Archive for the ‘Mass Balance’ Category

Phoenix Glacier relic ice

Tuesday, September 10th, 2013

I’m in South Greenland drilling low tech metal pipes into the ice to calibrate high tech satellite, aircraft, and model data.

Flying over this landscape, it’s stunning how much the ice has retreated. Annual (let alone summer) average air temperatures at nearby Narsarsuaq have been above the melting point 39 of the past 51 years [1]. Unequivocal evidence of rapid ice retreat; relic stranded ice [2] was what led Denmark to support scientists at GEUS to install modern ice monitoring measurements in 2001. The observations are now called “Q transect” as part of the PROMICE network around Greenland.

I was stunned to witness (and photograph) more stranded relic ice on the sides of the glacier. Notice how no ice is feeding Phoenix’s wings from upstream.

The glacier’s current shape resembles a Phoenix, with wings (relic ice) outstretched to the front, and the phoenix has a demise, like this glacier.

We’re here surveying the damage with Shane Smith of Vice media for an up coming spot on HBO.

Vice supported the installation of six ablation stakes at elevations between 390 and 1100 m on the Qassimiut lobe of the ice sheet, hence the name Q transect.

 The stakes are carefully tied into a coordinate system using the antenna at the upper right recording the site elevation and horizontal position by differential GPS.

This Phoenix should of course rise again, but not until after another ice age. When that happens? It’s gonna be a while.

Follow @PromiceGL on Twitter.

Work Cited

  • [1] Cappelen, John, DMI Monthly Climate Data Collection 1768-2010, Denmark, The Faroe Islands and Greenland. Dansk Meteorol. Inst. Tech. Rap., 11-05, 54 pp, 2011.
  • [2] Podlech; Steffen, Christoph Mayer, Carl Egede Bøggild, Glacier Retreat, Mass-Balance and Thinning: Sermilik Glacier, South Greenland, Geografiska Annaler: Series A, Physical Geography, Volume 86, Issue 4, pages 305–317, December 2004, DOI: 10.1111/j.0435-3676.2004.00234.x

Too late now for 2013 to produce Greenland ice surface melting anywhere near as large as in 2012

Monday, July 22nd, 2013

We’ve made it to the middle of the melt season 2013. It’s been a roller coaster for Greenland climate in 2013.

The year started out with an astonishing low albedo from a snow drought that made huge melt possible. Yet this was punctuated by the return of snow late April and prolonged low temperatures as the North Atlantic Oscillation (NAO) shifted from persistent negative that had been causing west Greenland temperatures to be abnormally warm while Copenhagen thad its coldest late winter and early spring in decades. The dipole in temperatures between NW Europe and W Greenland has been recognized for more than a century and called the “seesaw” in temperature (van Loon and Rogers, 1978).

Like in 2012, melt came on strong by early June but was shut down again by abnormally low temperatures, accompanied by additional snowfalls [1, Ruth Mottram, Danish Meteorological Institute, personal communication] in some areas, that lasted until mid July. The key difference between 2013 and the previous 6 summers (2007-2012) is the absence of a persistent negative NAO that drove south air over Greenland, heating it while promoting clear skies that maximized the impact of surface darkening through the albedo feedback (Box et al. 2012). With this much of a delayed start, the albedo feedback has not had enough time to produce strong melt. Given now that we are at the mid point of the melt season, it is too late now for 2013 to produce melting anywhere nearly as large as we saw in 2012.

The NASA MODIS data indicate that the 2013 Greenland mid melt season (mid-July) albedo is at its lowest in 4 years; behind 2009, 2010, 2011, and 2012.

The 2013 June ice sheet is more reflective across the southern third than the average of the recent decade. This may also be partly a consequence of the late season snowfall which was concentrated in the south eastern quarter (Ruth Mottram, DMI). Across the northern 2/3 of the ice sheet, the difference is below average, though not as far below average as in previous years, especially 2010, 2012.

But the bigger story seems to be the preliminary July 2013 average (the first 20 days of the month) where much of the lower elevation ablation area is more reflective than the recent decade (2000-2011). This is slowing down accumulated melt. Meanwhile, the upper elevations (inland) have below average reflectivity. Why are the upper elevations (inland) somewhat below normal reflectivity? While Dark Snow project was successful in gathering surface reflectivity samples from southwest Greenland this 8th and 9th July, the samples were not from where the high July albedo anomaly is. Were it anyway North American fire smoke contributing to the reduced ice reflectivity, it could be a.) lower than normal snowfall at the upper elevations over the year . Could the albedo of 2013 literally be reflecting the ice of 2012 buried less than 1 m below the surface? The albedo signal can originate from some 10s of cm below the surface. According to DMI’s HIRLAM model estimates, there is less than 1 m of snow accumulation over much of the higher elevations. Then again, the fire factor may also be at play. We’ll be looking into this with Dark Snow project.

  Works Cited

  • [1] Ruth Mottram, Danish Meteorological Institute (DMI), personal communication. The DMI High Resolution Limited Area Model (HIRLAM) simulates snowfall in southeast and east Greenland. The cumulative surface mass balance indicated net mass accumulation. HIRLAM is initialized by observations from satellites, weather balloons, aircraft, ground stations, buoys, etc.
  • 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
  • van Loon, Harry, Jeffery C. Rogers, 1978: The Seesaw in Winter Temperatures between Greenland and Northern Europe. Part I: General Description. Mon. Wea. Rev., 106, 296–310. doi:<0296:TSIWTB>2.0.CO;2

GRACE-cast: Greenland ice sheet mass loss *this week* turns toward average

Saturday, July 6th, 2013

In my new position, Professor of Glaciology at the Geological Survey of Denmark and Greenland (GEUS), I’ve started to gather momentum working with a fine group of people to establish for the first time, a Greenland ice sheet total mass balance product that estimates what the GRACE satellite measures and posting the estimate on-line 2-3 months ahead of the GRACE processing.

Our new “Nowcast” of Greenland ice sheet mass balance has as little as 24 h delay from realtime.

The product exploits the fact that on average, 90% of the time, when monthly all ice sheet reflectivity (also called “albedo”) goes up, the rate of total ice sheet mass change goes down and visa versa.

The Nowcast only works in the sunlit period from mid April to mid September.

So, now as we’re mid-melt season (6 July), we finally have some interesting news…delay of the 2013 melt season due to relatively northerly air flow along west Greenland has led to the lowest elevations of the ice sheet having an above average reflectivity due primarily to more persistent snowcover (snow patches) and secondarily due to summer snowfall in some areas. According to the empirical relationship, the rate of ice melt water loss from the ice sheet to the surrounding seas has declined and now approaches the average of the 2003-2009 period.

People involved with what I like to call the “GRACE-cast” include: GEUS glaciology post-doc William Colgan; Danish Meteorological Institute (DMI) ice climatologists Dr. Peter Langer and Dr. Ruth Mottram, and Danish Tecnhical University (DTU) geodesists Dr. Valentina Barletta and Dr. Rene Forsberg.

Technical details are documented in a .pdf file at the new product’s new home:
The cumulative sea level contribution is also updated on the new Danish web site.

Greenland ice sheet ablation area albedo above average, upper elevations below average

Saturday, July 6th, 2013

A delayed melting at low elevations and probably some summer snowfall blanketing the Greenland ice sheet ablation area with (highly reflective) fresh snow have resulted in an important slow down of Greenland melting. This pattern is in contrast to this time last year (in 2012) when record melting was emerging.

3 part study reconstructs Greenland ice sheet mass budget since 1840 and presents a theory connecting surface meltwater with ice deformational flow

Thursday, May 16th, 2013

It took 7 years to pull together a full ice sheet mass budget closure based on a fusion of observationally-based records from coastal and inland weather station temperature readings; ice cores; and regional climate modeling.

Below are links to pre-prints. The papers’ abstracts capture key results but are constrained by 250 word limits. I emphasize part III below. Parts I and II were foundational works with interesting aspects. Part III brings in necessary data from parts I and II.

Greenland ice sheet mass balance reconstruction. Part I: net snow accumulation (1600-2009)
Jason E. Box, Noel Cressie, David H. Bromwich, Ji-Hoon Jung, Michiel van den Broeke, J. H. van Angelen, Richard R. Forster, Clement Miège, Ellen Mosley-Thompson, Bo Vinther, Joseph R. McConnell
Abstract . PDF (3210 KB)

Greenland ice sheet mass balance reconstruction. Part II: surface mass balance (1840-2010)
Jason E. Box
Abstract . PDF (3322 KB)

Greenland ice sheet mass balance reconstruction. Part III: marine ice loss and total mass balance (1840-2010)
Jason E. Box, William Colgan
Abstract . PDF (2452 KB)

Paper III puts forth a theory* linking surface melting with ice flow dynamics. The two are by now too often examined in isolation. Our not so old science of glaciology, beginning in earnest in the late 1950s, can now begin unifying surface and ice dynamics processes at the ice sheet scale. In stark contrast to the messaging that the recent Nick et al modeling study produced, we may expect plenty more sea level contribution from Greenland than current models predict. The misreporting of otherwise good science refers to ice flow to the sea as “melt”. Ice deformational flow is a distinct process from melt. Yet, melt and ice deformational flow are in fact intertwined processes. Self-reinforcing amplifying feedbacks outnumbering damping feedbacks by a large margin (Cuffey and Patterson, 2010, chapter 14) ensure that given a climate warming perturbation, a.k.a. the Hockey Stick, we’ll see a stronger reponse of ice to climate than is currently encoded by models. More on that later.

Because the peak statistical sensitivity between meltwater runoff and ice flow discharge emerges at the decade scale (11-13 years), it seems that the ice softening due to more meltwater in-flow to the ice sheet, the Phillips Effect, if you will, is a central physical process behind a link between runoff and ice flow dynamics (Phillips et al. 2010; 2013).

Yet, on shorter time scales and resulting from a rising trend of surface melting, also to be considered is the effect of meltwater ejection at the underwater front of marine-terminating glaciers. The effect is to force a heat exchange between the glacier front and relatively warm sea water with the ice  (Motyka et al. 2003), melting it. This is, if you will, the Motyka Effect. Underwater melting undercuts the glacier front, promoting ice berg calving and thus providing a direct and immediate link between surface runoff and ice flow. Calving reduces flow resistance, causing ice flow acceleration.

January-February 2013, As I responded to 3 critical anonymous external reviewers and the sands of time were running low to make the 15 March, 2013 deadline for the IPCC AR5, in a bid to increase the likelihood of paper III’s acceptance, I brought on Liam Colgan. His fresh and sharp eyes would comb out any potential text and methodological snags from my major revision. While you may know Liam to be a frequent user of Monte Carlo methods, I already had that in this paper before thinking of his involvement. To his credit, Liam contributed the crevasse-widening aspect to the theory that builds coincidentally via Colgan et al. (2011)’s building on Pfeffer and Bretherton (1987). The Colgan Effect is thus the 3rd aspect of the unified theory this part III study puts forth.

As to the result of the mass budget reconstruction, it’s not surprising that Greenland ice sheet contribution to sea level has accelerated. After all, climate has emerged from the dim-sun Little Ice Age into the greenhouse gas-forced new post-industrial climate epoch, the Anthropocene. Greenland’s going. It’s a question of how fast. I’m happy to report that more to this story is in the works. So, stay tuned.

* A theory is a broad collection of knowledge based on hypotheses (emphasis plural) that have withstood skeptical inquiry and are accepted, unless otherwise proven, as Fact.

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

Works Cited
  • Colgan, W., K. Steffen, W. McLamb, W. Abdalati, H. Rajaram, R. Motyka, T. Phillips, and R. Anderson, 2011a: An increase in crevasse extent, West Greenland: Hydrologic implications, Geophy. Res. Lett. 38, doi:10.1029/2011GL048491
  • Cuffey, K.M. and W.S.B. Paterson (2010). The Physics of Glaciers, Fourth Edition. Elsevier, 693 pp.
  • Motyka, R. J., L. Hunter, K. A. Echelmeyer, and C. Conner, 2003: Submarine melting at the terminus of a temperate tidewater glacier, LeConte Glacier, Alaska, U.S.A. Ann. Glaciol., 36, 57-65.
  • Nick, F.M., A. Vieli, M.L. Andersen, I. Joughin, A. Payne, T.L. Edwards, F. Pattyn & R.S.W. van de Wal, 2013, Future sea-level rise from Greenland’s main outlet glaciers in a warming climateNature 497, 235–238 (09 May 2013) doi:10.1038/nature12068
  • Pfeffer, W. and C. Bretherton, 1987: The effect of crevasses on the solar heating of a glacier surface, IAHS Publication, 170, 191-205. 
  • Phillips, T., H. Rajaram, and K. Steffen, 2010: Cryohydrologic warming: A potential mechanism for rapid thermal response of ice sheets, Geophys. Res. Lett., 37, L20503, doi:10.1029/2010GL044397.
  • Phillips, T., W. Colgan, H. Rajaram and K. Steffen. Evaluation of cryo-hydrologic warming as an explanation for increased ice velocities near the equilibrium line, Southwest Greenland. J. Geophys. Res. ,2012JF002584, submitted 7 July 2012, revised 31 December 2012.

Greenland ice sheet albedo feedback: mass balance implications

Tuesday, 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.

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










Greenland Ice Sheet Getting Darker

Tuesday, January 10th, 2012

The following provides detail to a story run by NOAA entitled Greenland Ice Sheet Getting Darker

Freshly fallen snow under clear skies reflects 84% (albedo= 0.84) of the sunlight falling on it (Konzelmann and Ohmura, 1995). This reflectivity progressively reduces during the sunlit (warm) season as a consequence of ice grain growth, resulting in a self-amplifying albedo decrease, a positive feedback. Another amplifier; the complete melting of the winter snow accumulation on glaciers, sea ice, and the low elevations of ice sheets exposes darker underlying solid ice. The albedo of low-impurity snow-free glacier ice is in the range of 30% to 60% (Cuffey and Paterson, 2010). Where wind-blown-in and microbiological impurities accumulate near the glacier ice surface (Bøggild et al. 2010), the ice sheet albedo may be extremely low (20%) (Cuffey and Paterson, 2010). Thus, summer albedo variability exceeds 50% over parts of the ice sheet where a snow layer ablates by mid-summer, exposing an impurity-rich ice surface (Wientjes and Oerlemans, 2010), resulting in absorbed sunlight being the largest source of energy for melting during summer and explaining most of the inter-annual variability in melt totals (van den Broeke et al. 2008, 2011).

The photo below shows how dark the ice sheet surface can become in the lowest ~1000 m elevation in the “ablation area” after the winter snow melts away and leaves behind an impurity-rich surface. This dark area is where the albedo feedback with melting is strongest.

12 August 2005, 8 PM local time, I took this photo from a helicopter flying over the ice sheet surface at ~1500 feet altitude. This is how much darker the Greenland ablation area is than a fresh snow surface that blankets it in wintertime. Along much of the southwestern ice sheet at the lowest 1000 m in elevation, impurities concentrate near the surface and produce this dark surface. Not all of the ice sheet is this dark, only the lower ~1/3 of the elevation profile of the ice sheet is. However, as melting increases on the ice sheet, so does the area exposed that is this dark.

Satellite observations from the NASA Moderate-Resolution Imaging Spectroradiometer (MODIS)  indicate a significant Greenland ice sheet albedo decline (-5.6±0.7%) in the June-August period over the 12 melt seasons spanning 2000-2011. According to linear regression, the ablation area albedo declined from 71.5% in 2000 to 63.2% in 2011 (time correlation = -0.805, 1-p=0.999). The change (-8.3%) is more than two times the absolute albedo RMS error (3.1%). Over the accumulation area, the highly linear (time correlation = -0.927, 1-p>0.999) decline from 81.7% to 76.6% over the same period also exceeds the absolute albedo RMS error.

Greenland ice sheet average reflectivity or albedo (multiply by 100 to get % units) for 12 summer (June-August) periods.

Because of extreme 2010 melt and little snow accumulation during the melt season (Tedesco at al., 2011) and afterward, the ice sheet albedo remained more than two standard deviations below the 2000-2011 average in October. Like year 2010, 2011 albedos are more than 1 standard deviation below the 2000-2011 average.

Year 2011 albedo (multiply by 100 to get % units) over the Greenland ice sheet is the lowest observed in the 12 years since MODIS observations began day 65 year 2000. 11-day running median Greenland ice sheet albedo from Moderate Resolution Imaging Spectroradiometer (MODIS) MOD10A1 data. The dashed line represents the 2000-2011 daily average.

Darkening of the ice sheet in the 12 summers between 2000 and 2011 permitted the ice sheet to absorb an extra 172 quintillion joules of energy, nearly 2 times the annual energy consumption of the United States (about 94 quintillion joules in 2009).

This decline is not only over the lowest elevations, but occurs high on the ice sheet where melting is limited.

The greatest changes in reflectivity (or albedo, multiply by 100 to get % units) are found where a relatively dark surface of impurity rich "glacier ice" emerges once the snow cover melts. It's natural for snow cover to melt away at the lowest elevations of a glacier or ice sheet. However, the period of time over which the ice sheet surface is bare has increased significantly since year 2000 when these observations become available.

A significant albedo decline of 4.6±0.6% in the 2000-2011 period from a year 2000 value of 83.0% is observed for the accumulation area, where warming surface temperatures are enhancing snow grain metamorphosis.

Works Cited

  • Bøggild, C.E., Brandt, R.E., Brown, K.J., Warren, S.G. 2010: The ablation zone in northeast Greenland: ice types, albedos and impurities. Journal of Glaciology 56, 101-113.
  • Cuffey, K. M., & Paterson, W. (2010). The physics of glaciers Elsevier, ed (Vol. 4, p. 693).
  • Konzelmann, T., & Ohmura, A. (1995). Radiative Fluxes And Their Impact On The Energy-Balance Of The Greenland Ice-Sheet. Journal of Glaciology, 41(139), 490-502.
  • Tedesco, M., X. Fettweis, M.R. van den Broeke, R.S.W. van de Wal , C.J.P.P. Smeets, W.J. van de Berg, M.C. Serreze and, J. E. Box, The role of albedo and accumulation in the 2010 melting record in Greenland, 2011: Environ. Res. Lett. 6 014005, doi: 10.1088/1748-9326/6/1/014005.
  • van den Broeke, M. R., Smeets, C. J. P. P., & van de Wal, R. S. W. (2011). The seasonal cycle and interannual variability of surface energy balance and melt in the ablation area of the west Greenland ice sheet. Cryosphere, 5(2), 377-390. doi: 10.5194/tc-5-377-2011
  • van den Broeke, M. R., Smeets, P., Ettema, J., van der Veen, C., van de Wal, R. and Oerlemans, J.: Partitioning of melt energy and meltwater fluxes in the ablation area of the west Greenland ice sheet. The Cryosphere, 2(2), 179-189, 2008.
  • Wientjes, I. G. M., & Oerlemans, J. (2010). An explanation for the dark region in the western melt area of the Greenland ice sheet. Cryosphere, 4(3), 261-268. doi: 10.5194/tc-4-261-2010


This research was supported by The Ohio State University Climate Water and Carbon initiative. David Decker and Russell Benson gathered and helped grid the MODIS data.

Co-authors of the paper in progress include:

  • Xavier Fettweis, Department of Geography, University of Liège, Belgium
  • Julienne C. Stroeve, National Snow and Ice Data Center (NSIDC), Boulder, CO, USA & Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, USA
  • Marco Tedesco, The City University of New York, New York, NY, USA
  • Dorothy K. Hall, NASA Goddard Space Flight Center, Greenbelt, MD, USA

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Mapping Land Ice

Wednesday, September 28th, 2011

A recent hot topic has been circulating cyberspace re: a Greenland ice mapping fiasco that I happily was not involved with. Yet, by coincidence of a grant application submitted in 2009 and funded this year, I am able to assist in my role as a geographer to help complete the global land ice inventory and help resolve the issue so such fiascos don’t happen.

Image:2000.233 0250m refa 143 06600 11000-1.jpg

0.25 km satellite image of the east Greenland glacierized complex going by the names: Geicke Plateau and Blosseville Coast. The satellite image comes from the NASA MODIS sensor. The image was produced by J. Box, C. Chen, and D. Decker at Byrd Polar Research Center.

NY Times reporter, Felicity Barringer writes a second NY Times article illuminating the challenges of mapping land ice, that links to a page I constructed to provide background on a this new project.

Image:Map 1250m mask count.png

1.25 km satellite image -based classification of the East Greenland glacierized complex. The image is roughly co-registered with above image. The classification is according to a preliminary land surface classification on a coarser 1.25 km grid than the ultimate 0.25 km grid. We are in the process of producing the 0.25 km classifications and to compare these with GLIMS outlines.

A new Byrd Polar Research Center staff person Christine Chen was hired this September to begin her PhD work by advancing ice inventory work beyond the land ice classifications I made beginning in 2007. Christine is now simultaneously improving Greenland and Antarctic Peninsula land ice classifications. We will be sharing these data with the global scientific community in a fully transparent project with an independent validation effort involving colleagues in Switzerland and Boulder, CO.