Giant clam reveals Middle Ages were warmer than today

Giant clam

Giant clam. The scientists drilled tiny, precise holes that exposed daily growth lines and built up a temperature record spanning 2500 years (see below). Click for larger version.

One of the more troubling aspects of the global warming alarm campaign is the claim that modern temperatures are unprecedented. Never before (so the story goes) have temperatures been so high. Those making this claim have striven over many years to ‘get rid of’ the MWP and thus magnify the crisis we face.

Studies from around the world, hundreds of them archived at CO2 Science, show that the Medieval Warm Period (about AD 950 to 1250) appears to have been warmer than today, though the papers vary in their approach and quality.

If a careful study could show conclusively that modern temperatures are not in fact unprecedented, then a very great deal of steam would be lost from the global warming steamrolling machine.

And here it is

A paper using a novel and highly accurate drilling technique on giant clam shells appears to prove beyond a shadow of doubt that the Medieval Warm Period in the South China Sea was warmer than the present.

The paper is A composite sea surface temperature record of the northern South China Sea for the past 2500 years: A unique look into seasonality and seasonal climate changes during warm and cold periods, by Hong Yan, Willie Soon and Yuhong Wang (Dec 2014), available online at ScienceDirect (paywalled).

Rotten pile is teetering

The hits keep coming, yet already the DAGW science doesn’t stack up. The whole rotten pile is teetering and getting closer to a collapse. However, this information must be spread around or the collapse will not happen. It’s held up by propaganda so it must be brought down by publicity. Tell everyone!


High-resolution late Holocene climate records that can resolve seasonality are essential for confirming past climatic dynamics, understanding the late 20th century global warming and predicting future climate. Here a new composite record of the sea surface temperature, SST, variation in the northern South China Sea (SCS) during the late Holocene is constructed by combining seven seasonally-resolved coral and Tridacna gigas Sr/Ca-based SST time-windows with the instrumental SST record from modern interval between 1990 and 2000. This composite multi-proxy marine record, together with the reconstructions from mainland China and tropical Western Pacific, indicates that the late Holocene warm periods, the Roman Warm Period (RWP) and Medieval Warm Period (MWP), were prominently imprinted and documented in the climatic and environmental history of the East Asia–Western Pacific region. Meanwhile, substantial and significant SST seasonality variations during the late Holocene were observed in the composite record. The observed increase in seasonality (or amplitude of seasonal cycles) during the cold periods around our study area was probably caused by the different amplitudes between winter versus summer SST variations in northern SCS, with much larger SST variation during winters than during summers for the late Holocene. In addition, the distinctive warm, cold and neutral climatic episodes identified in our northern SCS composite SST record correspond well with other paleo reconstructions from mainland China and especially well with the Northern Hemisphere-wide composites by Moberg et al. (2005) and Ljungqvist (2010). The overall agreement however also calls for more information and insights on how seasonal temperatures and their ranges vary on decadal–centennial timescales.

Their press release

Giant clam reveals Middle Ages were warmer than today

China Sea’s biggest bivalve proves climate scientists were wrong to abolish the Medieval Warm Period.

Two recent papers, one in Earth-Science Reviews and the other in Chinese Science Bulletin, have studied key chemical contents in micro-drilled giant clam shells and coral samples to demonstrate that in the South China Sea the warm period of the Middle Ages was warmer than the present.

The scientists examined surveys of the ratio of strontium to calcium content and heavy oxygen isotopes, both sensitive recorders of sea surface temperatures past and present. The aragonite bicarbonate of the Tridacna gigas clam-shell is so fine-grained that daily growth-lines are exposed by micro-drilling with an exceptionally fine drill-bit, allowing an exceptionally detailed time-series of sea-temperature changes to be compiled – a feat of detection worthy of Sherlock Holmes himself.

By using overlaps between successive generations of giant clams and corals, the three scientists – Hong Yan, of the Institute of Earth Environment, Chinese Academy of Sciences, Willie Soon, of the Harvard-Smithsonian Center for Astrophysics, and Yuhong Wang, of Fudan University, Shanghai – reconstructed a record of sea-surface temperature changes going back 2500 years.

The Roman and Mediaeval Warm Periods both showed up prominently in the Western Pacific and East Asia. Sea surface temperatures varied considerably over the 2500-year period.

Changing patterns of winter and summer temperature variation were also detected, disproving the notion that until the warming of the 20th century there had been little change in global temperatures for at least 1000 years, and confirming that – at least in the South China Sea – there is nothing exceptional about today’s temperatures.

Dr. Yan said: “This new paper adds further material to the substantial body of real-world proxy evidence establishing that today’s global temperature is within natural ranges of past changes.”

Dr. Soon added: “The UN’s climate panel should never have trusted the claim that the medieval warm period was mainly a European phenomenon. It was clearly warm in the South China Sea too.”

Further details from Dr Hong Yan: and Dr Willie Soon:

I have been sent a copy of the paper but don’t have permission to post it online. If you write to me privately I could provide portions of it for review. Write to me at richard [at] and let me know what you’d like.

Views: 80

21 Thoughts on “Giant clam reveals Middle Ages were warmer than today

  1. Richard C (NZ) on 05/01/2015 at 1:31 pm said:

    >”Those making this claim have striven over many years to ‘get rid of’ the MWP and thus magnify the crisis we face.”

    Like this:

    “We have to get rid of the Medieval Warm Period”.

    Jay (Jonathan) Overpeck, senior scientific advisor to the IPCC, in an email to Professor David Deming.

    “try to “contain” the putative “MWP.””

    Michael Mann, the author of the original Hockey Stick study in a Climategate email to Phil Jones, the head of the Climate Research Unit at East Anglia.

    In February 2003, William Connolley, a climate scientist and leading Green Party politician in the UK, began erasing all references to the Little Ice Age and in October 2003 he deleted all references to the Medieval Warm Period from Wikipedia.

    Scoundrels, the lot of them.

  2. Andy on 06/01/2015 at 10:22 am said:

    There is something slightly “Dr Who” about the fate of humanity being decided by a Giant Clam, although it’s no worse that the Lone Tree of Yamal in that respect

    I hope this work gets proper scrutiny across the board before the usual suspects start maligning Willie Soon

  3. Richard C (NZ) on 08/01/2015 at 8:22 am said:

    ‘Climate change has instructive past’

    Written by George Will, Springfield News-Leader on 07 January 2015.

    […] Before wagering vast wealth and curtailments of liberty on correcting the climate, two recent books should be considered.

    In “The Third Horseman: Climate Change and the Great Famine of the 14th Century,” William Rosen explains how Europe’s “most widespread and destructive famine” was the result of “an almost incomprehensibly complicated mixture of climate, commerce, and conflict, four centuries in gestation.” Early in that century, 10 percent of the population from the Atlantic to the Urals died, partly because of the effect of climate change on “the incredible amalgam of molecules that comprises a few inches of soil that produces the world’s food.”

    In the Medieval Warm Period (MWP), from the end of the ninth century to the beginning of the 14th, the Northern Hemisphere was warmer than at any time in the last 8,000 years — for reasons concerning which there is no consensus. Warming increased the amount of arable land — there were vineyards in northern England — leading, Rosen says, to Europe’s “first sustained population increase since the fall of the Roman Empire.” The need for land on which to grow cereals drove deforestation. The MWP population explosion gave rise to towns, textile manufacturing and new wealthy classes.

    Then, near the end of the MWP, came the severe winters of 1309-1312, when polar bears could walk from Greenland to Iceland on pack ice. In 1315 there was rain for perhaps 155 consecutive days, washing away topsoil. Upwards of half the arable land in much of Europe was gone; cannibalism arrived as parents ate children. Corpses hanging from gallows were devoured.

    Human behavior did not cause this climate change. Instead, climate warming caused behavioral change (10 million mouths to feed became 30 million). Then climate cooling caused social changes (rebelliousness and bellicosity) that amplified the consequences of climate, a pattern repeated four centuries later.

    In “Global Crisis: War, Climate Change & Catastrophe in the Seventeenth Century,” Geoffrey Parker, a history professor at Ohio State, explains how a “fatal synergy” between climatological and political factors produced turmoil from Europe to China. What he calls “the placenta of the crisis” of that century included “the Little Ice Age” (LIA) between the 1640s and the 1690s. Unusual weather, protracted enough to qualify as a change in climate, correlated so strongly with political upheavals as to constitute causation.

    Whatever caused the LIA — decreased sunspot activity and increased seismic activity were important factors — it caused, among other horrific things, “stunting” that, Parker says, “reduced the average height of those born in 1675, the ‘year without a summer,’ or during the years of cold and famine in the early 1690s, to only 63 inches: the lowest ever recorded.”

    In northerly latitudes, Parker says, each decline of 0.5 degrees Celsius in the mean summer temperature “decreases the number of days on which crops ripen by 10 percent, doubles the risk of a single harvest failure, and increases the risk of a double failure sixfold,” For those farming at least 1,000 feet above sea level this temperature decline “increases the chance of two consecutive failures a hundredfold.”

    The flight from abandoned farms to cities produced “the urban graveyard effect,” crises of disease, nutrition, water, sanitation, housing, fire, crime, abortion, infanticide, marriages forgone, and suicide. Given the ubiquity of desperation, it is not surprising that more wars took place during the 17th-century crisis “than in any other era before the Second World War.”

  4. HemiMck on 09/01/2015 at 11:58 am said:

    Happy New Year and nice to come back to new material. The clam shell data seems to be some of the best.

    The connection between drastic climate change and the consequences on populations is also well documented in China.

    The worst historic scenarios seem to be cold periods not hot ones.

    • Richard C (NZ) on 09/01/2015 at 6:39 pm said:

      Interesting read Hemi. Double cropping succeeds in warm phases and fails in cool phases. 2006 paper that has no doubt been ignored by all western government agencies. But will have been bookmarked in China I suspect.

      And if the current regime is a warm phase then think about a cool phase given this:

      ‘Farmers fail to feed UK after extreme weather hits wheat crop’ – June 2013

      Wet autumn followed by cold spring has led to one of the smallest harvests in a generation, hitting food production

    • Andy on 09/01/2015 at 7:22 pm said:

      South Canterbury is almost in “official” drought and I can confirm it is very dry down here. The local Lake Opuha is Al Gores dream view

      Expect the wailing to commence any second…

    • Richard Treadgold on 10/01/2015 at 10:44 am said:

      Expect the wailing to commence any second…

      That’s Fairlie good, Andy, and you could get a few trout in there for sure, but there’ll be no whaling.

    • Andy on 10/01/2015 at 8:39 pm said:

      It is actually very dry and parched across the whole of Canterbury.
      i *demand* that our leaders do something to take action on our drought.

      When it gets a bit cooler, day around 11,pm I am going to,start a Twitter hashtag campaign demanding that our leaders take action.


      Ok, that should do it,

      Good night

  5. Emma L Wingrove on 13/01/2015 at 12:55 pm said:

    Unfortunately this new article is definitely going to be cherry-picked by those denying climate change… and I think it’s worth pointing out that one giant clam refers to the temperatures during one time period, in one location. Whereas global climate considers all time periods, and the entire globe.

    • Richard Treadgold on 13/01/2015 at 4:50 pm said:

      Hi Emma,
      You may be unaware that perhaps the most iconic and certainly the most famous temperature reconstruction of the last 30 years, Michael Mann’s “hockey stick” of the IPCC AR3 report in 2001, depended on a single Arctic study from the Yamal Peninsula to achieve the wonderful hockey stick shape—that’s not global. Shortly afterwards, it was shown by a famous climate sceptic, Steve McIntyre, that that single study relied upon a single bristlecone pine tree. That’s not global! As well, Bristlecone pines were known to be unreliable as temperature proxies because they grow at significantly different rates often not related to temperature. If they are removed, the conclusion that the 20th century is unusually warm compared to before 1450 is reversed. Yet Mann’s hockey stick was adopted as a climate change logo by the United Nations; they thought it was proof of dangerous man-made warming. Now you tell us that this new high-quality study of tropical temperatures covering the last 2500 years does not give a global picture. No temperature reconstruction I’ve seen other than the modern thermometer or satellite-based series provides what could be called a global view because they’re just not available.

  6. HemiMck on 13/01/2015 at 4:44 pm said:

    Emma I think the study uses a considerable number of overlapping shells and coral for the analysis. It is not just one clam shell. Admittedly just one location. An extended time series in the South China sea covering the medieval warm period and agreeing with western hemisphere data has to be significant.

    • Richard Treadgold on 13/01/2015 at 5:01 pm said:

      Yes, there were samples of three corals and two clams, but the record was amazingly precise. They obtained daily growth rates, covering from 3 to 15 years. It’s very high quality and provides accurate readings of sea surface temperatures for those periods. It’s very significant.

  7. Pat From Cork on 13/01/2015 at 8:59 pm said:

    I happen to know the alleged 32,757 year old man. He’s a complete fraud. I was in the cave when he was born. That was a measly 26,382 years ago. By the way, if you see him remind him that he still owes me 5 clams. Little clams.

  8. Alexander+K on 14/01/2015 at 2:32 pm said:

    I know those of Emma’s persuasion don’t rate science much, but there is good evidence that the effects of the MWP is measurable on various well-documented sites in NZ and around the Pacific.
    There is also a large body of evidence that the MWP was a positive influence on the exploratory and colonising voyages Polynesian peoples made to NZ and other areas of the Pacific. It is also interesting that educated Japanese consider that they share the same genetic heritage as Polynesian peoples and that they both originate somewhere in South China. I suspect that much oral material that would have delineated the origins of the Maori were not taken seriously by early European colonists here in NZ, who were convinced that a written history could be believed but an oral history handed down over generations could not. How fortunate for students of the Norse peoples that those people developed a written language!

  9. Andy on 16/01/2015 at 11:07 am said:

    Berkeley Earth report for 2014

    “…’Therefore it is impossible to conclude from our analysis which of
    2014, 2010, or 2005 was actually the warmest year…”

    ( Zzzzzzz….. )

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