Skip to content

Greenland’s Ice Mass Balance

August 26, 2018
tags:

By Paul Homewood

 

accumulatedsmb

http://www.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/#

 

As I pointed out the other day, the surface mass balance (SMB) in Greenland has increased way above the long term average for the second year running.

The question was raised as to the significance of this, given that the SMB does not include losses from calving. The DMI page on the SMB quotes:

The calving loss is greater than the gain from surface mass balance, and Greenland is losing mass at about 200 Gt/yr.

However, care needs to be taken with this, as the same statement has appeared every year recently, for instance in 2013 (see here). It is just a stock statement.

 

The simple answer is that the SMB is an extremely important part of the equation, otherwise DMI would not even be bothering to show it at all. Great effort is put into calculating SMB changes every single day of the year. The DMI certainly regard it as an extremely important measure.

It is also true that one of the most important determinants of glacier/ice sheet formation is snow downput, which in turn feeds into the SMB.

It also needs to be stated that, as far as I am aware, neither the DMI nor anybody else publishes regular estimates of calving loss. So, like it or not, we are left with SMB.

 

To put SMB into perspective, the DMI’s Ruth Mottram produced this table and chart  in her paper, Surface mass balance of the Greenland ice sheet in the regional climate model HIRHAM5: Present state and future prospects, in 2017:

image

image

https://r.search.yahoo.com/_ylt=AwrJS5jIuIJbQhwAYRRLBQx.;_ylu=X3oDMTEyZnRhdjgzBGNvbG8DaXIyBHBvcwMxBHZ0aWQDQjYxNjdfMQRzZWMDc3I-/RV=2/RE=1535322440/RO=10/RU=https%3a%2f%2feprints.lib.hokudai.ac.jp%2fdspace%2fbitstream%2f2115%2f65106%2f1%2f12_105-115.pdf/RK=2/RS=.7Z9eRcoYOAO.FPZtj4zRIzpjJg-

 

In other words, the SMB fell from 375 Gt pa in the 1980s, to 277 Gt between 2000 and 2014.

IPCC AR5 also gave us some figures for total ice loss, including calving, which mention a loss of 215 Gt pa from 2002-11:

 

 image

 https://ipcc.ch/report/ar5/wg1/

 

This would imply a loss from calving of roughly 500 Gt a year. Therefore an increase to over 500 Gt in the SMB for the last two years is highly significant, as it means that there is no ice loss at all.

 

Of course, this is only two years worth of data; mere weather. Arguably though,  so was the last decade. We certainly need to be looking at decades of data, covering the major ocean cycles.

And, of course, we should not be surprised that Greenland’s glaciers are receding, given that scientists say they were at their maximum extent since the early Holocene during the Little Ice Age.

No doubt, Greenland’s glaciers will continue to recede in the long term, just as they have in the past century.

The real question is whether ice loss will accelerate. And the answer to that lies in the SMB.

Will we see the great Greenland meltdown, that we hear so much about?

20 Comments
  1. MrGrimNasty permalink
    August 26, 2018 5:40 pm

    According to WUWT only 0.3% of the ice sheet didn’t survive the 20thC. In Gt that sounds massive, but in reality it is a minuscule loss as he puts into very clear perspective.

    https://wattsupwiththat.com/2015/12/30/greenland-retained-99-7-of-its-ice-mass-in-20th-century/

  2. August 26, 2018 5:45 pm

    Reblogged this on Climate Collections.

  3. GEORGE LET permalink
    August 26, 2018 7:46 pm

    The alarmists’ spin is that warmer ocean water is resulting in more snowfall on Greenland. It is again taking whatever the situation is and working backward to an “explanation”. Of course don’t forget the ultimate cause is fossil fuel CO2.

    • dave permalink
      August 26, 2018 8:22 pm

      The jet stream was over Greenland several times this summer and hence the cyclonic weather and precipitation was there while England had that bit of nice weather. I am sure that this temporary movement in the jet stream was a direct consequence of global warming, and was completely forecast as such by Professor Wadhams or Mann twenty years ago…

      • GEORGE LET permalink
        August 27, 2018 1:57 am

        dave, you say “I am sure that this temporary movement in the jet stream was a direct consequence of global warming” You must really be an “expert” to say that. And would you say you are sure the “global warming” is a direct consequence of fossil fuel CO2?

      • dave permalink
        August 27, 2018 7:08 am

        Sorry. I was being sarcastic, in articulating the immediate reaction of a warmunista.

        I should have remembered the old saying that “Sarcasm is the lowest form of humour.”

      • Tom O permalink
        August 27, 2018 9:26 pm

        Dave, no apology required. Since you finished with “was completely forecast as such by Professor Wadhams or Mann twenty years ago…” , only someone that didn’t bother to read the entire comment would have mistaken it for anything other that amusing sarcasm.

    • dave permalink
      August 26, 2018 8:34 pm

      Alarmists…everything they instigate turns out to be rubbish:

      https://www.thegwpf.com/canadian-tidal-energy-project-collapses/

  4. Ben Vorlich permalink
    August 26, 2018 11:05 pm

    Mère France reported snow falls in the Alps and frost over the night of 25/26th August. They had late falls so it’s been a, short summer for them

  5. Athelstan permalink
    August 27, 2018 1:12 am

    calving ice, we were taught means accretion in the higher reaches of the snow sheet/glacier, it is not a sign of melting – how many more times?

  6. GEORGE LET permalink
    August 27, 2018 1:51 am

    What is SMB? The caption says “The total daily contribution to the surface mass balance from the entire ice sheet”. So wouldn’t that be the net of gains from and losses such including losses from calving ice which falls into the ocean?

    • dave permalink
      August 27, 2018 7:36 am

      SMB stands for Surface Mass Balance. It means the balance between snowfall (gain) and “melt and runoff to the sea ” (loss). Runoff to the sea is important in the definition. If ice melts but refreezes before reaching the sea it obviously does not count as a loss. The word surface is appropriate because the gain and the loss occur there. Snowfall can occur at any time of the year in some part of Greenland. Melting can only occur in the summer. The melt does not happen simply because the air is warm (observe snow in shadow on a mountain; it stays through the summer). It happens because the sun gets up early and shines from directly overhead . Once a little water appears (melt ponds) more of the radiation is absorbed.

      The ice sheet as a whole can lose mass in other ways. The first is when the sea nibbles away at its edges. The second important way is when the ice actually flows into the sea under its own weight and bits break off – “calving.” Most of this ice is not actually from the surface. It is assumed that these mass losses are fairly steady

      Antarctica is very different from the Arctic. It has no runoff – it is so big and so cold that refreezing always happens. And the breakaway from calving is not so steady.

  7. Pethefin permalink
    August 27, 2018 7:12 am

    The figures and numbers by Mottram et al. are based on computer games with regional climate models as they explain:

    “Regional climate models (RCMs) and climate reanalysis are used to quantify SMB estimates. Although different models have different spatial and temporal biases and may include different processes giving significant uncertainty in both SMB and the ice sheet dynamic response to it, all RCMs show a recent declining trend in SMB from the Greenland ice sheet, driven primarily by enhanced melt rates. Here, we present new simulations of the Greenland ice sheet SMB at 5 km resolution from the RCM HIRHAM5. The RCM is driven by the ERA-Interim reanalysis and the global climate model (GCM) EC-Earth v2.3 to make future projections for climate scenarios RCP8.5 and RCP4.5.”

    They also openly show their captivity with the global warming paradigm by explaining that:

    “Future estimates of SMB are affected by biases in driving global climate models, and feedbacks between the icesheet surface and the global and regional climate system are neglected, likely resulting in significant underestimates of melt and precipitation over the icesheet.”

    • dave permalink
      August 27, 2018 8:11 am

      The usual bull-shit. A bad workman blames his tools. I have always (sixty years of personal acquaintance) found most scientists to be argumentative, whiny babies.

      In any case, such considerations can not possibly affect estimates of changes from year to year. The difference between 2012 and now is stark.

      • dave permalink
        August 27, 2018 8:30 am

        This is the social site of the lead authoress, Ruth Mottram:

        Having skimmed it, I would say that she is not whiny. However she is almost literally a baby!

      • dave permalink
        August 27, 2018 9:43 am

        This is the link to the paper:

        And this is the first paragraph:

        “Surface mass balance (SMB) is the builder of the Greenland ice sheet and the driver of ice dynamics. Quantifying the past, present and future state of SMB is important to understand the drivers and climatic processes to control SMB, and to both initialize and run ice sheet models which will help clarify sea level rise, and how likely changes in ice sheet extent feedback within the climate system.”

        Actually, it is not particularly dismissive of the existing DMI algorithm for the Greenland SMB. So my comment “A bad workman blames his tools” was not right. What they seem to do is set up computer models so they show a steady reduction in SMB (which probably seemed clever two years ago!) and then run them forward. So I stand with my “bullshit” comment. I did not bother to read far.

        However, if still interested, I leave it to you, gentle reader, to continue on the path alone.

  8. dave permalink
    August 27, 2018 9:45 am

    Rats!

    This is the link to the paper:

    https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/65106/1/12_105-115.pdf

  9. August 27, 2018 10:39 am

    Ruth Mottram is essentially a climate modeller: http://research.dmi.dk/staff/all-staff/rum/
    EU funding is also involved, so if the models didn’t support the paradigm, there would probably be no funding. Academically she has “grown up with global warming”. She is British, with a glaciology PhD from Edinburgh, awarded in 2008.

    Her CV:
    http://www.natur.gl/fileadmin/user_upload/Marin/Klimaforskningscenter/CV/Ruth%20Mottram%20CV.pdf

    “I currently work on the interface between climate modelling and ice sheet modelling, coupling the regional climate model (HIRHAM) constructed and run at DMI, with an ice sheet model (PiSM), using an energy balance model to derive the mass budget of the Greenland ice sheet.

    As part of the Ice2Sea project (EU funded), we aim to constrain estimates of sea level rise derived from ice sheet run off and dynamical changes to the Greenland ice sheet over the next two hundred years. We ultimately aim to have a fully integrated earth system model including atmosphere, ocean, sea ice, surface snow, ice sheet and fjord processes.”

    No mention of any actual measuring taking place. The impression given is that SMB is derived from ongoing satellite scans, but seems it is just modelling. She monitored some calving activity in 2005, with pressure sensors which she used for her PhD and has had a few field trips, but nothing since 2009, so she produces Greenland SMB at her computer desk.

    • dave permalink
      August 27, 2018 10:59 am

      “…Mottram…

      As the extract from the paper in question shows, her English is appalling.
      A point is reached, where grammar and organization are so poor that a paper is unacceptable. The co-authors are not English, but that is no excuse.

    • Tom O permalink
      August 27, 2018 9:35 pm

      Ah yes, another “modeler” modeling something that they don’t understand completely, probably leaving all of the questionable interactions out of the model by assigning them constant values. Another “simulation” writer, where being “in the ball park” is good enough.

Comments are closed.

%d bloggers like this: