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Author Topic: Arctic Beaches and derived interpretations of Paleoclimate conditions  (Read 7334 times)

jdallen

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Greetings all;

I was recently challenged by someone regarding the observation that 2015 extent is the lowest for the date in the current record.  The individual tried to draw me into a fight (on someone else's page), which I refused for propriety's sake.  Among the things he asserted and posted was this:

http://adsabs.harvard.edu/abs/2007AGUFMPP11A0203F

He was using that to defend an assertion that 5-7000 years ago the Arctic was hotter, and that the current changes were no big thing.

I'm curious as to what people have to say about this, as I've got little understanding of it.  My gut says that the conclusions are (1) unsupported and/or (2) being misrepresented.  I'd rather not argue from my gut, however.

Feedback would be appreciated.
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Buddy

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Neven

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He was using that to defend an assertion that 5-7000 years ago the Arctic was hotter, and that the current changes were no big thing.

Did he also say what was causing the Arctic to be warm, and is it the same thing that is causing the warming now? And how about the rate of warming?
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jdallen

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He was using that to defend an assertion that 5-7000 years ago the Arctic was hotter, and that the current changes were no big thing.

Did he also say what was causing the Arctic to be warm, and is it the same thing that is causing the warming now? And how about the rate of warming?

TL;dr version of what he said - CO2 isn't causing the warming, its natural, we've been this warm recently without CO2, there for warming is a hoax.

Primary goal he had I think was to puff himself up in "winning" a fight with a "warmist".  I didn't want to play (on someone elses Facebook page) and told him to PM me if he wanted to debate it. 

I *suspect* I scared him off - if he can't insult me in public, it apparently isn't as fun (or likely for him to "win"). 

*However*, I've seen the article he posted tossed around before, and wanted to get a sense of what other observations/papers we might have which support or dispute some of the conclusions the authors of it make.  Buddy's was a good start (hat tip).  That said, the wave/beach issue is being used to undermine basic premises behind AGW.  I'd like to be better informed so as to handle those conversations.
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jdallen

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There's been some recent stuff getting published about Arctic wave behavior such as this:

http://www.scientificamerican.com/article/giant-waves-quickly-destroy-arctic-ocean-ice-and-ecosystems1/

The upshot from one of the authors was that there needed to be open water all the way to the pole to get the wave-cut benches they found.  It's also interesting that since the original post, the article appears to have been removed from the Norwegian web site that was originally cited as a source. (this gives a 404 error:
http://www.ngu.no/en-gb/Aktuelt/2008/Less-ice-in-the-Arctic-Ocean-6000-7000-years-ago/
)

Other things come to mind as contributing, without having open water to the pole...

1) unrelated sea level change
2) melt water retention/freshwater sedimentation or even lake related wave action
3) creation via less vigorous wave action (not requiring a 500+KM fetch)

What does the collective brain trust have as possible source material to better evaluate this?
2)
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Neven

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TL;dr version of what he said - CO2 isn't causing the warming, its natural, we've been this warm recently without CO2, there for warming is a hoax.

There's the problem right there. We know what caused ice-free or near ice-free summers during the Holocene Climatic Optimum: "This climatic event was probably a result of predictable changes in the Earth's orbit (Milankovitch cycles) and a continuation of changes that caused the end of the last glacial period".

But the Earth at the moment doesn't experience a similar change in its orbit. Quite the contrary. So something is causing the same effect as the Northern Hemisphere receiving more solar radiation during summer, but we know it's not receiving more solar radiation now. What could that be?
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Chuck Yokota

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The period 5-7000 years ago was during the Holocene Thermal Optimum. This was the latest maximum temperature during the 100,000+ glacial/interglacial cycle. We know what causes these cycles: variations in the Earth's orbit called the Milankovitch cycles. Natural variation isn't some magic that varies for no reason, but is due to physical causes.

According to the Milankovitch cycles, we have been very slowly cooling off since the thermal maximum, as confirmed by research, and would have dropped into another glacial period in a few thousand years. But due to anthropogenic global warming, we have overcome that cooling trend of thousands of years, and surpassed the maximum in a couple of centuries. There is no natural cause that can explain this sudden global warming, but it it is well explained by the physics of greenhouse gas warming.

EDIT: Ninjad by Neven while I wa typing.

Timothy Astin

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Funder, S and Kjaer K.H 2007. Ice free Arctic Ocean, an Early Holocene analogue.
American Geophysical Union, Fall Meeting 2007, abstract #PP11A-0203

This is an abstract only for a conference presentation.  The significant paper is:

Svend Funder,, Hugues Goosse, Hans Jepsen, Eigil Kaas, Kurt H. Kjær1, Niels J. Korsgaard, Nicolaj K. Larsen, Hans Linderson, Astrid Lyså, Per Möller, Jesper Olsen, Eske Willerslev. 2011. A 10,000-Year Record of Arctic Ocean Sea-Ice Variability—View from the Beach. Science, 333, pp. 747-750.

Abstract

We present a sea-ice record from northern Greenland covering the past 10,000 years. Multiyear sea ice reached a minimum between ~8500 and 6000 years ago, when the limit of year-round sea ice at the coast of Greenland was located ~1000 kilometers to the north of its present position. The subsequent increase in multiyear sea ice culminated during the past 2500 years and is linked to an increase in ice export from the western Arctic and higher variability of ice-drift routes. When the ice was at its minimum in northern Greenland, it greatly increased at Ellesmere Island to the west. The lack of uniformity in past sea-ice changes, which is probably related to large-scale atmospheric anomalies such as the Arctic Oscillation, is not well reproduced in models. This needs to be further explored, as it is likely to have an impact on predictions of future sea-ice distribution.


This paper does not have the claims of an "ice-free arctic" of the original conference presentation. Rather it points to a) the local importance of the Holocene Thermal Maximum, and b) significant regional variations in summer sea ice distribution over time. As the paper says, there is more to explore to understand the meteorological causes of these past variations in detail.

(To evaluate the paper further we would need to look at the some 50 citations of this paper.)


The current situation is quite different, with a general, and rapid ice retreat taking place, with a cause that is demonstrably AGW.   The severity of this AGW is shown by the fact that it is having a much faster, and wide-ranging impact than the Holocene Thermal Maximum did.

jdallen

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But do we really see evidence for ice free summers?  The forcing dynamics would be a lot different - CO2 forcing in the arctic is far more important because humidity is so low, so even with a two C increase in temp, the heat would still be bore evenly applied in the Holocene max, when CO2 levels were only 280ish ppm.

The article Buddy supplied implied it's been over 40K years since it was this hot; that implies as much or more ice in the basin 7000YBP.
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jdallen

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Brilliant, Timothy... Dead on the mark.
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AbruptSLR

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As indicated by the attached plot (from the first of the two following linked web articles) the Holocene Thermal Maximum occurred between 9,000 and 5,000 years ago, and was a normal interglacial temperature maximum, and that the world was headed towards another glacial period when anthropogenic warming kicked in (note the attached plot assumes a pathway leading to a 3C anthropogenic temperature rise by 2100).  The plot makes it clear that today we are essentially back to the same global mean surface temperature as during the Holocene Thermal Maximum; so if we stopped all anthropogenic forcing today things might be alright.  Unfortunately, it is a daydream to believe that anthropogenic radiative forcing is going to stop before we exceed at least a 2C temperature rise; which will greatly exceed anything that the Arctic has seen in a few million years (ie back to the Pliocene).

http://www.realclimate.org/index.php/archives/2013/09/paleoclimate-the-end-of-the-holocene/

http://en.wikipedia.org/wiki/Holocene_climatic_optimum

Image Caption: "Figure 4 Global temperature variation since the last ice age 20,000 years ago, extended until 2100 for a medium emissions scenario with about 3 degrees of global warming."
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oren

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But do we really see evidence for ice free summers?  The forcing dynamics would be a lot different - CO2 forcing in the arctic is far more important because humidity is so low, so even with a two C increase in temp, the heat would still be bore evenly applied in the Holocene max, when CO2 levels were only 280ish ppm.

The article Buddy supplied implied it's been over 40K years since it was this hot; that implies as much or more ice in the basin 7000YBP.

If I understood correctly, at the top of the Milankovitch cycle the summers were hotter due to stronger insolation, while winters colder. Possibly summer saw more ice-free areas than today. Average temps could still have been same as today, or lower.

jdallen

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Similarly Brilliant, ASLR. Thanks to all of you, and pray continue
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AbruptSLR

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Similarly Brilliant, ASLR. Thanks to all of you, and pray continue

jdallen,

I am not an Arctic Sea Ice expert.  If you want to see an aggressive interpretation of the risks of potentially rapid Arctic Sea Ice loss then I suggest that on the home page of the forum that you search for "jai mitchell"; who has many, many posts on this topic (both rapid sea ice loss and on rapid Arctic Amplification) such as Reply #914 in the following linked thread:

http://forum.arctic-sea-ice.net/index.php/topic,1053.msg51292.html#msg51292

Best,
ASLR
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jdallen

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Similarly Brilliant, ASLR. Thanks to all of you, and pray continue

jdallen,

I am not an Arctic Sea Ice expert.  If you want to see an aggressive interpretation of the risks of potentially rapid Arctic Sea Ice loss then I suggest that on the home page of the forum that you search for "jai mitchell"; who has many, many posts on this topic (both rapid sea ice loss and on rapid Arctic Amplification) such as Reply #914 in the following linked thread:

http://forum.arctic-sea-ice.net/index.php/topic,1053.msg51292.html#msg51292

Best,
ASLR
Don't underestimate yourself. I know of Jai; we have dialogued previously.  I shall hunt him up again.
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wili

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Nice plot, ASLR.

IIRC, we passed that Holocene Optimum temperature a few years back and we're on our way to the Eemian now--probably above 1C over pre-1800 levels by the end of the year, unless the intensifying El Nino suddenly turns La Nina on us.
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AbruptSLR

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The following is a re-post from the Antarctic folder at, which I like because is provides both paleo-evidence of high Arctic Amplification (which is currently being cut roughly in half by aerosols from Asia) from Lake Elgygytgn in Russia; and also the Inter-hemispheric climate couple showing that SLR form Antarctica can increase the water deep in the Bering Strait sufficiently to allow warm water from the Pacific Ocean to flow into the Arctic Ocean (thus decreasing Arctic Sea Ice):

http://forum.arctic-sea-ice.net/index.php/topic,130.msg27687/topicseen.html#msg27687

"The following link leads to the University of Alaska Fairbank's website focused on Lake Elgygytgn research, and the extract following the link is from an article Posted on February 4th, 2014 by Laura Nielsen on "Inter-hemispheric climate coupling". The extract emphasizes that in the paleo-past the Antarctic generally responded more quickly to orbital induced solar insolation variations, and that repeatedly paleo-collapses of the WAIS resulted in subsequent Arctic amplification, due both to changes in ocean currents, and to increases in sea level pushing more warm Pacific water through the Bering St. into the Arctic Ocean.  If the WAIS collapses this century, we may soon see a marked increase in Arctic amplification:


http://frontierscientists.com/tag/lake-elgygytgyn/

Extract: "Antarctica and the Arctic
Climate at the North and South pole are connected. Sediment records from Antarctica show that the West Antarctic ice sheet melted at various times in history. Following many of those events, the Arctic warmed. These recurring intervals of paired warming show that climate in the two hemispheres is linked – it’s called inter-hemispheric climate coupling.
“When the West Antarctic ice sheet pulls back we see a corresponding warmth in the high lattitudes again, probably affecting the size of the Greenland ice sheet with major implications for changes in sea level,” says Julie Brigham-Grette. “Our results mesh with what glaciologists are seeing today. Seven of the 12 major ice shelves around the Antarctic are melting or are gone. We suspect the tipping point for the gradual de-glaciation of Greenland and the Arctic may be lower than glaciologists once thought.”
Complex systems
Earth is a complicated place. We can’t explain past warming using only orbital dynamics or levels of Carbon Dioxide. Scientists affiliated with the project outlined some past events that might explain the rapid warming the sediment records show occurred in both Antarctica and the Arctic around similar times.
When you imagine Antarctica, the picture includes large ice shelves that hang off the rocky edge of the ice-covered continent. Normally that ice keeps nearby ocean water very cold. The cold water travels along currents toward the north Pacific where it wells up to the surface. Ocean circulation can be affected, though. If Antarctic ice sheets disintegrate or melt away, they no longer enforce cold water currents that journey to the Arctic. Instead, surface ocean waters in the Arctic become warmer.
When Antarctica’s ice sheets disintegrate the ocean gains more water and sea levels rise globally. The Bering Strait usually restricts how much warm surface water approaches the Arctic from the south, but higher sea levels would mean warm surface water didn’t have to squeeze through such a narrow space, letting more warm water past the Bering Strait into the Arctic Ocean.
Either way, a warmer ocean means higher temperatures and more rainfall for the Arctic, which impacts paleoclimatology and sea ice history. Grasping the climate connections between the hemispheres gives us insight into our near future.""

Furthermore, I decided to add the four attached paleo plots for your general information.  The first image by Hansen & Sato compares modern global mean surface temperature with those for over the past 0.8 million years.
The second compare the rate of modern global mean surface temperature raise to that during the PETM (showing that we are way faster now by about a factor of 100 times). 
The third image compares the CMIP5 Arctic Sea Ice projections vs observed through 2012 (note that I believe that the 2013 CMIP5 projections err on the side of least drama). 
The fourth shows the results of a GCM projection of the estimated timing of acceleration of ocean heat content from the flow of warm Atlantic current into the Arctic Ocean following a BAU pathway.
« Last Edit: May 14, 2015, 03:55:00 PM by AbruptSLR »
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AbruptSLR

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Nice plot, ASLR.

IIRC, we passed that Holocene Optimum temperature a few years back and we're on our way to the Eemian now--probably above 1C over pre-1800 levels by the end of the year, unless the intensifying El Nino suddenly turns La Nina on us.

wili,

Of course you are correct able the historical temperature differences.  I was posting too fast in my earlier post; however, the Hansen & Sato figure that I provided in my last post provides some additional perspective (however, there is always uncertainties associated with paleo-data).

A few additional points for jdallen, with regard to reasons that Arctic Amplification will likely increase in the coming decades include: (a) Asian air pollution is projected to be reduced (which is current cutting Arctic Amplification in half); (b) shrub growth will decrease tundra albedo; (c) wildfires will decrease Arctic albedo; (d) Greenland's albedo is decreasing much more rapidly than CMIP5 projected and this loss will likely continue; (e) the extant Arctic Sea Ice is now dominated by first year ice, which is thinner and thus darker than multi-year ice, and as first year ice is flatter than multi-year ice the melt pond on first year ice spread-out more widely than is the case for multi-year and both of these effects reduce the albedo of Arctic Sea Ice; (f) relatively faster increasing in water vapor (which is a GHG) on a percentage basis in the Arctic as compared to lower latitudes; (g) changes in cloud-cover; and (h) a lower increase in change of blackbody radiation into space per unit of global warming than for lower latitudes.

There are many other positive feedbacks to Arctic Amplification (such as declining sea ice extent exposing more dark ocean surface and reduction in land based snow cover with increasing temperatures); which you can read about in the following linked references:

http://www.nature.com/ngeo/journal/v7/n3/full/ngeo2071.html?message-global=remove

http://www.skepticalscience.com/What-causes-Arctic-amplification.html

Best,
ASLR
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AbruptSLR

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The linked article states that projected increases in phytoplankton may increase Arctic Amplification by an additional 20%

http://www.carbonbrief.org/blog/2015/04/tiny-marine-plants-could-amplify-arctic-warming-by-20-percent-new-study-finds/
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Laurent

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Quote
http://adsabs.harvard.edu/abs/2007AGUFMPP11A0203F
If the study is real and significant, then that should not astonishe us, the arctic is really sensible. At that time the earth was 0,5°C higher than pre-industrial, we are at 0,8°C watching the ice disinteger under our very eyes.
I can imagine the arctic behing warm enough so the main pack is still there but the margins have melted, so it could explained why some studies show that where was still a lot of ice on the ground in northern Canada.

Andreas T

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I read the paper  here:http://www.researchgate.net/publication/51547629_A_10000-year_record_of_Arctic_Ocean_sea-ice_variability--view_from_the_beach my understanding is that it shows evidence for very different conditions in that region during the Holocene Thermal Maximum. There was multiyear ice in the Arctic ocean (as seen from long distance transport of driftwood) but it did at times not reach this part of Greenland. There were ice free parts of the coastline during summer which had higher insolation than now and probably higher melt discharge from the Greenland icecap. I could imagine that weathersystems would have been different under the conditions then too. It does raise the question of what Fram strait would have been like at that time.
I think it demonstrates variability of the Arctic in different forcings rather than random "natural variability" which is often discussed as the "anything but CO2" cause of warming.
Quote
To the north of 83°N beach ridges are restricted to bays and major river mouths, showing that this coast had permanent sea ice but was within the zone of coastal melt (Fig. 1C). Coastal melt is determined by local summer temperatures (15), and this indicates that summer temperatures during the HTM in north Greenland were 2° to 4°C warmer than now, as elsewhere in this part of the Arctic (17).Driftwood from this period is sparse, and be-cause there was free access to the coast, we can conclude that multiyear sea ice was reduced.
from the conclusions
Quote
In general, our sea-ice record for North Greenland follows the Holocene climate development, with an early warm period followed by declining temperatures, which were punctuated by relatively warmer and colder intervals(17,25). The reduction of the HTM sea ice in northern Greenland fits with the simulated ice distribution and surface temperature in orbitally forced ECHAM5/JSBACH/MPI-OM (EJM) andLOVECLIM general circulation climate model simulations (3,4,10)


another paper dealing with indications of higher HTM temperatures for the Northeastern corner of Greenland is :http://www.researchgate.net/publication/275837340_Lake_sediment_multi-taxon_DNA_from_North_Greenland_records_early_post-glacial_appearance_of_vascular_plants_and_accurately_tracks_environmental_changes
Quote
Using ancient DNA from a lake sediment core, we wereable to analyze vascular plants, bryophytes, diatoms and otheralgae, and copepods throughout the Holocene in northernmostGreenland. Both the plant and algal DNA records indicate relativelyhigh summer temperatures in the early Holocene, with severalidentified plant taxa being present shortly after deglaciation,including the woody plantEmpetrum nigrum.

Timothy Astin

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Andreas,

The 2015 paper you linked to is a neat piece of work.
The more geologists/environmental scientists find out about changes during the Holocene Thermal Maximum, the more we discover how responsive to quite subtle environmental change the planet is.

At first sight, the sea ice at the very north of Greenland seemed to be very stable.  The Funder at al. paper, which you summarised nicely, is a neat example of field observations leading to a realisation of how sensitive it is to other environmental change.

Like many here, I am both fascinated by the profound and rapid environmental change in the Arctic under our massive AGW intervention.  Such geological study leads me expect the environmental surprises in the Arctic to be on the side of more rapid change, and in some still unforeseen ways, than most people, including many scientists, anticipate.