There’s a new article at Nature News where they report on an amazing new paleoclimatology breakthrough with temperature reconstructions using clamshells. The Nature article reports on a new paper in PNAS from William Patterson at the University of Saskachewan. Here’s a short excerpt:
The study used 26 shells obtained from sediment cores taken from an Icelandic bay. Because clams typically live from two to nine years, isotope ratios in each of these shells provided a two-to-nine-year window onto the environmental conditions in which they lived.
Patterson’s team used a robotic sampling device to shave thin slices from each layer of the shells’ growth bands. These were then fed into a mass spectrometer, which measured the isotopes in each layer. From those, the scientists could calculate the conditions under which each layer formed.
Unlike counting tree rings which have varying widths due to all sorts of external influences such as rainfall, sunlight, temperatures, available nutrients, and available CO2, this method looks at the levels of different oxygen isotopes in their shells that vary with the temperature of the water in which they live. One simple linear relationship.
The data resolution from isotope counts is incredible.
“What we’re getting to here is palaeoweather,” Patterson says. “We can reconstruct temperatures on a sub-weekly resolution, using these techniques. For larger clams we could do daily.”
The reconstruction is shown below. We see familiar features the little ice age, the medieval warm period and the downturn which led to the extinction of Norse settlements on Greenland.
And the feature of this reconstruction to surely stick in the craw of many who think we are living in unprecedented times of warmth is the “Roman Warm Period”. Have a look:
From Nature: Shellfish could supplant tree-ring climate data
Temperature records gleaned from clamshells reveal accuracy of Norse sagas.
Richard A. Lovett
Oxygen isotopes in clamshells may provide the most detailed record yet of global climate change, according to a team of scientists who studied a haul of ancient Icelandic molluscs.
Most measures of palaeoclimate provide data on only average annual temperatures, says William Patterson, an isotope chemist at the University of Saskatchewan in Saskatoon, Canada, and lead author of the study1. But molluscs grow continually, and the levels of different oxygen isotopes in their shells vary with the temperature of the water in which they live. The colder the water, the higher the proportion of the heavy oxygen isotope, oxygen-18.
The study used 26 shells obtained from sediment cores taken from an Icelandic bay. Because clams typically live from two to nine years, isotope ratios in each of these shells provided a two-to-nine-year window onto the environmental conditions in which they lived.
Patterson’s team used a robotic sampling device to shave thin slices from each layer of the shells’ growth bands. These were then fed into a mass spectrometer, which measured the isotopes in each layer. From those, the scientists could calculate the conditions under which each layer formed.
“What we’re getting to here is palaeoweather,” Patterson says. “We can reconstruct temperatures on a sub-weekly resolution, using these techniques. For larger clams we could do daily.”
It’s an important step in palaeoclimatic studies, he says, because it allows scientists to determine not only changes in average annual temperatures, but also how these changes affected individual summers and winters.
“We often make the mistake of saying that mean annual temperature is higher or lower at some period of time,” Patterson says. “But that is relatively meaningless in terms of the changes in seasonality.”
For example, in early Norse Iceland — part of the 2,000-year era spanned by the study — farmers were dependent on dairy farming and agriculture. “For a dairy culture, summer is by far the most important,” he says. “A one-degree decrease in summer temperatures in Iceland results in a 15% decrease in agricultural yield. If that happens two years in a row, your family’s wiped out.”
Technically, the molluscs record water temperatures, not air temperatures. But the two are closely linked — specially close to the shore, where most people lived. “So, when the water temperatures are up, air temperatures are up. When water temperatures are down, air temperatures are down,” Patterson says.
Read the complete article at Nature News
Willis Eschenbach (01:29:14) :
Yes. That point is worth repeating. Moreover, this particular paper is ostentatiously about establishing the accuracy of Norse Sagas, but it establishes the reliability of a new method for study of climate in the past as well. Other papers studying the global climate from clamshells will probably come months and years from now.
I find this quite an exciting piece of research. The point that is obvious to me is that whilst alive, a particular clam species will move so as to remain within a particular narrow environment, described by parameters such as water depth, depth in the sediment column, salinity level etc. The same cannot be said for trees or more benthic oceanic species.
Studies on the descendants of these clams (or their close relatives) might enable one to delineate this near shore zone, define its temperature history and then perform a study to determine the relationship between temperatures within this zone and the overlying atmosphere.
Cheers
Jim
Re Pamela Gray (19:00:06) :
“…So does Mann NOT read Wiki? Why on Earth would he go around goring poor defenseless trees…”
Pamela, did you mean goreing?
I do second what Willis stated above. I spent at least two hundred hours of reading climate audit before beginning to form any opinion on AGW.
I also second, or is it third or fourth, the question of why, if this method was available for 50 years and has less noise then tree ring data, was this not used in the climate history proxy studies?
I also am curious on how water depth is quantified. I guess I will have to follow what Willis suggested, and read the paper. Until then I will just “clam up”
Willis Eschenbach (01:29:14) : “A couple people have complained about the study making broad generalizations, […]
Actually, what this proves is how readily people are ready to jump up and make half baked claims when they haven’t read the paper. It says nothing about the global climate. The word “global” doesn’t appear anywhere in the paper.”
I’m one that made such a complaint, but I was careful not to overstate anything. What I said was “I just can’t see how it [is] possible to draw any major conclusions from such a small sample covering such a small amount of time, and possibly (I haven’t read the actual paper) unknowns such as water depth. Count me sceptical.”.
The WUWT article says “We see familiar features the little ice age, the medieval warm period and the downturn which led to the extinction of Norse settlements on Greenland.
And the feature of this reconstruction to surely stick in the craw of many who think we are living in unprecedented times of warmth is the “Roman Warm Period”.” and “Oxygen isotopes in clamshells may provide the most detailed record yet of global climate change”
I have now read a bit of the paper, and checked that it matches the quoted sample size and clam lifespan. While it is very interesting that the study does provide evidence [NB. evidence not proof] of the MWP etc, I still don’t think that it can be used for any major conclusions.
But it is reasonable to suppose – as one poster has – that it may be a valuable line of research if a large number of samples from many locations can be analysed.
“That is placing a lot of confidence in the accuracy of the dating of the stratigraphy in the cores. That is putting all your clams in one basket!”
Not really, because they have cross-checked the stratigrpahy by carbon-dating the clams as well. So then they have cross-checked points of reference that tell them that some of the strata are where they think they should be, so using the strata in between those cross-checked reference points to interpolate the years between the carbon dated reference points is not at all unreasonable.
This is so much better science than the ridiculous tree-ring density nonsense. Oxygen isotope ratios are known to be a reasonable proxy for temperature, but tree ring densities are affected by so many factors, not just temperature – CO2, for instance, can have a big impact!
Anyway, this looks like promising research. It shows periods in the historical record that the tree ring data did not, suggesting it probably is a better proxy than the tree-ring data as we might expect.
Interesting is the Roman warm period. It has long been suspected that Britain was warmer during the Roman occupation, and interesting that by the end of the roman occupation it has become significantly cooler (the Roman empire had shifted south by then and renamed itself the Byzantine empire – did they do that to get out of the cold?).
If it isn’t scientific enough for anyone, I’m sure somebody can weave it into a story about capitalist imperialist sexist white suprematist privileged oppression of the last tribes of the world.
This “science” appears to run contrary to established consensus by the IPCC and as such, raises questions about the motivations of the people promoting this “clam” claim and their funding…
… shell company funding.
Willis, you hit the nail on the head. Further than that, it does not say anything about the ocean currents and the runoff from land ice. In Florida that may not mean a lot. But if you are melting ice on the main part of Iceland, its going to cause some pretty cold water flow down into some of the near coast. A change in currents such as the gulf stream would effect stuff too. Certainly this is and should be taken for what it is, but no more. It is an accurate measure of the water temperature at one place over time. As you said, nothing global in the slightest. If they extend the isotope analysis to other places over the globe we can get a more accurate picture. Hopefully they do that.
A few graps from CO2-Science showing MWP in Iceland:
Lake Haukadalsvatn, West Iceland
http://www.co2science.org/data/mwp/studies/l2_haukadalsvatn.php
See also this interesting article: A 2000 year record of climate variations reconstructed from Haukadalsvatn, West Iceland.
http://www.springerlink.com/content/2305471k06745398/fulltext.pdf
–
Lake Stora Viðarvatn, Northeast Iceland
http://www.co2science.org/data/mwp/studies/l1_lakestora.php
–
Northern Icelandic Coast
http://www.co2science.org/data/mwp/studies/l1_northiceland.php
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Northern Icelandic Shelf, North Atlantic Ocean
http://www.co2science.org/data/mwp/studies/l1_icelandicnshelf.php
–
(The above is from my blog http://agbjarn.blog.is/blog/agbjarn/entry/896498/ )
April fools? This is a joke, isn’t it? Hasn’t Mann only recently been strung up from one of his own trees specifically because of his use of minuscule and localized test-samples to reach a global conclusion? I think a little more scepticism is needed here.
Leif: I think the new thing here is not the dating method but the slicing. By slicing growth rings you can get a much more detailed picture of the temperature changes.
A C (00:43:43) : said
“I’m worried about that Roman Warm Period. Didnt the Roman Empire collapse?’
Yes, as the climate cooled.
tonyb
I’ve not read the paper or through all the comments so don’t know if someone has already mentioned this but …… the graph stops at 1800 so we don’t know what those other periods are like relative to our own. Also, the temperature on the graph only goes up to around 13C and the current “global” average is around 15C isn’t it?
I’m a sceptic, but I don’t see what there is in this that suggests we aren’t in a period of human induced warming.
However, the fact that I’m sitting here in the UK freezing my a*** off in the middle of March does!
“Hasn’t Mann only recently been strung up from one of his own trees specifically because of his use of minuscule and localized test-samples to reach a global conclusion? I think a little more scepticism is needed here.”
I think this was just a feasibility study. The researcher is asking for more funds to have a proper crack at it. But the results so far look more promising than the tree-ring nonsense which gave results that didn’t correlate with known historical facts.
This could be the most important climate paper ever written. A sticky should be put on this paper. Its a wonderful piece of work.
Kate (00:18:43) :
If Lovelock thinks it, can the rest of the UK’s climate scientists be far behind?
(…)
Thomas Crowley, professor of geoscience at Edinburgh University, responded: “People have thought about the possibility of an ice age but it wouldn’t be for many thousands of years. Dr Lovelock might be right in the abstract but this does not necessarily mean that CO2 is good now.”
(…)
——————
Reply:
I’m not aware of any other “professor of geoscience” that has the same view as Thomas Crowley regarding the next ice age. The past four interglacials are of equivalent duration; this current interglacial has lasted as long as the average so the Earth is due for another ice age; I don’t believe it is “many thousands of years” away. There is no reason why our current interglacial should be of longer duration than prior interglacials.
I also wouldn’t give much credibility to the idea that CO2 is delaying the next ice age—since we’re seeing that the Medieval Warm Period and the Roman Warm Period are both warmer than today, it doesn’t give his hypothesis of an ice age delayed by CO2 much credibility because I doubt the last two warming periods were caused by CO2.
However, I think current elevated CO2 level do indeed have benefits completely avoided by the AGW crowd. Their argument is pretty shaky just based on their “science” alone; applying a cost/benefit analysis that includes CO2 upside would certainly put it all in perspective and nobody in their right mind could consider AGW viable.
Pat @ur momisugly 18:46: Don’t kid yourself. The same day he lectured the ABC troops about even-handed coverage, The Drum published another unhinged rant about the evils of “deniers”. As a five-part series from Clive “Crazy Cat” Hamilton wasn’t enough!
Just for laughs and to see where our tax dollars are going:
http://www.abc.net.au/unleashed/stories/s2842091.htm
Actual temperatures might vary from one location to another – but surely the trends could be expected to be the same where ever. These graphs show the various warm periods cold periods etc which the IPCC seek to obliterate.
roger samson – make that a hockey sticky
Clams got legs!
(Old BC comics reference…)
It’s somewhat disappointing to read the sarcastic attempts at humor reflected in many of the comments regarding an analytical method which shows great promise compared to what passes as present day accepted climatological methodology. The application of chemometrics and ANNS (Artificial Neural Networks) has provided insights into areas that were previously untenable via the accepted methodologies. The methods described here may provide an extremely valuable insight into climate history that is sensitive, precise and reproducible. This approach represents a definite improvement over dendroclimatological methods.
AlexB (22:53:31) :
Hmmm, over two thousand years of climate history deduced from 26 2-9 year intervals from one icelandic bay. I’m sorry but I’m a little skeptical
Must agree with this – it is a VERY small sample, in a rather odd area of the world.
Iceland is warmed by the THC. A minor variation in this could change the icelandic temperature with little global effect.
Also don’t clasms live in water? So we are measuring water not air temp.
I would propose the term Chrematology, from the greek “Χρεμα”=money, for describing the activity of selling one’s own convictions in exchange of money.
I wonder what homogenized clam tastes like?
Makes me happier than a clam with Misssissippi mud in his beard.