Jakobshavn record retreat

What a coincidence. Yesterday I wrote in a comment:

There's a fantastic segment on the Arctic Sea Ice Forum for discussing Greenland and its glaciers, with people presenting all kinds of analysis and satellite images. Really top quality stuff.

Well, the folks there (forum member Espen Olsen to be precise) have spotted a large change in Jakobshavn Isbræ, Greenland's fastest glacier draining 6.5 % of the Greenland ice sheet, between August 14th and 16th:

Espen reckons this is one of the largest calvings in many years, if not the largest. It also means that last year's retreat line has been passed now (date should be Aug 16 2015):

I'll update this blog post as more becomes known about this calving event, especially the size of the calving. In the meantime, here's an image showing the previous retreat lines through the years, found in this blog post on the Great White Con blog that described another big calving event earlier this year in February:

As Great White Con blogger Jim Hunt wrote at the time:

This most recent event does not bring the calving face further east than the position in summer 2014. However the sun’s rays are only just returning to that part of the planet, and the next one may well do so.

Well, there you have it, Jim. It's there.

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Update:

It is estimated over on the Forum that the total area of ice that has calved off Jakobshavn Glacier measures 12.5 km2, as compared to the estimated 7 km2 back in February and another 7 km2 back in 2010 (according to NASA). This image made by forum member A-Team shows the area:

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Update August 19th:

There's a great article up on the Washington Post website linking to this ASIB blog post, with reactions from glacier experts like Richard Alley, Jason Box and Eric Rignot.

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Update August 20th:

NASA's Earth Observatory website also has an article up, accompanied by a fantastic image comparison tool. I want it.

Comments

[Espen Olsen]

Neven thanks for showing this event so quickly and thanks to A-Team for the additional documentation.
I am convinced this is largest single calving event that ever happened at Jakobshavn since the glacier went dual (southern and northern branch).
My present estimate is Jakobshavn lost somewhere between 11 and 12,5 km2 from August 14 to August 15 2015.

[Neven]

Thanks, Espen! And thanks for any additional info.

[steven verstegen]

Ihank you for this big news. there's a wrong date of the year in the second animation. This calving is also visible on eosdis worldview.

[David Appell]

I am having trouble seeing how the first GIF shows a calving. What are the telltale signs?

[A-Team]

I recalculated the area calved as 6.3 km2 and the volume calved as 8.8 km3 (assuming 1400 m average depth of ice). This is done by counting pixels and multiplying by the resolution (area) of a (square) pixel.

I see few prospects for making this any more accurate: it is hard to tell what has calved but hasn't fallen away, is about to calve, and where the white is a vertical face or just a gnarly crevassed area at the front. Similarly for volume, it would be difficult to subtract off air in deep near-calving front crevasses.

None of this ice was floating so it all goes to sea level rise: 8.83 * 2.78 = 24.5 microns (0.0000245 meters, or 0.0245 millimeters, acording to this site:
https://climatesanity.wordpress.com/conversion-factors-for-ice-and-water-mass-and-volume/

Also, steven v notes above (?) for the 2014 comparison, that date was September 28th. I fixed the Landsat path,row mismatch and re-did the comparison at 7.5 m (instead of Espen's initial 30 m).
http://forum.arctic-sea-ice.net/index.php/topic,154.msg60953.html#msg60953

We actually commented on unusual crevasse pre-conditioning beginning on the 14th but the event itself was even larger.
http://forum.arctic-sea-ice.net/index.php/topic,154.msg60773.html#msg60773

Nukefix also has made a very important contribution here in getting Sentinel into Landsat-matching mercator coordinates, near the links above. This allows us to monitor the calving front at shorter intervals and also under dark or cloudy conditions.

[A-Team]

steven, I recommend the DMI site as a much fast and better way of watching Greenland than Eosdis worldview. Espen and I already processed way back the underlying Modis images Eosdis is now projecting, the 15-08-2015 Terra and 16-08-2015 Aqua.
http://ocean.dmi.dk/arctic/disko.uk.php

David, please always include a url with a question -- there are several hundred gifs on the Jakobshavn forum.

The telltale signs of a calving might not be seen unless you click on the animation to get it rolling. We don't use gifs except for animations (jpg or png otherwise). Watch the dates and look for calving front changes in the later date.

[A-Team]

What happens next? Wait and see -- there's still 6 weeks left in the season (per 2014).

There's no specific guidance on this from the many Jakobshavn journal articles published to date and we certainly don't know any better over at the forum.

However rubikscube posted some initial thoughts on what "crossing the sill" might mean for future retreat and I elaborated on the two main scenarios, starting at:

http://forum.arctic-sea-ice.net/index.php/topic,154.msg60950.html#msg60950

[TenneyNaumer]

There are some very interesting changes taking place on the north-northeast side of the south branch -- exactly where the number 2009 in brown lettertype is printed on the image showing prior retreat lines.

That region showed changes in the week or so leading up to this calving event.

I guess we'll just have to wait and see what happens next.

[A-Team]

We only have this dated to a 48 hour interval. If, like in Chasing Ice, it all happened in 45 minutes, there would have been a monumental series of tsunamis coming down the fjord as mile-high bergs rolled over on their sides.

Most of the scientific instrumentation is on the rock peninsula on the south side, which according to google earth elevations is ~250 meters or more above sea level, so gear and observers are not at risk.

The north side has had a real-time, open source web cam run by Dr. Holland of NYU Courant to monitor the fjord (not so much the calving front). If someone feels like chasing our time frame down on this to clarify the event sequence, that would be a great help.

[Neven]

I am having trouble seeing how the first GIF shows a calving. What are the telltale signs?

David, I've adapted the first animation and added a circle to show where the calving took place.

there's a wrong date of the year in the second animation.

Thanks, steven. I've adapted the text.

[Sam]

Neven,

I think what may be confusing some readers is that often 'calving' often is ice falling into oceans. With no ocean in the close up it isn't obvious what's happening.

In this case, the Greenland ice sheet is to the right. The glacial channel is to the left. The structure of the glacier has slowly failed backing up the channel to the point it is now over the ridge in the subsurface that separates the main ice sheet from the channel. And it appears the breakup of the glacier may now have moved farther right past the ridge into the main ice cover for Greenland.

This is important, as that ridge entry to the channel is a choke point slowing the ice. If the failure and melting move landward from there potentially melting could occur more quickly.

The ice is failing from left to right within your red circle across the lip of the ridge.

Sam

[A-Team]

Tenney, I posted a bunch of time series animations today that include the north-northeast side of the south branch, quite an interesting and active area

Start with the overview and finish with a more focused view:
http://forum.arctic-sea-ice.net/index.php/topic,154.msg61008.html#msg61008

[Tanada1945]

Do we have any data on how far back into the ice sheet the next grounding line is if this one gets melted past?

[John Christensen]

@Tanada1945,

Look at this excellent article, page 2, figure D:

http://ocean.dmi.dk/staff/mhri/Docs/Holland_et_al_NatureGeoscience2008.pdf

The fjord is very deep and goes far inland under the current south part of the glacier tongue, which explains why this area is receding.

As the article also argues, the major calving events tend to follow events, where warmer than usual sea water from the Irminger Current makes it across the threshold at the entry of the glacier fjord.

Given the geography it seems like this glacier would continue to retreat, as it has done since measurements started in 1849.

From the article also:

"We argue that the 1997 warm, subsurface pulse in Disko Bay flooded the Jakobshavn ocean fjord, and that warm bottom waters have been there since."

[John Christensen]

Following the argument from the article above, it is probably quite rare for such a pulse of warm water to make it into the Jakobshavn fjord, as the glacier front was practically immobile from 1964 - 2001, after having receded significantly earlier in the 20th century.

[Lennartvdl]

Look who's tweeting:
https://twitter.com/erignot/status/633572684710866948

[Neven]

Wow, that's cool. Thanks, Lennart.

[John Christensen]

Last key point to make regarding the warm pulse from the Irminger Current in 1997 (Which can be seen initiated in 1996, page 5, figure 4 in the same article) and text:

"Given an ocean-forced mechanism for Jakobshavn Isbræ, the question remains: what drives the change in the subsurface ocean? The warm, subsurface waters off the west Greenland coast are fed from the east by the subpolar gyre of the North Atlantic, via the Irminger current. Since the mid-1990s, observations show a warming of the subpolar gyre, and the northern Irminger Basin. A key source of variability in the forcing of the subpolar gyre is the North Atlantic Oscillation (NAO). A major change in the behaviour of the NAO was observed during the winter of 1995–1996, when it switched from a prolonged positive phase with strong westerly winds to a negative phase with weaker winds. The net effect of the change was to weaken the subpolar gyre with the consequence of moving the subpolar frontal system (the boundary between cold polar waters and warm subpolar waters) from an easterly position to a more westerly one. Such a large-scale change in the subpolar gyre allowed warm subpolar waters to spread westward, beneath colder surface polar waters, and consequently on and over the west Greenland continental shelf (Fig. 4)."

This change in NAO happens to be the same that can be observed in the AO index, which went from strongly positive (Arctic low-pressure dominance combined with more northerly and stronger jet stream flow) to a negative index (Arctic high-pressure and weakened jet stream flow).
From the AO data this extreme positive AO index event is visible as starting in August 1988 and ending rather abruptly by the end of March 1995.
The duration and strength of this event is unprecedented in the 1950-2015 AO index record - but again; given the special geography of the Jakobshavn glacier fjord and the documented retreat of the glacier front between 1851 and 1964, there must have been prior occurrences of warm, salty water from the Irminger Current flowing into the Jakobshavn glacier fjord.

[A-Team]

2008? John C, you might want to look at Holland's more recent papers, especially the 2015:

Oceanic Boundary Conditions for Jakobshavn Glacier. Part I: Variability and Renewal of Ilulissat Icefjord Waters, 2001–14
CV Gladish et al
http://tinyurl.com/qer3sfw

Oceanic Boundary Conditions for Jakobshavn Glacier. Part II: Provenance and Sources of Variability of Disko Bay and Ilulissat Icefjord Waters, 1990–2011
CV Gladish, DM Holland…
http://tinyurl.com/npy55ca

[AbbottisGone]

Things like this graph, https://www.ncdc.noaa.gov/sotc/service/global/sh-seaice/201502.gif , really seem to corroborate the fact that something is at play here don't they?

Briefly, what do we all think are the starkest examples of corroborating evidence toward climate change?

[John Christensen]

Hi A-Team,

Yes, I have read the more recent papers, both by Myers and Ribergaard (2013) as well as the new papers by Gladish et al (2015), but kept the reference to the 2008 paper, which has the most basic explanation as well as a nice graphic of the sub-glacial fjord in response to Tanada1945 above.

What is new and most clearly pronounced is that more emphasis is placed on the East and West Greenland Currents (EGC and WGC), which are surface currents, in explaining the changes in water temperature impacting the Jakobshavn icefjord (Gladis et al, 2015, p. 60):

"They [EGC and WGC] are sometimes as warm as 2C in summer and 6C in autumn at a[density level of] 27.0.."
"Temperature variability in East/West Greenland Current polar waters therefore impacts the thermal boundary conditions of Jakobshavn Glacier."

But - and this is a significant limitation, (Footnote #4, page 60 of the same 2015 paper):

"It is ambiguous whether a typical East/West Greenland Current polar water parcel maintains a relatively constant salinity during its journey around Greenland, being warmed by surface fluxes, or whether West Greenland Current polar water parcels are actually the product of mixing between very cold and very low-salinity PSW and pure Irminger Current waters where they meet south of Denmark Strait. In the first case, the fjord basin temperature could be sensitive to changes in summer air–sea heat fluxes in the Greenland boundary currents, and in the second case it would be more sensitive to changes in mixing at the density front between the East Greenland Current and Irminger Current."

So, it is actually hard to tell how significant the EGC (surface current) is, when explaining the impact of the WGC on the ice fjord basin temperature.

And then finally from the 2015 paper (Page 60 also):

However, as Myers and Ribergaard (2013) proposed to explain the warming of Disko Bay polar waters around 1997, a shift in the fraction of West Greenland Current polar waters compared to Baffin Current polar waters entering Disko Bay would also
bring about major temperature changes, impacting not just the above-sill waters in Ilulissat Icefjord but also the basin waters."

Myers and Ribergaard 2013 explains the impact of the Baffin Current:

"This study presents hydrographic data from Disko Bay, additionally revealing that there was also a significant warming of the cold polar water entering Disko Bay from the mid-to-late 1990s onward. This layer, which lies at a depth of ~30–200 m, warmed by 1°–2°C. The heat content of the polar water layer increased by a factor of 3.6 for the post-1997 period compared to the period prior to 1990. The heat content in the west Greenland Irminger water layer between the same periods increased only by a factor of 2, but contained more total heat. The authors suggest that the changes in the polar water layer are related to circulation changes in Baffin Bay."

As seen above the heat content change in the mid/late 90s was more significant with the Irminger Current than with the polar waters coming out of Baffin Bay, i.e. the Irminger Current remaining as the more significant factor.

That said; for a very significant event to take place, you often need the confluence of several factors to create a perfect storm, and that seems to be what happened with the result that the Jakobshavn glacier went from a nearly immobile state to rapid retreat by the end of the 1990s.

[John Christensen]

Sorry; I need to retract that last piece:
I had read the 2013 paper as saying that a factor 2 heat content increase of the IC was larger than a factor 3.6 increase of the Baffin Current, which may not be the case, and the circulation changes in the Baffin Current may therefore have played a more prominent role.

[Kris]

A-Team wrote:

The north side has had a real-time, open source web cam run by Dr. Holland of NYU Courant

Could you publish the new link to this cam, as the old one

http://efdl_5.cims.nyu.edu/aws_jig/jig_camera_A.html

isn't valid anymore.

[Lennartvdl]

Alley, Box and Rignot commenting via the Washington Post:
http://www.washingtonpost.com/news/energy-environment/wp/2015/08/19/one-of-the-worlds-fastest-melting-glaciers-may-have-just-lost-its-biggest-chunk-of-ice-ever/

[P-maker]

Kris,

Previous footage from the Jakobshavn calving front retreat were quite scary. In the old days, the ice stream carried Inland Ice from the centre of Greenland (now colloquially called the “Southern Branch”) towards the coast, which helped to keep the ice level high near the coast. After the initial retreat of the ice front some years ago, it was quite obvious that a new “Ice-Fall” developed on the northern shore of the newly developed “Southern Ice-fjord”.

It is ridiculous to discuss the detailed forth and back of the current calving front of the Southern ice-stream on a daily, weekly or even monthly basis. Fact is that year to year changes since the incursion of Atlantic warm salty waters across the sill at the entrance of the Jakobshavn Ice-fjord has gone only one way: DOWN.

Looking ahead some few years, we may foresee a retreat of the calving front Eastwards some 40 km from the current setting. This will open up 2x40 km’s of ice-falls on the northern and southern side of the Southern Branch.

I am fully aware that Ice-streams have one kind of flow properties. However, Ice-falls are a completely different kettle-of-fish. Ice-falls may actually be compared with solid precipitation, since examples show that ice falls do not need physical connection to carry on moving massive amounts of glacier ice downhill from a plateau to a fjord.

Getting the new landscape details correct is essential. Getting the true glaciologist onboard is even more important. My bet is that the Greenland Ice-sheet will provide the first 7m of sea level rise through the ice-fall mechanism. Later on , we should expect to see the West Antarctic contribute another 7m of sea level rise due to essentially the same Ice-fall mechanism.

[Neven]

NASA's Earth Observatory website also has an article up, accompanied by a fantastic image comparison tool.

[Clare]

Goodness me, links to this Blog are popping up all over the place!
Congratulations Neven & all contributors for the high quality of posts & discussions here & over at the Forum.

[Marcel_g]

P-maker,

Interesting comments about ice falls vs ice streams, do you know if that's included in Hansen's recent paper about abrupt sea level rise?

Abrupt sea level rise is something I'm quite worried about. I originally thought that droughts, floods and fishery collapses would be the initial fronts of climate disruption and SLR would impact later, but after seeing what Dr. Rignot and his colleagues found in West Antarctica (unstoppable collapse already started due to warm water under cutting the ice sheet) and what Dr. Box has found about Greenland's melt factors (albedo, moulin drainage, ice softening), I don't think we can discount the possibility of sea level rise happening much more quickly.

That being said, I don't think Greenland is going to contribute all 7m before the WAIS: once Greenland's marine terminating glaciers have retreated back to being above sea level, or too far from deeper warm sea water, they'll slow down, and WAIS is going to melt very fast. Rignot said at the current rate it will take the Pine Island area about 200 years, but that the rate is accelerating. If I remember correctly, that area has 1.2m of SLR in it. And there are other areas in WAIS and the Totten area in East Antarctica which are marine terminating and accelerating, so I think the WAIS is going to be contributing significantly at the same time as Greenland.

Neven, as an avid lurker, thanks very much for the blog and the forum.

[P-maker]

Marcellus,

wellcome to the blog. I trust you are one of those "true glaciologists" advertised for.

I generally concur with your reasoning. My main point was that Greenland melt would have to come first in order to lift up the WAIS.

I must admit, that I have not yet finished reading the Hansen et al. draft, so I honestly don't know, whether they have included this ice-fall mechanism or not.

Nevertheless, it is good to have you onboard. Please provide reflections and observations at your convenience.

Cheers P

[Marcel_g]

Thanks for the welcome P-maker. Unfortunately, I'm not a true glaciologist, rather I'm just an amateur observer who, like many others here, can't take my eyes away from this incredible spectacle of melting ice.

Unfortunately I won't ever have time to actually read Hansen's paper, I'm just going by the summaries provided by various climate centred sites like climatecrocks.com.

Before Hansen's paper came out, but after seeing the news about Rignot's work on the Pine Island Glacier and its neighbours in WAIS, and reading that some of the significant glaciers in Greenland and the Totten are in East Antarctica are similarly based well below sea level, I plotted out melt rates on a crude graph to see how the various contributors would add up.

It was a fun exercise, but really only for my own purposes and all pretty speculative. I included the Pine Island area (1.2m over 150 yrs), the rest of WAIS (3m over 320 yrs), marine terminating Greenland (1.5m over 200yrs), and 4m from the rest of Greenland over 320 yrs (leaving 2m of Greenland ice intact). I made assumptions that the ice melt would continue to accelerate, and I used tanh curves to approximate my assumption that overall, the ice melt will start slowly, go the fastest in the middle, then slow down again as it approaches equilibrium or zero.

This all added up to roughly 30cm by 2050 and 2m by 2100. These numbers didn't include other terrestial glaciers, the Totten glacier (1m+), thermal expansion of the oceans, or the slowing of the AMOC. I found that to be fairly alarming, because once the other contributors are factored in, sea level rise at this rate would be very disruptive and within 35 yrs.

And then Hansen comes out with his paper that a really sudden pulse of SLR is plausible enough to put it up for peer review.

cheers,
marcel

[Marcel_g]

P-maker, I think the work that Rignot and his colleagues did in the Pine Island Area wasn't about the WAIS lifting mechanically, it was that the changed ocean currents around the continent, combined with the surface layer of colder fresher water from increased ice melt, were causing the base of the glaciers' terminii to be exposed to much warmer sea water, thus increasing their discharge rates.

As well, in the case of the Pine Island area, Rignot discovered that the glaciers there have had their grounding lines melt back behind a restraining ridge of bedrock, meaning that there is no longer anything to physically slow them down and the warmer sea water can go downhill as it eats away at the base.

[Espen Olsen]

Who need a foe when having this friend:

http://www.washingtonpost.com/news/energy-environment/wp/2015/08/20/greenlands-stunning-melting-in-24-unforgettable-images/

[P-maker]

Marcel_g

Sorry to have confused you with a well-known fracking formation in the US underground.

Again, I largely concur with your reflections on the Rignot et al. papers over the years.

I have myself been over that same exercise of adding numbers from snow cover sublimation, sea ice melt, shelf-ice disintegration, ice-stream calving, mountain glaciers melting, permafrost thawing etc. It is a lot of fun doing the maths, but not really applicable in a public context.

Maybe Rignot et al. tried to see the disintegration as a 2-dimensional problem. In reality – as shown by the recent disintegration of the Southern Branch of the Jakobshavn Isbræ – there are actually 4 dimensions to the problem:

1) Retreat of the calving front due to warmer oceans
2) Lowering of the ice-stream surface due to this retreat
3) Ice fall from surrounding plateaux due to less buttressing
4) Global sea level rise over time due to 1-3 above.

Please remember that there is always a grounding line available somewhere under the ice-sheet. I still reckon, that since both Dansgaard-Oescher- and Heinrich events happened in the Northern Hemisphere concurrently, we have to combine all our knowledge about catastrophic palaeo-events with the most recent observations from the most likely source of natural variability.

Disregarding for a moment your timing estimates, I came up with following cumulative SLR:

GrIS............4.5 m
GrIs Add........2.0 m
WAIS------------4.2 m
Totten..........1.0 m
Mountain Gl. ..0.3 m
Ocean warm....0.3 m

Total.........-.12.3 m

It's not that far off my initial estimate of 14 m. What the heck, I consider this a rounding error of no practical importance on the time scales we consider here.

[P-maker]

Chris Mooning

I think you are kidding…

James Balog’s 2009 TED-talk video here: https://www.youtube.com/watch?v=DjeIpjhAqsM shows around minute 16:00 some time lapse footage of the ice fall in the background.

I recall having seen even more dramatic and more recent time lapse photos of the ice fall on the northern shore of the Southern Branch.

If someone could just point me to such footage off the beaten track, that would extremely helpful.

[P-maker]

Even Danish media have now picked up this story:

see: http://ing.dk/blog/verdens-varmeste-maaned-178151

About 15 cm down, there is a link to this thread. Lookout for the keyword "Jakobshavn" and please ignore the discussion (mainly in Danish).

[P-maker]

Marcel,

I just got through the Hansen et al. draft, and I am pretty sure they did not consider the ice fall mechanism.

During my reading of the manuscript, I discovered that you had overlooked the contribution from one retrograde glacier basin in Antarctica. Apparently the Cook glacier may over time contribute about half of the SLR of the Totten glacier (possibly 0.5 m in your numbers). Hansen et al. also reminded me that continental droughts may soon contribute a few decimeters to the overall SLR picture, which brings the overall total closer to 13 m.

However, when I started to dig into the underlying references, they suddenly opened up a can of worms. On several lines of evidence, I do not concur with the authors. When it comes to the “chevron ridges and wave run-up deposits on Bahamas” (Hearty et al. (1998), I respectfully have to disagree.

The interpretation of these morphological units is utter nonsense. Nowhere are these aeolian parabolic features made by waves, and the (apparently wave washed) 2000 t boulders are not even described in the paper. This thread is however not the right place for a discussion like that, so I will eventually have to move the discussion to this thread: http://forum.arctic-sea-ice.net/index.php/topic,1327.0.html in due course.

[Espen Olsen]

P-Maker, why ignore the discussion ;-)?

[Espen Olsen]

But I am surprised one of the biggest or rather most important tourist- and natural sites in the Kingdom of Denmark, was not mentioned to my knowledge in any danish media, but then other the other hand I am not that impressed with them anyways!

[Espen Olsen]

And DMI did not mention it either?

[P-maker]

Hi Espen,

because Neven says that this blog is for news and the forum is for discussion. Details of Substage 5e some 125 thousand years ago on a remote tropical island can hardly be called news these days...

Cheers P

[Espen Olsen]

Sorry I meant the discussion in Ingenøren?

[P-maker]

Espen,
at the moment I see 183 more or less meaningless contributions to that thread in Ingeniøren. I am as disappointed as you are, that this story has not been picked up by any news media in our country.

On the other hand, when I see how the Washington Post treated this story, I came to think of a new term: journalistic reticence.

[AbbottisGone]

In regards to the media: some say the world changes at the pace it can handle...

...the media won't help the cause until Everest melts or some-such because the media are just rich-guys getting richer!

[Iain]

The UK BBC has picked up on it today:

http://www.bbc.co.uk/news/science-environment-34041531

Interesting times for Auntie Beeb. It's as free of political and commercial interest as is practical to be.
UK govts don't like it, as they are asked all the hard questions.
UK opposition parties do like it as they get a platform.

The Licence fee system is under threat, and BBC is to end it's contract for weather forecasting with the Met Office, which has been vocal in warning of Climate change and it's effects.

Iain

[Neven]

The UK BBC has picked up on it today:

As have The Christian Science Monitor and Mashable (Andrew Freedman). And they at least link to this blog post where the news broke first.

[Iain]

Neven, yours is a very worthwhile blog and I’ve learned a great deal from it.

My post was largely in response to Abbotisgone’s comment re. media being unhelpful.

CC Deniers just don’t appear on the Beeb, though they can be found in our broadsheets and tabloids – the Telegraph, Daily Mail.

For the reasons in my OP above, the BBC is a trusted, near-neutral, source of news and they have to be careful to maintain this. Hence the ref to the ESA, which will be known to readers.

From my point of view, being right about the progress and likely future effects of CChange is not enough. Only if the electorate is aware can they influence the elected.

In that wider sense, the BBC is helping the cause.

Iain

[AbbottisGone]

Thanks, Iain, it is a conversation worth having IMHO.

In Australia we have the ABC (The National Broadcaster we call Auntie) and they have been under a little suspicion as of late of actually pushing this exponential growth phenomenon in relation to overconsumption,.. the accuser was a guy called Dick Smith. This bloke simply wanted to start the conversation on overconsumption/exponential growth and the whole sustainability question in general.

The point is it is complicated and only the virginal are pure, if you know what I mean.

The solutions are on one hand simple but economies still have to function and the idea of demand that drives markets is drummed up through advertising and the more subtler forms of propaganda.

People still have to work and then there is the idea of panic from too much change which governments always want to keep their finger on the pulse of...

Then there's the unknown unknowns of course...lol

Anyway- I just think it's an important conversation which maybe I should try taking to those forums mentioned earlier but cheers for the response.

[Jim Hunt]

Iain,

I fear you and I will have to disagree about Auntie Beeb and "CC Deniers". For one recent example of what I mean see this article in the Guardian (which is not from one of the usual suspects!):

http://www.theguardian.com/environment/2015/aug/05/whats-the-point-of-bbc-editorial-guidelines-climate-change

Two of the three MPs interviewed are long-time climate contrarians Graham Stringer and Peter Lilley.

There are any number of similar cases. Paraphrasing how Espen put it recently, "With friends like that, who needs foes?"

[John Christensen]

Jim Hunt,

The news media is all involved in the climate discussion. There are powerful economic interests on both sides, and given these interests - together with the need to please their audience, I don't see any chance that news media can be trusted overall.

The Guardian ended an article with this great quotation recently:

(http://www.theguardian.com/us-news/2015/aug/20/california-drought-blame-global-warming)

"Jessica Blunden, a Noaa climate scientist, said that heat records like this were “getting to be a monthly thing”."

This remark seems unbalanced and not warranted by observed data, and The Guardian chose it as the ending paragraph to increase the shock effect rather than checking if this could be valid.

My point is that news media - and even scientists - have other interests than describing to us as accurately as possible, what is happening, and what will happen. I am not trying to get into a discussion here, and would suggest we focus on what is happening with the ice.

[Susan Anderson]

We have been having a lot of heat records broken monthly, haven't we? Perhaps the context is too reminiscent of phony skeptic emphasis on short term but the fact remains that the rise keeps building. Sorting short-term evidence from trends is important, but I don't think we should avoid talking about the extraordinary rise over the last couple of years.

http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=85083

That's 2014, and AFAIK 2015 is moreso. So I don't think "not warranted by observed data" is quite accurate, though I sympathize with the desire to ease off on hype.

[Espen Olsen]

ESA managed to hi-jack the calving story, I guess the main reason for doing that was that the original story released in Arctic Sea Ice Forum
https://forum.arctic-sea-ice.net/index.php/topic,154.msg60933.html#msg60933
was based on USGS material and NASA, that was not a pretty ESA thing to do!!!

[Espen Olsen]

And by the way the ESA story was without the name of the Author, now you know why!

[Marcel_g]

P-Maker, very interesting.

Thanks for pointing me to that thread, although I almost hesitate to look at it because I'll never get any work done once I do! ;-)

I was kind of wondering about whether Hansen et. al had more evidence for super storms than a couple of boulders and the ridges.

And yes, I didn't include Totten or Cook in my numbers, or thermal expansion, or other land based glaciers. Add in the slowing of the AMOC, and the east coast of the US is in for some serious SLR in short order.

As well, regarding PIG and Thwaites (the main part of the WAIS) the ice fall mechanism (if I understand what you mean by ice falls) won't come into play because their grounding lines have already passed the highest point of bedrock, so the grounding line will continue to go 'downhill' as it melts inland.

cheers,
Marcel

[Ncdave4life]

The news from NASA today is that Jakobshavn is now advancing, rather than retreating. It's probably a temporary change, but, even so, it's remarkable, considering that the glacier has been retreating for over 150 years:

https://climate.nasa.gov/news/2852/cold-water-currently-slowing-fastest-greenland-glacier/

[Snip, no links to climate risk denier sites, thanks; N.]

[AnotherJourneybyTrain]

Neven, why are there no links to climate risk denier sites allowed?

[Neven]

Why do you think?