“The more interesting and potentially controversial result is that our data indicate surface water temperatures during a part of the Medieval Warm Period that are similar to today’s…”
“Although there are significant uncertainties with our own reconstruction, our work raises the idea that perhaps even the Northern Hemisphere temperature reconstructions need to be looked at more closely.”
Woods Hole Oceanographic Institution: News Release : New Temperature Reconstruction from Indo-Pacific Warm Pool
The First Word in an Unfolding Story
Media Relations Office
93 Water Street MS #16
Woods Hole Oceanographic Institution
A new 2,000 year long reconstruction of sea surface temperatures (SST) from the Indo-Pacific warm pool (IPWP) suggests that temperatures in the region may have been as warm during the Medieval Warm Period as they are today.
The IPWP is the largest body of warm water in the world, and, as a result, it is the largest source of heat and moisture to the global atmosphere, and an important component of the planet’s climate. Climate models suggest that global mean temperatures are particularly sensitive to sea surface temperatures in the IPWP. Understanding the past history of the region is of great importance for placing current warming trends in a global context.
The study is published in the journal Nature.
In a joint project with the Indonesian Ministry of Science and Technology (BPPT), the study’s authors, Delia Oppo, a paleo–oceanographer with the Woods Hole Oceanographic Institution, and her colleagues Yair Rosenthal of Rutgers State University and Braddock K. Linsley of the University at Albany-State University of New York, collected sediment cores along the continental margin of the Indonesian Seas and used chemical analyses to estimate water past temperatures and date the sediment. The cruise included 13 US and 14 Indonesian scientists.
“This is the first record from the region that has really modern sediments and a record of the last two millennia, allowing us to place recent trends in a larger framework,” notes Oppo.
Global temperature records are predominantly reconstructed from tree rings and ice cores. Very little ocean data are used to generate temperature reconstructions, and very little data from the tropics. “As palaeoclimatologists, we work to generate information from multiple sources to improve confidence in the global temperature reconstructions, and our study contributes to scientists’ efforts towards that goal,” adds Oppo.
Temperature reconstructions suggest that the Northern Hemisphere may have been slightly cooler (by about 0.5 degrees Celsius) during the ‘Medieval Warm Period’ (~AD 800-1300) than during the late-20th century. However, these temperature reconstructions are based on, in large part, data compiled from high latitude or high altitude terrestrial proxy records, such as tree rings and ice cores, from the Northern Hemisphere (NH). Little pre-historical temperature data from tropical regions like the IPWP has been incorporated into these analyses, and the global extent of warm temperatures during this interval is unclear. As a result, conclusions regarding past global temperatures still have some uncertainties.
Oppo comments, “Although there are significant uncertainties with our own reconstruction, our work raises the idea that perhaps even the Northern Hemisphere temperature reconstructions need to be looked at more closely.”
Comparisons
The marine-based IPWP temperature reconstruction is in many ways similar to land temperature reconstructions from the Northern Hemisphere (NH). Major trends observed in NH temperature reconstructions, including the cooling during the Little Ice Age (~1500-1850 AD) and the marked warming during the late twentieth century, are also observed in the IPWP.
“The more interesting and potentially controversial result is that our data indicate surface water temperatures during a part of the Medieval Warm Period that are similar to today’s,” says Oppo. NH temperature reconstructions also suggest that temperatures warmed during this time period between A.D. 1000 and A.D. 1250, but they were not as warm as modern temperatures. Oppo emphasizes, “Our results for this time period are really in stark contrast to the Northern Hemisphere reconstructions.”
Reconstructing Historical Temperatures
Records of water temperature from instruments like thermometers are only available back to the 1850s. In order to reconstruct temperatures over the last 2,000 years, Oppo and her colleagues used a proxy for temperature collected from the skeletons of marine plankton in sediments in the Indo-Pacific Ocean. The ratio of magnesium to calcium in the hard outer shells of the planktonic foraminifera Globigerinoides ruber varies depending on the surface temperature of the water in which it grows. When the phytoplankton dies, it falls to the bottom of the ocean and accumulates in sediments, recording the sea surface temperature in which it lived.
“Marine sediments accumulate slowly in general — approximately 3 cm/yr — which makes it hard to overlap sediment record with instrumental record and compare that record to modern temperature records,” says Oppo. “That’s what is different about this study. The sediment accumulates fast enough in this region to give us enough material to sample and date to modern times.”
The team generated a composite 2000-year record by combining published data from a piston core in the area with the data they collected using a gravity corer and a multi-corer. Tubes on the bottom of the multi-corer collected the most recently deposited sediment, therefore enabling the comparison of sea surface temperature information recorded in the plankton shells to direct measurements from thermometers.
Oppo cautions that the reconstruction contains some uncertainties. Information from three different cores was compiled in order to reconstruct a 2,000-year-long record. In addition sediment data have an inherent uncertainty associated with accurately dating samples. The SST variations they have reconstructed are very small, near the limit of the Mg/Ca dating method. Even in light of these issues, the results from the reconstruction are of fundamental importance to the scientific community.
More Questions to Answer
The overall similarity in trend between the Northern Hemisphere and the IPWP reconstructions suggests that that Indonesian SST is well correlated to global SST and air temperature. On the other hand, the finding that IPWP SSTs seem to have been approximately the same as today in the past, at a time when average Northern Hemisphere temperature appear to have been cooler than today, suggests changes in the coupling between IPWP and Northern Hemisphere or global temperatures have occurred in the past, for reasons that are not yet understood. “This work points in the direction of questions that we have to ask,” Oppo says. “This is only the first word, not the last word.”
The US National Science Foundation and the WHOI Ocean and Climate Change Institute provided funding for this work.
The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment.
h/t to WUWT reader Glenn
CAPT CHARLES : Methinks the Woods Hole jar runneth over with AGW cookies already . Maybe they decided to blow some of them on real science , for a change .
Also, I expect a meltdown at Reallywrong Climate in three….two…..one……
Andrew (10:01:09) :
Dodgy Geezer (08:56:04) :
philincalifornia (09:48:23) :
Actually, Shell and BP are heavily invested in renewables, not questioning alarm.
Even Exxon is backing away from questioning this business, to the extent that they ever did. The power of intimidation is striking.
_________________________________________
Yeah, I’ve actually worked on one of the above projects – paid by an oil company, ironically, to save the planet !!
My impression is that it is more bet-hedging than intimidation.
3cm/yr is a screaming fast sedimentation rate. 3cm per thousand years or less is typical for most of the ocean. Bio-turbation of the sediment only extends about 10-20 centimeters in oxygenated bottom waters so the forams can’t be mixed too badly. No doubt there are other microfossils to sample and chemistry that can be done to check these results. Like treerings there are ecological issues that can muddy a signal but these look like golden cores and lots more useful data can come out of them.
I don’t understand all the excitement over this paper. Maybe I’m missing something. Aren’t the authors merely saying their SST reconstruction closely follows Mann’s except for a 250-year period from 1000 – 1250 AD? And even then I don’t see the “stark contrast” they refer to. I can envision Mann and his supporters claiming that this study actually reaffirms Mann (2008) because it follows it so closely overall despite using entirely different methodology.
In any case, our understanding of the study is based on a PR-generating press release. Maybe someone qualified to evaluate it (not me) should read the actual study and tell us what it means.
[snip -ad hom]
I would expect that the proposed(unproven but recorded) destruction of Krakatoa in AD 535, separating the islands of Sumatra and Java into two separate islands, might have changed water flow. Before that, might not the ocean between SumatraJava and Borneo gotten even warmer?
The damage to the credibiilty of science in general is what concerns me most. I am also involved in the (anti)evolution wars – anti-evolutionists are continually making heavy water about evolutionary theory being nothing more than an article of faith, a belief system, in the same way relgion is. Once it is seen by the general populace that so-called AGW science IS nothing more than a belief system with no real underpinnings of science, expect a new spate of anti-evolution activity in your schools.
I have been trying to make sense to some of the bloggers on evolution for years to not tie the two topics together – people like P.G. Myers are wont to make statements such as “People who don’t accept evolution also don’t accept global warming” It’s an idiotic and sanctimonious attitude for a sicentist, but they have tied the two together – once one is determined to be a belief system…..
There should now be a very high level of confidence that recent temperature rate of increase as well as levels are not un-precedented.
It seems clear that the MWP was good in Greenland and Europe.
Did it have particularly adverse effects anyplace else? Africa? Asia? Oz?
That oil in the Gulf of Mexico does not exist. I know this because I fed all of the rock solid assumptions of the peak oil set into my model, and the output showed no oil there.
hmmmm (09:03:16) – I think that Mann claims that recent tree rings have changed and can no longer be used to measure climate. Thus he claims that you can’t compare last year’s tree rings to last year’s temperature, so it’s impossible to disprove his claims about past ring-to-temperature relationships.
I have been reading 1066-the year of the conquest-about one of my direct
ancestors-William the Conqueror.TheAuthor is David Howarth-the Howarth
family are made up of Sailors and yachtsmen, so the flavor of this book tends to be a bit ah nautical.One of the themes repeated in the book was how warm and
comfortable things were in the Northern Europe-and the rest of the world at that time.
A sub theme is about the inepitidue of King Harold and the way the English
handled the defense of the homeland.Willian and the Normans were so despised that Norman rule was done within two generations,and set the stage for Agincourt-Three hundred years or so later…
Sargasso sea reconstruction was pretty the same:
http://blog.sme.sk/blog/560/186850/sargasso.jpg
In general, sea surface reconstruction is quite a good proxy for global temperature. If you compare HadSST with UAH since 1978, it is almost identical:
http://www.woodfortrees.org/plot/uah/from:1978/plot/hadsst2gl/from:1978
So much for claim that MWP was localized in Europe only, as Wiki still boldly claims :-/
Dodgy Geezer– No need to blame Shell and BP. Just look at “Indonesia Ministry of Science” as a co-sponsor, and do a little research on Indonesia’s coal production and exports. . . . Impugning motives is rarely very difficult to come up with something.
This piece in the conclusion suggests that they accept Mann’s view of recent temperatures:
” On the other hand, the finding that IPWP SSTs seem to have been approximately the same as today in the past, at a time when average Northern Hemisphere temperature appear to have been cooler than today, suggests changes in the coupling between IPWP and Northern Hemisphere or global temperatures have occurred in the past, for reasons that are not yet understood.”
They do say questions need to be asked, but whether of their own work or Mann’s is unclear. However “Changes in the coupling” suggests acceptance of Mann’s picture, despite their results. So don’t expect explosions from the Team.
TJA (11:18:52) :
That oil in the Gulf of Mexico does not exist. I know this because I fed all of the rock solid assumptions of the peak oil set into my model, and the output showed no oil there.
___________________________________
See, models do work. When BP’s imaginary oil is burned up in automobiles, the imaginary CO2 will not cause any global warming.
This fits nicely with the AGW politician’s model – inventing a global problem and not solving it, thereby doing absolutely nothing except collecting lots of taxes.
…. and they all lived happily everafter.
we sure could have saved alot of time and money by studying the archaeological data we already have. in 1990 archaeologists DUG THROUGH PERMAFROST to unearth a viking colony that THRIVED for 200 years in greenland (you know, the place north of iceland). they raised cattle and crops and were self sufficient. this could not be accomplished in today’s climate, not because it is warmer, but because it is now COLDER than it was during the medieval warm period. tree rings and bug skeletons? this is science, but it aint rocket science.
“Something that historians have known for years.”
I agree. Lamm and his progeny make a compelling case. The warmists get around it by claiming that the medieval warm period was conveniently limited to areas in which historical records were kept.
Fundamentally, this is the same (in my opinion) as television psychics who argue that their powers don’t work when skeptics are around.
A few weeks ago there was a thread here to which my-and others- response was; ‘ But I was taught that at school decades ago.’
This study falls into the same category. You would have to have a very great belief in your own infallibility to believe that your hockey stick was more reliable than the knowledge we have accumulated over the years.
tonyb
Whilst I have no problem with dendrochronology per-se, I do have difficulty with the idea that tree-ring thickness variations can tell us much about past temperatures.
The most cursory inspection of any felled tree-stump will show enormous radial variations in the thickness of annual growth-rings. And, these variations change in orientation over time, presumably with changes in all sorts of factors such as changes in prevailing local wind, shade, proximity to other trees, etc. So unless one measures the total area of each growth-ring, to measure the tree’s total yearly conversion of co2 and h20 into biomass, and thus a proxy for local temperature, It is clearly not enough to use a single radial core-sample.
So, how do they do it?
Anybody got a link to the methodology of tree-ring/temperature divination?
AGW is a fraud, but even though this paper would assume to prove how poor AGW science is (and it is), it is just more unverifiable junk science chasing junk science:
There are no verified temperature proxies. NOT one proxy for thermometers has been verified to be associated with temperature in an engineering style test. Ice cores, speleothum, tree ring widths, tree ring latewood density, boreholes, pollen, sediments, mollusk shells or historic records. They are un-calibrated and completely unverified and several may be completely unrelated.
Source: http://noconsensus.wordpress.com/2009/08/28/ten-unprecedented-points/
According to Auntie Beeb it matters not a damn what happened before or however warm it has been. It is now too warm for coral, and that’s official!
http://news.bbc.co.uk/1/hi/sci/tech/8233632.stm
In Jasper Kirkby’s “Cosmic Rays and Climate,” the graph on page 3, Figure 2(c), shows how the Venezuelan tropical glaciers have now retreated to where they were during the Medieval Warm Period.
By the way, the advance and retreat of those glaciers parallel the change in the Galactic cosmic ray count and northern hemisphere temperature (Fig. 2 a&b). The Mann hockey stick is shown by way of contrast to scientific reconstruction of temperature.
http://aps.arxiv.org/PS_cache/arxiv/pdf/0804/0804.1938v1.pdf
Crosspatch (09:40:18) :
“And my point to posting the above is that glacial advance and retreat is not always related to temperature but can also be related to amounts and nature of precipitation falling on them.”
This is exactly what is happening in the Southern Alps. On the west side of the ranges around Mt Cook, glaciers such as the Fox and Franz Josef are advancing quite rapidly, whereas literally over the hill, on the eastern side, the Tasman and Mueller are retreating significantly.
Andrew said..
———-
Actually, Shell and BP are heavily invested in renewables, not questioning alarm.
Even Exxon is backing away from questioning this business, to the extent that they ever did. The power of intimidation is striking.
———
These corporations are simply investing in Corporate Relations, they invest some money in R&D and to meet the ethanol mandates for blending. It is a go with the flow attitude and wait until the world comes to its senses.
They are demonized enough, so this just smoothes the waters and costs them really nothing compared to all advertising and lobbying efforts. This is a war that their participation in would arm the enemy.
Go Along to get along. This will not hurt revenue.