Holocene, historic and recent global temperatures from temperature proxies.
Guest post by: Frank Lansner, civil engineer, biotechnology
NOTE: Link to PDF of this article is HERE
In the climate debate, the temperatures of the past are used to determine if the present temperatures are unique and alarming. Any viewpoint can be supported by choosing specific science papers as reference
This paper is one of many attempts to give a realistic overview of the actual messages we get from the temperature proxies.
(“Temperature proxy”: Past temperatures reconstructed from samples using a row of techniques.
The “Spaghetti graphs” in the following gives an impression of the huge variability among the datasets. The essence of each graphic is the major trends. To enable display of multiple data series it was often necessary to interpolate temperature values to the specific years used in graphics.
To avoid most calibration problems, I have set specific years to zero for the different graphs I chose a year where practically all graphs has data, and no further calibration needed. In few cases I have calibrated from 1980-1990-2000 using UAH trend of approx. +0,1K/decade.)
Recent temperature proxies – 120 years
Fig 1: 10 multi proxies shown for the 20´th century. In addition 14 temperature proxy datasets. The black curve shows average of the 14 datasets as 1 multi proxy. This multi proxy + the 10 of the most used bigger multi-proxy series is the basis for the WHITE graph: “Average of 11 multi proxies”.
The temperature proxies does not show strong net warming since around 1940. In fact, proxy data does not show any warming since 1940. This is no news, it has been recognised for example here:
http://www.ldeo.columbia.edu/res/fac/trl/downloads/Publications/divergence2007.pdf
The authors call the missing global warming in proxies for “The Divergence problem”. And they try to give reasons for this problem using characteristics of trees. But since other proxies than using tree ring proxies also indicates no global warming after around 1940, the problem seems not related with tree rings measurements.
“The divergence problem”:
Fig 2: The “divergence problem”.
The “All China” multi proxy: A reliable work where 8 regions of China where studied and then yield the final China multi proxy temperature line. The “All USA”, NOAA raw, is the official measured USA temperatures minus the official correction, that is, the raw USA temperature dataset. I find it stunning how close All-China and All-USA matches each other, see fig 2! (- a dataset of measured temperature compared to a dataset of proxies). And unlike GISS 2009, the Northern Hemisphere temperature set of 1976 supports the raw trends of US and China. Several of the multi proxy series have been smoothed with a “50 year weighted Gaussian filter” etc. and therefore any bigger dive around 1970 could not be seen in the multi proxy graph.
We see a divergence after 1950 between:
- GISS 2009 vs. Average of the multi proxies, that is, the temperature evidence in the ground and trees.
- GISS 2009 vs. USA, CHINA and NH temperatures
- GISS 2009 vs. Solar activity.
So, at least when comparing with mostly raw datasets, the GISS 2009 dataset could seem to be the source of “the divergence problem” – “the outlier”. Problems for the GISS data set might be incorrect adjustments, problems with UHI and poor measuring sites, see www.surfacestations.org!!
The “divergence problem” also seems to vanish when using satellite data (UAH/RSS) in stead of GISS data:
Fig 3: A: Briffa´s 2001 illustration of tree ring proxies combined with the GISS dataset as “Observations” (as the adjusted GISS temperatures are called). B: Same, however this time “Observations” are raw satellite data UAH from 1980 – 2000 with a slope of 0,1K/decade.
There is no divergence problem when using satellite temperature data as “Observations”. We now have total compliance between proxy data and modern temperature measurements stating: No net warming since around 1940-50.
Historic temperature proxies – 1200 years
For this analysis 33 data sets was used. The first that strikes you when working with historic temperature proxies is the apparent chaos of data. However, after keying in 6-8 data sets the well known features “Middle age warm period” and “The little Ice Age” becomes clear. Keying in the rest of datasets doesn’t change much.
First, take a good look at the period 1900 to 2000..
Notice how these 33 datasets confirms the trends from fig 1, the recent temperature proxies. We can conclude that we have a good ability to reproduce the result quite accurate with quite different datasets, and thus, neither of the graphs ( fig 1 and fig 4) are likely to reflect “random” results. All data evidence used in fig 1. + fig 4. actually suggests that today’s temperatures resemble the temperatures of 1940-50. Yes, a divergence problem for the temperature data from GISS and Hadcrut.
Fig 4: Historic temperature proxy data. Practically all methods and regions of the globe are represented.
6 of the data sets originate from tree ring data.
We see the Medieval Warm Period apparently ongoing already in year 800 and goes on for 5-600 years. First around year 1400 the Little Ice Age really takes over. It was around year 1400 the Vikings left the freezing Greenland.
From year 800 to year 1300 temperatures appears around 0,3 K higher than today. And from around year 1400 to 1900 temperatures appears to be are around 0,4 K lower than today. A difference from MWP to LIA of 0,7 K in average globally. (Max difference approx 1,1 K),
We will return to these historic data later, but lets first take a look even further back in time.
Holocene temperature proxies – 12000 years
For this analysis 29 long datasets where used. All graphs are calibrated to zero for year 1000.
First focus on years 800 to 2000…
Once again we see a reproduced trend between 2 different data sets. And again, the accuracy is nice. The MWP here appears almost 0,8 K degrees celcius warmer than the LIA, very close to what we saw it on fig 4, the historic data 0,7K. This once again confirms the impressing usefulness of data despite the chaotic and random appearance. There is however a tiny difference between the 2 graphs, around 0,1K. But it should be noted, that for the Holocene temperatures, no tree ring data was used. According to Loehle 2007, tree ring data tends to suppress the MWP somewhat. This we will return to.
Fig 5: Holocene temperature data.
The data point for year 2000 are based on too few datasets to be really trustworthy. Therefore I have inserted the red star where I use the value of todays temperature taken from fig 4, historic temperatures. By doing so, temperature for year 2000 got 0,2 K warmer than from Holocene data.
Fig 5 also shows that the whole debate about MWP is irrelevant. Imagine there was no MWP. Practically ALL of the Holocene period the eath appears to be between 0,5 and 1,5 K warmer than today. The little ice age does resemble a mini ice age or at least it appears to be the coldest period in over 10.000 years.
Finally, the overall picture from the graph is an almost perfect mathematical curve that tops around 5-6000 years ago. These Data tells the story quite clear: We are on a down trend in temperatures globally, we should not fear warmth by now. How much lower can the temperatures on earth go before we reach a tipping point to much colder temperatures at earth?
Medieval warm period
Arguments against the MWP often focus on the “fact” that the warmer temperatures from that period are a phenomenon exclusively to have appeared on the northern hemisphere.
Fortunately, the results from fig 4 and fig 5 shows an excellent match for the period year 800 to year 2000. It thus makes very good sense to combine the datasets and then obtain a better data foundation to analyse the MWP.
Datasets from fig 4 and fig 5 combined, a northern/southern hemisphere display of the Medieval Warm Period:
Fig 6: Historic temperatures, North and south hemispheres separated. Let’s first see what the graph actually says, very roughly:
NH MWP, 42 datasets:
Ongoing in year 800, temperatures mostly 0,3-0,4 K higher than today.
The temperature creeps below today’s level and ends around year 1300.
SH MWP, 13 datasets:
Ongoing in year 800, temperatures mostly 0,2-0,3 K higher than today.
The temperature creeps below today’s level and ends around year 1350.
Northern hemisphere is still much better represented than the southern hemisphere, so what can we conclude on this ground? Can we conclude anything?
On this ground I find it safe to accept the NH MWP approximately as described above.
To accept that globally there where no MWP, we will have to accept the following:
The 2 hemispheres have the ability to maintain a quite different temperature development for at least 500 years and did so from year 800 to year 1300.
What can we demand to accept this idea? We can demand solid evidence.
Anyone claiming the above must present solid evidence for a MEDIEVAL COLD PERIOD on the southern hemisphere.
IF data showed that the southern hemisphere had a MCP where temperatures for 500 years was 0,3-0,4 degrees colder than today, would this “kill” the MWP? Certainly not. Because, then we would have had 500 years with global temperatures just like today globally… – In that case, certainly no reason to be alarmed about the temperatures today.
No, if today’s temperatures should be alarmingly warm, the S. hemisphere temperature should show a very strong MCP at least 0,4 degrees colder than today in the 500 year period.
Is there ANY indication of a 500-year strong MCP in the southern hemisphere indicated in the data above? No, certainly not. There are not that many SH data, but still, there is not the slightest indication of a strong MCP on the S. Hemisphere.
Until the strong 500 year long MCP on SH has been proven, there is nothing that shakes the acceptance of a global MWP with temperatures resembling or higher than today’s temperatures.
I believe a massive use of tree ring graphs exclusively might show a strong southern MCP. In this case, the idea that there is no MWP globally is dependent on only on one specific method of making temperature proxies, tree rings. Tree rings are 1 of at least 20 different methods to measure temperatures of the past. As such, they should never dominate the measurements.
The South pole and MWP:
While examining temperature proxies, I found some odd results:
Fig 7: -A stunning mismatch between 2 Antarctic data series.
Not only are they both from Antarctica, but they are both from near the south pole. The well known “MWP-signature” has found its way not only to the Southern hemisphere, but to the south pole. But in the near by Vostok location, for many centuries, there has been absolutely no sign of the MWP? Obviously this is absurd, so at least one of the two results is not accurate.
The black graph (from “Remote Plateau”) has a resolution of 1 – 3 years per sample, excellent. The blue graph (vostok) has approx 23 years between data points. Both series should be considered fine quality then.
How likely is it, that the “MWP/LIA-signature” has come up in “Remote plateau” (black graph) data by a coincidence? When it has also been spotted many other places on the SH? See fig 6: The Vostok data has a dotted red line. How well does vostok data then fit the rest of the Southern hemisphere data?
The use of vostok data also moves the SH temperature profile away from the NH average.
Tree rings
If the MWP only disappears using one a specific measuring method, the idea as well as the method is invalid.
Proxy temperature data from tree rings are easy to get, but the quality?
Craig Loehle: “There are reasons to believe that tree ring data may not capture long-term climate changes”.
Indeed. A good warm year will obviously help a tree growing, but decades of increasing temperatures could affect the whole area so for example more trees might be able to survive, the root nets would only be able to grow to some extend for other trees etc.
Example: Imagine that a warming after decades is accompanied by 10% more trees surviving in an area and eventually demands their “place in the sun”. By measuring tree rings for an individual tree you are not measuring the overall tree growth of the area. And measuring 10.000 trees does not change anything as all trees would have the same problem. Measuring tree pollen or isotopes etc in sediment cores avoids these problems and it makes me wonder how come so much energy has been used for tree ring analyses.
Selective adjustments?
Many kinds of adjustments are used in connection with climate results. But one adjustment I haven’t heard of is the down-adjustment of recent temperatures from temperature proxy data due to CO2-induced extra growth. If the CO2 level is indeed extraordinary high, then it is a fact that plants grow markedly more. And they grow at higher altitude etc.
Here is an impressing overview of plant response to extra CO2 in the atmosphere:
http://www.co2science.org/data/plant_growth/dry/dry_subject_p.php
I have chosen the letter P for the link since several tree ring analysis are made for pine trees. Check the responses for pine trees when adding extra CO2.
Therefore any temperature proxy based on plant growth should be adjusted down in times of high CO2. Otherwise you will measure CO2 and not heat. But this obvious kind of adjustment seems not to happen? Or? Can it really be, that the crew of alarmists so happy for adjusting for all kinds of tiny issues, simply don’t adjust when there is a really good reason to do so?
Fig 8: Historic temperature proxy data with focus on tree ring-method. In the analyses I have used, it turned out that 7 of 55 datasets where from tree rings. On this figure, these 7 datasets actually does seem to differ in trend from all the rest. The 7 tree ring datasets suggests no MWP, in fact, they suggest that the MWP was 0,3-0,4 K COLDER than today’s temperatures. Quite the opposite result than the majority of datasets concerning MWP.
On might say that these 7 datasets are too little a basis for any conclusion, and therefore I have included a bigger tree ring multi proxi, “Esper et al 2002” and the trend from the 7 tree ring datasets are confirmed:
Unlike all other methods, tree rings shows no warm MWP.
Example, the European Alps:
Fig 9: Here from fig 4, we have 2 different temperatures in the same area, the European Alps.
Quite like Antarctica, we have 2 datasets, one showing the well known “MWP/LIA-signature” and one not showing this. Both cannot be correct, so we know that at least one of the datasets is faulty.
In addition, these measurements where taken in the middle of Europe where we have an overwhelming amount of non-tree temperature proxy datasets confirming a very warm MWP.
Therefore, if the tree ring method was useful, we definitely should see a warm MWP from tree ring data in Europe. But we don’t. And unless all the other temperature proxy methods just shows a very warm MWP in Europe by coincidence, the tree ring method does appear to be the faulty method.
The tree graph appears flat compared to the other methods (- a “yummy” to use if you want to produce a hockey stick), but we are not here to produce a hockey stick, we seek the temperatures of the past.
Now it becomes relevant to examine jus non-tree temperature proxies (As Loehle concluded) for better accuracy:
Fig 10: The Historic temperature proxy trend based on 27 non tree ring proxies show a slightly warmer MWP than when including tree rings, fig 4. The average temperature for year 800-1400 is approx 0,4 K warmer than today, and the years 1400-1900 is around 0,4 K colder than today. So the non tree historic temperatures now gives a MWP/LIA difference of 0,8 K like the (non tree) Holocene temperatures, fig 5.
We even see “peaks” in the MWP up to 0,6K warmer than today, and now 1950 actually appears slightly warmer than today.
Fig 11: Briffa’s 2001 all tree ring proxy data, compared with non tree ring data.
First of all, I have every respect for the huge work done using tree rings. There are indeed many sources to errors (like the idea about different SH/NH temperature development etc.) – but despite all, this graph speaks a very clear language.
Here we see the 27 datasets of non-tree rings, together with the well known tree ring graphs.
It becomes clear, that the non tree rings world wide – THICK BLUE CURVE – matches extremely well in the 20’th century and all the way back to year 1450. Then exactly as the MWP starts, the tree rings and the non
tree rings simply “looses contact”.
What ever the reason for the differences between tree ring or non tree ring temperature proxies,
it becomes evident, that choosing tree rings or not is the same as choosing a MWP or not.
.
One partly explanation for this huge mismatch could be CO2. If indeed the CO2 concentration today is a lot higher in the atmosphere than it was in the MWP, then trees simply grows faster than in the MWP, apparently even though temperatures are not higher.
S
Conclusion:
– Its way too early to consider the MWP gone. There is a lot of scientific work to be done before any such conclusion has any weight. MWP disappears when using tree ring data.
– In this writing we see that 48 non tree ring temperature proxies combined shows a MWP around 0,4 K warmer than today, lasting at least 500 years.
– Besides the MWP discussion: 80-90% of the Holocene period (last 10-12.000 years) has been warmer than today. The last 6000 years, the general temperature trend has been steady cooling. The temperature levels in the Little Ice Age were the lowest in the Holocene period.
I find it relevant to study the consequences of further cooling.
– Except for strongly adjusted temperature data, there is compliance between recent temperatures measured from satellites, evidence from tree-proxies, evidence from non-tree-proxies and more showing that: It does not appear warmer today than around 1940-50.
This is in compliance with solar activity in the 20’th century.
This does not suggest a warming effect of CO2 in the atmosphere.
ome of the non-tree-ring measurement methods includes Be, O and C isotopes etc, that in some cases are more independent of changing tree growth or the like. These methods would be preferable if we wanted to clear CO2-induced errors on temperature measurements.
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Great post. And I literally fell out of my chair laugh at sod’s zebra comment. How exactly are they supposed to have crossed the Sahara desert in a ~warmer~ climate? Which is generally thought to have also been drier (well, in the tropical regions, it is thought that there was a “mega drought” around this time-popular speculation has it the change crashed the Mayan civilization-I doubt it)? If anything, Zebras and other Savanna fauna were probably pushed south by dry conditions.
Thanks for your extensive work….great reading. On tree rings: I have two trees at one end of my property that were dying and I replanted them in a corner to hide them…. well, they recovered immediately and took off, now soaring over some others they were previously dwarfed by…. turns out, my neighbor had a remote water bib there that has been leaking. Moral of the story: Sun/heat is important, but water is at least as important if not more so. We need studies on growth of each species in each scenario (Hot/dry) (Hot/wet) (cool/dry)(cool/wet) (and perhaps projected precip patterns to give meaning to tree ring data. Thanks again…
Also want to comment on this for Richard M, A recent article here noted declining humidity: http://wattsupwiththat.com/2009/03/05/negative-feedback-in-climate-empirical-or-emotional/
Do we ultimately lose our water vapor blanket at some tipping point, and fall into the next ice age?
Anthony,
“How can you say “All of the satellite data presented here end in 2000″ when we clearly have UAH plot lines extending to 2008 on several graphs? And, what correction are you referring to?”
Apologies if I missed it, but which of the figures above are you referring to?
“And, what correction are you referring to?”
The corrections since 2000, endorsed by Spencer and Christy, which produce the current publicly available satellite dataset of temperatures.
REPLY: Now I understand what you are talking about. The UAH data available today, and for the last few years has already been corrected for that issue. In fact it is pretty hard to find the UAH data prior to that correction. Frank mentioned earlier today he is preparing a digital archive of all data used and when it is ready, I’ll add it here. I think it is an assumption that he used uncorrected data. As for the other data sets, we’ll also be able to see when they end.
I see the point you are trying to make about 2000 as an endpoint, but if you have UAH data to 2008/2009 there’s really not much you can do in the way of comparison if the endpoint for other datasets stops before that. Choosing an endpoint for all comparisons that “fits” all the datasets is of course subjective. Note for example in figure 3, many don’t make it all the way to 2000. I did make an error on interpreting figure 11, I thought I saw the x scale ending at 2008 for the UAH data, but that was an artifact of size compression and viewing on a laptop screen. Now seeing on my large 24″ screen at home I see that was not the case.
I think Frank has done an amazing job in his spare time, and the endpoint of 2000 seems to be a choice he made based on fitting the endpoints of the proxies to a reasonable and common endpoint, 200 makes a good choice when many proxies end near it. As I said before, using the 2009 data would leave a line with no data to compare to in the vicinity. When Frank publishes the datafiles he used, we can then decide if the complaint has any merit. – Anthony
Keohane (14:10:19 :
The study you referenced was posted about here when it came out,
http://wattsupwiththat.com/?s=tree+leaves+maintain+their+own+Steve )
I thought it suggested pretty strongly that whatever tree ring variations were recording, it very likely wasn’t temperature.
Hope all this AGW BS goes away soon as I really don’t have more time to waste on the debate, even if it means all these pro-and anti sites will slowly die away as interest dies LOL sorry
One last comment on my CO2-ice age hypothesis. If true it means both the skeptics and the climate scientists are right. Think of the trend line as being downward instead of flat for current natural climate feedbacks. The release of soot and CO2 is then warming the planet from an ever decreasing base. The “expected” warming of the AGW science turns out to be correct. The fact the “data” did not support the science, the complaint of many skeptics, is resolved.
The only losers in this scenario are those who want catastrophic warming or who want to use AGW for political purposes. Both the physics and the data start to come together.
Now all that is needed is to find someway to determine if the natural forcings really were on a downward trend. An interesting task for some enterprising climate scientists.
I would doubt that ring growths are good for anything longer than their stage of life around a particular event, for example noting the effect of a volcanic eruption. I don’t see how you could extrapolate this to all biological proxies though. The position of the margin of a population of trees would move as the climate varied over the centuries, and the rings would be sampled from these marginal trees, automatically minimizing the centuries long variation in the cumulative record. Unless this particular line of reasoning applies to any other proxy, then it is not necessarily suspect.
I would say that the relationship is complex and chaotic but also that most would understand this. Thats why multiple proxies are employed and averaged. However saying its all too complicated is a bit of a cop-out.
I was over at solarcycle24.com looking at the latest string of spotless days that stands at 35 (soon to be 36). It seems to me that this is the longest string I remember seeing going back to the beginning of 2008, but I don’t have access to the same data to do the analysis myself. Any thoughts or input? It seems that the current string is quite interesting given how we are supposed to have passed the solar minimum.
Frank, thank you for this amazing body of work.
This will go a long way toward showing the utter futility of measuring the global temperature. As I have stated on WUWT and other fora, one can only control what one can accurately measure.
The entire concept of controlling global temperature by adjusting (reducing) atmospheric CO2 is beyond hopeless. Anyone who believes they can do so, will be defying the fundamentals of control theory and applications.
Readers might be interested in browsing the US National Climate Data Centre.
In particular their
listing of data sets (many of which are downloadable).
And their archive of 92 high-resolution temperature records covering the last 2+ millenia all of which are downloadable.
They include lists of the research papers (all peer reviewed) which present the datasets and the methodologies used.
Frank,
This is a tremendous post. It seems to drive a steel spike through the tree ring as temperature proxy hypothesis, and smashes the hockey stick forever.
Richard M.:
could it be that ice ages occur when CO2 gets too low?
Interesting, but temperatures seem to fall off before CO2, and CO2 follows. It looks like CO2 slows the cooling process. There was good post on this a few weeks ago on WUWT. So I thinkan ice age starts before CO2 gets low.
Trees.
About 1974 I was at Prudhoe Bay watching the cuttings from the drill flow into the mud pit. They were drilling the surface hole at about 1,200′ One of the things that came out of the hole was a perfect Douglas Fir cone, solid, pliable, and with the characteristic “mouse tails”.
Prudhoe is on the outwash plain of the Sag River. The cone could have come out of the hole sidewall anywhere between the bit and the surface. Debris in the outwash plain comes from the mountains. The nearest Douglas Fir I know of are coastal SE Alaska and central British Columbia.
So when did Doug Fir grow in the mountains of northern Alaska, and how much warmer and wetter would it have been then than now? If memory serves, current precipitation on the North Slope is around 3″ to 5″ per year. With less than 1,200 feet of debris it can’t be too long ago.
“Now all that is needed is to find some way to determine if the natural forcings really were on a downward trend. An interesting task for some enterprising climate scientists.”
God protect us from enterprising climate scientists!
@Pearland Aggie: for consecutive spotless day periods, see:
http://users.telenet.be/j.janssens/Spotless/Spotless.html#Period
I like using CO2 as a proxy for the temperature a few months earlier. 🙂
http://www.woodfortrees.org/plot/esrl-co2/isolate:60/mean:12/scale:0.2/plot/hadcrut3vgl/isolate:60/mean:12/from:1958
Steve Keohane (14:10:19) :
I woke up with the same paper in mind:
From Canada to the Caribbean: Tree leaves control their own temperature, Penn study reveals http://www.eurekalert.org/pub_releases/2008-06/uop-fct061108.php
I think that what the temperature from tree rings tells us is that trees control their temperature with feedback mechanisms to keep it at their desired optimum. In a sense proving the above paper.
It tells us that you cannot tell the ambient temperature from a tree temperature in the same way you cannot tell the ambient temperature from a human’s temperature,
( were you able to use it as a proxy) except in extremes, as we are watching with the Catlin expedition.
Frank Lasner: a great post.
“So when did Doug Fir grow in the mountains of northern Alaska, and how much warmer and wetter would it have been then than now?”
The last interglacial was significantly warmer than this one has been. I believe tree lines were about 400 miles North of current tree line. Would that be far enough North to put that cone in the drainage basin and possibly end up there?
From the link I gave above:
The research, published online in this week’s Nature, contradicts the longstanding assumption that temperature and relative humidity in an actively photosynthesizing leaf are coupled to ambient air conditions. For decades, scientists studying climate change have measured the oxygen isotope ratio in tree-ring cellulose to determine the ambient temperature and relative humidity of past climates. The assumption in all of these studies was that tree leaf temperatures were equal to ambient temperatures.
Researchers at Penn, using measures of oxygen isotopes and current climate, determined a way to estimate leaf temperature in living trees and as a consequence showed this assumption to be incorrect.
This is an unfortunate finding for the potential to reconstruct climate through tree-ring isotope analysis
anna v (19:58:34):
Steve Keohane (14:10:19) :
I woke up with the same paper in mind:
From Canada to the Caribbean: Tree leaves control their own temperature, Penn study reveals http://www.eurekalert.org/pub_releases/2008-06/uop-fct061108.php
I’m conducting an experiment on spearmint (Mentha viridis L.) thermoregulation. Here an advance of my investigation:
http://biocab.org/Biophysics.html#anchor_36
Obviously, most living beings are not adequate as proxies for paleothermometry because, though plants are poikilotherms, they count also on thermoregulatory processes which permit them to survive at extreme temperatures. Their processes are not as efficient as birds and mammals thermoregulatory processes, but they react before changes of the environmental temperatures.
crosspatch:
I don’t think 400 miles will get it done. Probably closer to 1.000 miles.
Doug fir grow in the Colorado Mountains, I believe above 8.000′, as well as the lowlands of WA and OR, but said to be two different races. Provenance, and all that
Someone mentioned the time to read and digest this and then get in timely comments. Likewise for me, so:
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1. I think everyone should be aware that tree rings were used for dating ancient sites and for comparisons with other dating methods – varve counting comes to mind. Temps were not the initial focus, I don’t think. Correct me if I’m wrong.
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2. Allan M R MacRae (16:01:07) : “. . .cherry picking graph. . .”
Take the larger image view – it works
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3. And “sod” commented (pro) on the quality of the GISS data
sod (13:04:32) “the claims about GISS are extremely problematic.”
Are not the GISS temperatures an extension of the process begun in the US – using station data that is highly problematic, as shown here
http://www.surfacestations.org/
for the US. Some similar reports are available for other countries also.
Also, has there not been a lot of rural station drop-out in many countries?
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4. Is there a statement showing how the “mannian” hockey stick weighted the bristlecone proxy? I have Steve McIntyre’s statement that the proxy was weighted by (400x, I think it was) so much that nothing else really mattered, and this post shows this to be wrongheaded. I’m asking for an equation or a table that would show what was done.
THIS IS FANTASTIC! This is a woirk of art!
I beg you… do tell…whom do I contact to purchase a reproduction in the quality suitable for my livingroom wall?
This is an AMAZING work of art. I simply MUST have it. (Assuming I can afford it.)
Terry J, there is also the possibility that it floated there from afar.
But look at the diagram on this page in the “Evolutionary History” section. You will notice a triangle on the North coast of Alaska. That means that there were Douglas fir fossils found there dating to the Quaternary. Picture here.