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The Dirty Little Secret About Arctic Ice
#21
From GeoScienceWorld


Holocene fluctuations in Arctic sea-ice cover: dinocyst-based reconstructions for the eastern Chukchi Sea


Selected Excerpt:


Quote:The results of this study clearly show that sea-ice cover in the western Arctic Ocean has varied throughout the Holocene. More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century.
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
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#22
Polar Bear Science

Polar bears barely survived the sea ice habitat changes of the last Ice Age, evidence suggests

April 21,2015

by Dr. Susan Crockford

Excerpt:

While the polar bear is an Ice Age species, genetic and fossil evidence suggests it barely survived the profound sea ice changes associated with the Last Glacial Maximum, one of the most severe glacial periods of the Pleistocene.

A map of sea ice extent at the climax of the Last Glacial Maximum (both perennial and seasonal ice), prepared with the help of a colleague, makes it possible to discuss what genetic and fossil evidence can tell us about the probable effects of glacial conditions on polar bears and ringed seals.

LINK
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
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#23
From Watts Up With That?

New study shows Arctic sea ice extent ~6000 years ago was much less than today

March 24,2014

Excerpt:

This is interesting, somehow the Earth managed to reduce a good portion of the Arctic Ice Cap during the Holocene Climate Optimum from approximately 10,000-6,000 years ago without the help of the industrial revolution, fossil fuels, or automobile emissions.

This new paper published in Quaternary Science Reviews finds Arctic sea ice extent and thickness was much less than present-day conditions and according to the authors,

LINK
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
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#24
Publication: American Geophysical Union

Ice free Arctic Ocean, an Early Holocene analogue.

Quote:Abstract

Extensive systems of wave generated beach ridges along the North Greenland coasts show that these areas once saw seasonally open water. In addition to beach ridges, large amounts of striated boulders in and on the marine sediments from the same period also indicate that the ocean was open enough for ice bergs to drift along the shore and drop their loads. Presently the North Greenland coastline is permanently beleaguered by pack ice, and ice bergs are very rare and locked up in the sea ice. Predictions of the rapidly decreasing sea ice in the Arctic Ocean generally point to this area as the last to become ice free in summer. We therefore suggest that the occurrence of wave generated shores and abundant ice berg dropped boulders indicate that the Arctic Ocean was nearly free of sea ice in the summer at the time when they were formed. The beach ridges occur as isostatically raised "staircases", and C14-dated curves for relative sea level change show that they were formed in the Early Holocene. A large set of samples of molluscs from beach ridges and marine sediments were collected in the summer of 2007, and are presently being dated to give a precise dating of the ice free interval. Preliminary results indicate that it fell within the interval from c. 8.5 to c. 6 ka - being progressively shorter from south to north. We therefore conclude that for a priod in the Early Holocene, probably for a millenium or more, the Arctic Ocean was free of sea ice at least for shorter periods in the summer. This may serve as an analogue to the predicted "greenhouse situation" expected to appear within our century.

LINK
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
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#25
More evidence of ice free Summers in the Arctic region.


Georgia before People


Seasonal Dissolution of the North Polar Ice Cap During the Early Holocene

January 31, 2016

EXCERPT:

Scientists drill cores in ocean sediment because this mud contains evidence of past climatic fluctuations.  Layers within these cores are radio-carbon dated, and the data gleaned between layers provides proxy evidence for the climatic conditions that occurred within different periods of time.  Scientists have recently drilled cores at various sites in the Arctic Ocean.  One site at Lomonosov Ridge yielded a 428 meter core, revealing a 56 million year record of Arctic Circle climate.

LINK
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#26
From No Tricks Zone

Solar Forcing Of Modern, Historic Arctic Sea Ice
Only Slightly Less Sea Ice Now Than Little Ice Age

March 2,2017

Kenneth Richards

Excerpt:

In a new paper (Stein et al., 2017), scientists find that Arctic sea ice retreat and advance is modulated by variations in solar activity.

In addition, the sea ice cover during the last century has only slightly retreated from the extent reached during coldest centuries of the Little Ice Age (1600s to 1800s AD), which had the highest sea ice cover of the last 10,000 years and flirted with excursions into year-round sea ice.

The Medieval Warm Period sea ice record (~900 to 1200 AD) had the lowest coverage since the Roman era ~2,000 years ago.
Of note, the paper makes no reference to carbon dioxide or anthropogenic forcing as factors modulating Arctic sea ice.

[Image: Arctic-Sea-Ice-Holocene-Stein-17-768x496.jpg]


LINK
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#27
From Science Matters

Arctic Ice Goes Above Average

4/26/2017

Ron Clutz

Excerpt:

"The title of this post sounds contradictory to most of what the media is saying about Arctic ice being in a tailspin, setting records for low extents, etc. And reports of ice blocking Newfoundland also fly in the face of media claims.

I will let you in on a secret: Arctic Ocean ice is doing fine and well above the decadal average. The only place where ice is below normal is outside the Arctic Ocean, namely Bering and Okhotsk Seas in the Pacific. Claims of disappearing ice pertain not to the Arctic itself, but to marginal Pacific seas that will melt out anyway in September.

I noticed the pattern this April when it became obvious that including Bering and Okhotsk in the Arctic totals gives a misleading picture. For sure they are part of Northern Hemisphere (NH) total sea ice, but currently the Pacific is going its own way, not indicative of the sea ice in the Central and Atlantic Arctic."

LINK
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#28
Birds and Climatic Change

Kenneth Williamson

Published in 1975

Selected Excerpt:

HISTORICAL REVIEW
Between 1000 and 1300 average summer temperatures were about 1°C higher
than today, with the mean annual temperature higher by perhaps 4°C in a
largely ice-free Arctic. Eric the Red, a renowned world citizen of that time, has
been much maligned as the first progressive publicity man for giving Greenland
a false image in order to attract settlers; but in truth, the southwest of that vast
country was warmer and greener by far than at any time until the Fieldfares
Turdus pilaris arrived there in the mid-1930s. The sea-temperature of the Atlantic
was higher than it has been since, and there appears to have been none or very
little ice to hinder the Vikings' communications between Iceland, Greenland,
Newfoundland and Labrador (Mowat 1965). Indeed Brooks (1926) considers that
the polar ice-cap may have disappeared entirely during the summer months, to
build anew each winter.


Page 2 of PDF
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#29
Holocene fluctuations in Arctic sea-ice cover:
dinocyst-based reconstructions for the eastern
Chukchi Sea

J.L. McKay, A. de Vernal, C. Hillaire-Marcel, C. Not, L. Polyak, and D. Darby

2008

Abstract:
Cores from site HLY0501-05 on the Alaskan margin in the eastern Chukchi Sea were analyzed for their geochemical (organic carbon,d13 C org,C org/N, and CaCO3) and palynological (dinocyst, pollen, and spores) content to document oceanographic changes during the Holocene. The chronology of the cores was established from 210 Pb dating of near-surface sediments and\14C dating of bivalve shells. The sediments span the last 9000 years, possibly more, but with a gap between the base of the trigger core and top of the piston core. Sedimentation rates are very high (*156 cm/ka), allowing analyses with a decadal to centennial resolution. The data suggest a shift from a dominantly terrigenous to marine input from the early to late Holocene. Dinocyst assemblages are characterized by relatively high concentrations (600–7200 cysts/cm3) and high species diversity, allowing the use of the modern analogue technique for the reconstruction of sea-ice cover, summer temperature, and salinity. Results indicate a decrease in sea-ice cover and a corresponding, albeit much smaller, increase in summer sea-surface temperature over the past 9000 years. Superimposed on these long-term trends are millennial-scale fluctuations characterized by periods of low sea-ice and high sea-surface temperature and salinity that appear quasi-cyclic with a frequency of about one every 2500–3000 years. The results of this study clearly showthat sea-ice cover in the western Arctic Ocean has varied throughout the Holocene. More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century

PDF LINK
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#30
From Hide the Decline blog,

Arctic Sea ice data collected by DMI 1893-1961

By Jeremy Bowman | Published May 2, 2012

Excerpt:


I came across a number of maps showing Arctic ice extend from 1893 to 1961 collected by DMI in “Nautisk Meteorologisk Aarbog”. Each year DMI have collected information on sea ice extend so that normally each of the months April, May, June, July and August ice extend was published.
There is much more to be said about these, but this is my summary for now.

LINK
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply


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