J. Climate Editor Anthony J Broccoli deserves thanks for, presumably, working extra in recognition of critical timeline.

Figure 1. Western ice sheet snowfall totals are 30%-70% of normal. Brown areas have less than ‘normal’ precipitation. Blue/purple areas are anomalously ‘wet’. The precipitation anomalies are calculated from ‘re-analyses’ data after Kalnay et al. (1996).

Multiple melt factors combine to increase the odds of more melt water runoff from the ice sheet during the 2013 melt season:

1. less ‘cold content’ of snow to melt away (ablate) for a given energy input before bare ice is exposed;
2. a longer period of exposed darker bare ice, in this case weeks earlier bare ice exposure is likely unless a big snow dump before or during the coming warm season;
3. Less snow leads to a smaller refreezing capacity in the lower accumulation area. Thanks Robert Fausto of GEUS for reminding me of this one.
4. a possible higher concentration of light absorbing impurities per unit volume of snow, assuming that the impurities are deposited whether or not it snows.

This pattern results from a persistent atmospheric anomaly, blocking cold air transport southward along west Greenland, producing relatively warm temperatures there while northwestern Europe has had a cold winter (Figure 2).

Figure 2. The data after Kalnay et al. (1996) indicate tendencies toward offshore flow over western Greenland, opposite for what is needed to produce normal snowfall. 

The precipitation anomaly is manifesting in abnormally low land and ice sheet reflectivity (albedo) (Figure 3).

Figure 3. April 2013 surface albedo (a.k.a. reflectivity) anomaly. Substantially lower albedo anomalies on land are due to the dearth of snow revealing a much darker underlying tundra. The red areas across the northern 1/3 of Greenland are uncertain due to low solar illumination angles.

Low snowfall anomalies precondition Greenland ice for enhanced melt (Mote, 2003; Box et al. 2005; 2012), especially for the western ice sheet where the snowfall amounts are less than over the east.

From 20 March – 20 April, the snow drought drove ice sheet reflectivity well below values in 13 years of (NASA MODIS sensor) satellite observations since 2000 (Figure 4). Negative North Atlantic Oscillation (NAO) has promoted Greenland heating, melting and snow drought for now 6 summers in a row (Tedesco et al. 2013; Fettweis et al. 2013). Negative late winter NAO packs a similar punch. Negative NAO has prevailed much of the past decade and is largely to blame for Greenland’s astonishing melt increase. Whether negative NAO is promoted by an earlier loss of snow on land and declining Arctic sea ice area is something I’ve been wondering about.

Figure 4. Greenland ice sheet (land excluded) reflectivity or albedo updated after Box et al. (2012).

Then the weather flipped and ice sheet reflectivity rebounded toward normal values in the latest 10 days (Figure 4). Ice sheet reflectivity and accumulated precipitation remains lower than average for the year to date through 1 May (not shown), it therefore remains more likely than not that we’ll see a big melt in 2013.

References

• Box, J.E., L. Yang, J. Rogers, D. Bromwich, L.-S. Bai, K. Steffen, J.C. Stroeve, and S.-H. Wang, 2005: Extreme precipitation events over Greenland: Consequences to ice sheet mass balance. Preprints, Eighth Conf. on Polar Meteorology and Oceanography, San Diego, CA, Amer. Meteor. Soc., CD-ROM, 5.2. PDF
• Box, J. E., X. Fettweis, J.C. Stroeve, M. Tedesco, D.K. Hall, and K. Steffen: Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers, The Cryosphere, 6, 821-839, doi:10.5194/tc-6-821-2012, 2012. open access
• Fausto, Robert, provided point 3 above.
• Fettweis, X., Hanna, E., Lang, C., Belleflamme, A., Erpicum, M., and Gallée, H.: Brief communication “Important role of the mid-tropospheric atmospheric circulation in the recent surface melt increase over the Greenland ice sheet”, The Cryosphere, 7, 241-248, doi:10.5194/tc-7-241-2013, 2013.
• Mote, T., 2003: Estimation of runoff rates, mass balance and elevation changes on the Greenland ice sheet from passive microwave observations. Journal of Geophysical Research-Atmospheres, 108, 4056. DOI
• Kalnay et al.,The NCEP/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437-470, 1996.
• The data are constrained by measurements from weather stations, weather balloons, ships, aircraft, and satellites. I total precipitation for 1 January – 30 April, 20130 and difference these with the average total for the same interval over each year in the most recent 30-year ‘climate normal’ spanning 1981-2010.
• Tedesco, M., Fettweis, X., Mote, T., Wahr, J., Alexander, P., Box, J. E., and Wouters, B.: Evidence and analysis of 2012 Greenland records from spaceborne observations, a regional climate model and reanalysis data, The Cryosphere, 7, 615-630, doi:10.5194/tc-7-615-2013, 2013. open access

While we were not permitted to use black carbon, the erosion of the ice sculpture by the sunlight and dark grey chalk we were sprinkling on it exceeded my expectations.

While we were not permitted to use black carbon, the erosion of the ice sculpture by the sunlight and dark grey chalk we were sprinkling on it exceeded my expectations.

We were working the crowd, having one-on-one (or two) conversations and getting $5-$20 pledges from half of the folk, entirely within reason. It was interesting to see some folks’ interest change to vacancy once the description turned to an ask for $. It was exhausting giving the “elevator pitch” over and over and over. It was hard to not let rejection get to you, especially as the day wore on and the fatigue grew. My favorite pseudo-rejection experience was pitching to three very wealthy looking foreigners, really nice clothing, accessories; they listened with apparent interest and when I asked for $ support, they nodded… I got five dollars.

What did not happen and I cannot be surprised is some wealthy person pledging $1000 or so. We had I think two $100 donations another two $50 pledges but I think these were from friends. What I learned from this was it’s hard work getting donations using the “elevator pitch” on the street to innocent bystanders. Who likes getting asked for money by a stranger?

For the day, we netted ~$1200, in line with my expectations. The mGive text donation may add up to more but I doubt another $1200. We spent far more on the installation and yet more of the investment was time. I’m not discouraged because I would not be surprised that the visibility from this event evolves into more support as time goes on.

I guess at least 5000 people stopped and looked at the sculpture. Many of them took photos and I hope that they shared those with their social network. Thus, the Dark Snow Brand gains traction.

I think we had no doubt the most interesting installation at the Earth Day event, also what people told us. The green car show next to us was a formidable competitor.

The sculpture was produced at cost by Stan (The Ice Man) from upstate New York. He is one of now dozens of people spending their free time to contribute to this Earth Day something of memory, something to inspire, and this is a fundraiser for a Greenland expedition I’m organizing for this June.

We aim to sample Greenland’s ice in key areas to measure how much of the record 2012 melt is attributable to wildfire soot absorbing more sunlight, multiplying the effect of warming.

I had worked the previous years publishing an article, live June 2012, just prior to this “surprising” melt. Well, the 100% surface melting wasn’t that surprising because as the paper predicted warmth had only to remain at the 2010 or 2011 level… “Thus, it is reasonable to expect 100% melt area over the ice sheet within another similar decade of warming”

June 2012 was already emblazoned in my memory, the fires of my home state were at record level. I had been focused on the effects of heat driving melt.  But now, the soot factor had to be incorporated into the calculation, adding another layer of precision and complexity.

An intermediate step was to examine atmospheric laser scans from NASA’s CALIPSO satellite. That search quickly revealed smoke clouds drifting over and apparently in contact with the ice sheet surface.

The ice sculpture work is by Stan the Ice Man. That's me Jason Box in the lower right advertising the stickers that supports get with a $25 donation at http://www.indiegogo.com/projects/dark-snow-project/ and at the Earth Day event. The ancient Greenlandic-inspired glacier glasses are going to donors at the NY event who give at the $400 level. The glasses are also available at http://www.indiegogo.com/projects/dark-snow-project/ but are discounted for the Earth Day event.

The ice sculpture is a metaphor for the connection between human agency, ice and climate, linked with sea level rise, fire and ice.  The sculpture is instead of another chart or table of data or thousand page scientific assessment.

The underlying message is the need to work toward harmony between humans and the environment upon which we depend.

To make the Greenland expedition happen, to move the science forward together, we’re asking you in the US to “Txt DARKSNOW to 50555 to pledge $10. Supporters will get a response asking to share that they have pitched in, to their social network. With just another few clicks, the fund raising can have some virality.

Or consider giving through our web site.

Incidentally, I had to go back and make corrections…The voice recognition I increasingly use in lieu of typing translates Earth Day as “birthday”. And why not celebrate the Earth’s birthday?

Have an ice Earth Day!

Given the non-trivial complexity of the issue and that Greenland has been contributing more than 2:1 that of Antarctica to global sea level in the recent 19 years (1992-2010)^[iv], let’s not consider Greenland of neglible policy relevance until that ratio is 1:1 if not reversed, say, 0.5:1. Greenland, currently the leading contender with surface melting dominating its mass budget^[v], the positive feedback with surface melting and ice reflectivity doubling Greenland’s surface melt since year 2000^[vi]. Professor Richard Alley weighs in again: “We have high confidence that warming will shrink Greenland, by enough to matter a lot to coastal planners.”

That’s not to say that Antarctica couldn’t take over from Greenland the position of number 1 global sea level contributor in the foreseeable future. Nor should one be surprised if it did, given that Antarctica contains a factor of 10 more ice than Greenland^[vii],[viii].  And it is probable that the planetary energy imbalance^[ix] caused by elevated greenhouse gasses, expressed primarily through massive oceanic heat uptake^[x], is delivering enough erosive power to destabilize the 3.3 m of sea level^[xi] in the marine-based West Antarctic ice sheet. Yet, for today, consider also that climate change if increasing Antarctic precipitation a few percent can tip its mass balance toward the positive, lessening its sea level contribution^[xii] even while its glaciers retreat.

Irrespective of sea level forcing, through its ice mass budget Greenland plays an important role to North Atlantic climate through ocean thermohaline circulation, even being suggested as the Achilles heel of the global climate system^[xiii]. I wouldn’t tell our European friends Greenland’s hardly policy-relevant when climate change offers higher amplitude extremes in precipitation if not also temperature, as North Atlantic climate shifts in partial response to changes in neighboring Greenland.

Key differences between the modern Anthropocene and the Eemian interglacial suggest anthropogenic climate change may drive a different cryosphere response than during the Eemian…

Today, greenhouse gas concentrations are rising beyond 120% to 250% of peak Eemian values^[xiv],[xv], driving today’s global warming and the aformentioned ocean heat content uptake that contrasts from the Eemian when warming was driven by northern latitudes receiving 30-50 Watts per sq. meter more solar energy, a more regionally-forced climate change. Anthropocene climate is forced an estimated 4/5 by by elevated greenhouse gasses and black carbon aerosols^[xvi], the latter rising recently in significance after being more completely bounded^[xvii]. Anthropogenic warming is clearly overwhelming the modern orbital cooling^[xviii] and the decrease in solar output since the late 1970s^[xix].

Because the Greenland ice sheet surface undergoes much more seasonal melting than the surface of the Antarctic ice sheet, in Greenland decanting a factor of 2 increase of meltwater runoff annually since 2000^[xx], anthropogenic sources of light absorbing impurities provide a mechanism to multiply the cryospheric albedo feedback in ways presumably not occurring during the Eemian. Today, the combination of a.) land clearing by humans using fire, b.) industrial soot from fossil fuel combustion, and perhaps c.) larger fires the a legacy of fire suppression are in contrast to Eemian wildfire, that (as far as we know) did not include human factors. All me to here plug Dark Snow Project^[xxi] that is currently soliciting donations to crowdfund a field and laboratory campaign designed to assess the impact of increasing wildfire on darkening the Greenland ice sheet.

Richard Alley: “While Antarctica is relatively unknown, Greenland is relatively known and therefore useful to guide policy even if the ice sheet becomes second most important to sea level, and to provide guidance to Antarctic colleagues [in surface melt studies]”

In the end, what matters to our concerns about the rate of sea level rise is the sum total volume change of all land ice. As long as glaciers and ice caps (GICs) (excluding the ice sheets) remain significant contenders (GICs lost mass at a rate of 148 ± 30 Gt per year from January 2003 to December 2010)^[xxii], Antarctica lost 40% less during this period than GICs, and Greenland lost more than the two combined, we should stay focused on understanding the dynamics of all crysopheric systems in relation to the serious perturbation imposed by human activity. The Eemian has its own limits of utility in informing humanity of the trajectory we’re on.

Works Cited

Sifting through data from NASA’s Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) revealed smoke clouds near, over, and even in contact with Greenland.

The discovery was reported widely ^{1, 2, 3, 4, 5, 6, 7, 8, 9} .

Myself and intern Nathaniel Henry find other similar cases in the CALIPSO data, most are less obvious because the smoke disperses into the atmosphere from its source. In the above case, the source fire was active in nearby Labrador for several days.

Stay tuned to meltfactor.org as this story evolves and as we attempt the first-of-a-kind crowdfunded Greenland expedition via http://darksnowproject.org/

Fig. 1. Surface solar reflectivity retrieval from the NASA MODIS sensor on the Terra satellite

Fig. 2. Land surface temperature retrieval from the NASA MODIS sensor on the Terra satellite.

For more information about these analyses see http://bprc.osu.edu/wiki/Greenland_Ice_Albedo_Monitoring and http://bprc.osu.edu/wiki/Greenland_Ice_Surface_Temperature_Monitoring

Area changes at select Greenland marine-terminating glacier outlets are measured in consecutive annual end-of-melt-season NASA MODIS satellite images (Box and Decker, 2011). Here, the same approach is applied to updated our area change estimates to span the 12 annual intervals since year 2000.

Flying over Ilulissat glacier this July, it was stunning to notice how retreat has proceeded upstream into a northern tributary, producing effectively two main calving fronts to this ice sheet outlet. The faster stream from the west off the right side of the photo also remains in retreat. The glacier is based below sea level more than 75 km inland (Thomas et al. 2011).

On 22 July, 2012, the northern branch of the Ilulissat (a.k.a. Jakobshavn) glacier had retreated to a new minimum. It's arguably divided into two glaciers, one stream from the northeast (featured here) and a faster stream from the west off the right side of the photo. Photo - J. Box

The Ilulissat glacier is considered the most productive in the Greenland in terms of ice flow discharge into the ocean (see e.g. Rignot and Kanagaratnam, 2006), even the fastest continuously flowing glacier in the world.

Thomas et al. (2011) summarize key aspects of what is known of this glacier, including its retreat history since 1852, its doubling in speed in the 2000s:

Ilulissat glacier ” has a balance discharge (equivalent to total snowfall within its catchment basin) of about 30 km3 ice per year (Echelmeyer et al., 1991), and converges into a rapidly moving trunk ~4 km wide, that flows into a deep fjord on the west coast of Greenland. Until recently, a 15‐km floating glacier tongue was wedged between the fjord walls. VHF‐band radar surveys (J. Plummer et al., A high‐resolution bed elevation map for Jakobshavn Isbræ, West Greenland, submitted to Journal of Glaciology, 2011) show the fastest part of the glacier flowing in a deep trough, more than 1000m below sea level. Between 1850 and 1962, the calving front retreated ∼25 km up the fjord, and then stabilized to within 3 km until the mid‐1990s. During the 1980s and early 1990s, the glacier had a small positive mass balance [Echelmeyer et al., 1991]. Then, probably in 1997, the glacier began to thin (Thomas et al., 2003) at rates that increased to 15 m per year near the calving front, where its speed almost doubled to >12 km per year by 2003 as the floating tongue finally broke up, with continued increases since (Joughin et al., 2008), (Figure 1). Progressive retreat of the grounding line resulting from the rapid thinning reduced the basal and lateral drag acting on the glacier [Thomas, 2004], and by 2005 the glacier was thinning by >2 m per year at a distance of 50 km from the calving front, increasing to >5 m per year between 2005 and 2007.

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. .PDF
• Echelmeyer, K., T. Clarke, and W. Harrison (1991), Surficial glaciology of Jakobshavns Isbrae, west Greenland: Part I. Surface morphology, J. Glaciol., 37(127), 368–382.
• Joughin, I., W. Abdalati, and M. Fahnestock (2004), Large fluctuations in speed on Greenland’s Jakobshavn Isbrae Glacier, Nature, 432(7017), 608–610, doi:10.1038/nature03130.
• Joughin, I., I. Howat, M. Fahnestock, B. Smith, W. Krabill, R. Alley, H. Stern, and M. Truffer (2008), Continued evolution of Jakobshavn Isbrae following its rapid speedup, J. Geophys. Res., 113, F04006, doi:10.1029/2008JF001023.
• Rignot, E. and P. Kanagaratnam (2006), Changes in the velocity structure of the Greenland Ice Sheet. Science, 311(5673), 986– 990.
• Thomas, R. (2004), Force‐perturbation analysis of recent thinning and acceleration of Jakobshavn Isbræ, Greenland, J. Glaciol., 50(168), 57–66, doi:10.3189/172756504781830321.
• Thomas, R., W. Abdalati, E. Frederick, W. Krabill, S. Manizade, and K. Steffen (2003), Investigation of surface melting and dynamic thinning on Jakobshavn Isbrae, Greenland, J. Glaciol., 49, 231–239, doi:10.3189/ 172756503781830764.
• Thomas, R., E. Frederick, J. Li, W. Krabill, S. Manizade, J. Paden, J. Sonntag, R. Swift, and J. Yungel (2011), Accelerating ice loss from the fastest Greenland and Antarctic glaciers, Geophys. Res. Lett., 38, L10502, doi:10.1029/2011GL047304.

Fig. 1. Greenland clear sky ice surface temperature anomaly relative to the 2000-2009 baseline.

To a first approximation, when ice sheet temperature increases, its reflectivity decreases (Box et al. 2012). After a low temperatures 10-13 August, 2012 the surface reflectivity of sunlight (a.k.a. albedo) increased from the accumulation of fresh bright snow (Fig. 2). Then as surface temperatures rose again, above one standard deviation of the 2000-2009 average, the ice sheet albedo again dropped 18-23 August, 2012 below previous observations (since 2000), especially at the intermediate elevations of 1000-1500 m where melting in all likelihood remains active this year. As reported by Marco Tedesco, 2012 melting is already setting the record since the late 1950s, and with this late melt season albedo drop and high surface temperature anomaly, this “Goliath” melt has got to be growing.

The daily albedo anomaly map (Fig. 3) indicates widespread low reflectivity, especially at the ice sheet periphery where surface elevations are lower, the atmosphere is warmer, and melting persists. Positive reflectivity anomalies over the northwest ice sheet suggest the return and persistence of fresh snow.

Fig. 3. Daily albedo anomaly map.

About the surface temperature data

Land surface temperature MODIS thermal infrared observations enable retrieval of land surface temperature (LST) under cloud-free conditions at 1 km horizontal resolution. The MODIS MOD11A1 data product is based on daily averaged LST retrievals from swath data and a split-window algorithm using MODIS thermal bands 31 (11 μm) and 32 (12 μm) (Wan et al., 2002). These data have a RMS error 1 deg. C in comparison with independent in-situ observations (Wan et al., 2008), with higher RMS errors found over Greenland (Hall et al., 2008a; Hall et al., 2008b; Koenig and Hall, 2010).

Works Cited

• Box, J. E., Fettweis, X., Stroeve, J. C., Tedesco, M., Hall, D. K., and Steffen, K.: Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers, The Cryosphere, 6, 821-839, doi:10.5194/tc-6-821-2012, 2012. open access
• Hall, D. K., Williams Jr., R. S., Luthcke, S. B., and Digirolamo, N. E.: Greenland ice sheet surface temperature, melt and mass loss: 2000–2006, J. Glaciol., 54, 81–93, doi:10.3189/002214308784409170, 2008a.
• Hall, D. K. J. E. Box, K. Casey, S. J. Hook, C. A. Shuman, K. Steffen, Comparison of satellite-derived and in-situ observations of ice and snow surface temperatures over Greenland, Remote Sensing of Environment, 2008b
• Koenig, L. S., and D. K. Hall, 2010: Comparison of satellite, thermochron and station temperatures at Summit, Greenland, during the winter of 2008/09. J. Glaciol., 56, 735–741.

See also:

Byrd Polar Research Center Near Real-time Greenland Ice:

1. Surface Temperature Monitoring  
2. Ice Albedo Monitoring

@climate_ice on Twitter

Jason Box homepage

larger and more numerous albedo dips

Apparently distinct from previous years in number and intensity of low albedo (evidence of melt) episodes, the 2012 melt season is characterized by 4 anomalous lows, centered on: 2 June (71.4%); 27 June (67.4%); 16 July (64.0%); and 1 August (65.2%).

The albedo lows are punctuated by the brightening effect of snowfall events. There could be a late season melt episode as in 2004 or 2003.

Below, a similar pattern is evident at the highest (coldest) 700 m (2000 ft) of the ice sheet.

lowest albedo since year 1150?

The 16 July low was the lowest in the satellite observational record and coincided with 97% of the ice sheet surface area melting. Previous maximum melt extent values since 1978 (when satellite obseravations begin, this is what NASA meant by “unprecedented”) are under 60% of the ice sheet area. Because the 2012 summer temperature was warmer than previous years (as I tweeted 5 August: June 2012, warmest on record for Greenland’s capital Nuuk since at least 1866 when continuous record keeping began, +7.2 C vs +4.3 C average), warmer than 1929 by at least 0.5 deg. C, and if the near surface air temperature records, continuous since 1840, are any indication (Box et al. 2009) this albedo anomaly and accompanying melt extent is probably without precedent since the Medieval Warm Period when the Norse settled Greenland.  Greenland temperature variability is high and there is evidence during the late Medieval Warm Period of a warm period in year 1150, that is 862 years before present (Kobashi et al. 2011). Other factors than warming that could have temporarily lowered Greenland ice reflectivity include the effect of major volcanic eruptions or wild fires. The latter I speculated here. The former has a noteworthy cooling effect but could conceivably still blanket the ice sheet with low reflectivity soot.

Kobashi et al. 2011 Fig. 1.

The albedo work is based largely on:

• Box, J. E., Fettweis, X., Stroeve, J. C., Tedesco, M., Hall, D. K., and Steffen, K.: Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers, The Cryosphere, 6, 821-839, doi:10.5194/tc-6-821-2012, 2012. open access

Works Cited

• Box, J.E., L. Yang, D.H. Browmich, L-S. Bai, 2009: Greenland ice sheet surface air temperature variability: 1840-2007, J. Climate, 22(14), 4029-4049, doi:10.1175/2009jcli2816.1. PDF
• Kobashi, T., K. Kawamura, J. P. Severinghaus, J.‐M. Barnola, T. Nakaegawa, B. M. Vinther, S. J. Johnsen, and J. E. Box (2011), High variability of Greenland surface temperature over the past 4000 years estimated from trapped air in an ice core, Geophys. Res. Lett., 38, L21501, doi:10.1029/2011GL049444.

See also:

Byrd Polar Research Center Greenland Ice Albedo Monitoring

@climate_ice on Twitter

Jason Box homepage