Medieval Warm Period: Fact or Fiction?

http://www.youtube.com/watch?v=CY4Yecsx_-s&sns=em

http://m.youtube.com/watch?v=CY4Yecsx_-s


Quote:

This video looks at the scientific research to answer three basic questions: 1) Was the Medieval Warm Period global? 2) Was it warmer than today? 3) And what does this all mean anyway? I examine the internet feud over the hockey stick and the various myths and misinterpretations about the Medieval Warm Period that seem to be rife on the Internet. My sources for the myths are blogs and videos; my sources for the facts are scientific papers.

That's a great video, I wait in anticipation for the confusionalists to comment.Though I expect they  will hide under their beds. ::)

skippy. wrote on Jul 29^th, 2012 at 2:41pm:

That's a great video, I wait in anticipation for the confusionalists to comment.Though I expect they  will hide under their beds. ::)

I doubt they will watch it, skippy.

MWP fact.

progressiveslol wrote on Jul 29^th, 2012 at 3:01pm:

MWP fact.

How do you know, progs?

MOTR wrote on Jul 29^th, 2012 at 3:06pm:

progressiveslol wrote on Jul 29th, 2012 at 3:01pm: MWP fact. How do you know, progs?

HE DOESN'T CARE IF IT IS OR IT ISN'T: HIS JOB IS SIMPLY TO TRY AND CHEW UP THE ENTIRE INTERNET ADDRESS SPACE!!

Gotta love those 'proxy' calculations.
That's the Church of Global Warming language equivalent for 'guess'.
And a guess is what it is.
Let me know when Godzilla comes back will you. :)

chicken_lipsforme wrote on Jul 30^th, 2012 at 9:05pm:

Gotta love those 'proxy' calculations. That's the Church of Global Warming language equivalent for 'guess'. And a guess is what it is. Let me know when Godzilla comes back will you. :)

Do you even have a reason for dismissing proxy temperature reconstructions out of hand or are you just  denying everything on principle without bothering to stop and think about things?

If it's the latter then just let me know now, save me ever mistaking you for someone I should bother explaining myself to.

Upton Sinclair wrote on Jul 30^th, 2012 at 9:33pm:

chicken_lipsforme wrote on Jul 30th, 2012 at 9:05pm: Gotta love those 'proxy' calculations. That's the Church of Global Warming language equivalent for 'guess'. And a guess is what it is. Let me know when Godzilla comes back will you. :) Do you even have a reason for dismissing proxy temperature reconstructions out of hand or are you just  denying everything on principle without bothering to stop and think about things? If it's the latter then just let me know now, save me ever mistaking you for someone I should bother explaining myself to.

No, save your fingers.
If I want a guess, I'll make my own.

Sure. Why not? Much easier to deny science than to attempt to understand it.

MOTR wrote on Jul 29^th, 2012 at 3:06pm:

progressiveslol wrote on Jul 29th, 2012 at 3:01pm: MWP fact. How do you know, progs?

peer-reviewed papers map of MWP
http://www.co2science.org/data/timemap/mwpmap.html

Latest MWP paper states
our ikaite record builds the case that the oscillations of the MWP and LIA are global in their extent and their impact reaches as far South as the Antarctic Peninsula

http://wattsupwiththat.com/2012/03/22/more-evidence-the-medieval-warm-period-was-global/

You can see how the IPCC has pretty much ignored all the scientists in the map above and instead likes to rely on the hockey stick team for their moogles data
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch6s6-6.html

MOTR wrote on Jul 29^th, 2012 at 2:08pm:

1) Was the Medieval Warm Period global? 2) Was it warmer than today? 3) And what does this all mean anyway?

1.  Well that guy with the smart Rs voice in the vid seemed to think so.......so it must be true... :D

2.  Well 'today' was pretty bloody brassy here but then I suppose today in Darwin was maybe giving it a shot.... :D

3.  That's obvious.  Buy up property in Greenland folks... ;D

progressiveslol wrote on Jul 30^th, 2012 at 10:27pm:

peer-reviewed papers map of MWP http://www.co2science.org/data/timemap/mwpmap.html Latest MWP paper states our ikaite record builds the case that the oscillations of the MWP and LIA are global in their extent and their impact reaches as far South as the Antarctic Peninsula http://wattsupwiththat.com/2012/03/22/more-evidence-the-medieval-warm-period-was-global/ You can see how the IPCC has pretty much ignored all the scientists in the map above and instead likes to rely on the hockey stick team for their moogles data http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch6s6-6.html

I see you and I raise you. Every paper published between 2010 - 2011 on the subject of the paleoclimate of the last 2000 years.

Cherry picking examples and basing all of your conclusions on that while ignoring the vast wealth of OTHER research is a classic symptom of denial.


Quote:

Last 2000 years Response of Norwegian Sea temperature to solar forcing since 1000 A.D. - Sejrup et al. (2010) Drought duration and frequency in the U.S. Corn Belt during the last millennium (AD 992–2004) - Stambaugh et al. (2010) Reconciling pollen-stratigraphical and tree-ring evidence for high- and low-frequency temperature variability in the past millennium - Helama et al. (2010) Support for global climate reorganization during the “Medieval Climate Anomaly” - Graham et al. (2010) Cereal harvest dates in the Czech Republic between 1501 and 2008 as a proxy for March–June temperature reconstruction - Možný et al. (2011) A reconstruction of annual Greenland ice melt extent, 1784–2009 - Frauenfeld et al. (2011) A 2000 year record of Atlantic Water temperature variability from the Malangen Fjord, northeastern North Atlantic - Hald et al. (2011) The anomalous winter of 1783–1784: Was the Laki eruption or an analog of the 2009–2010 winter to blame? - D'Arrigo et al. (2011) Foraminiferal faunal evidence of twentieth-century Barents Sea warming - Wilson et al. (2011) Waniyetu Wówapi: Native American Records of Weather and Climate - Therrell & Trotter (2011) Extensive glaciers in northwest North America during Medieval time - Koch & Clague (2011) Climate forcing reconstructions for use in PMIP simulations of the last millennium (v1.0) - Schmidt et al. (2011) Coupled climate–carbon simulations indicate minor global effects of wars and epidemics on atmospheric CO2 between AD 800 and 1850 - Pongratz et al. (2011) Influence of human and natural forcing on European seasonal temperatures - Hegerl et al. (2011) European temperature records of the past five centuries based on documentary/instrumental information compared to climate simulations - Zorita et al. (2011) Spatial and Temporal Characteristics of Climate in Medieval Times Revisited - Diaz et al. (2011) Tree ring-based winter temperature reconstruction for Changting, Fujian, subtropical region of Southeast China, since 1850: linkages to the Pacific Ocean - Chen et al. (2011) Southern Hemisphere high-resolution palaeoclimate records of the last 2000 years - Neukom & Gergis (2011) Climate in medieval time: How anomalous? - Diaz (2011) Solar and volcanic fingerprints in tree-ring chronologies over the past 2000 years - Breitenmoser et al. (2011) A pollen-based reconstruction of summer temperature in central North America and implications for circulation patterns during medieval times - Wahl et al. (2011) Variation of accumulation rates over the last eight centuries on the East Antarctic Plateau derived from volcanic signals in ice cores - Anschütz et al. (2011) Pacific and Atlantic influences on Mesoamerican climate over the past millennium - Stahle et al. (2011) The climate of North America during the past 2,000 years reconstructed from pollen data - Viau et al. (2011) Assessing El Niño Southern Oscillation variability during the past millennium - Khider et al. (2011) South Pole ice core record of explosive volcanic eruptions in the first and second millennia A.D. and evidence of a large eruption in the tropics around 535 A.D. - Ferris et al. (2011) A robust spatial reconstruction of April to September temperature in Europe: Comparisons between the Medieval period and the recent warming with a focus on extreme values - Guiot (2011) Global and hemispheric temperature reconstruction from glacier length fluctuations - Leclercq & Oerlemans (2011) The medieval climate anomaly in Europe: comparison of the summer and annual mean signals in two reconstructions and in simulations with data assimilation - Goosse et al. (2011) Anthropogenic soils are the golden spikes for the Anthropocene - Certini & Scalenghe (2011) The earliest temperature observations in the world: the Medici Network (1654–1670) - Camuffo & Bertolin (2011) Response of Earth's surface temperature to radiative forcing over A.D. 1–2009 - Friend (2011)

And more:


Quote:

Holocene Holocene carbon emissions as a result of anthropogenic land cover change - Kaplan et al. (2010) Disentangling seasonal signals in Holocene climate trends by satellite-model-proxy integration - Schneider et al. (2010) Post-glacial regional climate variability along the East Antarctic coastal margin—Evidence from shallow marine and coastal terrestrial records - Verleyen et al. (2010) Land surface temperature changes in Northern Iberia since 4000 yr BP, based on δ13C of speleothems - Martín-Chivelet et al. (2011) Climate change and human impact at Sacrower See (NE Germany) during the past 13,000 years: a geochemical record - Enters et al. (2011) Recent melt rates of Canadian Arctic ice caps are the highest in four millennia - Fisher et al. (2011) Relative sea-level fall since the last interglacial stage: Are coasts uplifting worldwide? - Pedoja et al. (2011) The early Holocene sea level rise - Smith et al. (2011) Patterns of local and regional grain size distribution and their application to Holocene climate reconstruction in semi-arid Inner Mongolia, China - Yin et al. (2011) Response of a marine-terminating Greenland outlet glacier to abrupt cooling 8200 and 9300 years ago - Young et al. (2011) Abrupt cooling repeatedly punctuated early-Holocene climate in eastern North America - Hou et al. (2011) High variability of Greenland surface temperature over the past 4000 years estimated from trapped air in an ice core - Kobashi et al. (2011) Structure and origin of Holocene cold events - Wanner et al. (2011) Polar amplification in the mid-Holocene derived from dynamical vegetation change with a GCM - O'ishi & Abe-Ouchi (2011) Observational constraints on the causes of Holocene CO2 change - Goodwin et al. (2011) Climate changes during the last c. 7500 years as recorded by the degree of peat humification in the Lofoten region, Norway - Vorren et al. (2011) Evidence for Younger Dryas Global Climate Oscillation and Human Response in the American Southwest - Ballenger et al. (2011) Pleistocene The Younger Dryas impact hypothesis: A requiem - Pinter et al. (2011) Timing and duration of North American glacial lake discharges and the Younger Dryas climate reversal - Rayburn et al. (2011) The Mysterious Onset Of The Younger Dryas - Fiedel (2011) A benthic δ13C-based proxy for atmospheric pCO2 over the last 1.5 Myr - Lisiecki (2010) High carbon sequestration in Siberian permafrost loess-paleosols during glacials - Zech et al. (2011) Interglacial and glacial variability from the last 800 ka in marine, ice and terrestrial archives - Lang & Wolff (2011) Late Pliocene to Pleistocene sensitivity of the Greenland Ice Sheet in response to external forcing and internal feedbacks - Koenig et al. (2011) Pre-glacial and interglacial pollen records over the last 3 Ma from northwest Canada: Why do Holocene forests differ from those of previous interglaciations? - Schweger et al. (2011) Individual contribution of insolation and CO2 to the interglacial climates of the past 800,000 years - Yin & Berger (2011) Do blue-ice moraines in the Heritage Range show the West Antarctic ice sheet survived the last interglacial? - Fogwill et al. (2011) Last Glacial Maximum CO2 and δ13C successfully reconciled - Bouttes et al. (2011) Annual layering in the NGRIP ice core during the Eemian - Svensson et al. (2011) Heinrich event 1: an example of dynamical ice-sheet reaction to oceanic changes - Álvarez-Solas et al. (2011) NALPS: a precisely dated European climate record 120–60 ka - Boch et al. (2011) Sea surface and high-latitude temperature sensitivity to radiative forcing of climate over several glacial cycles - Rohling et al. (2011) High-resolution 14C dating of a 25,000-year lake-sediment record from equatorial East Africa - Blaauw et al. (2011) Was the Middle Würmian in the High Alps warmer than today? - Döppes et al. (2011) The role of ocean thermal expansion in Last Interglacial sea level rise - McKay et al. (2011)

And yet more:


Quote:

Neogene and older Stratigraphic evidence for the Hirnantian (latest Ordovician) glaciation in the Zagros Mountains, Iran - Ghavidel-syooki et al. (2011) A record of Antarctic surface temperature between 25 and 50 m.y. ago - Dallai & Burgess (2011) How likely was a green Antarctic Peninsula during warm Pliocene interglacials? A critical reassessment based on new palynofloras from James Ross Island - Salzmann et al. (2011) Mass extinction and recovery of the early toarcian (early Jurassic) brachiopods linked to climate change in Northern and Central Spain - Joral et al. (2011) Slow release of fossil carbon during the Palaeocene–Eocene Thermal Maximum - Cui et al. (2011) Extremely elevated CO2 concentrations at the Triassic/Jurassic boundary - Steinthorsdottir et al. (2011) Climate and environment of a Pliocene warm world - Salzmann et al. (2011) Climate variability in the Early Pliocene Arctic: Annually resolved evidence from stable isotope values of sub-fossil wood, Ellesmere Island, Canada - Csank et al. (2011) The evolution of mid Paleocene - early Eocene coral communities: How to survive during rapid global warming - Zamagni et al. (2011) Reconstruction of a continuous high-resolution CO2 record over the past 20 million years - van de Wal et al. (2011) Millennial-scale climate cycles in Permian–Carboniferous rhythmites: Permanent feature throughout geologic time? - Franco et al. (2011) El Niño–Southern Oscillation variability from the Late Cretaceous Marca Shale of California - Davies et al. (2011) Snapshots of the Greenland ice sheet configuration in the Pliocene to early Pleistocene - Solgaard et al. (2011) A warm Miocene climate at low atmospheric CO2 levels - Knorr et al. (2011) El Niño in the Eocene greenhouse recorded by fossil bivalves and wood from Antarctica - Ivany et al. (2011) Early Cretaceous atmospheric pCO2 level recorded from pedogenic carbonates in China - Huang et al. (2011) Warm, not super-hot, temperatures in the early Eocene subtropics - Keating-Bitonti et al. (2011) Others The dendroclimatic potential of conifers from northern Pakistan - Ahmed et al. (2010) Paleoclimatic warming increased carbon dioxide concentrations - Lemoine (2010) Rapid climate change: lessons from the recent geological past - Holmes et al. (2010) Floodplains, permafrost, cottonwood trees, and peat: What happened the last time climate warmed suddenly in arctic Alaska? - Mann et al. (2010) Development and refinement of proxy-climate indicators from peats - Chambers et al. (2011) Exceptional fossil preservation during CO2 greenhouse crises? - Retallack (2011) Environmental Reconstruction Inferred From The Intestinal Contents Of The Yamal Baby Mammoth Lyuba (Mammuthus Primigenius Blumenbach, 1799) - Kosintsev et al. (2011) Dynamic relationships between Picea crassifolia growth and climate at upper treeline in the Qilian Mts., Northeast Tibetan Plateau, China - Zhang et al. (2011) Modelling prehistoric land use and carbon budgets: A critical review - Boyle et al. (2011) Characterizing the statistical properties and interhemispheric distribution of Dansgaard-Oeschger events - Thomas et al. (2011) Discovery of a nanodiamond-rich layer in the Greenland ice sheet - Kurbatov et al. (2011) Sun-earth relationship inferred by tree growth rings in conifers from Severiano De Almeida, Southern Brazil - Prestes et al. (2011) Geological record of ice shelf break-up and grounding line retreat, Pine Island Bay, West Antarctica - Jakobsson et al. (2011) Deglacial radiocarbon history of tropical Atlantic thermocline waters: absence of CO2 reservoir purging signal - Cléroux et al. (2011) The climatic significance of artefacts related to prehistoric reindeer hunting exposed at melting ice patches in southern Norway - Nesje et al. (2011) Is climate change affecting rates of dune migration in Antarctica? - Bristow et al. (2011)

MWP fact. Just cause some Uptony loon can type with no links, and does not even type about MWP, does not make the MWP go away.

Lib voters pimp thier kids: fact!!

progressiveslol wrote on Jul 31^st, 2012 at 7:08pm:

MWP fact. Just cause some Uptony loon can type with no links, and does not even type about MWP, does not make the MWP go away.

Strawman - the argument isn't about whether the MWP is 'real' or not, it's "1) Was the Medieval Warm Period global? 2) Was it warmer than today? 3) And what does this all mean anyway?". The answers, as they stand, is that the MWP was indeed real, that it appears to have been largely regional, although there is still some dispute as to its extend, and that it was most definitely not warmer than today. As for significance, well, it's interesting and it certainly adds to our understanding of the dynamics driving the climate system but it doesn't in any way change in the slightest what we know about the current observed warming.

As for links; that was an oversight. All the papers can be found here:

http://agwobserver.wordpress.com/

Compiled for Skeptical Science here:

http://www.skepticalscience.com/new_research_special_paleoclimate.html

Upton Sinclair wrote on Jul 31^st, 2012 at 7:48pm:

progressiveslol wrote on Jul 31st, 2012 at 7:08pm: MWP fact. Just cause some Uptony loon can type with no links, and does not even type about MWP, does not make the MWP go away. Strawman - the argument isn't about whether the MWP is 'real' or not, it's "1) Was the Medieval Warm Period global? 2) Was it warmer than today? 3) And what does this all mean anyway?". The answers, as they stand, is that the MWP was indeed real, that it appears to have been largely regional, although there is still some dispute as to its extend, and that it was most definitely not warmer than today. As for significance, well, it's interesting and it certainly adds to our understanding of the dynamics driving the climate system but it doesn't in any way change in the slightest what we know about the current observed warming. As for links; that was an oversight. All the papers can be found here: http://agwobserver.wordpress.com/ Compiled for Skeptical Science here: http://www.skepticalscience.com/new_research_special_paleoclimate.html

http://joannenova.com.au/globalwarming/skeptics-handbook-ii/web-pics/loehle_e-e_2007-5-fig-2-web.gif

http://wattsupwiththat.com/2009/12/04/jo-nova-finds-the-medieval-warm-period/


http://www.co2science.org/data/mwp/mwpp.php

progressiveslol wrote on Jul 31^st, 2012 at 8:26pm:

http://wattsupwiththat.com/2009/12/04/jo-nova-finds-the-medieval-warm-period/ http://www.co2science.org/data/mwp/mwpp.php

Dodge noted. You clearly couldn't answer the questions.

I do have to point out though that, despite the way Jo Nova has creatively shifted the time-set, the Lohele 2008 data only goes up to 1935 -  what you might describe as 'hiding the incline'. This is what it really looks like, compared to multiple other reconstructions, with the instrumental record added to the end:


Quote:

So who's right?  Does Ljungqvist confirm the results of Mann (2008) and Moberg (2005)?  Or do his results agree with Loehle and McCulloch (2008)?  Figure 2 provides a comparison of them all, starting in AD 500 (the earliest date in Mann 2008's global reconstruction), with the northern hemisphere instrumental record shown for comparison. http://www.skepticalscience.com/images/recon_lj_with_others.png Figure 2.  Comparison of northern hemisphere and global temperature reconstructions.  Northern hemisphere instrumental temperature records shown for comparison (CRUTEM land only, and HADCRUT land/ocean). It's worth noting that all the reconstructions show the Medieval Warm Period, the Little Ice Age, and 20th-century warming (though Loehle 2008 only runs through 1935).  Loehle's Medieval Warm Period is both warmer and earlier than the rest (and, as noted above, Loehle recognizes that his early peak circa AD 850 is probably incorrect).  Loehle also shows a much colder Little Ice Age.  All of the reconstructions diverge more in the period before AD 800, with Moberg being the coolest, Loehle the warmest, and Mann and Ljungqvist being in the middle of the pack. When comparing Ljungqvist 2010 to Loehle 2008, it's important to remember that Ljungqvist's reconstruction is for the mid- and high-latitude Northern Hemisphere only, while Loehle's was supposed to be global.  In this light, the presence of relatively extreme temperatures in Loehle's reconstruction during both the Medieval Warm Period and the Little Ice Age ought to be viewed somewhat skeptically.  Whether or not these episodes were truly "global", they were certainly strongest in the Northern Hemisphere, particularly in the North Atlantic region. Ljungqvist 2010 suggests that his own reconstruction may have underestimated the magnitude of Northern Hemisphere cooling during the Little Ice Age, but Loehle's still appears to be an outlier if it is considered as a global reconstruction. Finally, it's worth noting that comparison to the instrumental record suggests that modern temperatures are significantly warmer than those during the height of the Medieval Warm Period.  Additional projected 21st Century warming will produce a climate unlike anything experienced in the history of human civilization. http://www.skepticalscience.com/print.php?n=394

I remember reading a paper in New Scientist a couple of years ago that showed that the MWP was a regional phenomenon caused by a strong prolonged La Nino event.  It was almost certainly a regional phenomenon only.

Upton Sinclair wrote on Jul 30^th, 2012 at 10:15pm:

Sure. Why not? Much easier to deny science than to attempt to understand it.

A guess made by a scientist is still a guess no matter who makes it eh.

chicken_lipsforme wrote on Jul 31^st, 2012 at 10:30pm:

Upton Sinclair wrote on Jul 30th, 2012 at 10:15pm: Sure. Why not? Much easier to deny science than to attempt to understand it. A guess made by a scientist is still a guess no matter who makes it eh.

Depends how you define "guess", I guess. If you define it as "everything I don't understand that seems to conflict with my political ideology", then sure. If, however, you make nuanced distinctions between Mr Joe Average taking a drunken stab in the dark at something and a statistical probability assigned to an outcome based solely on an empirical process of testing and measuring observations then a "guess", made by a scientist adhering to the rigours of the scientific method, is most definitely is not just a guess.

I can only imaging what camp your learned self must fall into ;D