It is now likely 2017 will see below average ice loss (at the surface, due to melting). And this is despite strong early and late May melt episodes due to overall warmth in May. We have seen below average Greenland June air temperatures despite warm temperatures over Siberia, the Arctic Ocean, Alaska, etc.
See graphic below how the albedo over the ice sheet declines through the year, as normal, then the 27 June to 5 July jump in the blue curve ‘reflects’ (pun intended) mid summer snowfall.
Another graphic below shows the Greenland whiteness (albedo) map is overall very blue around the periphery where most melting occurs…
Weather or Climate?
Danish Meteorological Institute: Jesper Rosberg explains, “we have seen a persistent positive North Atlantic Oscillation this summer and the jet stream has been very far south of Greenland with very cold air over the ice sheet, so the precipitation falling this summer has mostly been snow, rather [than] rain.”
Still, with global atmospheric absolute humidity rising due to warming, now all weather systems form in an environment that is wetter and warmer on average. So, as I see it, it’s simple to expect the average weather system to dump more precipitation, whether that is rain or snow.
More Rain With Warming?
Indeed, over Greenland, we already find more rain at the expense of snow with climate warming. However, the increased rain is concentrated at the lowest 1/3 of elevations around the ice sheet periphery and anyway is so far not at play this year.
So, I’ve presented that in a warmer atmosphere, higher absolute humidity, increased potential (and actual) precipitation rates… We see a global pattern of precipitation increase. Now, what may seem ironic is that soil moisture can decrease in a warming climate despite increased precipitation. How? evaporation rates increase more than soil recharge rates. On glaciers in the Arctic, we still get more net ice loss. Why? The increase in melting is larger than the increase in snowfall. So, warmer Arctic, more snow, is an example of a negative feedback.
- Box, J.E., N. Cressie, D.H. Bromwich, J. Jung, M. van den Broeke, J.H. van Angelen, R.R. Forster, C. Miège, E. Mosley-Thompson, B. Vinther, J.R. McConnell. 2013. Greenland ice sheet mass balance reconstruction. Part I: net snow accumulation (1600-2009). Journal of Climate, 26, 3919–3934. doi:10.1175/JCLI-D-12-00373.1
- 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.
- Hartmann, D.L., A.M.G. Klein Tank, M. Rusticucci, L.V. Alexander, S. Brönnimann, Y. Charabi, F.J. Dentener, E.J. Dlugokencky, D.R. Easterling, A. Kaplan, B.J. Soden, P.W. Thorne, M. Wild and P.M. Zhai, 2013. Observations: atmosphere and surface. In: 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.), Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press.
- Kapsner, W.R., R.B. Alley, C.A. Shuman, S. Anandakrishnan and P.M. Grootes. 1995. Dominant influence of atmospheric circulation on snow accumulation in Greenland over the past 18,000 years. Nature, 373(6509), 52–54.
In partnership with Adventure-preneur Ramon Larramendi and trace chemist Ross Edwards, the Dark Snow Project is to sample snow across Greenland May 21 – 22 June, 2017.
The key innovation is using wind & solar energy.
We are crowdfunding this activity.We don’t have all our costs covered. But the work is too cool to not do and we’re confident people like you can help us make it happen (click here).
A 3 minute video…
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??
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.
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.
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.
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.
Warm Arctic Cold Continents
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.
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.
- 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.
- 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.