Skip to comments.A Global Temperature History of the Past Two Millennia [PEER-REVIEWED!!! WITH SOURCE!!!]
Posted on 01/29/2008 11:13:13 AM PST by E. Pluribus Unum
Download original article here.
A Global Temperature History of the Past Two Millennia
Loehle, C. 2007. A 2000-year global temperature reconstruction based on non-treering proxies. Energy and Environment 18: 1049-1058.
What was done
Using data from eighteen 2000-year-long proxy temperature series from all around the world that were not developed from tree-ring data (which provide significant interpretive challenges), the author (1) smoothed the data in each series with a 30-year running mean, (2) converted the results thereby obtained to anomalies by subtracting the mean of each series from each member of that series, and then (3) derived the final mean temperature anomaly history defined by the eighteen data sets by a simple averaging of the individual anomaly series, a procedure that he rightfully emphasizes is "transparent and simple."
What was learned
The results obtained by this procedure are depicted in the figure below, where it can be seen, in the words of its creator, that "the mean series shows the Medieval Warm Period (MWP) and Little Ice Age (LIA) quite clearly, with the MWP being approximately 0.3°C warmer than 20th century values."
What it means
Loehle notes that "the 1995-year reconstruction shown here does not match the famous hockey stick shape," which clearly suggests that one of them is a poorer, and the other a better, representation of the truth. Because of its simplicity and transparency, as well as a host of other reasons described in detail by Loehle -- plus what we have learned since initiating our Medieval Warm Period Record-of-the Week feature -- it is our belief that Loehle's curve is by far the superior of the two in terms of the degree to which it likely approximates the truth.
Reviewed 30 January 2008
The AGW propononents use a single temperature proxy, tree-rings, to predict global catastrophe.
This article uses the average of 18 temperature proxies for the past two-thousand years.
This is definitive data, folks.
Any time an enviro-wacko calls you a global-warming denier, wave this article in their face and ask them to refute it.
If there isn't any global warming, there isn't any anthropogenic component either.
bump for ammo.
Coincidence? I think not.
I’ll bet that their sacrifice quota shot way up. And rightly so.
Thanks. Well Done.
I downloaded the article immediately.
I didn't notice it was missing.
Too bad they can’t get sunspots data going back that far, or can they?
Gadzooks. The author used creditable data, processed it in a meaningful way, did not throw away “inconvenient” data, and presented the results in a clear and understandable way. He’ll never be reported in the NYT.
Must be a witch. Burn him!
The graph helps. I am at work, so I have to scan articles.
Was that John McCain I heard today pledging to be green and to do something about greenhouse gases?
Gorey be to Al !
A HERETIC !! A HERETIC !!
A HERETIC PRESENTING AN INCONVENIENT TRUTH !!
Let him be subjected to le pein forte et dure !!
So you know and I know, but how do we get past the steel bars of the MSM cage and get the message public? What to use as a hacksaw so to speak?
I’ll pass this on to many, but that is a few only, and many of those folks will look at this, their eyes will glaze over, and the delete button will serve its purpose.
But what about the shrinking Polar bear testicles?
Dont be silly that is no longer acceptable per PC rules. We must tie a stone to him and through him in a pond.
This is the key statement near the end which allows both that previous data still need to be compared to the authors’ methods and that this study, like all scientific studies that are not biased by agenda, are merely signposts on a roadmap that will lead to the true destination.
“While instrumental data are not strictly comparable, the rise in
29 year-smoothed global data from NASA GISS (http://data.giss.nasa.gov/gistemp)
from 1935 to 1992 (with data from 1978 to 2006) is 0.34 Deg C. Even adding this rise
to the 1935 reconstructed value, the MWP peak remains 0.07 Deg C above the end of
the 20th Century values, though the difference is not significant.
The main significance of the results here is not the details of every wiggle, which
are probably not reliable, but the overall picture of the 2000 year pattern showing the
MWP and LIA timing and curve shapes. Future studies need to acquire more and
better data to refine this picture.”
Chinese records of sunspot activity go back to around 800 BC, although spotty (no pun intended) and incomplete. But according to another article, tree rings have also recorded sunspot activity and can be used to track them back to the last ice age.
Trees and tree rings contain carbon, which they get from carbon dioxide in the atmosphere. Some of that carbon is the isotope carbon-14, which is created in the Earth's atmosphere by cosmic rays flying in from outside the solar system.
But those cosmic rays can't reach Earth when the Sun is stormy with sunspots and the solar wind is roaring. So a tree ring containing low carbon-14 is a sign of few cosmic rays in that growth year. This is an indicator of a stormy Sun, said researchers led by Professor Sami Solanki from the Max-Planck Institute for Solar System Research and colleagues.
cogitator needs to add this to his archive.
Not necessarily. Does he weigh the same as a duck?
Who knew you were so wise in the ways of science!
Oh good grief. Something has got to give about what "scientists" are willing to conclude from tree ring data. How can we put these presumptions to the test? Could not the carbon have been high for some other reason?
TO READ LATER, THX
Science used to be hard. Now, thanks to Al Gore, and the IPCC, it's really easy. Just decide how much you want to raise taxes, enter that number into the patented Climate Change Computer model, and volia, multiple climate horror stories guaranteed to open the wallet of even the tightest skin flint. No more late nights in the lab. No more pesky peer review. The Global Climate Change Computer does it all for you.
But the more data (as long as it is properly analyzed and reviewed), the clearer the overall picture.
The scientific consensus is already in.
No further data is required.
Carbon-credit brokers, start your money-churns!
CO2 is plant food. It's where trees get pretty much all their carbon from. Think back to your high-school biology class, where you learned that aside from a few trace nutrients all a plant needs is water and air to grow.
Sounds like an ad hominem attack, to me.
So Mann's hockey stick is still the gospel according to Algore, eh?
Yep, sure is. But I'm not sure what your point is, or maybe you didn't get what mine was.
The National Science Foundation investigaterd the Algore version of history (which emasculates the little ice age), and said it is not inconsistent with the data. This is not an affirmation. This is a statement that the UN was in the no man’s land between science and fraud. The NAtional Science Foundation then adopted something like this version of history (with the little ice), and the clear implication that we are currently in a not unusual warming phase in the hsitory of the world. As to whether human activity is ADDING TO this warming phase remains a legitimate question.
Looks like an oscillation with around a 1300 year cycle. What with data we’re seeing about variations in solar output, I’m thinking there may be more coming from solar output oscillation than any human cause
First impressions: Looking at the map of locations, it says there are 18 series, but I only count 15. There are likely more than one series from a couple of locations. Based on what I can see, 7 out of the 15 are extra-tropical in either North America, the North Atlantic, or Europe. So this area is over-represented and the Northern Hemisphere is over-represented.
Why is this important? Because previous work on the Medieval Warm Period has indicated that it was primarily a Northern Hemisphere event strongest in North America and Europe. (The LIA was more global.) So seeing it (a warming event occurring over about 400 years) in this data is not surprising.
2. Got this from Climate Audit, actually (which is instructive, 320 comments in the "Loehle Correction" thread). His last actual data point is 1935 (which is where his corrected Figure 2 ends). If you read the last paragraph of the correction, the difference between MWP and "end of 20th century values" is not significant. He calculated end-of-20th-century using a GISTEMP addendum, it appears.
3. What is significant? The warming rate. Reading Figure 1 roughly, the temperature increase is about 0.6 C in 400 years (I put the peak at about 900 AD). The warming rate in the 20th century was 0.6 C in 100 years, and the rate in the past 25 years was 0.4 C, which is 1.6 C in 100 years. So while comparing peak temperatures is a fun exercise, the rate of warming observed since 1900 is much faster than the rate of warming to the peak of the MWP.
Intriguing pattern: there is a big up and down temperature excursion right after 900 AD. I'd really like to see if that has a global signature or if it was regional.
Comments on "Loehle Correction" (Climate Audit)
Skimming, I note posts 16, 69 (Loehle is skeptical of rates, so I should be too), 95, 199, 203, and 301.
“Why is this important? Because previous work on the Medieval Warm Period has indicated that it was primarily a Northern Hemisphere event strongest in North America and Europe. (The LIA was more global.) So seeing it (a warming event occurring over about 400 years) in this data is not surprising.”
Current temperature models are primarily based on North American readings (most pervasive and “accurate”). Then there is the apples to oranges aspect to your retort - that being modern sampling techniques versus historical climate reconstruction. Consequently, the only possible comparisons are the peaks and valleys.
I’m calling BcoughULLcoughcoughSHcoughIcoughT.
I think we’re kind of stuck with mostly northern hemisphere data since there aren’t many good sampling locations down under.
The rate of increases are notable just because of their lack of periodicity yet the graphs show that each period of cooling began nearly precipitously which might make one question what shut off the cause of warming so suddenly.
Thanks for the ping!
E-mail to Gore.
They had to change out their light bulbs too.......
We need too waterboard Al and get the real inconvenient truth.........