New paper shows Medieval Warm Period was global in scope

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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far faster? what temporal resolution did they manage to get, in the Holocene?

Jeff Norman

“” 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. “”
That means these water masses have only warmed ~0.25° C since the LIA? Does this conflict with the conclusions of Levitus et al 2012?

The evidence that the Medieval Warm Period was global, & that it, the Roman & Minoan WPs & the Holocene Climatic Optimum, or whatever the latest fashion in its nomenclature might be, plus the deglaciation phase prior to it, were also warmer than now has been abundant & growing since Lamb, at least, ie 50 years. The LIA & previous cold periods were also global.
Which is why Mann needed fraudulent “tricks” & apparently intentionally inept statistical techniques or lack thereof to try to show recent warming to be special & scary.

lurker, passing through laughing

To: Prof. Michael Mann
REF: Irony
Dear Sir,
Thank you for providing us all the ironic and incredibly pleasing spectacle of watching your nasty arrogant attitude at play as the work of your life is brought down around you.
Sincerely,
Etc.

John W. Garrett

Chalk up yet another chink in the crumbling edifice of Michael “Piltdown” Mann.

see also the editor’s comment on sciencemag.org:
Deep Heating
Global warming is popularly viewed only as an atmospheric process, when, as shown by marine temperature records covering the last several decades, most heat uptake occurs in the ocean. How did subsurface ocean temperatures vary during past warm and cold intervals? Rosenthal et al. (p. 617) present a temperature record of western equatorial Pacific subsurface and intermediate water masses over the past 10,000 years that shows that heat content varied in step with both northern and southern high-latitude oceans. The findings support the view that the Holocene Thermal Maximum, the Medieval Warm Period, and the Little Ice Age were global events, and they provide a long-term perspective for evaluating the role of ocean heat content in various warming scenarios for the future.

Jquip

omnologos: “far faster? what temporal resolution did they manage to get, in the Holocene?”
This^. Be good to hear from someone that can go beyond the paywall and comeback with a notion of how moving the moving average is. My bet: Like all other claims, they didn’t look, don’t care, or didn’t average the modern moving average over the same range for a same comparison. Which is why we keep getting:
“The twitchy average is twitchier than the untwitchy one! We are doomed! Doomed, I say!”

Mike Bromley the Kurd

lurker, passing through laughing says:
October 31, 2013 at 11:59 am
Precisely. If he keeps it up, he’s aneurism-from-cognitive-dissonance bound.

Jim G

“New paper shows Medieval Warm Period was global in scope”
We need to start using words like “postulates”, or “hypothesizes” rather than “shows”. Most of these papers are “theorizing”, at best. “Suggests” is also a good word used in a previous post. It’s kind of like saying that anomalies in the rotational velocities and movements of some galaxies “show” that there is dark matter involved when they really only show that we cannot explain the velocities and movements and dark matter is “theorized” as a solution to the problem.
And latest experiments to find some have failed. Need more grant money.

Dagfinn

Acccording to what I’ve read elsewhere, “far faster” applies to the last 60 years. That’s back to about 1950. But surface temperatures increased as fast, or almost as fast, during the first half of the 20th century.
This smells wrong.

JimS

This is not the first research paper to confirm that the Medieval Warming Period was global. Prior to Mann’s hockey stick nonsense, it was generally accepted that the MWP was global in nature by the climate science community. Even the IPCC very early on published charts to show that the MWP was global. After Mann’s hockey stick nonsense, some in the climate science community reinvestigaged the MWP and confirmed that it was global in nature. There is nothing new here… move on.

John W. Garrett said:
October 31, 2013 at 12:02 pm
Chalk up yet another chink in the crumbling edifice of Michael “Piltdown” Mann.
————————————-
“Piltdown” Mann
Good one Sir! Thanks for the LOLZ 🙂

Manfred

That would mean current ocean heat content is low and the increase since the Little Ice Age is tiny.

“Michael Mann can’t be happy about this work”
Mann has been infuriated about suggestions that the MWP was global since at least 2001 when a paper was published in Science enetitled “Was the Medieval Warm Period Global?”, which basically said that it was. This is documented in at least 2 climategate emails:
http://hockeyschtick.blogspot.com/2010/01/blog-post_26.html

Steve (Paris)

I just want to scream ‘what do you mean by heat?’ Ask a layman and heat means HOT. Here they are flagging 0.5-08°c, which is not HEAT. Revkin should stop pretending to be journalist.

ronald

They don’t understand that the climate is the sum of all average temperatures. Strange? Naaaa not if you know how it works. All over the world the temperature is watch t so all those temperatures to getter make one number and that s the climate where in.
So is the average temperature 16 degrees Celsius then we have the climate optimum. Whit 12 degrees its smack in the middle and whit 8 degrees its freezing cold. Now whit all the data manipulation going on where not sure were we at in this time, oke AGWers call it 14 degrees but I think where more like 11 degrees or there about. So closer to freezing than to nice warm.
The only thing is that both half’s of the world have different seasons but that wont make the sum different. Only in the sick head off someone like Mann the world works like that. In the real world it docent matter. And yes it works now it will work over 10 years and it work d 2200 years ago.
Its the same as CO2 being Capable to warm one spot and 1000 miles a way not. Stupid CO2 is as dump as the next AGWer it do sent know boundary’s. If Mann and all agwers for that mater really thinks the medieval warming was a local thing they are ready to have brain surgery. If only to look for some kind of brain or at least some thing looking like brain. A peace of hamburger from MC Donalds would do the trick.

tango

the gooses will not believe the sun controls the heating and cooling, ps” you cannot tax the sun ” if you have time read this paper.http://www.cdejager.com/wp-content/uploads/2013/10/2013-CdeJ-HN-Sun-climate-NS-5-1112.pdf

Kasuha

“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.”
When looking at the _current_ global warming pattern, it looks fairly limited to Northen Hemisphere to me.

groovyman67

Jim G, i couldn’t agree more. The Scientismic Elites in nearly every field speak with such absolute authority, such certainty about very complex things that happened 10,000 (or 100,000 millions) years ago. The hubris is absolutely breathtaking. How long until the next study ‘shows’ something different?
The real crime is these are the people who direct and police academia, who then teach all the ‘skulls full of mush’ in the same manner. No intelligence allowed.

Hoser

Maybe the climate freak-outs should start describing temperature in Kelvin rather than °C. Then 273 “degrees” would sound even more scary than it actually is. Although, I wouldn’t want to go swimming in water about the same temperature as many people did when the Titanic sank.

aaron

The oceans temps are more stable than the atmosphere, aren’t they. They find the opposite, when they compare the proxies. I think this is more evidence that the atmospheric temp proxies are missing a lot of activity.

mkelly

Jquip says:
October 31, 2013 at 12:09 pm
omnologos: “far faster? what temporal resolution did they manage to get, in the Holocene?”
Heard this “far faster” term used last night while listen to Sirius/XM. They made the far faster than anytime in X million years claim along with “every day is earth day”.

Theo Goodwin

As most everyone knows, I am skeptical of “paleo” studies. However, let me set aside that skepticism for a minute to explain what this paper means to Mann and his followers.
If the medieval warm period was global and reached temperatures comparable to today then natural variability can explain all warming to this time. Natural variability is the full range of our data. With regard to surface temperature data, it is the full range of data from lowest to highest value through the period of time that we can reasonably investigate.
There is no need to invoke CO2 forcing to explain a rise in temperatures from 1979 to 1998. If Mother Earth has done it before then we cannot be surprised when she does it again. There is no need to invoke any forcing as there is nothing to explain.
Of course, the fact that natural variation can account for the temperature rise does not prove that CO2 has no impact but it does put the ball in the warmest ballpark. They can no longer claim that CO2 is necessary to account for the rise. Now they must show the mechanism and the evidence for it; that is, they must solve the forcings and feedbacks equation and show that the net is positive. They have made no headway in that regard.

Patagin

CO2science has a very extensive database of publications showing the global scope of the MWP:
http://www.co2science.org/data/mwp/mwpp.php
A recent one is for me key: what was a large forest doing in Patagonia 400 years ago in what is now a very large glacier: http://www.clim-past.net/8/403/2012/cp-8-403-2012.pdf (see figure 4).

Lance Wallace

jquip–
I did go beyond the paywall as you requested. Haven’t got much time to look at the results but here is Figure 3 and the Supplementary materials. A little something for every one, as they show temps higher than now throughout most of the Holocene, but also show the rate of increase much higher at present day. That was in Figure 4 of the main paper but I wasn’t able to extract that separately.
Figure 3 compares Mann to Moberg and to Oppel (2009) SST. Shows clearly how the Mann curve pushes down the Medieval period and raises up the modern, but the MOberg and Oppel agree in finding both the Medieval and the Roman periods higher than present.
Marcott 2013 also makes an appearance in the main text. Unclear whether the authors are accepting the results, but they do show them.
https://dl.dropboxusercontent.com/u/75831381/Rosenthal%20ocean%20temps%20%20Figure%203.docx
https://dl.dropboxusercontent.com/u/75831381/Rosenthal%20ocean%20temps%20Supplementary%20Materials.pdf
https://dl.dropboxusercontent.com/u/75831381/Rosenthal%20ocean%20temps%20Holocene%20Science%20Nov%201%202013.pdf

from one ocean basin they jump to global conclusions.
what would folks say if the sediments showed the opposite

Latitude

so we have a change in temperature….for centuries…that was a local event
…who was stupid enough to believe that in the first place

Dave in Canmore

Given the location of the cores could it be that large ENSO events would be recorded? They did admit they only had decadal resolution. Darn paywall means I can only speculate.
Wondering if Bob Tisdale has a thought on this?

Kon Dealer

@Steve Mosher “what would folks say if the sediments showed the opposite”
Why not try asking Professor Mann? He knows all about inverted sediments..

TImothy Sorenson

They claim that a 1000m depth in the tropical latitudes imply that when it changes rapidly that it must have been global. Suspect it is based on a mixing model involving currents in both the north pacific as well as the south pacific. Perhaps reading the paper will clear that up @SteveM.

Sven

Mann understands well enough how devastating this might be for him. So, as fast as lightening, he’s out with quite a ridiculous response in Huffington Post.
http://www.huffingtonpost.com/michael-e-mann/pacific-ocean-warming-at-_b_4179583.html
One funny thing is that his headline reads “Pacific Ocean Warming at Fastest Rate in 10,000 Years”. So the main take-away message where there is no doubt for him is the only thing that in the interview the authors clearly said they can not really be certain about. All the rest he finds BAD BAD BAD. And almost all of the refuting, of course, comes from “Mann”, “Mann et al”, realclimate (Mann), “Mann and Jones” and so on. What narcissism…

This has been suggested by several earlier studies. Oppo’s 2009 reconstruction of the Pacific Warm Pool suggested the Medieval warm period was at least as warm as today.ReadOppo. D., et al., (2009) 2,000-year-long temperature and hydrology reconstructions from the Indo-Pacific warm pool. Nature, vol. 460, p.1113-1116.
Esper’s reconstrcution of Scandinavian tree rings also showed that the Roman period was warmer than the Medieval Warm Period which was warmer than the 1940s which was warmer than today. http://landscapesandcycles.net/image/75158734_scaled_586x204.png
And Esper’s tree rings agreed with local instrumental data that was not tainted by urbanization and data homogenization. Mann’s hockey stick relied on essentially calling tree rings deniers that diverged from his homogenized data set.
The truth is out there! And it is slowly coming into view.

With strong written evidence for MWP in Europe and East Asia (the main places they were writing stuff down) I rather guessed it might be global. Next we’ll be told it wasn’t a constant and regular warming. Sounds just like our Modern Warming, doesn’t it?
Anyone notice some strenuous attempts lately to bring back that hockey stick in its pristine 1990s glory? What next? Ban the Icelandic Sagas from school libraries like they banned Noddy? Snorri Sturluson to go the way of Enid Blyton?

milodonharlani

Steven Mosher says:
October 31, 2013 at 1:21 pm
You don’t get it. CACA advocates have tried to argue that the Medieval Warm Period was restricted to the North Atlantic region. Study after study from around the world has shown this to be a bald-faced lie. Now the western Pacific has been added to that long list.
Besides which, the site surveyed also samples water masses linked to North Pacific & Antarctic intermediate waters.
But please by all means try to support a regional, not global Medieval Warm Period if you think that you can. I’ve observed its signs in southern South America myself, so you’ll have a hard sell.

My apologies to the original author, as I neglected to note their name or bookmark it:
One Tree to rule them all,
One Tree to warm them,
One Tree to graph them all
and in Global Warming bind them.
Mann’s Yamal tree still trumps the mountains of evidence from the rest of the world. In his own mind.

george e. smith

Some years ago, Dr Willie Soon, and Dr Sally Baliunas wrote a paper that was a review of many papers and reports from worldwide that showed that the MWP and the LIA were global phenomena, and not local peculiarities.
On the other hand, I believe if you look at the ORIGINAL presentation of Michael Mann’s hockey stick graph, which was in one of the IPCC reports, it states quite clearly on that graph that it is Northern Hemisphere only. In other words, Mann’s hockey stick was given to us as a local curiosity; not a global phenomenon. Of course, later expurgatory episodes, removed those limiting words, to hide the truth.

Mosher: “from one ocean basin they jump to global conclusions.”
A pretty big ocean. 46% of the Earth’s water surface. And one that spans both hemispheres.

Sven

Who’s the editor of Science? High time to get him sacked!
We’ll probably find out more from the eventual Climategate 2014 mails. If “the cooch” will not succeed before that…

Roy
Sven

Mosher: “from one ocean basin they jump to global conclusions.”
As I understand it, the logic was that NH medieval warm period and little ice age were already agreed upon, though recently declared just regional by Mann and the Team. Now they found the same thing in the SH. So that’s the reason for “global conclusions”.

@omnologos: “far faster? what temporal resolution did they manage to get, in the Holocene?”
Your comment proposes a test:
How must faster is now, than the rest?
Did they slice the cores fine?
How precise is their line?
“Century-scale resolution, at best”
— (at 4:00 in the video)

BRAD: We have fossils that have been bioturbated … we have pretty high accumulation rates, but we don’t have annual resolution .. You could say that we probably have century-scale resolution at best… It’s possible that the sediments just didn’t record similar warmings in the past.” YAIR: The deep ocean tends to average and smooth the record … I think it’s fair to say that it’s unlikely that very rapid changes on the order of, let’s say, years or even decades … would show up in the record.”

The presumption that this claims to “show”?
They are stating here: They cannot know.
But they quickly recover, at last:
“Recent warming is very, very fast!”
But they’re fuzzy on just how they’re sure
Andy Revkin gave up. It’s obscure…
They like Marcott! And they complement it
And they compliment. They might regret it.
They admit other parts may be cooling
“Need more data!” (That’s always the ruling.)
They’d like to talk to ocean scientists
(And they haven’t yet? One gap that still exists…)
===|==============/ Keith DeHavelle

Billy Liar

Steven Mosher says:
October 31, 2013 at 1:21 pm
from one ocean basin they jump to global conclusions.
what would folks say if the sediments showed the opposite

Everyone knows the Pacific has no effect on the rest of the world.

Resourceguy

It’s about time real science caught up and with sediment cores. Now move the drill ship to the Atlantic.

Duster

Steven Mosher says:
October 31, 2013 at 1:21 pm
from one ocean basin they jump to global conclusions.
what would folks say if the sediments showed the opposite

That “ocean basin” occupies nearly half the globe. You would be mistaken if you did not draw global implications.

Gunga Din

george e. smith says:
October 31, 2013 at 1:49 pm
…..On the other hand, I believe if you look at the ORIGINAL presentation of Michael Mann’s hockey stick graph, which was in one of the IPCC reports, it states quite clearly on that graph that it is Northern Hemisphere only. In other words, Mann’s hockey stick was given to us as a local curiosity; not a global phenomenon. ….

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And, if I’m not mistaken, Mann even got that wrong.

Gunga Din

http://wattsupwiththat.com/2013/10/31/new-paper-shows-medieval-warm-period-was-global-in-scope/#comment-1462643
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To clarify, the “warmth” wasn’t even local.
(Sometimes we say things that, in retrospect, can be taken two ways.)

Jimbo

Since Dana Nuttercelli insists the ‘missing heat’ went into the oceans and that it’s a robust measure of global warming I wonder what he has to say about the oceans now?

MarkB

Mann has posted a detailed commentary on the paper here: http://www.huffingtonpost.com/michael-e-mann/pacific-ocean-warming-at-_b_4179583.html

Janice Moore

@ Lance Wallace — THANK YOU (at 1:21pm today) for so generously sharing with the rest of us.
A Lance for Truth and Liberty!

Jimbo

Steven Mosher says:
October 31, 2013 at 1:21 pm
from one ocean basin they jump to global conclusions.
what would folks say if the sediments showed the opposite

Do you mean like Yamal?
And what would you have said had it had come to opposite conclusions?