Earth Day ice sculpture debrief

April 22nd, 2013

Earth Day Sunday 21 April temperatures were not high (max 57 F, 14 C) despite full sun all day. I was down to a T-shirt for 1/10th the day.

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.

Have an ice Earth Day!

April 20th, 2013

Laying awake at 4 AM in a New York City hotel thinking on tomorrow’s Earth Day, and its theme: sea level rise. We’re installing a 4 ton ice sculpture at Union Square. Its characters #DARKSNOW sprawl 40 feet. It’s height is the sea level rise reasonable to expect this century, 5 feet (1.5 m). It’s to be sprinkled with soot symbolizing the effects of increasing wildfire and industrial pollution.

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!

 

icy contenders weigh in

January 27th, 2013

Dahl-Jensen et al. (2013)[i] suggest that the Greenland ice sheet was more stable than previously thought[ii], enduring ~6k years of temperatures 5-8 C above the most recent 1000 years during the Eemian interglacial 118-126k years before present, its loss at the time contributing an estimated 2 m (6.6 ft) of global sea level compared to a total of 4-8 m (13-26 ft)[iii], implying Antarctica was and will become the dominant source of sea level change. Consequently, environmental journalist Andrew Revkin writes: “The dramatic surface melting [in Greenland], while important to track and understand has little policy significance.”

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



[i] Eemian interglacial reconstructed from a Greenland folded ice core, D. Dahl-Jensen, M.R. Albert, A. Aldahan, N. Azuma, D. Balslev-Clausen, M. Baumgartner, A. Berggren, M. Bigler, T. Binder, T. Blunier, J.C. Bourgeois, E.J. Brook, S.L. Buchardt, C. Buizert, E. Capron, J. Chappellaz, J. Chung, H.B. Clausen, I. Cvijanovic, S.M. Davies, P. Ditlevsen, O. Eicher, H. Fischer, D.A. Fisher, L.G. Fleet, G. Gfeller, V. Gkinis, S. Gogineni, K. Goto-Azuma, A. Grinsted, H. Gudlaugsdottir, M. Guillevic, S.B. Hansen, M. Hansson, M. Hirabayashi, S. Hong, S.D. Hur, P. Huybrechts, C.S. Hvidberg, Y. Iizuka, T. Jenk, S.J. Johnsen, T.R. Jones, J. Jouzel, N.B. Karlsson, K. Kawamura, K. Keegan, E. Kettner, S. Kipfstuhl, H.A. Kjær, M. Koutnik, T. Kuramoto, P. Köhler, T. Laepple, A. Landais, P.L. Langen, L.B. Larsen, D. Leuenberger, M. Leuenberger, C. Leuschen, J. Li, V. Lipenkov, P. Martinerie, O.J. Maselli, V. Masson-Delmotte, J.R. McConnell, H. Miller, O. Mini, A. Miyamoto, M. Montagnat-Rentier, R. Mulvaney, R. Muscheler, A.J. Orsi, J. Paden, C. Panton, F. Pattyn, J. Petit, K. Pol, T. Popp, G. Possnert, F. Prié, M. Prokopiou, A. Quiquet, S.O. Rasmussen, D. Raynaud, J. Ren, C. Reutenauer, C. Ritz, T. Röckmann, J.L. Rosen, M. Rubino, O. Rybak, D. Samyn, C.J. Sapart, A. Schilt, A.M.Z. Schmidt, J. Schwander, S. Schüpbach, I. Seierstad, J.P. Severinghaus, S. Sheldon, S.B. Simonsen, J. Sjolte, A.M. Solgaard, T. Sowers, P. Sperlich, H.C. Steen-Larsen, K. Steffen, J.P. Steffensen, D. Steinhage, T.F. Stocker, C. Stowasser, A.S. Sturevik, W.T. Sturges, A. Sveinbjörnsdottir, A. Svensson, J. Tison, J. Uetake, P. Vallelonga, R.S.W. van de Wal, G. van der Wel, B.H. Vaughn, B. Vinther, E. Waddington, A. Wegner, I. Weikusat, J.W.C. White, F. Wilhelms, M. Winstrup, E. Witrant, E.W. Wolff, C. Xiao, and J. Zheng, Nature, vol. 493, pp. 489-494, 2013.

[ii] Substantial contribution to sea-level rise during the last interglacial from the Greenland ice sheet, Kurt M. Cuffey* & Shawn J. Marshall, Nature 404, 591-594 (6 April 2000) | doi:10.1038/35007053

[iii] Kopp, R. E., Simons, F. J., Mitrovica, J. X., Maloof, A. C. & Oppenheimer, M. Probabilistic assessment of sea level during the last interglacial stage. Nature 462, 863–867 (2009). & Dutton, A. & Lambeck, K. Ice volume and sea level during the last interglacial. Science 337, 216–219 (2012).

[iv]A Reconciled Estimate of Ice-Sheet Mass Balance, Andrew Shepherd, Erik R. Ivins, Geruo A, Valentina R. Barletta, Mike J. Bentley,Srinivas Bettadpur, Kate H. Briggs, David H. Bromwich, René Forsberg, Natalia Galin,Martin Horwath, Stan Jacobs, Ian Joughin, Matt A. King, Jan T. M. Lenaerts, Jilu Li,Stefan R. M. Ligtenberg, Adrian Luckman, Scott B. Luthcke, Malcolm McMillan, Rakia Meister,Glenn Milne, Jeremie Mouginot, Alan Muir, Julien P. Nicolas, John Paden, Antony J. Payne,Hamish Pritchard, Eric Rignot, Helmut Rott, Louise Sandberg Sørensen, Ted A. Scambos,Bernd Scheuchl, Ernst J. O. Schrama, Ben Smith, Aud V. Sundal, Jan H. van Angelen,Willem J. van de Berg, Michiel R. van den Broeke, David G. Vaughan, Isabella Velicogna,John Wahr, Pippa L. Whitehouse, Duncan J. Wingham, Donghui Yi, Duncan Young, H. Jay Zwally, , Science, 338 (6111) 1183-1189, DOI: 10.1126/science.1228102,

[v] Partitioning recent Greenland mass loss, van den Broeke, M. R., J. Bamber, J. Ettema, E. Rignot, E. Schrama, W. J. van de Berg, E. van Meijgaard, I. Velicogna and B. Wouters, 2009: Science, 326, 984-986.

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

[vii] BEDMAP: A new ice thickness and subglacial topographic model of Antarctica, Lythe, M.B., D.G. Vaughan, and the BEDMAP Group, 2001:  J. Geophys. Res., 106(B6), 11335–11351.

[viii] A new ice thickness and bedrock data set for the Greenland ice sheet, 1, Measurement, data reduction, and errors, Bamber, J. L., R. L. Layberry, S. P. Gogineni, J. Geophys. Res., 106(D24), 33773-33780, 2001.

[ix] Earth’s Energy Imbalance and Implications, James Hansen, Makiko Sato, Pushker Kharecha, Karina Von Schuckmann, Atmospheric Chemistry and Physics (2011), Volume: 11, Issue: 24, Pages: 39

[x] Global ocean heat content 1955–2008 in light of recently revealed instrumentation problems, Levitus, S., J. I. Antonov, T. P. Boyer, R. A. Locarnini, H. E. Garcia, and A. V. Mishonov, 2009:, Geophys. Res. Lett., 36, L07608, doi:10.1029/2008GL037155.

[xi] Reassessment of the Potential Sea-Level Rise from a Collapse of the West Antarctic Ice Sheet, Jonathan L. Bamber, Riccardo E. M. Riva, Bert L. A. Vermeersen, Anne M. LeBrocq, Science 15 May 2009: Vol. 324 no. 5929 pp. 901-903 DOI: 10.1126/science.1169335

[xii] Snowfall-Driven Growth in East Antarctic Ice Sheet Mitigates Recent Sea-Level Rise, Curt H. Davis, Yonghong Li, Joseph R. McConnell, Markus M. Frey, Edward Hanna, SCIENCE, 308, 24 JUNE 2005

[xiii] Thermohaline Circulation, the Achilles Heel of Our Climate System: Will Man-Made CO2 Upset the Current Balance? Wallace S. Broecker, SCIENCE, 278, 28 NOVEMBER 1997

[xiv] Climate Change 2007: The Physical Science Basis, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change ,Solomon, S., D. Qin, M. Manning, Z. Chen, M,. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.), IPCC (Intergovernmental Panel on Climate Change), 2007. Cambridge University Press, Cambridge United Kingdom and New York, NY, USA, 996 pp.

[xv] Recent Greenhouse Gas Concentrations, Blasing, T.J., DOI: 10.3334/CDIAC/atg.032 http://cdiac.ornl.gov/pns/current_ghg.html

[xvi] Climate Change 2007: The Physical Science Basis, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change ,Solomon, S., D. Qin, M. Manning, Z. Chen, M,. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.), IPCC (Intergovernmental Panel on Climate Change), 2007. Cambridge University Press, Cambridge United Kingdom and New York, NY, USA, 996 pp.

[xvii] Bounding the role of black carbon in the climate system: A scientific assessment, T. C. Bond, S. J. Doherty, D. W. Fahey, P. M. Forster, T. Berntsen, B. J. DeAngelo, M. G. Flanner, S. Ghan, B. Kärcher, D. Koch, S. Kinne, Y. Kondo, P. K. Quinn, M. C. Sarofim, M. G. Schultz, M. Schulz, C. Venkataraman, H. Zhang, S. Zhang, N. Bellouin, S. K. Guttikunda, P. K. Hopke, M. Z. Jacobson, J. W. Kaiser, Z. Klimont, U. Lohmann, J. P. Schwarz, D. Shindell, T. Storelvmo, S. G. Warren and C. S. Zender, Accepted manuscript online: 15 JAN 2013 07:30AM EST | DOI: 10.1002/jgrd.50171

[xviii] Modeling the Climatic Response to Orbital Variations, J Imbrie, J Z Imbrie (1980). Science 207(4434): 943–953. doi:10.1126/science.207.4434.943.

[xx] after Estimating Greenland ice sheet surface mass balance contribution to future sea level rise using the regional atmospheric climate model MAR Fettweis, Xavier; Franco, Bruno; Tedesco, M.; van Angelen, J.; Lenaerts, J.; van den Broeke, M.; Gallée, H. in Cryosphere Discussions (The) (2012), 6

[xxii] Recent contributions of glaciers and ice caps to sea level rise, Thomas Jacob, John Wahr, W. Tad Pfeffer & Sean Swenson, Nature 482, 514–518 (23 February 2012) doi:10.1038/nature10847

where there’s fire there’s smoke

December 31st, 2012
Wildfire, increasing with climate change [123], deposits increasing amounts of light-absorbing black carbon [soot] on the cryosphere [snow and ice], multiplying the existing heat-driven ice-reflectivity feedback [a.k.a. albedo feedback].

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 123456789 .

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/

early September Greenland ice reflectivity remains low, some melting remains active

September 7th, 2012

While ice sheet average temperatures are declining with the return of the cold season this September, ice sheet reflectivity (a.k.a. albedo) remains anomalously low (Fig. 1). The low albedo values reflect (pun alert) where snow accumulation has not yet covered the darkened surface. There remain some areas where melting remains active at the lowest elevations of the ice sheet (Fig. 2). Melt promotes or maintains low ice reflectivity.  Available sunlight in 2012 thus continues to heat the ice and snowpack more than it has in the period of observations beginning in 2000. Less heat will be required to maintain melting or bring the ice to the melting point in the future. It is easy to predict early melt onset in 2013 and a continuation of increasing ice sheet melt rates that contribute to the recently observed net ice loss from Greenland.

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

 

continued retreat of Greenland’s most productive glacier

September 5th, 2012

In terms of ice flow discharge, one of Greenland’s most productive outlets from the inland ice sheet, if not the most productive glacier in the Northern Hemisphere, the Ilulissat glacier (also known as the Jakobshavn glacier) continues to retreat. The net area change at this glacier since late summer 2000 is a loss of 122 sq km, equivalent with 1.4 x Manhattan Is., retreating effectively 18 km (11.2 mi) in 12 years. In 2012, this glacier front lost an an area of 13 sq km, measured from August 2011 to August 2012. Thi’s year’s area loss is the largest since the 2007-2008 interval. A concern is that this and other major marine terminating glaciers, as they retreat, they accelerate, increasing their global sea level contribution. Indeed, once the ice shelf in front of this glacier disintegrated, by the end of summer 2003, it’s speed had doubled (Joughin et al. 2004).

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.

This May 2002 view features the now gone Manhattan Is. sized ice shelf flowing out of the frame to the WNW. Photo – J. Box

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.

High late August 2012 Greenland ice temperature maintains low ice sheet reflectivity and melting

August 24th, 2012

Daily surface temperatures in June-August 2012 have peaked more than 5 C (~9 F) warmer for the whole ice sheet than the 2000-2009 daily averages according to my analysis of ice surface temperatures from  daily NASA MODIS MOD11 satellite derived Land Surface Temperature (LST) retrievals. Over the highest elevations, surface temperatures were nearly 10 C (~18 F) warmer than in the 2000’s decade, leading to an area of ice sheet surface melting, unprecedented in the satellite observational record beginning in 1978.

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.

Fig. 2. Daily Greenland ice sheet reflectivity (a.k.a. albedo) values spanning nearly 13 years; 2000-2012.

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

2012 summer Greenland ice reflectivity, lowest since year 1150?

August 15th, 2012

After a weeklong delay in data availability from a 61st satellite maneuver in 13 years to makeup low earth orbit drag, we find Greenland ice reflectivity (a.k.a. albedo) returning toward higher values, evidence of fresh snowfall accumulation and accompanying lower temperatures now as the melt season approaches its end. The latest average Greenland ice reflectivity (69.2%) from 13 August is at a level still below 1 standard deviation from the 2000-2009 10 year ‘climatology’. 2012 values are right on track with the previous record low year 2011.

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

 

Greenland ice sheet albedo feedback: mass balance implications

August 7th, 2012

Here’s a preview of my American Geophysical Union presentation abstract…

Greenland ice sheet albedo feedback: mass balance implications

Jason E Box1, Marco Tedesco2, Xavier Fettweis3, Dorothy K Hall4, Konrad Steffen5, Julienne Christine Stroeve6

  1. Byrd Polar Rsch Ctr Scott Hall, The Ohio State University, Columbus, OH, United States.
  2. The City University of New York, New York City, NY, United States.
  3. Department of Geography, University of Liege, Liege, Belgium.
  4. NASA Goddard Space Flight Center, Greenbelt, MD, United States.
  5. Swiss Federal Institute for Forest, Snow and Landscape Research ( WSL) , Birmensdorf, Switzerland.
  6. National Snow and Ice Data Center, Boulder, CO, United States.
 Greenland ice sheet mass loss has accelerated responding to combined glacier discharge and surface melt water runoff increases. During summer, absorbed solar energy, modulated at the surface primarily by albedo, is the dominant factor governing surface melt variability in the ablation area. NASA MODIS data spanning 13 summers (2000 – 2012), indicate that mid-summer (July) ice sheet albedo declined by 0.064 from a value of 0.752 in the early 2000s. The ice sheet accordingly absorbed 100 EJ more solar energy for the month of July in 2012 than in the early 2000s. This additional energy flux during summer doubled melt rates in the ice sheet ablation area during the observation period.

Abnormally strong anticyclonic circulation, associated with a persistent summer North Atlantic Oscillation extreme 2007-2012, enabled 3 amplifying mechanisms to maximize the albedo feedback: 1) increased warm (south) air advection along the western ice sheet increased surface sensible heating that in turn enhanced snow grain metamorphic rates, further reducing albedo; 2) increased surface downward shortwave flux, leading to more surface heating and further albedo reduction; and 3) reduced snowfall rates sustained low albedo, maximizing surface solar heating, progressively lowering albedo over multiple years. The summer net infrared and solar radiation for the high elevation accumulation area reached positive values during this period, contributing to an abrupt melt area increase in 2012.

A number of factors make it reasonable to expect more melt episodes covering 100% of the ice sheet area in coming years: 1) the past 13 y of increasing surface air temperatures have eroded snowpack ‘cold content’, preconditioning the ice sheet for earlier melt onset. Less heat is required to bring the surface to melting; 2) Greenland temperatures, have lagged the N Hemisphere average in the 2000s, need to increase further for Greenland to be in phase with the N Hemisphere average. 3) Arctic amplification of enhanced greenhouse warming is driven by albedo feedback over sea ice, terrestrial environments, and through autumn-winter heat release from open water areas. Likely melt area increases is despite a second order negative feedback operating in the accumulation area identified statistically from more summer snowfall (brightening effect) in anomalously warm summers. Without this negative feedback, the accumulation area complete surface melting may have happened sooner than in 2012.

While it has been shown that the ice sheet dynamics can adjust rapidly to ice flow perturbations, a negative feedback responsivity, the mass imbalance of the ice sheet in the coming decades is likely to be increasingly negative because of the positive feedback from surface albedo with air temperature. Surface melting may therefore increasingly dominate ice sheet mass loss, as glaciers retreat from a marine termini and the area of low albedo expands over the gradually sloping ice sheet. The albedo feedback ensures an increasing solar energy absorption. What could shut the positive feedback down would be a combination of an anomalously cold winter and anomalously thick snowpack. This scenario is possible given the cooling effect of a major N Hemisphere volcanic eruption or some other event to reduce surface heating.

http://bprc.osu.edu/wiki/Greenland_Ice_Albedo_Monitoring

KEYWORDS: [0726] CRYOSPHERE / Ice sheets, [0758] CRYOSPHERE / Remote sensing, [0740] CRYOSPHERE / Snowmelt, [0776] CRYOSPHERE / Glaciology.

 

 

 

 

 

 

 

 

 

early-August 2012 Greenland ice reflectivity dips again below 2 standard deviations

August 6th, 2012

As in the mid-July case, the early August ice sheet albedo has declined to an average more than 5% (or 2 standard deviations) below the average of the previous 12 years (2000-2011). A “2-sigma” event has a probability of occurrence under 5% in a random climate.

 

The decline is again concentrated in the accumulation area above 1500 m elevation where melting is less common as it is in the lower elevations.

The thermodynamic impact of widespread reflectivity decline is:

  1. more ice sheet solar energy absorption
  2. more erosion of snowpack heat content
  3. more preconditioning of future early melt onset cases
  4. more melting in 2012

…all in a self-reinforcing feedback loop that amplifies melting (see Box et al. 2012, link below).

The early August decline is similar to August declines in 2008, 2004, and 2001. What is different is that the decline is from a lower point.

The 4 August 2012 albedo is not as low as the lowpoint reached on 15 July, 2012.

Work 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

My climate-cryosphere updates on Twitter

My Byrd Polar Research Center homepage