Medieval Warm Period rehabilited

[gdfernan]

Sept 3, 2009 18:26:45 GMT socold said:

Sept 2, 2009 22:20:02 GMT nautonnier said:

What a difference an internal memo makes -

"U.S. Senate Committee on Environment & Public Works
Hearing Statements
Date: 12/06/2006

Statement of Dr. David Deming
University of Oklahoma
College of Earth and Energy
Climate Change and the Media"

"Mr. Chairman, members of the Committee, and distinguished guests, thank you for inviting me to testify today. I am a geologist and geophysicist. I have a bachelor's degree in geology from Indiana University, and a Ph.D in geophysics from the University of Utah. My field of specialization in geophysics is temperature and heat flow. In recent years, I have turned my studies to the history and philosophy of science. In 1995, I published a short paper in the academic journal Science. In that study, I reviewed how borehole temperature data recorded a warming of about one degree Celsius in North America over the last 100 to 150 years. The week the article appeared, I was contacted by a reporter for National Public Radio. He offered to interview me, but only if I would state that the warming was due to human activity. When I refused to do so, he hung up on me.I had another interesting experience around the time my paper in Science was published. I received an astonishing email from a major researcher in the area of climate change. He said, "We have to get rid of the Medieval Warm Period."

The Medieval Warm Period (MWP) was a time of unusually warm weather that began around 1000 AD and persisted until a cold period known as the "Little Ice Age" took hold in the 14th century. Warmer climate brought a remarkable flowering of prosperity, knowledge, and art to Europe during the High Middle Ages.

The existence of the MWP had been recognized in the scientific literature for decades. But now it was a major embarrassment to those maintaining that the 20th century warming was truly anomalous. It had to be "gotten rid of.""


epw.senate.gov/hearing_statements.cfm?id=266543

And subsequent to that memo - the IPCC used Mann's hockey stick instead which DID get rid of the MWP.

If any of this is true why would Deming not post the memo in full (to exclude the possibility he is cherrypicking 3 words) and also publicize who the "major researcher" was?

Who is he trying to protect? Himself from libel?

Either this happened and Deming is almost obliged to give the details rather than helping to cover it up. Or it didn't happen and Deming is lying.

SOCOLD and GLC too.

The person who sent this email, apparently according to Dr Tim Ball, is Jonathan Overpeck, a a lead author of "IPCC"

canadafreepress.com/index.php/article/14664

[icefisher]

Sept 11, 2009 18:38:19 GMT glc said:

Returning to the LIA issue for a moment:

Icefisher and Woodstove seem to go with Akasofu who seem to be saying that the LIA ended in 1800.

From a WUWT post, Henrik Svensmark says

"It is important to note that the Little Ice Age was a global event. It ended in the late 19th century and was followed by an increase in solar activity."

This reinforces the point I made. There is no agreement on the duration of the LIA. It's a period to suit whatever theroy is being put forward.

I fully expect that if you live long enough GLC in a hundred years, after a hundred years of roller coaster cooling; you will still be arguing alarmist CO2 warming. . . .

I think the problem is we have too little data. . . .still to conclude with authority anything regarding climate.

The last thing I want to do is spend money on changing the climate.

Tell me some of my tax money is going to go to intercepting the next meteor from space and you get some buy in on that. . . .the only problem with that from a political standpoint is its not clear who the winners and losers are.

[steve]

Sept 8, 2009 2:13:48 GMT nautonnier said:

This may have been noted somewhere. Its the MWP but not in Armagh

The Middle Ages were warmer than today: Pescadero Basin, Gulf of California, Mexico
 Barron, J.A. and Bukry, D. 2007.

Solar forcing of Gulf of California climate during the past 2000 yr suggested by diatoms and silicoflagellates. Marine Micropaleontology 62: 115-139. Barron and Bukry (2007) developed high-resolution records of diatoms and
silicoflagellate assemblages spanning the past 2000 years from analyses of a sediment core extracted from Pescadero Basin in the Gulf of California (24°16.78'N, 108°11.65W). Results indicated that the relative abundance of Azpeitia nodulifera (a tropical diatom whose presence suggests the occurrence of higher sea surface temperatures), was found to be far greater during the Medieval Warm Period than at any other time over the 2000-year period studied, while during the Modern Warm Period its relative abundance was actually lower than the 2000-year mean.

This is a good example of where reports of papers highlight a phenomenon that is possibly due to warm periods during the 900-1450 period, but they don't highlight the periods (in this case between 1020 and 1100 when the Greenland colonies were roaring ahead) where the phenomenon does not occur.

[nautonnier]

Oct 1, 2009 14:05:30 GMT steve said:

Sept 8, 2009 2:13:48 GMT nautonnier said:

This may have been noted somewhere. Its the MWP but not in Armagh

The Middle Ages were warmer than today: Pescadero Basin, Gulf of California, Mexico
 Barron, J.A. and Bukry, D. 2007.

Solar forcing of Gulf of California climate during the past 2000 yr suggested by diatoms and silicoflagellates. Marine Micropaleontology 62: 115-139. Barron and Bukry (2007) developed high-resolution records of diatoms and
silicoflagellate assemblages spanning the past 2000 years from analyses of a sediment core extracted from Pescadero Basin in the Gulf of California (24°16.78'N, 108°11.65W). Results indicated that the relative abundance of Azpeitia nodulifera (a tropical diatom whose presence suggests the occurrence of higher sea surface temperatures), was found to be far greater during the Medieval Warm Period than at any other time over the 2000-year period studied, while during the Modern Warm Period its relative abundance was actually lower than the 2000-year mean.

This is a good example of where reports of papers highlight a phenomenon that is possibly due to warm periods during the 900-1450 period, but they don't highlight the periods (in this case between 1020 and 1100 when the Greenland colonies were roaring ahead) where the phenomenon does not occur.

So because they call it the MWP and don't specifically quote the period of Viking settlement - their data is incorrect?

[sigurdur]

A study about Chinese MWP. Couldn't find it in regular press.

www.agu.org/pubs/crossref/2009/2009GL037375.shtml

[magellan]

A sampling:

Matul, A.G., Khusid, T.A., Mukhina, V.V., Chekhovskaya, M.P. and Safarova, S.A. 2007. Recent and late Holocene environments on the southeastern shelf of the Laptev Sea as inferred from microfossil data. Oceanology 47: 80-90.
tinyurl.com/o78286

A. J. Chepstow-Lusty1,2, M. R. Frogley3, B. S. Bauer4, M. J. Leng5, K. P. Boessenkool6, C. Carcaillet2,7, A. A. Ali2, and
A. Gioda8 2009. Putting the rise of the Inca Empire within a climatic and land management context
tinyurl.com/qo8vux

Mazepa, V.S. 2005. Stand density in the last millennium at the upper tree-line ecotone in the Polar Ural Mountains. Canadian Journal of Forest Research 35: 2082-2091.
tinyurl.com/oz4an8

Sidorova, O.V., Vaganov, E.A., Naurzbaev, M.M., Shishov, V.V. and Hughes, M.K. 2007. Regional features of the radial growth of larch in North Central Siberia according to millennial tree-ring chronologies. Russian Journal of Ecology 38: 90-93.
tinyurl.com/qjpfx2

MacDonald, G.M., Kremenetski, K.V. and Beilman, D.W. 2008. Climate change and the northern Russian treeline zone. Philosophical Transactions of the Royal Society B 363: 2285-2299.
tinyurl.com/3fjnfu

Linderholm, H.W. and Gunnarson, B.E. 2005. Summer temperature variability in central Scandinavia during the last 3600 years. Geografiska Annaler 87A: 231-241.
tinyurl.com/qxlrxd

Axford, Y., Geirsdottir, A., Miller, G.H. and Langdon, P.G. 2009. Climate of the Little Ice Age and the past 2000 years in northeast Iceland inferred from chironomids and other lake sediment proxies. Journal of Paleolimnology 41: 7-24.
tinyurl.com/ph2oxj

Seppa, H. and Birks, H.J.B. 2002. Holocene climate reconstructions from the Fennoscandian tree-line area based on pollen data from Toskaljavri. Quaternary Research 57: 191-199.
tinyurl.com/obkfop

Weckstrom, J., Korhola, A., Erasto, P. and Holmstrom, L. 2006. Temperature patterns over the past eight centuries in Northern Fennoscandia inferred from sedimentary diatoms. Quaternary Research 66: 78-86.
tinyurl.com/rchk56

Sicre, M.-A., Jacob, J., Ezat, U., Rousse, S., Kissel, C., Yiou, P., Eiriksson, J., Knudsen, K.L., Jansen, E. and Turon, J.-L. 2008. Decadal variability of sea surface temperatures off North Iceland over the last 2000 years. Earth and Planetary Science Letters 268: 137-142.
tinyurl.com/6c3v7j

Justwan, A., Koc, N. and Jennings, A.E. 2008. Evolution of the Irminger and East Icelandic Current systems through the Holocene, revealed by diatom-based sea surface temperature reconstructions. Quaternary Science Reviews 27: 1571-1582.
tinyurl.com/pe52fq

Jiang, H., Ren, J., Knudsen, K.L., Eiriksson, J. and Ran, L.-H. 2007. Summer sea-surface temperatures and climate events on the North Icelandic shelf through the last 3000 years. Chinese Science Bulletin 52: 789-796.
tinyurl.com/pkpu2h

Grudd, H. 2008. Tornetrask tree-ring width and density AD 500-2004: a test of climatic sensitivity and a new 1500-year reconstruction of north Fennoscandian summers. Climate Dynamics: 10.1007/s00382-0358-2.
tinyurl.com/pugsos

Grudd, H., Briffa, K.R., Karlen, W., Bartholin, T.S., Jones, P.D. and Kromer, B. 2002. A 7400-year tree-ring chronology in northern Swedish Lapland: natural climatic variability expressed on annual to millennial timescales. The Holocene 12: 657-665.
tinyurl.com/qs7qr5

Andersson, C., Risebrobakken, B., Jansen, E. and Dahl, S.O. 2003. Late Holocene surface ocean conditions of the Norwegian Sea (Voring Plateau). Paleoceanography 18: 10.1029/2001PA000654.
tinyurl.com/pfn4h3

Geirsdottir, A., Miller, G.H., Thordarson, T. and Olafsdottir, K.B. 2009. A 2000-year record of climate variations reconstructed from Haukadalsvatn, West Iceland. Journal of Paleolimnology 41: 95-115.
tinyurl.com/puo5fk

Haltia-Hovi, E., Saarinen, T. and Kukkonen, M. 2007. A 2000-year record of solar forcing on varved lake sediment in eastern Finland. Quaternary Science Reviews 26: 678-689.
tinyurl.com/p36wrq

Grinsted, A., Moore, J.C., Pohjola, V., Martma, T. and Isaksson, E. 2006. Svalbard summer melting, continentality, and sea ice extent from the Lomonosovfonna ice core. Journal of Geophysical Research 111: 10.1029/2005JD006494.
tinyurl.com/p435nr

Eiríksson, J., Knudsen, K.L., Haflidason, H. and Heinemeier, J. 2000. Chronology of late Holocene climatic events in the northern North Atlantic based on AMS 14C dates and tephra markers from the volcano Hekla, Iceland. Journal of Quaternary Science 15: 573-580.
tinyurl.com/o78286

(NOTE: This one seems to have an interesting update)
Kullman, L. 1998. Tree-limits and montane forests in the Swedish Scandes: Sensitive biomonitors of climate change and variability. Ambio 27: 312-321.
tinyurl.com/quzdck

Berge, J., Johnsen, G., Nilsen, F., Gulliksen, B. and Slagstad, D. 2005. Ocean temperature oscillations enable reappearance of blue mussels Mytilus edulis in Svalbard after a 1000 year absence. Marine Ecology Progress Series 303: 167-175.
tinyurl.com/p2z3mh

Guilizzoni, P., Marchetto, A., Lami, A., Brauer, A., Vigliotti, L., Musazzi, S., Langone, L., Manca, M., Lucchini, F., Calanchi, N., Dinelli, E. and Mordenti, A. 2006. Records of environmental and climatic changes during the last Holocene from Svalbard: palaeolimnology of Kongressvatnet. Journal of Paleolimnology 36: 325-351.
tinyurl.com/p7uu7k

Ojala, A.E.K. and Alenius, T. 2005. 10,000 years of interannual sedimentation recorded in the Lake Nautajärvi (Finland) clastic-organic varves. Palaeogeography, Palaeoclimatology, Palaeoecology 219: 285-302.
tinyurl.com/pje7mx

Kullman, L. 2005. Pine (Pinus sylvestris) treeline dynamics during the past millennium - a population study in west-central Sweden. Annales Botanici Fennici 42: 95-106.
tinyurl.com/pkhn8q

Murdmaa, I., Polyak, L., Ivanova, E. and Khromova, N. 2004. Paleoenvironments in Russkaya Gavan' Fjord (NW Novaya Zemlya, Barents Sea) during the last millennium. Palaeogeography, Palaeoclimatology, Palaeoecology 209: 141-154.
tinyurl.com/qxqcf8

Helama, S., Merilainen, J. and Tuomenvirta, H. 2009. Multicentennial megadrought in northern Europe coincided with a global El Niño-Southern Oscillation drought pattern during the Medieval Climate Anomaly. Geology 37: 175-178.
tinyurl.com/ryroau

Zabenskie, S. and Gajewski, K. 2007. Post-glacial climatic change on Boothia Peninsula, Nunavut, Canada. Quaternary Research 68: 261-270.
tinyurl.com/qerj5s

Dansgaard, W., Johnsen, S.J., Reech, N., Gundestrup, N., Clausen, H.B. and Hammer, C.U. 1975. Climatic changes, Norsemen and modern man. Nature 255: 24-28.
tinyurl.com/pz73nb

Johnsen, S.J., Dahl-Jensen, D., Gundestrup, N., Steffensen, J.P., Clausen, H.B., Miller, H., Masson-Delmotte, V., Sveinbjörnsdottir, A.E. and White, J. 2001. Oxygen isotope and palaeotemperature records from six Greenland ice-core stations: Camp Century, Dye-3, GRIP, GISP2, Renland and NorthGRIP. Journal of Quaternary Science 16: 299-307.
tinyurl.com/qqz6bx

Johnsen, S.J., Dahl-Jensen, D., Gundestrup, N., Steffensen, J.P., Clausen, H.B., Miller, H., Masson-Delmotte, V., Sveinbjörnsdottir, A.E. and White, J. 2001. Oxygen isotope and palaeotemperature records from six Greenland ice-core stations: Camp Century, Dye-3, GRIP, GISP2, Renland and NorthGRIP. Journal of Quaternary Science 16: 299-307.
tinyurl.com/qqz6bx

Loso, M.G. 2009. Summer temperatures during the Medieval Warm Period and Little Ice Age inferred from varved proglacial lake sediments in southern Alaska. Journal of Paleolimnology 41: 117-128.
tinyurl.com/qk2r93

Cook, T.L., Bradley, R.S., Stoner, J.S. and Francus, P. 2009. Five thousand years of sediment transfer in a high arctic watershed recorded in annually laminated sediments from Lower Murray Lake, Ellesmere Island, Nunavut, Canada. Journal of Paleolimnology 41: 77-94.
tinyurl.com/q9y397

Hu, F.S., Ito, E., Brown, T.A., Curry, B.B. and Engstrom, D.R. 2001. Pronounced climatic variations in Alaska during the last two millennia. Proceedings of the National Academy of Sciences, USA 98: 10,552-10,556.
tinyurl.com/pxfnuq

Loso, M.G., Anderson, R.S., Anderson, S.P. and Reimer, P.J. 2006. A 1500-year record of temperature and glacial response inferred from varved Iceberg Lake, southcentral Alaska. Quaternary Research 66: 12-24.
tinyurl.com/pw2rt4

Lassen, S.J., Kuijpers, A., Kunzendorf, H., Hoffmann-Wieck, G., Mikkelsen, N. and Konradi, P. 2004. Late-Holocene Atlantic bottom-water variability in Igaliku Fjord, South Greenland, reconstructed from foraminifera faunas. The Holocene 14: 165-171.
tinyurl.com/oqkjka

Podritske, B. and Gajewski, K. 2007. Diatom community response to multiple scales of Holocene climate variability in a small lake on Victoria Island, NWT, Canada. Quaternary Science Reviews 26: 3179-3196.
tinyurl.com/pvw6h8

Besonen, M.R., Patridge, W., Bradley, R.S., Francus, P., Stoner, J.S. and Abbott, M.B. 2008. A record of climate over the last millennium based on varved lake sediments from the Canadian High Arctic. The Holocene 18: 169-180.
tinyurl.com/5fa4bd

Jennings, A.E. and Weiner, N.J. 1996. Environmental change in eastern Greenland during the last 1300 years: evidence from foraminifera and lithofacies in Nansen Fjord, 68°N. The Holocene 6: 179-191.
tinyurl.com/oe4evx

Kaplan, M.R., Wolfe, A.P. and Miller, G.H. 2002. Holocene environmental variability in southern Greenland inferred from lake sediments. Quaternary Research 58: 149-159.
tinyurl.com/o5vz9w

Wiles, G.C., Barclay, D.J., Calkin, P.E. and Lowell, T.V. 2008. Century to millennial-scale temperature variations for the last two thousand years indicated from glacial geologic records of Southern Alaska. Global and Planetary Change 60: 115-125.
tinyurl.com/qvfgbk

Lloyd, J.M. 2006. Late Holocene environmental change in Disko Bugt, west Greenland: interaction between climate, ocean circulation and Jakobshavn Isbrae. Boreas 35: 35-49.
tinyurl.com/og5fz9

Jensen, K.G., Kuijpers, A., Koç, N. and Heinemeier, J. 2004. Diatom evidence of hydrographic changes and ice concentrations in Igaliku Fjord, South Greenland, during the past 1500 years. The Holocene 14: 152-164.
tinyurl.com/qnz8zq

Jennings, A.E., Knudsen, K.L., Hald, M., Hansen, C.V. and Andrews, J.T. 2002. A mid-Holocene shift in Arctic sea-ice variability on the East Greenland Shelf. The Holocene 12: 49-58.
tinyurl.com/pp5eb7

[steve]

Oct 1, 2009 18:25:49 GMT nautonnier said:

Oct 1, 2009 14:05:30 GMT steve said:

This is a good example of where reports of papers highlight a phenomenon that is possibly due to warm periods during the 900-1450 period, but they don't highlight the periods (in this case between 1020 and 1100 when the Greenland colonies were roaring ahead) where the phenomenon does not occur.

So because they call it the MWP and don't specifically quote the period of Viking settlement - their data is incorrect?

I haven't criticised the paper. The interpretation of the paper doesn't tell the full story though. There is a flaw in the argument that evidence of growing grapes in Greenland in 1050, or whatever, is good evidence of global warmth.

[steve]

Noting that these are all far northern Hemsphere links, unfortunately, CO2 science summaries are somewhat partial. The partial summaries suggest to me that their selection of papers is also partial.

So this list doesn't answer the question as to whether the MWP was globally as warm or warmer than now.

Examples of partial summaries:

Besonen, M.R., Patridge, W., Bradley, R.S., Francus, P., Stoner, J.S. and Abbott, M.B. 2008. A record of climate over the last millennium based on varved lake sediments from the Canadian High Arctic. The Holocene 18: 169-180.

Abstract says:

"varve thickness record suggests that summer temperatures in recent decades were among the warmest of the last millennium, comparable with conditions that last occurred in the early twelfth and late thirteenth centuries [1080-1320]" ie. when Erik the Red was long dead.

CO2 science seems to have focused their summary on results on the sedimentation accumulation rates which the abstract implies may not be such a good proxy. Not sure without reading the full paper.

Oxygen isotope and palaeotemperature records from six Greenland ice-core stations: Camp Century, Dye-3, GRIP, GISP2, Renland and NorthGRIP
Sigfus J. Johnsen

Abstract mentions LIA but not MWP, and notes a "a clear signal of climate warming during the last century."

Hu, F.S., Ito, E., Brown, T.A., Curry, B.B. and Engstrom, D.R. 2001. Pronounced climatic variations in Alaska during the last two millennia. Proceedings of the National Academy of Sciences, USA 98: 10,552-10,556.

CO2 science says "The Medieval Warm Period occurred between AD 850 and 1200 and was of comparable warmth to the Current Warm Period."

Paper says, in a very qualified way, "although the 20th Century...was among the warmest periods of the past two millennia, two earlier intervals may have been comparably warm"

[radiant]

This is the sea between turkey and europe at Istanbul

There seems plenty of evidence that some kind of cold period developed about 3 hundred years ago and from about 200 years ago we have been warming from that period

www.springerlink.com/content/h5074687r5380mn3/fulltext.pdf?page=1

After a slight temperature increase up to the beginning of the 8th century, the
third cold period extended from the mid-8th to the 13th century, during which
the Bosphorus and even parts of the Black Sea were repeatedly frozen, and
floating ice masses entered the Sea of Marmara. Winters were markedly mild
for 400 years starting from the mid-13th century. The fourth cold period
began early in the mid-17th century and has lasted to the present day; it has
been characterized by severe winters, however, the intensity of the winter cold
has gradually diminished during this interval.

As far as I know the Bosphorous was partially frozen early in the 1960's, a little more so in the 1950's , more so in 1929 but not solidly frozen over until you go back to about the 1870's.

And from the historical record there have been 40 severe winters in Instanbul over the last 2000 years.

[glc]

After a slight temperature increase up to the beginning of the 8th century, the third cold period extended from the mid-8th to the 13th century, during which the Bosphorus and even parts of the Black Sea were repeatedly frozen, and floating ice masses entered the Sea of Marmara. Winters were markedly mild
for 400 years starting from the mid-13th century. The fourth cold period began early in the mid-17th century and has lasted to the present day; it has been characterized by severe winters, however, the intensity of the winter cold has gradually diminished during this interval.

"The mid 8th to the 13th century" ... ? Doesn't that cover about 300 years of the MWP?

"Winters were markedly mild for 400 years starting from the mid-13th century" ...? I thought the LIA kicked in around 1350. When did the vikings start abandoning their Greenland farms.

Like I said I doubt that the MWP and LIA were simultaneous global events.

[icefisher]

Oct 3, 2009 9:07:02 GMT glc said:

"The mid 8th to the 13th century" ... ? Doesn't that cover about 300 years of the MWP?

"Winters were markedly mild for 400 years starting from the mid-13th century" ...? I thought the LIA kicked in around 1350. When did the vikings start abandoning their Greenland farms.

Like I said I doubt that the MWP and LIA were simultaneous global events.

Here is temp reconstruction for Greenland.



Looks like the Vikings arrived around 980 and the smaller settlement failed 370 years later, followed a century later by the larger one.

It makes sense they would arrive at the optimum be very successful then gradually decline as the climate works against them for centuries.

www.expressnews.ualberta.ca/article.cfm?id=776

This link suggests that maybe it wasn't the weather that pushed them off but instead sand slides from advancing glaciers.

Looks like to me a 900 year pattern with a smaller 150 year pattern. Hmmmm, 1850 to 2000? Maybe the 2nd cycle peak in 2000 with warming to resume in about 75 years, huh?

Maybe its going to take another 600 years to get those Birch forests on the coast of Greenland that the vikings found when they arrived.

p.s. looking at the graph one could surmise an extra .5C in the Greenland temp for the last warming. Sure would be a shame if scientists not sticking to science gives science such a bad name that the 75 year half cycle puts global warming into the nutcase category.

[hunter]

Oct 3, 2009 10:48:13 GMT icefisher said:

Oct 3, 2009 9:07:02 GMT glc said:

"The mid 8th to the 13th century" ... ? Doesn't that cover about 300 years of the MWP?

"Winters were markedly mild for 400 years starting from the mid-13th century" ...? I thought the LIA kicked in around 1350. When did the vikings start abandoning their Greenland farms.

Like I said I doubt that the MWP and LIA were simultaneous global events.

Here is temp reconstruction for Greenland.



Looks like the Vikings arrived around 980 and the smaller settlement failed 370 years later, followed a century later by the larger one.

It makes sense they would arrive at the optimum be very successful then gradually decline as the climate works against them for centuries.

www.expressnews.ualberta.ca/article.cfm?id=776

This link suggests that maybe it wasn't the weather that pushed them off but instead sand slides from advancing glaciers.

Looks like to me a 900 year pattern with a smaller 150 year pattern. Hmmmm, 1850 to 2000? Maybe the 2nd cycle peak in 2000 with warming to resume in about 75 years, huh?

Maybe its going to take another 600 years to get those Birch forests on the coast of Greenland that the vikings found when they arrived.

p.s. looking at the graph one could surmise an extra .5C in the Greenland temp for the last warming. Sure would be a shame if scientists not sticking to science gives science such a bad name that the 75 year half cycle puts global warming into the nutcase category.

What is interesting is why the true believers cannot simply accept history.

[sigurdur]

Oct 3, 2009 9:07:02 GMT glc said:

After a slight temperature increase up to the beginning of the 8th century, the third cold period extended from the mid-8th to the 13th century, during which the Bosphorus and even parts of the Black Sea were repeatedly frozen, and floating ice masses entered the Sea of Marmara. Winters were markedly mild
for 400 years starting from the mid-13th century. The fourth cold period began early in the mid-17th century and has lasted to the present day; it has been characterized by severe winters, however, the intensity of the winter cold has gradually diminished during this interval.

"The mid 8th to the 13th century" ... ? Doesn't that cover about 300 years of the MWP?

"Winters were markedly mild for 400 years starting from the mid-13th century" ...? I thought the LIA kicked in around 1350. When did the vikings start abandoning their Greenland farms.

Like I said I doubt that the MWP and LIA were simultaneous global events.

GLC:
You are looking at regional events rather than the whole picture. Even with the warming of the past 30 years the summer where I live is 378 growing degree day units below normal. As the AGW people keep saying, even with warming there can be cold pockets.......which there are.
Emperical data supports a world wide MWP, and also a world wide LIA.

There are reasons that those want to be gotten rid of as from what I read, and not only here, is that the models can't handle either the warmth nor the cold when doing retro analysis. So the easiest way to make them work is to get rid of the MWP and LIA.

But in reality, that only covers their flaws. Instead the modelers should be working day and night to figure out what they have wrong in the models, rather than trying to get rid of the MWP and LIA.

[nonentropic]

I am with GLC on this there is quite a bit of cherry picking going on.

It is interesting that the Black Sea froze but we also know that the wind direction in that region is like a temperature switch. Three weeks of strong Northerly winds in the peak of winter in the warmest of global periods would yield a frozen Black Sea.

In the southern hemisphere this winter we had a lot of southerly winds and it was very very cold for a long period and not just locally but a number of regions. It could be a change to long term cooling but I suspect we will not be clear on this for a decade.

Anyway lets enjoy the sensational return of skiing over the last 3 or 4 years to many regions that were never to see skiing again according to the AGW's

[hunter]

Oct 3, 2009 19:24:20 GMT nonentropic said:

I am with GLC on this there is quite a bit of cherry picking going on.

It is interesting that the Black Sea froze but we also know that the wind direction in that region is like a temperature switch. Three weeks of strong Northerly winds in the peak of winter in the warmest of global periods would yield a frozen Black Sea.

In the southern hemisphere this winter we had a lot of southerly winds and it was very very cold for a long period and not just locally but a number of regions. It could be a change to long term cooling but I suspect we will not be clear on this for a decade.

Anyway lets enjoy the sensational return of skiing over the last 3 or 4 years to many regions that were never to see skiing again according to the AGW's

There are very heavy winters in the northern Black Sea. I bet that freeze ups even at Sevastopol, are rare.
But when the water freezes hard at Istanbul, in the far south of the Black Sea, that is exceptional.