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Discussion > BBD: Antarctic ice questions

I noticed the interesting discussion about antarctic land ice over on the SS thread. It's not something I know much about, but I do have a couple of question you might be able to answer.

[1] Is the land ice loss you mention localized or is it spread over the entire continent?
[2] Both the UAH and RSS satellite temperatures there show no trend over the last 30 odd years - e.g. http://www.climate4you.com/Polar%20temperatures.htm - which presumably means temperature is not the cause. Is it known what is the cause of the land ice loss?

Sep 22, 2011 at 6:55 PM | Unregistered CommenterPhilip

1) No, it's most pronounced across the West Antarctic Ice Sheet (WAIS).

2) Surface temperature is irrelevant. A real sceptic red herring. Don't be distracted. I did go over this on the thread at the time: warmer subsurface coastal waters on the West Antarctic seaboard are breaking up the ice sheets and loosening the glacial snouts from their frozen footings on submarine rock.

Gravity does the rest. Ice sheets are plastic - they flow. Remove the obstructions at the snouts of the major glaciers draining the WAIS, and their flow-rate increases. Ice mass loss rate increases. And increases. This appears to be what is starting to happen.

This graph shows the increase in ocean heat content for the Southern Ocean (data from NODC).

It's from this review of NODC OHC data by Bob Tisdale.

These are very useful, as is everything else on Bob's site.

(If you have Excel, and want to check the graph by replicating it yourself, I will be happy to explain how to access the NODC data via KNMI Climate Explorer and generate a graph from it.)

Sep 23, 2011 at 1:30 PM | Unregistered CommenterBBD

Since Antartica is not warming above zero except in part of the Peninsula, the land ice loss is the result of glacial movement.
Now land ice is decreasing because its loss is not replentished fast enough. Is this because there is not enough moisture being carried to the continent? If the Earth is indeed warming, surely there should be an increase in average atmospheric water vapour content.Since Antartica is surrounded by the ocean, any inland wind should bring moisture. For wind to consistently blow the other direction and led to net land ice loss, it would suggest that the Antartic has cooled so that dry inland wind blows out and prevent moisture from reaching the continent. Is this true?
When looking at the Earth as a whole and we simplify it as a globe with balanced heat budget. To increasing ice cover at the poles would result in a higher mean temperature in the other regions in order to preserve the total heat energy. By lossing ice cover, the mean temperature would decrease. (Sea level is another matter.)
But this is only a decadal weather effect and a self correcting mechanism of Earth, so that warming would result in subsequent cooling and vice versa on a pendulum swing.
Should we be so alarmed by looking as decadeal data?
Aparantly our climate model has got Earth's radiating ability wrong according to Dr Roy Spencer. http://www.physorg.com/news/2011-07-climate-energy-wrong-hot-global.html
Our green house effect is much less than we modeled and it will take a long long time to melt all those ice.

Sep 23, 2011 at 3:43 PM | Unregistered CommenterEdwin

BBD:

OK, thank you, very kind, and my apologies for missing your original explanation on that thread (there were a lot of comments!).

I'll explore Mr Tisdale to see what he has to say on the subject. But meanwhile may I also probe a little more concerning your answer to (2)?

Is the subsurface ocean temperature increase similar in all of the coastal areas of Antarctica? The reason I ask is that as far as I can tell from GISS, the air surface temperature along the coast has indeed been increasing around the peninsula, but looks more or less flat elsewhere.

And yes please, do leave a URL for the KNMI Climate Explorer or any data sets you think I should take a look at.

Sep 23, 2011 at 3:51 PM | Unregistered CommenterPhilip

Edwin

You are muddying the waters:

To increasing ice cover at the poles would result in a higher mean temperature in the other regions in order to preserve the total heat energy. By lossing ice cover, the mean temperature would decrease.

This, for example, is incorrect. Ice-albedo feedback would reduce GAT if the polar ice sheets increase in area. Conversely, when they decrease in area, ice-albedo feedback causes GAT to rise.

What you say about Spencer & Braswell 2011 is also incorrect.

First, SB11 does not show that the 'models are wrong'. It's weak conclusion is that there is no solution to the problem of measuring atmospheric feedback, or words to that effect.

Second, neither SB11 or any other published work by Spencer demonstrates any evidence for a low climate sensitivity.

Which means that this is unfounded and entirely misleading:

Our green house effect is much less than we modeled and it will take a long long time to melt all those ice.

I'm trying to answer Philip's questions in good faith. Stuff like this does not help at all.

Sep 23, 2011 at 4:02 PM | Unregistered CommenterBBD

Philip

Sorry for the delay. Fridays, eh?

Is the subsurface ocean temperature increase similar in all of the coastal areas of Antarctica?

As I said elsewhere (I think), the West Antarctic seaboard is experiencing warmer subsurface currents. And it is the instability of the WAIS that is cause for concern. The surface temperatures are not really relevant.

To retrieve NODC OHC data via the KNMI Climate Explorer, pick 'monthly observations' from the 'Select a field' list.

Scroll down to 'Heat content' and pick '1955 - now: NODC 0-700m'.

In the Field screen, enter the appropriate co-ordinates, eg '-90' deg N and '-60' deg N to define the Southern Ocean.

Click 'Make time series' to view Southern Ocean OHC for the 700m layer 1955 - present.

To get the raw data, scroll down to the third graph 'Anomalies' and pick 'raw data' from the text above the graph.

Select all, and copy.

Open MS Excel* and click cell A1. Paste.

Click Data tab, then Text-to-columns.

Select Fixed width.

Check that column divider is correctly placed and click Finish to convert data into two columns.

Insert a row at the top and type in a header for each column: Month (A1) and [Data Set Name] as applicable (B1).

Select both columns.

Pick the Insert tab, then ‘Scatter with straight lines’.

Use Chart Tools, Layout to format the graph as required.

You're on your way. Have fun!

*[I am using Excel 2007; exact procedures vary between versions]

Sep 23, 2011 at 7:42 PM | Unregistered CommenterBBD

BBD:

That's very helpful, both answers and instructions, thank you. Have a good weekend!

Sep 23, 2011 at 8:09 PM | Unregistered CommenterPhilip

BBD (and Philip) - as the discussion has moved over here just for the record I will re-post my last post on the Cooking the books thread: (http://bishophill.squarespace.com/blog/2011/9/20/cooking-the-books.html?currentPage=7#comments)

BBD - I know all that (gravity, glacier snouts impeded by ice bound to rock etc). But don't buy it. I live in a landscape carved by glaciers. Ice is elastic and a when glacier meets a particularly obstinate mountain it just bends round it. I could see how your concerns could have some validity wrt dodis (dead ice) which is on a incline. But the idea that because sea temperatures have risen half a degree, the whole WAIS is going to suddenly unstick and start sliding into the ocean is just alarmist bollocks.

The average temperature on the continent is about -30C? Even an average temperature rise of 5C or 10C will not make a big difference to the dynamics or resulting ice-scape. The WAIS survived the MWP, RWP, Minoan WP, and Holocene optima, all times when when it was warmer than today. You seem to give far too much credence to the alarmist scientists.

btw - I never got back to you on the Santer thread, sorry, been busy. The Evans&Puckrin paper was interesting thanks, and it was good to see some climate science based on observation and not models. I am not convinced by it, but am prepared to accept that increased CO2 may be responsible for about 0.25C of the 1C rise in the last century. I still contend that H2O is by far the main player, and that the potential negative feedback from increased cloud cover and reduced insolation over the tropics and mid latitudes soon dwarfs any forcing from any extra CO2. [Sep 22, 2011 at 7:59 AM, lapogus]

Sep 23, 2011 at 8:54 PM | Unregistered Commenterlapogus

lapogus

BBD - I know all that (gravity, glacier snouts impeded by ice bound to rock etc). But don't buy it. I live in a landscape carved by glaciers. Ice is elastic and a when glacier meets a particularly obstinate mountain it just bends round it. I could see how your concerns could have some validity wrt dodis (dead ice) which is on a incline. But the idea that because sea temperatures have risen half a degree,

The average temperature on the continent is about -30C? Even an average temperature rise of 5C or 10C will not make a big difference to the dynamics or resulting ice-scape. The WAIS survived the MWP, RWP, Minoan WP, and Holocene optima, all times when when it was warmer than today. You seem to give far too much credence to the alarmist scientists.

There's a good article about what's happing to the Pine Island and Thwaites glaciers here.

I would agree that any claim that "the whole WAIS is going to suddenly unstick and start sliding into the ocean is just alarmist bollocks".

But I'd caution against dismissiveness. Remember that in the Eemian, MSL was ~5m higher than today, with 1 - 2m believed to have come from the Greenland Ice Sheet (which still covered most of Greenland - it did not disappear; far from it). The WAIS looks to be the only serious candiate for the source of the other 3 - 4m. Partial depletion is all that's required, not break-up or anything like it.

The average temperature on the continent is about -30C? Even an average temperature rise of 5C or 10C will not make a big difference to the dynamics or resulting ice-scape.

For the nth time! Surface temperature is not the issue here. It's warming sub-sea currents that are causing the problems. Please see Sep 23, 2011 at 1:30 PM above, and
Sep 23, 2011 at 7:42 PM for instructions on verifying the OHC graph yourself if you want to.

Sep 25, 2011 at 7:29 PM | Unregistered CommenterBBD