Archive for the ‘Uncategorized’ Category

Siberian tundra holes are a mystery to me

Wednesday, July 30th, 2014

An Australian news piece juxtaposes mysterious Siberian holes with my Arctic tundra carbon release concerns but I have no idea about the cause of the holes. As a physical geographer, I’m aware of pingos that these features resemble but these features are holes and pingos are mounds. If you ask me, talk to field scientists with expertise in permafrost. For further reporting on the mysterious holes, see here.

screenshot searching “Sberian hole” in Google images

 

mid 2013 melt season average Greenland ice sheet reflectivity 5% above 2012 value

Friday, July 26th, 2013

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

Monday, 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

Greenland albedo rebounds from snowfall but is again followed widespread high air temperatures

Wednesday, August 1st, 2012

In the latest update of daily Greenland reflectivity (a.k.a., albedo) observed by the NASA MODIS sensors, we see the effect of fresh snow brightening the ice sheet surface after the extreme low albedo in mid July, 2012. Late July’s reflectivity remains below other years in the observational record since 2000 and the values are trending lower again because of the darkening effect of near-surface air temperatures reported for 24-31 July being near or above the melting point, according to ground observations maintained by Konrad Steffen, director of the Swiss Federal Institute for Forest, Snow and Landscape Research. The earlier high melt area episode was 11-15 July, 2012.

Daily ice sheet averaged reflectivity values for 13 individual years beginning in 2000. 0-3200 m refers to the elevation range of the whole ice sheet.

If the 24-31 July high temperatures are on par with those from 11-15 July, 2012 and if there is not another summer snowfall at the higher elevations of the ice sheet, I’d expect the albedos to decline further, reaching say 65.5% in the coming days.

These results are after the externally-reviewed publication Box et al. (2012), citation below.

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

Reflectivity (a.k.a. albedo) anomaly computed as the July average albedo for 5 km grid cells for the 12 year period (2000-2011) minus July 2012 values. Negative anomaly values mean the ice sheet is darker than average.

Greenland ice sheet albedo continues dropping at highest elevations

Wednesday, June 27th, 2012

Greenland ice sheet albedo in the elevation range from 2000-2500 m. This is the accumulation area where some melting is observed. Much more melting occurs at lower elevations.

With the most recent update to our near-real time monitoring of ice sheet albedo, we observe that the ice sheet albedo continues dropping into unprecedented low values especially at the higher elevations where there is little melting.

I wonder:

  1. Are the widespread wildfires, for example in Siberia or in Colorado adding to the albedo reduction?
  2. Or given that “Since 2000, global coal consumption has grown faster than any other fuel. ” … “Around 6 Gt of hard coal were used worldwide last year and 1 billion tonnes of brown coal. ” source: http://www.worldcoal.org/coal/uses-of-coal/ Is coal combustion part of the problem?

Specialists in snow impurities and albedo are on this problem. But, what are their results?

Petermann ice “island” now off the Labrador coast

Thursday, July 14th, 2011

Since August 2010, The Canadian Ice Service (CIS) has been tracking the largest several fragments of the 4x Manhattan Is. (290 sq. km, 112 sq mi) largest observed single iceberg calving from Greenland. The fragments pose a significant shipping and oil platform hazard. Some other fragments are grounded along Canadian Arctic islands.

Petermann_ice_island_PII-A_2011_07_08

A 2/3 Manhattan sized (~50 sq km, ~20 sq mi)  fragment is now ~150 km (~100 mi) off the Labrador coast at a latitude below 54 degrees. This rectangular  fragment, has side lengths of ~8 km x ~6 km (5 mi x 4 mi) and a thickness of ~30 m (~100 ft). Thus, the volume is ~1.5 cubic km  (0.36 cubic miles), or 1.5 trillion liters (400 billion gallons).

Observers aboard the Canadian Coast Guard Ann Harvey identified ~1000 harp seals resting on the ice island, 8 June 2011 . Photo: Jay Barthelotte. Courtesy of Ingrid Peterson Coastal Ocean Science, Bedford Institute of Oceanography, Fisheries and Oceans Canada

The glacier this ice island comes from discharges annually ~1.2 cubic km (Rignot and others, 2001). The year 2010 ice detachment represented several years of ice discharge from this glacier.

According to Johannessen, Babiker, and Miles, “there have been at least four massive (100+ km2) calving events over the past 50 years: (1) 1959–1961 (~153 km2), (2) 1991 (~168 km2), (3) 2001 (~71 km2) and (4) 2010 (~270 km2)”. The available evidence suggests a retreat to a new minimum extent.

Johannessen and others 2011 Fig. 3. "Petermann Glacier calving-front positions (+ symbol) observed between 1953 and 2010, cf. Fig. 2b–d. Positions are indicated relative to an arbitrary reference point along the longitudinal axis of the floating ice tongue. Solid line: Interannual variability of the calving-front position, 1991–2010, derived from satellite images, Dashed line: Variability of the calving front position, 1953–1991, derived from sporadic satellite and aerial observations. Red numbers denote the four largest changes in the record: (1) 1959–1961, (2) August–September 1991, (3) September 2001 and (4) August 2010."

This adds concern to the growing ice mass budget deficit of the Greenland ice sheet. As ice breaks away from the front of glaciers at a faster rate than it is replaced, the glacier flow has less resistance to flow and speed increases follow. Satellite gravity surveys indicate an accelerating mass loss from Greenland and Antarctica. The year 2010 detachment occurred in the warmest year on record for west Greenland. Yet, it is difficult to establish a cause-effect relationship with the de-glaciation of Greenland. Physical mechanisms we are aware of that contribute to abnormal ice shelf detachment include:

    1. Box and Ski (2007) write “Theoretical calculations by Weertman (1973), Van der Veen (1998) and Alley and others (2005) lead to the conclusion that a water-filled crevasse has unlimited capacity, acting under gravity, to force water to the bottom surface of a glacier.” This process of hydrofracture is confirmed for the Antarctic Larsen B ice shelf disintegration which was preceded by widespread surface water ponding on the ice shelf surface. When surface air temperatures are above the melting point and are, further, above normal, more extensive hydrofracture is elementary.
    2. Satellite remote sensing indicates a reduced season of solid sea ice extent and concentration in front of glaciers around Greenland. As such there is less capping of the water from atmospheric interaction from winds. Wind action on the water surface promotes water circulation that can promote increased heat exchange between the ice shelf and the ocean waters. Especially if relatively warm water is forced to circulate more than it otherwise would, against the sub-marine ice, enhanced melting would be expected. Further, the sea ice may provide mechanical stability (buttressing or glueing) to the glacier front, rift areas, and fractured areas pieces. So, melting can enhance the unglueing effects, promoting fracture propagation.

      Yet, other processes such as high tides and strong wind events could also have contributed, and even been the straw that broke the glacier’s back. So, it’s not always obvious to make the link with climate warming even as nearly 100% of glaciers are in a state of retreat.

      Works Cited

      • Alley, R.B., T.K. Dupont, B.R. Parizek and S. Anandakrishnan. 2005. Access of surface meltwater to beds of subfreezing glaciers: preliminary insights. Ann. Glaciol., 40, 8–14.
      • Box, J.E. and K. Ski, Remote sounding of Greenland supraglacial melt lakes: implications to sub-glacial hydraulics, 2007: Journal of Glaciology, 181, 257 – 265, 2007.
      • Johannessen, O.M., M. Babiker, and M.W. Miles (2011) Petermann Glacier, North Greenland: massive calving in 2010 and the past half century, The Cryosphere Discuss., 5, 169–181, 2011, www.the-cryosphere-discuss.net/5/169/2011/ doi:10.5194/tcd-5-169-2011.
      • Rignot, E., S.P. Gogineni, I. Joughin, W. Krabil, (2001) Contribution to the glaciology of northern Greenland from satellite radar interferometry, Journal of Geophysical Research, vol. 106, no. D24, Pages 34,007-34,019.
      • Van der Veen, C.J. 1998. Fracture mechanics approach to penetration of surface crevasses on glaciers. Cold Reg. Sci. Technol., 27(1), 31–47.
      • Velicogna, I. (2009), Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE, Geophys. Res. Lett., 36, L19503, doi:10.1029/2009GL040222.
      • Weertman, J. 1973. Can a water-filled crevasse reach the bottom surface of a glacier? IASH Publ. 95 (Symposium at Cambridge 1969 – Hydrology of Glaciers), 139–145.

      verbatim review of Frauenfeld, Knappenberger, Michaels, Journal of Geophysical Research, 2011

      Tuesday, April 19th, 2011

      I below post, for the public record, my anonymous review of a new paper published in Journal of Geophysical Research.

      I rank the paper: “Good” because the paper’s methods seem solid. Yet, depth with regard to examining causal factors is missing. Further, the paper’s main point, as it seems, that recent warming is not without precedent, may already be obsolete because 2010 was such an extreme melt year AND that more warming in Greenland is likely simply for Greenland to be in sync with the northern hemisphere. The paper thus, in the very least, requires a revision that includes consideration of 2010 data. Yet, consideration of causal factors of cooling and warming and treatment of the Box et al. (2009) prediction, which for 2008-2010 has been accurate, would give the paper the depth consistent with JGR’s standard.

      Major Critique:

      As is, the only depth of the paper is the statistical modeling, that is, the regressions to reconstruct melt area and comparison of the recent warming versus past warm episodes. There is theory to explain warming and cooling episodes in Greenland. Yet, the paper does include this important dimension. Therefore, to increase the depth or impact of the work, the paper should elaborate causal factors that explain the ups and downs in the reconstruction.

      The paper may already be obsolete without considering the extreme melting in 2010. I would therefore not recommend accepting the paper without a revision that included 2010. the numerous statements throughout the paper, like that in line: 19 “We find that the recent period of high melt extent is similar in magnitude but, thus far, shorter in duration, than a period of high melt lasting from the early 1920s through the early 1960s.”

      One thing different about the recent warming versus the 1920s warming is that Greenland climate continues to lag the northern hemisphere pattern… The work should therefore reflect on the prediction made in Box et al. (2009) that: simply to be in sync with the northern hemisphere pattern, Greenland climate must warm (after year 2007) by 1.0 – 1.5 C. In the years after 2007, that is, 2008-2010, this prediction has held true. And that still more warming should happen in Greenland in the coming few years is more likely than not. A major volcanic eruption, of course, see relevant literature, would cool Greenland’s climate for 1-3 years.

      The pre-1840 results should be abandoned because is cannot or at least it has not been demonstrated that there sufficient sampling to compare with the subsequent complete series.

      Title: A less ambiguous time frame should be included in the title than:  “A Reconstruction of Annual Greenland Ice Melt Extent Going Back to 1784” is needed…Something like: “A Reconstruction of Annual Greenland Ice Melt Extent 1784-2009”. Why? If the paper is published, some years down the line, the title would become ambiguous.

      Minor Critique:

      line 12 “three decades” instead of “several decades”

      line 52: the following statement seems not accurate: “Such a comprehensive, annually resolved reconstruction has not previously been undertaken, and will better place current observations of melt extent in a longer-term historical perspective.” Box et al. (2009) modelle an annually resolved temperature reconstruction for the Greenland ice sheet.

      line 103 define “closely match” quantitatively.

      line 124 define “quite similar” quantitatively.

      line 140: Does this relationship account for sub-monthly melt frequency? “Our Greenland melt reconstruction therefore focuses on the relationship between monthly average temperatures” I suspect a reduced sensitivity to melt intensity for 2 reasons: 1.) summer variability is minimal; 2.) a summer average of e.g. 0 C still includes periods above melting.

      line 162: explain “the direct measure of JJA temperature subsumes the summer NAO influence.”

      line 166 “winter conditions act to pre-condition summer ice melt through a snow/albedo response” certainly because of thermal erosion of heat content. “snow/albedo response” is vague and does not mention important heat content issue.

      line 195: suggest “strong warming trend” instead of “strong positive trend”

      line 195: “~1979-2009” instead of “The last ~30 years”

      line 211: By the same token as the arguments that the recent warming is not statistically unprecedented, the following statement need be substantiated using probabilities: “several sustained periods can be identified when a greater and/or more prolonged”

      line 221-223: a good point: “It is worth noting that the satellite observations of Greenland‘s total ice melt, which begin in the late 1970s, start during a time that is characterized by the lowest sustained extent of melt during the past century (Figure 2).”

      line 248: remove “much”, overstatement

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      Monday, February 14th, 2011

      http://twitter.com/climate_ice

      Arctic Warm – Continents Cold

      Monday, December 6th, 2010

      The anomalously cold weather is part of a new climate pattern: Arctic Warm – Continents Cold

      The emerging explanation in a nutshell: because of less Arctic sea ice, there is more heat exchange between ocean and atmosphere, this is altering planetary-scale circulation patterns in ways that the cold air normally ‘bottled up’ in the Arctic is flushing out to the south. James Overland – NOAA/PMEL Seattle USA has lead most of the explanatory work I have seen. So, while the mid-latitude (especially central north Asia) is cold, the Arctic winter is a shocking up to 20 Celsius (36 Fahrenheit) ABOVE NORMAL temperature. See the daily temperature anomaly map below…

      http://bprc.osu.edu/mediawiki/images/a/af/Sfctmpmer_01a.fnl.29.gif

      Temperature departures from normal. http://www.esrl.noaa.gov/psd/map/images/fnl/sfctmpmer_01a.fnl.anim.html

      The extreme cold, e.g. record low of 34 F on 24 Nov. 2010 in Oakland, CA, is leading to a false conclusion that global warming has been ‘canceled’, when in fact the Arctic is heating faster than ever. This new pattern is ‘what global warming looks like’ and why it’s always been more accurate to think in terms of ‘climate change’ instead of ‘global warming’, even though the latter, is still happening GLOBALLY AVERAGED, not regionally! 2010 has been the warmest year on record.

      This same recent climate pattern seen in the above daily temperature anomalies is evident in the winter of Dec 2009 – Feb 2010. see below…

      http://bprc.osu.edu/mediawiki/images/4/4c/GHCN_GISS_HR2SST_1200km_Anom1203_2009_2010_1951_1980.gif

      Seasonal temperature departures from normal. Note the pattern of cold continents and warm Arctic. Make plots like this here.

      plan-Z

      Monday, September 13th, 2010

      We cling to the hope to visit Petermann glacier this year. By 7 Sept, the only option became an alternative helicopter charter company, Air Greenland. A new charter agreement requires more time than would fit in my additional week in Greenland, time, that is to re-arrange the fuel needed to make this long lap and draw up more paperwork. Key in the delay was: there were insufficient fuel drums of a very certain kind in Qaanaaq and in Thule AFB. Air Greenland has new and more strict guidelines for fuel drums. Another complication: because we aim to re-activate the equipment and not just do a “grab” operation, we can’t just use a volunteer who is already there, a “frozen chosen” that is. We need someone familiar with the equipment and who’s judgment we can rely on, for example, whether or not to fly in marginal conditions and at great expense. We therefore plan for it to be one of us (Jason, Alun, Sam, or Richard) on this flight, some time before mid-October when the days become too short to get the flight in with light to fly by. I (Jason) am now back in the US. Needless to say, it was difficult to turn south without the data. U. Wales collaborator, Alun Hubbard has volunteered to be the man to fly on “Plan-Z”, October 2010. I have prior commitments. If not this year, then, we aim for March, 2011. The March, 2011 trip I can be on. It would probably be Jason and Alun making the March, 2011 mission.