From “The Hockey Schtick“, some inconvenient truth that breaks Mann’s already broken hockey stick into even smaller pieces. A new paper finds significant cooling of Atlantic Ocean over past millennium, making the MWP warmer in terms of sea surface temperature than today. Since land temperatures (including forest lands of Sheep Mountain and Yamal) respond significantly to ocean temperatures (the ocean is the big kahuna of global heat sinks) it is a pretty safe bet that those favored trees (including YAD 061) experienced warmer temperatures during the MWP than today. The eastern tropical North Atlantic reconstruction of SSTs was based on foraminiferal (marine plankton shells) Mg/Ca ratios that resolves multidecadal variability over the past 1700 years. see below:
The paper, published December 29th, 2011 in the journal Paleoceanography finds that Atlantic Ocean surface temperatures have significantly cooled over the past millennium, since the Medieval Warming Period from about 950-1200 AD.
- Monsoon season SST is reconstructed for the past 3 millennia
- Over the past 1700 years, several intervals show multidecadal SST variability
- Late medieval cooling amounts to approximately 0.5 degree Celsius
PALEOCEANOGRAPHY, VOL. 26, PA4224, 11 PP., 2011
doi:10.1029/2011PA002130
Henning Kuhnert et al
Multidecadal variations in Atlantic sea surface temperatures (SST) influence the climate of the Northern Hemisphere. However, prior to the instrumental time period, information on multidecadal climate variability becomes limited, and there is a particular scarcity of sufficiently resolved SST reconstructions. Here we present an eastern tropical North Atlantic reconstruction of SSTs based on foraminiferal Mg/Ca ratios that resolves multidecadal variability over the past 1700 years.
Spectral power in the multidecadal band (50 to 70 years period) is significant over several time intervals suggesting that the Atlantic Multidecadal Oscillation (AMO) has been influencing local SST. Since our data exhibit high scatter the absence of multidecadal variability in the remaining record does not exclude the possibility that SST variations on this time scale might have been present without being detected in our data. Cooling by ∼0.5°C takes place between about AD 1250 and AD 1500; while this corresponds to the inception of the Little Ice Age (LIA), the end of the LIA is not reflected in our record and SST remains relatively low.
This transition to cooler SSTs parallels the previously reconstructed shift in the North Atlantic Oscillation toward a low pre-20th century mean state and possibly reflects common solar forcing.
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This paper confirms earlier findings using sea shells, which provide high levels of resolution and would be no surprise to anyone who enjoys reading the current literature concerning this area.
Notice how none of the graphs are consistent?
At what level of accumulated evidence will Mike Mann and other MWP deniers accept that they are wrong? How much longer can the hockey and the rabid response teams remain in tree ring “hide the decline” fantasy land?
Ahh.The good old days.
I would think that sea surface Temperatures, would be more representative of the earth’s stored solar energy, than are atmospheric (lower troposphere) Temperatures, given the low thermal mass of the atmosphere compared with the oceans.
And the oceans are a much better approximation to a black body, as far as radiative cooling of the planet goes, whereas some claim that the atmosphere emits no BB like thermal radiation whatsoever, but only specific molecular resonance spectral lines; that are characteristic of the molecular species and not the Temperature.
So with foraminiferal Mg/Ca ratios as a proxy they find North Atlantic sea temperatures show some evidence of the AMO, a 50-70 year quasi-cyclic variation. However there is a high degree of variation – scatter – in the results, some of the early values would need to be well supported by other data/methods before the extreme variations shown around 350AD could be taken seriously.
But most damaging to the credibility of their results would seem to be the inability to detect any warming since the onset of the LIA. It seems to be well established from multiple lines of evidence that the AMO has been in a positive phase since ~1920 and this is often invoked to explain (some of ?) the warming since then. Although there is a logical inconsistency in using the AMO which is a description derived from temperature variation as a causal explanation.
Presumably the inability to detect the known warming from the LIA over the last century is a defect of the foraminiferal Mg/Ca ratios method.
At least I presume nobody actually thinks that the absence of the post-LIA warming from this record throws doubt on all the other evidence for this last decade being warmer than any in the last two centuries.
Clunk! The sound of a hockey stick against a manns head.
I’m perplexed how why you think data showing cooling over the last millennium “breaks Mann’s already broken hockey stick into even smaller pieces?”
Because of thermal mass I would not expect ocean data to show a recent warming ~ 100 years.
This long term trend data would seem to support the argument that other climate driving terms are not driving warming, thus supporting CO2 as the cause (as the only rapidly changing driver.)
Can you explain? This isn’t my field.
I wouldn’t say the graphs are inconsistent. Increasing irradiance corresponds with increasing AMO and a flattening of the sea surface temperature graph. It would make sense that the sea surface temperatures would only flatten out rather than increase, too, because the ocean temperatures are likely based on the temperatures of the last 4000 years or so which have been warmer than today except for the period during the LIA. In other words, the oceans, while warming a bit from their LIA temperatures, are still cooling overall from their Holocene Climate Optimum temperatures. A long period of negative AMO will likely reduce solar irradiation and possibly continue the cooling off of the Atlantic. Notice that sea surface temperatures only leveled off during the period of increased irradiance, they didn’t increase. Any decline in solar irradiance is likely to result in a continuing of the decline.
This might be the reason why the pattern of the past 2000 years or so has been cool periods with each one being cooler than the previous and warm periods that never quite get as warm as the previous one.
I don’t think that the tropical area is a good representation of the N.Atlantic SST. The AMO oscillations are initiated by sybpolar gyre, the Irminger Sea leads the way and the rest of the North Atlantic responds.
http://www.vukcevic.talktalk.net/NA_SST.htm
Data prior to 1960s are not entirely reliable.
Happy New Year to all.
Vuk
Why did the Medieval Warmed Crusaders head off to do their deeds in the Middle East? Because the land was producing loads of food/wool/wood etc and all the poor serfs were not frozen and miserable!
Happy New Year to those who know what it means……….
Mann was right!
People are using information to show he was wrong. All data of all forms must be held and protected in a bunker in an undisclosed location to protect the integrity of the correct view.
This is bad. Confusing. Complicated. The correct message is very simple.
“…forest lands of Sheep Mountain…”
———————————————–
The name of that place is prolly what Mann and his buddies were doin’ there.
I have just spoken to Dr Mann. He assures me the problem with the shape of the temperature chart is simply solved by turning it upside down – he also says in climate science this is a typical example of one of several generally acceptable procedures to correct inconvenient data.
@- crosspatch says: December 31, 2011 at 10:41 am
“In other words, the oceans, while warming a bit from their LIA temperatures, are still cooling overall from their Holocene Climate Optimum temperatures.”
Thats a credible hypothesis. Every other interglacial period shows a maximum temperature shortly after the rapid melt and shows a gradual decline with pauses and ‘noise’ at the decadal scale for the millenia after that peak.
@-“A long period of negative AMO will likely reduce solar irradiation and possibly continue the cooling off of the Atlantic. Notice that sea surface temperatures only leveled off during the period of increased irradiance, they didn’t increase.”
I suspect you meant this the ‘other way round’. Solar irradience is more likely to drive the AMO than the reverse!
However while SST may show periods of cooling and leveling off in the past, since the 1950s while the AMO was going negative the SST and ocean heat content have increased.
The rate at which the oceans are losing heat – perhaps gained during the Holocene optimum ~8000 years ago – seems to have slowed and reversed during the last few decades; despite the inability of this study to detect that.
Something seems to have altered and reduced the rate of cooling of the oceans while solar irradiance has been stable or falling. Land-locked ice around both poles is now melting revealing drift-wood and sea-shore sediments that have been frozen and ice-covered at least since the Holocene optimum. Other evidence such as sea level indicates that the oceans are now at least as warm as they were immediately after the end of the last glaciation during the Holocene maximum.
There are few candidates for a causal role in this reduced rate of cooling – and warming – of the oceans….
bcwebb says:
December 31, 2011 at 10:32 am
“I’m perplexed how why you think data showing cooling over the last millennium “breaks Mann’s already broken hockey stick into even smaller pieces?” ”
Because it contradicts his multiple attempts at showing constant temps in pre-industrial times.
The same results with from Europe and the North Atlantic
http://www.uibk.ac.at/geologie/pdf/mangini07.pdf
And it now appears that Keith Briffa recognized that Southern Hemisphere temperatures were as warm or warmer in the MWP than now.
http://notalotofpeopleknowthat.wordpress.com/2011/12/26/briffa-confirms-mwp-in-southern-hemisphere/
Not sure which is the chicken and which the egg but I was assuming more cloud cover during negative AMO meaning lower irradiation of the surface of the ocean. It was all about clouds when I was thinking about that.
As for revealing wood dating from the Holocene Optimum, it might mean something or it might not. We don’t know how many times it has been exposed in the past or if it is currently in the same position that it was in the past. That wood might have been transported to that location by the ice or floated there and cast onto the beach by the sea. The problem with shoreline wood residue is that it is (or was) potentially mobile. It may or may not be telling us much by where we find it.
Just because it is exposed now doesn’t mean it wasn’t also exposed in the 1930’s or at other times.
“And it now appears that Keith Briffa recognized that Southern Hemisphere temperatures were as warm or warmer in the MWP than now.”
And Phil Jones is co-author of a paper that shows the same thing. Shows both the MWP and the LIA in the SH. Mann must be blowing a gasket.
How on earth did this get past pal review? Surely the whole point of the system is to stop good scientific papers being published? The Team must be furiously emailing each other now – I hope somebody out there is capturing them for our future amusement.
Let’s hope we have another good year of shooting down warmists in 2012.
izen says:
December 31, 2011 at 10:11 am
If I may
My understanding is that the AMO wasn’t identified until 1994. Estimates of past AMO are done using North Atlantic SST data.
Put simply, if this authors paleoreconstruction of SSTs was used to determine the AMO signal, the sign of AMO may have been different.
Izen,
Sagas mention a Viking swimming out to an island, killing a sheep, and swimming back with the meat to feed an honored guest. No one could make that swim today without hypothermia setting in.
All the archeology suggests Mann was quite wrong, especially about Greenland. Unfortunately the funding for archeology went down as Mann got pampered.
You need to study the archeology and geology more, and the “climatology” less.
It is difficult to guage the ancient shorelines, because the land has also risen due to Isostatic uplift, however there is a clear difference between shorelines created by surf and shorelines created by grinding and slamming ice, and there are definite surf-created shorelines above the current one. In some cases those shorelines hold wood, behind currently-existing ice-shelves, and while most date from the Holocene, I recall reading of some chips that tested as being more recent than the Holocene.
Also it is interesting to study the Independence I culture, who were the first (we know of) to walk arctic shores. There was enough driftwood for them to heat, cook and even build with it. Eventually they passed the point of “Peak Driftwood,” and had to adjust.
I get the definate feeling there have been several warm periods since the Holocene where the arctic was more ice-free than it is now.
A warmer and globally synchronous MWP means that climate sensitivity must be higher and positive feedbacks more pronounced to give that degree of climate variation.
That has obvious implications for the climate response to the increased CO2.
@-Baa Humbug says: December 31, 2011 at 2:12 pm
“My understanding is that the AMO wasn’t identified until 1994. Estimates of past AMO are done using North Atlantic SST data.
Put simply, if the authors paleoreconstruction of SSTs was used to determine the AMO signal, the sign of AMO may have been different.”
Its worse than that.
The AMO is a postulated cycle. Accurate SST records can only give a couple of apparent peaks. Identifying a ‘cyclic period’ from less than 3 cycles is suspect at best.
This research is an attempt to identify the AMO from paleoclimate proxy records of SST.
Although they put the best gloss on it –
“Since our data exhibit high scatter the absence of multidecadal variability in the remaining record does not exclude the possibility that SST variations on this time scale might have been present without being detected in our data.”
– it is possible that the AMO is an artifact of the short SST record and spurious curve-fitting. The lack of a detectable AMO in parts of the paleo-record may indicate that it is an a-periodic variation which is sometimes negligible in magnitude.
As far as I can tell this research does little to decide the issue either way.