan Rahmstorf https://twitter.com/rahmstorf/status/842049720205864961

At this stage, by supporting dirty energy from projects like the Keystone XL and Dakota Access pipelines, against the will of the majority of people and treaties signed with indigenous first nations peoples, it’s clear US climate denial is a result of a bought-out political system and a fossil fuel dominated economy. US republicans and some democrats are choosing more expensive climate destabilizing energy over cleaner and safer energy systems that benefit people and nature long term.

oil-train2

http://housedemocrats.wa.gov/the-advance/oil-trains-tragedy-just-a-derailment-and-spill-away/

Why fossil energy is behaving like a cornered beast is the plunging price of renewable energy makes end of fossil fuels inevitable. The most profitable industry in history, rather than using their capital and technical capacity to transition itself to become sustainable energy, its leaders like Exxon have chosen an anti-science, greedy, and reckless path.

Fortunately, and despite obfuscation from fossil fuel corporations, fossil energy is clearly emerging as yesterday’s energy. Still, clean energy couldn’t be coming on soon enough given that carbon emissions and concentrations are already so high that we’re losing the ice sheets and harming our oceans through carbonic acidification. Our species needs to find a way to maintain a steep fall rate for carbon emissions for the foreseeable future and engage in what has been largely a missing conversation and action of turning emissions negative until we stabilize somewhere below 350 parts per million CO2. We’re currently more than 40% above pre-industrial CO2. We thus need not only to cut carbon emissions but drawdown many Giga tons carbon from the atmosphere. While an enormous task, it’s possible and urgent to avoid a Mad Max future.

Note: views expressed here are my own.

North Pole Overheating 2016

The combination of 1.) extra ocean to atmosphere heat transfer enabled by record low sea ice and 2.) pulses of warm air from the south has produced stunning large temperature departures from normal.

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…

plot_anom_zonal2016_320-321 plot_anom_zonal2016_359-360
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.
_zonal_interval_1
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.

Separation of Manhattan Is. sized ice shelf pieces from 79 Glacier far northeastern Greenland

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.

nat-jesse-wilson-the-new-crack-looking-toward-dijmphna-sound

2016 aerial of ‘the new rift’ from Nat J. Wilson

20160907_1618_sentinel2a_spaltegletscher-jpg

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.

2016-09-03-2 2015-08-14-2 2014-07-22-2 2013-08-20-2

More context

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.

  1. Work Cited
    Box, J.E. and D.T. Decker, 2011: Greenland marine-terminating glacier area changes: 2000–2010, Annals of Glaciology, 52(59) 91-98.
  2. Box, J.E. and K. Hansen, 2015. Survey of Greenland glacier area changes, PROMICE newsletter 8, december 2015, http://promice.org/Newsletter_08.pdf
  3. 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
  4. Howat, I.M. and A. Eddy. 2011. Multidecadal retreat of Greenland’s marine-terminating glaciers. J. Glaciol., 57(203), 389–396.
  5. Van der Veen, C. J., 1998: Fracture mechanics approach to penetration of surface crevasses on glaciers. Cold Reg. Sci. Technol., 27, 31–47.
  6. Weertman, J., 1973: Can a water-filled crevasse reach the bottom surface of a glacier? IAHS Publ., 95, 139–145.