CCD Myths – East Antarctica

20 comments on “CCD Myths – East Antarctica ”

• Comments are now closed

1. andrei 1

   11 May 2009 at 9:37 pm

   The resulting mass-wasting of the WAIS after the Ross ice shelf disintegrated (as has been seen in the Antarctica Peninsula) would then start to cause some serious sea level rises

   You are obviously scientifically illiterate to make such a statement.

   I suggest you check out Archimedes principle before posting on this topic again.because as it is you look more foolish than those you criticize.
   • r0b 1.1

     11 May 2009 at 10:01 pm

     Andrei, you’re new here, welcome to The Standard.

     You should know that a lot of the debate here is well informed. Make quite sure you know what you’re talking about before you accuse other people of foolishness. In particular, you should be aware that the author of this post, lprent, knows his climate science.

     In this case the mistake is yours. The Ross shelf floats, Archimedes applies. But the post refers to the West Antarctic Ice Sheet (WAIS), which doesn’t float, and will cause sea level rises as stated.
     • Pascal's bookie 1.1.1

       11 May 2009 at 10:15 pm

       You are obviously scientifically illiterate to make such a statement.

       I suggest you check out Archimedes principle before posting on this topic again.because as it is you look more foolish than those you criticize.

       In this case the mistake is yours. The Ross shelf floats, Archimedes applies. But the post refers to the West Antarctic Ice Sheet (WAIS), which doesn’t float,…

       “if your enemy is hungry, feed him. For if he is thirsty, give him a drink. If you do this, you will pile burning coals on his head.”
     • andrei 1.1.2

       11 May 2009 at 10:18 pm

       Indeed so but the major part of West Antarctic Ice Sheet that is not floating is well below sea level and a curious feature of H2O is that in its solid form it has a lower density than when in liquid form (hence ice floats).

       Therefore the melted WAIS would take up less volume than today’s solid WAIS. So rather than adding to sea level rise it could potentially lower it as the oceans fill the void in the basin it currently inhabits.

       Its all hypothetical anyway because its not going to happen in our lifetimes nor nor anytime in the foreseeable future
       • r0b 1.1.2.1

         11 May 2009 at 10:49 pm

         So rather than adding to sea level rise it could potentially lower it as the oceans fill the void in the basin it currently inhabits.

         Yeah nice try at a recover, but contradicted by the experts who actually know something about it. From the Wikipedia link WAIS above:

         In January 2006, in a UK government-commissioned report, the head of the British Antarctic Survey, Chris Rapley, warned that this huge west Antarctic ice sheet may be starting to disintegrate, an event that could raise sea levels by approximately 5 metres (16 ft).

         Its all hypothetical anyway because its not going to happen in our lifetimes nor nor anytime in the foreseeable future

         You continue to be just as wrong as wrong can be. Read the Wikipedia stuff. It’s happening now.
   • lprent 1.2

     12 May 2009 at 8:44 am

     I suggest that you do, and please read the post and background materials.

     In particular the height of the WAIS and its average depth, and its probable volume above sea level. It is going to give you a shock.
2. outofbed 2

   11 May 2009 at 9:52 pm

   You are obviously scientifically illiterate to make such a statement
   No it’s exactly right
   Suggest you do a little research
3. bustedblonde 3

   11 May 2009 at 10:20 pm

   We wondered where the traffic to roarprawn was coming from. Keep the debate up – debate is good. Drinking is better though. Sort of loosens you up a bit and may we recommend that you drink more often – you see better after a couple of gins. And we are happy being shallow – less likelihood of drowning… hugs and kisses

   PS Anyone over here know Rangi Kemara?
   • lprent 3.1

     12 May 2009 at 11:14 am

     Poor taste drinking gin. When I used to drink spirits it was always a single malt scotch. However it eventually it interfered with learning and programming too much, so was left behind with my other youthful pursuits like playing ‘tag’ or ‘bottles’.
4. burt 4

   11 May 2009 at 11:58 pm

   How do we measure historic sea levels when land masses are also sinking and rising over time?
   • lprent 4.1

     12 May 2009 at 8:33 am

     Fortunately the sea level at one point in time is close to being the same world wide and block faulting and other geomorphological deformation tends to be site specific. So the only real issue is to date and look at averages.

     Look at numbers of sites with coastal features across geographical regions and date them – typically using carbon dating in buried seashells and other techniques. You can eliminate sites with obvious signs of block faulting.

     The average across sites world-wide at roughly the same time will give a pretty accurate measure. The further back in time you push this the less accurate it gets. Firstly because the inaccuracy of the dating techniques errors increase, and secondly because there is more geomorphological movement. Therefore you need more sites.

     However the sea level history above our current levels has been pretty well established for the last couple of million years during the Pleistocene and Holocene. The lower sea levels (during glaciations) have had less sites currently available, and those mainly block faulted upwards. So I’d guess they are still pretty inaccurate.

     It is tricky, but they’ve been doing this particular task decades before I was at uni the first time in the late 70’s.

     Is this research to improve the accuracy of your new site? It needs it. 😈
5. burt 5

   12 May 2009 at 9:20 am

   So the short answer is we can’t accurately determine mean sea levels over time.

   Imagine if I spread 10cm of rocks over the bottom of my bath and just covered them in water. If I then pushed all the rocks into a pile I could conclude that the water level has dropped because there would be rocks sticking out of the water and the water level would have dropped relative to the top of the bath.

   Ok one more question lprent. Given that three quarters of the planet surface is water, if sufficient land based ice were to melt causing a 6m increase in sea levels there would need to be an average of 18m of ice covering all land as we know it today. If the land based ice were evenly distributed across all land would it be 18m thick?
   • lprent 5.1

     12 May 2009 at 9:41 am

     Nothing in science can be said to be 100% accurate. Your average physicist will not give you an absolute assurance on really basic matters such as constants like the speed of light or that gravity on earth is a constant when you are looking through time.

     What you’re looking for is a reasonable level of certainty under the conditions of what you are using as a framework.

     I’m afraid that you have to leave absolute certainty to people of faith who have an ability to ignore evidence that challenges their beliefs. Of course some people still have faith that the earth is flat. Or probably in your case that climate change is not happening despite any evidence to the contrary.

     If the land based ice were evenly distributed across all land would it be 18m thick?

     It isn’t evenly distributed, and never has been as far as we know (nearest would have been if the Snowball Earth hypothesis actually happened). However ice is many 1000’s of metres thick over large areas in Antarctica and Greenland. For instance the Vostok core in Antarctica was 3623 metres. It isn’t the deepest area (and I don’t think they hit bottom – but I could be wrong).

     I presume that there is some illogical reason for the question? You sound like someone looking at a thought experiment like a perfect black body or a sunflower world. They’re useful for determining the extremes of a vastly simplified system, but not for any system with multiple complex factors causing chaotic effects.
   • Maynard J 5.2

     12 May 2009 at 9:46 am

     No, the short answer is we can.

     I like your line of reasoning though – it smacks of desperation when people stop arguing that the warming isn’t happening, and instead begin to dispute the effects. I have a mental image – a slight loosening of the finger in your left ear, and maybe a flicker of a tightly shut eyelid.

     BTW Antarctica – land area 14m km/2, average ice depth 1.6km. (that’s 90% of all ice)

     Earth – 148m km/2. So antarctic ice over all land would be about 160m. I think…
     • lprent 5.2.1

       12 May 2009 at 10:29 am

       Maynard: burt is attempting the Wishart style of argument (seen here many times) which is less concerned with finding out information than it is with getting people to admit certainty, which they then argue is a sign of faith rather than science. If you admit to uncertainty then they argue that since the outcomes are unknown we should just carry on what we are doing.

       What they hate is the norm of science which is ‘grey’ – looking at reasonable degrees of certainty on outcomes and relative risk levels.

       It is one of those really boring techniques that the CCD’s have come up with so they can stop arguing about evidence and argue about people – which is where they feel comfortable. Personally I’d just wish that they’d expend some of that considerable effort simply doing some learning.
       • Maynard J 5.2.1.1

         12 May 2009 at 10:39 am

         Lprent, I know, those who profited from soft coal, DDT, thalidomide and tobacco followed the same pattern, as did the corporate sycophants and useful idiots who supported them out of ideology.
     • bilbo 5.2.2

       12 May 2009 at 5:13 pm

       And how much would the temperature have to rise to in Antartica for all that ice to melt …. just wondering ?
       • lprent 5.2.2.1

         12 May 2009 at 6:06 pm

         No-one really knows, obviously we haven’t seen it before except what has been observed at the Peninsula. There was a 5C change there over 50 years, and after about 30 years the ice-shelfs started breaking up. However that was with a slow effect of about 0.1C increase per year on average. A faster temperature rise is likely to get faster effects.

         Problem is that the gas buffering into the oceans that has been largely protecting us isn’t coping with the massive increases over recent decades. The oceans are getting much more acidic more rapidly (which is pretty freaky when you consider how much they have to adsorb to show those effects). That means oceans are unlikely be as effective at adsorption in the future. The question becomes how long the temp rise outside Antarctica in both air and sea temperature goes without disrupting the weather pattern that is keeping most of Antarctica in the deep freeze.

         About 2-3 degrees regionally at the Ross shelf would probably be sufficient over a few decades. That seems to be sufficient to cause the ice shelf to get surface melt pools, and under-side mass wasting. At least that is what seems to have happened in the Peninsula. That eventually leads to a breakup of sections. Outside of the current weather pattern around Antarctica there is a pretty strong temperature gradient – at least 5 degrees in summer. So it really depends on if anything disrupts that weather pattern.

         But it is more likely that an earlier sea level rise from the rapid melt-off of Greenland icecap (which appears to be proceeding) is going to cause a breakup in the Ross shelf. Ice floats, cracks and would cause mechanical wasting. That would melt causing more sea level rise etc… etc… Nasty feedback effect.

         Whole thing is way too risky. I suspect that one way or another we’ll find out over the next 20-30 years if not sooner. Whatever happens, I suspect that once started it will only take a decade to get rid of the Ross and other shelfs. That releases the brakes on the ice streams behind them (like the WAIS). Eventually we start getting ice wasting in the cap.

         Fortunately there don’t appear too much happening in East Antarctica. That would give a *lot* of water. But there is no way to predict the potential feedbacks accurately. We’re already beyond the worst projections of the IPCC for effects.
6. Andrew D 6

   12 May 2009 at 4:37 pm

   Thanks for the plug, lprent.
   • lprent 6.1

     12 May 2009 at 6:08 pm

     Good post. I was digging around on the east Antarctica sea ice when I saw your post. That helped a lot reduce the hunt a lot.

• Comments are now closed

• Log in
• Donate
• Contribute post

• Articles RSS