Andrew Revkin writes:
Michael Mann can’t be happy about this work.
Here’s a chat with two authors of an important new Science paper examining 10,000 years of layered fossil plankton in the western Pacific Ocean. The paper finds that several significant past climate ups and downs — including the medieval warm period and little ice age — were global in scope, challenging some previous conclusions that these were fairly limited Northern Hemisphere phenomena.
(video follows, an interview with authors)
The study finds that the rise in ocean temperatures in recent decades is far faster than anything seen earlier in the Holocene, the period since the end of the last ice age. But the researchers say that this rise is from a relatively cool baseline. Between 10,000 and 8,000 years ago, at depths between 500 and 1,000 meters, the Pacific Ocean was 2 degrees Celsius (3.6 degrees Fahrenheit) warmer than today. (text from the video description)
The paper is here:
http://www.sciencemag.org/content/342/6158/617
Pacific Ocean Heat Content During the Past 10,000 Years
Yair Rosenthal, Braddock K. Linsley, Delia W. Oppo
Abstract:
Observed increases in ocean heat content (OHC) and temperature are robust indicators of global warming during the past several decades. We used high-resolution proxy records from sediment cores to extend these observations in the Pacific 10,000 years beyond the instrumental record. We show that water masses linked to North Pacific and Antarctic intermediate waters were warmer by 2.1 ± 0.4°C and 1.5 ± 0.4°C, respectively, during the middle Holocene Thermal Maximum than over the past century. Both water masses were ~0.9°C warmer during the Medieval Warm period than during the Little Ice Age and ~0.65° warmer than in recent decades. Although documented changes in global surface temperatures during the Holocene and Common era are relatively small, the concomitant changes in OHC are large.
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Yes, the globe is cooling at multimillenial scales (since the Holocene peak). It’s almost basic education.
Oppo Gangnam style
A few back of postage stamp calculations from this, if they’re right that current oceans are approx 0.65K colder than during the MWP. Or, to put it another way, the oceans would have to absorb enough heat energy to raise their temperature by 0.65K in order to get to where we were back then.
Total mass of the oceans is setimated at 1.4 x 10^21 kg
Specific heat capacity of seawater is (very approximately) 3900 J.kg-1.K-1
So, total heat energy needed to raise the oceans by 0.65k is about 2500 x 10^21 J
Trusting the opposition’ s figures here: http://www.skepticalscience.com/Measuring-Earths-energy-imbalance.html they show an imbalance of about 10 x 10^21 J per year in the earth’s energy budget.
So, if every single joule of that imbalance goes into heating the oceans, it would require about 250 years for the oceans to warm back up to where they were when mankind was thriving in an optimum climate.
That doesn’t need model assumtions, only data ones – IF the various figures used are about correct then its a matter of very simple physics that it’ll take at least 250 years for the oceans to be back where they were in the good times.
This also makes me wonder how much modern agricultural runoff effects the modern plankton measurement
Mr. Mosher this is why I believe we are are talking past each other in this debate:
In short, the data is enormously sparse, of low quality/accuracy, and the uncertainty is large enough to accommodate multiple theories. This is especially true of the paleo reconstructions, where we have conflicting data you alluded to. Serious skeptics think mainstream climate scientists have picked from this one narrative which fits their viewpoint and fits within the overwhelming uncertainty, using assumptions that skeptics believe are not any more justifiable than many alternatives. Skeptics also think the assumptions and their effects are often glossed over in a manner which obfuscates (for example, hiding the decline, where assumptions about tree-ring divergence is alluded to in only a very obscure and unresolved manner).
When an alternative narrative like this study comes along it is attacked (or ignored or is never allowed through peer review) with a level of criticism which does not seem to be applied to the mainstream theory’s supporting studies. In fact if this same level of criticality were applied to mainstream climate studies, I wouldn’t be surprised if the result would be “we really don’t know”. This is a fine answer to have if it is the truth. However, as things stand, the deck is stacked one way from on top; climate-gate laid that bare for all of us to see.
So yes you are right; there is plenty to criticize with this paloe-reconstruction. And plenty to criticize in the mainstream reconstructions. Which ones will see the light of day in IPCC reports and politician decision-making? Which points of view will be pursued via public science funding? Does the paleoclimate community have enough incentive to be honest about the uncertainty?
When you see skeptics cheering when a paper like this comes out, you are right when you point out that many are not exploring the weaknesses of such a study. What I don’t think you realize is that in the background most of these same skeptics are probably not accepting this paper as the absolute truth on the matter either. They are interested in revealing a different viewpoint to try to balance against the mainstream to provide a more balanced big picture veiw. If you were to ask them to create a reconstruction themselves, and they took you up on the task, they would probably end up telling you it may not be possible unless you want your uncertainty bands so high as to render it meaningless. These are not the sorts of mentalities that attract government grants for controversial science effecting huge swaths of the economy demanding high levels of certainty (though perhaps they should be as a check/balance).
Many years ago I tried to edit wikipedia to balance the biased view that the mwp was purely an european event giving many citations to papers which were ignored. This was tag team edited by the GW brigade who live there and blocked. Perhaps we can have another go?
The implications of a global Medieval Warm Period are not as clearcut as you think wrt Mann.
Mann’s statement that the MWP was regional, implies that there was a negative feedback that moderated the warming that did happen. This negative feedback would mean that there is a natural mechanism that would moderate CO2 warming. If the MWP was global, then this feedback leaves Mann’s equations, and he is free to declare runaway warming.
It used to really, really annoy me when the warmists would refuse to call the MWP for what it is being of course the MWP. They would call it a “Local Abnormality”. Well they can all suck eggs now, not that will make any difference as they suck, suck and dribble ” It was Local Abnormality, really was, MM said so.!
I am glad to see signs the obvious is being recognized. I can’t tell you how irked I was by the “science” which attempted to downplay the MWP. What was most irksome was that, in downplaying the MWP, they were dismissing the hard work of many good scientists, who often labored in uncomfortable surrounding in the arctic, back before we had arctic vehicles with heated cabs, or DEET.
I think we shall now see a creep towards a vision of a warmer and warmer MWP, as it becomes less a sort of professional suicide to dare say it was warmer in the past.
Having the ocean only a half degree warmer may not seem like much, however it makes quite a difference in terms of sea ice. I think we will eventually see a vision of a MWP where the sea ice formed later and melted earlier, and the northeast and northwest passages were wide open in the summer. (Imagine a time when a map like 2007’s would be representative of an especially cold year.)
Rather than a bad thing, I think a less-ice-choked arctic was a very good thing. One thing I have noticed is that, until those arctic waters freeze over in the autumn, the north, off-the-water winds in arctic regions are not as harsh and bitter as they get, once the sea becomes a wasteland of white. For example, in Siberia in early October a sea breeze is a “warm” breeze, relative to winds off the snow-covered Tundra.
In terms of the Vikings in Greenland, I think this made a huge difference to the growing season. If, in the the MWP, the autumnal months saw north winds come from an Arctic Sea which was not frozen until December, they had two or three months where the north winds were maritime air, and their pastures stayed unfrozen. It would have been like northern Norway, where the days grow too short to grow anything, but the pasture doesn’t turn to permafrost.
Looking at old papers, I get the feeling that the idea of a relatively ice-free Arctic Sea was already known, or, at the very least, was seriously considered, in the past. As the attempt to “erase the MWP” falls apart due to the weight of its own stupidity, I think we will see a time of rediscovering what we already knew.
Dr Mann does not understand how the global weather work, perhaps because he does not work with the weather each day. If he did, he would understand that by and large there is always back and forth, and if he wants to argue that their was regional warmth HE HAS TO PRODUCE THE REGIONAL COLD THAT BALANCES IT ( assuming there was no global warmup). Practicing meteorologists are well aware of teleconnections, for instance a large ridge in the southwest Pacific and a westward moving typhoon usually means one will find a ridge in the southeast or southern plains of the US several days later. The ridge position in this crucial source region will telegraph a chain of events that will occur in many cases. Recurving typhoons mean the ridge is further east, allowing the pattern to help with troughs deepening in the east. Anyone notice as typhoons recurved near and east of Japan, the cold came east from where it was when they were moving west? The latest modeling is showing alot of ridging back the first 1-2 weeks of November over the southeast.. we just had a typhoon move west through the Philippines .
Here is my point. There is only a very small chance, perhaps .04% ( thats a joke okay, its small but not as small as the amount of co2 in the atmosphere) that it could have been warm in just one place in a repetitive fashion without compensating reactions on global scale. Dr Mann’s work is flawed right off the bat in that if there is no global warm period, he has to find where it was cooler to compensate for the warmth that did occur in areas we know it did. If he worked as a meteorologist, he would understand that. Remember Climatology is a BUILDING BLOCK for meteorology, its only recently that somehow its status was elevated to a level where ideas count more than the reality of the ideas. So where was it? Can he please let us know. If we are to assume the earth was not warmer in that time, the areas known to be warmer had to have had compensating areas that should have been colder. That is simply the way the atmosphere works. for one and for two, if in telling us there was no period globally that was warmer, where was it colder to balance it out?
In a way, its intuitive, that in the grand scheme of things, the big long lasting events are the main controllers, and there is nothing new under the sun
Have any of the papers that claim the MWP was a European phenomena explain the conditions that could stall warm meteorological structures over Europe and only over Europe from AD 950–1250 during the MWP ???
Caleb,
I look forward to the day when crocodiles are back swimming in arctic waters, now those were the days.
The terms “Meltdown Mann” and “Piltdown Mann” are pretty good, but my favorite (coined by Mosher as I recall) is “Siltdown Mann”, for MM’s incorrigible inversion of the Tiljander sediments in his temperature “reconstructions”.
“””””…..milodonharlani says:
October 31, 2013 at 4:56 pm
TimTheToolMan says:
October 31, 2013 at 4:44 pm
Two K might seem like a lot, but the drop from “normal” to La Niña conditions along the west coast of South America can be twice that much. Granted, that’s from the upwelling of cold water from below, but even in the western Pacific, centuries of greater warmth could IMO produce a difference of two K warmer than now, coming off the LIA as we are……”””””
Well I believe 2K is below the freezing point of Hydrogen, so yes, it would not seem like a lot, on your thermometer. The freezing point of water, is about 273.15 K
I think they mean the Temperature is/was 2 deg C warmer.
george e. smith says:
November 1, 2013 at 1:08 pm
I used 2 K instead of typing “two degrees C”. It is confusing, since it’s wrong to use “degrees” with Kelvin units. I didn’t mean two degrees above absolute zero. I should have said 2 K higher or lower, you’re right, in which case typing two degrees C would have been just as easy.
milodonharlani writes “Doesn’t seem strange to me that in the western Pacific the Medieval Warm Period might have enjoyed SST two K higher than now.”
Various people (eg Lucia, Lubos and I think Willis) have calculated that given the amount of energy accumulated in the oceans their temperature is increasing at around 0.065C per 45 years for the 0-2000m depth range.. So to change 2C for half that volume (ie 0-1000) would be around 0.13C per 45 years or 700 years.
And that’s at today’s “rapid” rate. How can that have happened for the MWP? There’s just not enough time. So for me it fails the plausible sniff test and hence I believe the proxy isn’t saying what they think its saying and/or it was a local effect.
TimTheToolMan says:
November 1, 2013 at 3:05 pm
Why would you say not enough time? The Medieval Warm Period was hotter than now & lasted hundreds of years; the Modern Warm Period only about 150.
milodonharlani writes “Why would you say not enough time?”
Because 700 years is too long to fit into history. I quoted 700 years as a “very best” but in fact I dont think you can ignore the deeper water and I think the warming rates would actually be closer to our measured values of 0.065C per 45 years and that makes a more realistic 1400 years to change 2C. It doesn’t feel right to me.
Its revealing of the political distortion of climate science that a few mosses from a small Arctic island allow proclamation of warmest temperatures since the middle of the last ice age, but data from the Pacific ocean covering half the world has only regional implications, apart from a fraudulent Marcottian claim to fastest temp rise based on comparing sharply resolved recent data with more smoothed older data. (In image processing this is called the “unsharp mask”. Perfect for un-sharp scientists.)
TimTheToolMan says:
November 1, 2013 at 3:45 pm
The observations (please see graphs from Climate Audit below) disagree with your feel. Forgive me, but I don’t know to whom you refer by “our”. I’m also mystified by your cryptic, “700 years (being) too long to fit into history”. Why should warming or cooling always occur at the same pace, anyway?
McIntyre eviscerates the bogus press release touted by Mann:
http://climateaudit.org/2013/11/02/rosenthal-et-al-2013/#more-18530
writes “The observations (please see graphs from Climate Audit below) disagree with your feel.”
No they dont. That graph shows about 1C change (downwards) in about 700 years and then another 0.5C change in about 350 years (upward). And that is about twice the rate of 0.065C per 45 years that we’re measuring today and calling “rapid”. And none of it a 2C change for anything.
I am highly sceptical of these ocean temperature reconstructions. I dont think we’ve got a good handle on the OHC when we were sporadically measuring it in the 50s let alone when we weren’t measuring it at all. You can see in the Rosenthal graph enormous OHC changes in very short amounts of time. My intuition strongly tells me the proxy isn’t primarily temperature dependent in those cases.
From the abstract,
Can anyone figure out the relative temperatures of the MWP and recent decades from this? First glance suggests that recent decades are 0.25C warmer than the MWP, but it’s actually not that straightforward.
The fact is people were farming on Greenland during the medieval warm period. This is not possible at this time and should be simplistic for settling any argument.