Yet another paper demonstrates warmer temperatures 1000 years ago and even 2000 years ago.

Yesterday I highlighted the paper The extra-tropical Northern Hemisphere temperature in the last two millennia: reconstructions of low-frequency variability, by B Christiansen of the Danish Meteorological Institute and F C Ljungqvist of Stockholm University which showed that using a multitude of proxy samples in the norther hemisphere, that:

“The level of warmth during the peak of the MWP (Medieval Warm Period) in the second half of the 10th century, equaling or slightly exceeding the mid-20th century warming, is in agreement with the results from other more recent large-scale multi-proxy temperature reconstructions.”

Now another paper, by Esper et al published in the Journal of Global and Planetary Change, shows that not only was the summers of the  MWP equal or greater than our current warmth, but that the summers of the Roman Warm Period of 2000 years ago were significantly warmer than today.

Fig. 4. Northern Scandinavian JJA temperatures back to 138 BC. The annually resolved N-Scan record (blue curve) shown together with 100-year filters of the reconstruction (red curve) and uncertainty estimates integrating standard and bootstrap errors (dashed curves). Light and dark grey bars indicate exceptionally warm and cold 30-year periods during the Roman, Migration, Medieval Warm, Little Ice Age, and Modern Warm Periods. Temperatures are expressed as anomalies with respect to the 1951–1980 mean.

Variability and extremes of northern Scandinavian summer temperatures over the past two millennia

Jan Esper, Ulf Büntgen, Mauri Timonen, David C. Frank

Abstract

Palaeoclimatic evidence revealed synchronous temperature variations among Northern Hemisphere regions over the past millennium. The range of these variations (in degrees Celsius) is, however, largely unknown. We here present a 2000-year summer temperature reconstruction from northern Scandinavia and compare this timeseries with existing proxy records to assess the range of reconstructed temperatures at a regional scale. The new reconstruction is based on 578 maximum latewood density profiles from living and sub-fossil Pinus sylvestris samples from northern Sweden and Finland.

The record provides evidence for substantial warmth during Roman and Medieval times, larger in extent and longer in duration than 20th century warmth.

The first century AD was the warmest 100-year period (+0.60 °C on average relative to the 1951–1980 mean) of the Common Era, more than 1 °C warmer than the coldest 14th century AD (−0.51 °C). The warmest and coldest reconstructed 30-year periods (AD 21–50=+1.05 °C, and AD 1451–80=−1.19 °C) differ by more than 2 °C, and the range between the five warmest and coldest reconstructed summers in the context of the past 2000 years is estimated to exceed 5 °C. Comparison of the new timeseries with five existing tree-ring based reconstructions from northern Scandinavia revealed synchronized climate fluctuations but substantially different absolute temperatures. Level offset among the various reconstructions in extremely cold and warm years (up to 3 °C) and cold and warm 30-year periods (up to 1.5 °C) are in the order of the total temperature variance of each individual reconstruction over the past 1500 to 2000 years. These findings demonstrate our poor understanding of the absolute temperature variance in a region where high-resolution proxy coverage is denser than in any other area of the world.

[…]

Discussion and Conclusions

The MXD-based summer temperature reconstruction presented here sets a new standard in high-resolution palaeoclimatology. The record explains about 60% of the variance of regional temperature data, and is based on more high-precision density series than any

other previous reconstruction. Importantly, MXD sample replication prior to the Little Ice Age, during Medieval times and throughout the first millennium AD, is much better than in any other record, and we demonstrated – based on calibration trials using reduced

datasets – that these early sections of the N-Scan record likely still contain useful climate information. This persistent climate signal allowed an estimation of temperature variability throughout the Common Era, revealing warmth during Roman and Medieval times were larger in extent and longer in duration than 20th century conditions.

According to this new record, summer temperatures varied by 1.1 °C among the 14th and 1st centuries, the coldest and warmest 100-year periods of the past two millennia. Temperatures ranged by more than 5 °C among the five coldest and warmest summers of the past 2000 years. These estimates are, however, related to the approach used for proxy transfer, i.e. figures would change, if the calibration method, period, and/or target were modified (Frank et al.,2010b). For example, variance among the 30 coldest and warmest N-Scan summers (Table 3) increases from 3.92 °C to 5.79 °C, if scaling (i.e. adjustment of the mean and variance) instead of OLS regression is used for proxy transfer. These differences between scaling- and regression-based approaches are proportional to the unexplained variance of the calibration model (Esper et al., 2005), and we suggest

smoothing the proxy and instrumental timeseries prior to calibration, as this procedure decreases the unexplained variance in all Scandinavian tree-ring records and thus minimizes the differences between various calibration methods (Cook et al., 2004).

Our results, however, also showed that these methodological uncertainties are dwarfed by the variance among the individual reconstructions.

Differences among six northern Scandinavian tree-ring records are>1.5° in 30-year extreme periods and up to 3 °C in single extreme years, a finding we didn’t expect, as the proxy records: (i) all calibrate well against regional instrumental data, (ii) partly share the same measurement series (or use differing parameters – TRW and MXD – from the same trees), and (iii) originate from a confined region in northern Scandinavia that is characterized by a homogeneous temperature pattern. Since we here calibrated all reconstructions using the same method, between-record differences are likely related to varying data treatment and chronology development methods, measurement techniques, and/or sampling strategies, as well as the remaining uncertainty typical to such proxy data. For example, splicing of MXD data on recent TRW trends as done in Briffa92 might have caused this reconstruction to appear at the lower (colder) end of the ensemble, whereas the combination (and adjustment) of novel digital MXD measurements with traditional X-ray based MXD data as done in Grudd08 might have caused this reconstruction to appear at the upper (warmer) end of the ensemble. Other differences are likely related to the combination of sub-fossil material from trees that grew in wet conditions at the lakeshores with material from living trees growing in dryer ‘inland’ sites. Also varying variance stabilization (Frank et al., 2007) and detrending techniques (Esper et al., 2003) in association with temporally changing sample replications and age distributions of the underlying data (Melvin, 2004) likely impacted the variance structure of the long-term records and consequently the absolute levels of reconstructed temperatures.

Between-reconstruction variance as revealed here represents a pending challenge for the integration of proxy records over larger regions and the development of a single timeseries that represents the Northern Hemisphere (e.g., Mann et al., 2008), for example. The composition of such records commonly relies on the calibration statistics derived from fitting regional proxy records against instrumental data (D’Arrigo et al., 2006). However, the records analyzed here would all easily pass conventional calibration-based screening procedures. Yet our analysis revealed that choosing one Scandinavian record instead of another one can alter reconstructed temperatures by 1.5-3 °C during Medieval times, for example. On the other hand, consideration of all records presented here would likely promote a less variable climate history, as the combination of diverging records tends to reduce variance in the mean timeseries (Frank et al., 2007). If such a mean is then combined with instrumental data covering the past 100–150 years, this approach might facilitate hockey stick-shaped reconstructions (Frank et al., 2010a). This seems to be a tricky situation in which expert teams including the developers of proxy records might need to be involved to help assessing timeseries beyond the typical ranking based on calibration statistics.

Our results showed that introducing an improved temperature reconstruction does not automatically clarify climate history in a given region. In northern Scandinavia, we now arrive at a situation where a number of high-resolution proxy records – all passing classical calibration and verification tests – are available within a confined region that is characterized by homogeneous temperature patterns. These records, however, differ by several degrees Celsius over the past two millennia, which appears huge if compared with the 20th Century warming signal in Scandinavia or elsewhere. We conclude that the temperature history of the last millennium is much less understood than often suggested, and that the regional and particularly the hemispheric scale pre-1400 temperature variance is largely unknown. Expert teams are needed to assess existing records, and to reduce uncertainties associated with millennium-length temperature reconstructions, before we can usefully constrain future climate scenarios.

Full paper here (PDF -link fixed)

h/t to WUWT reader Gordon Pye and Tory Aardvarrk

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Kurt in Switzerland

I wonder if this will make it to the IPCC’s AR5 next year.
Taking any bets?
Kurt in Switzerland

ob

Just a note. As far as I understand it, the reconstruction is the same as used in Esper et al. 2012 in Nature Climate Change
I think Figure 6 is interesting.

Peter Miller

Clearly, the following applies here:
1. The data has not been subjected to interpretation by Mannian mathematics.
2. It will be ignored by the alarmist community, especially the IPCC, and/or
3. It will be condemned by the alarmist community as being not representative – northern Scandinavia only.
There are some river banks in southern Iceland, where I have seen the remains of huge tree trunks, clear evidence of much warmer conditions than today.
Icelandic joke: “What do you do if you get lost in an Icelandic forest?” Answer: “Stand up.”

Your link to the PDF of the paper is broken.
Thanks
JK

Between-reconstruction variance as revealed here represents a pending challenge for the integration of proxy records over larger regions and the development of a single timeseries that represents the Northern Hemisphere
There is a single proxy for whole of the northern hemisphere: geo-solar oscillations or interaction between changes in the solar activity and the Earth’s interior periodic undulation
http://www.vukcevic.talktalk.net/EarthNV.htm

No doubt these findings advocate that we need to research more on the causes of global warming i.e. is it human or naturally induced?. However, which ever side your bread is buttered with regards to climate change, there are increases in global temperatures and burning fossil fuel is only adding to the problem. The problem is that there is competition amongst the economies of the world, and it is compromising the world of the future generations. I seriously think we need to start acting and as soon as possible to prevent further damage.

philemon

The link to the paper isn’t working

pat

what’s 1,000 or 2,000 years when climate models for mars prove CAGW climate models for earth are valid?
18 Oct: MSNBC: Reuters: Deborah Zabarenko: Models of Earth’s climate change confirmed on Mars
Astronomers find that computer calculations match up with traces of ancient snowfall
Astronomers say computer models have accurately forecast conditions on Mars and are valid predictors of climate change on Earth.
These computer programs predicted Martian glaciers and other features on Earth’s planetary neighbor, a U.S.-French team of scientists found.
“Some public figures imply that modeling of global climate change on Earth is ‘junk science,’ but if climate models can explain features observed on other planets, then the models must have at least some validity,” lead researcher William Hartmann of the Planetary Science Institute said Tuesday in a statement.
The team’s findings were presented at the annual meeting of the American Astronomical Society’s planetary sciences division in Reno, Nev…
***”We do have a lot of public figures, in our country particularly, saying that the global climate modeling studies have very little value,” Hartmann said. “If the global climate modeling people can run these models on Mars and we actually see things that come out of the model on another planet, then the climate modeling people must be doing something right.”
http://www.msnbc.msn.com/id/49456341/ns/technology_and_science-space/

kadaka (KD Knoebel)

Thankfully the Great Climate Wall at the equator prevented these brief regional warming periods from being global events.
The hottest July in the contiguous US (after adjustments) is proof of anthropogenic global warming. A single inconveniently-located hurricane is proof of anthropogenic global warming. But the Northern Hemisphere being far warmer than today cannot be an example of historical global warming greater than today’s global warming, because local cannot be global unless humans are to blame.

Brian H

The signal is so strong it’s fudge-proof. Another disaster for CAGW. Even lukewarmism, as both those periods were manifestly better for all species concerned, including ours. And CO2 was waaaaayyy lower.
Edit: “the summers of the Roman Warm Period of 2000 years ago was ” //were//

Link to .pdf of full paper doesn’t work.
Kurt in Switzerland

The Romans produced red wine from locally grown grapes north of York, UK. A similar grape now grows south of Dijon in France over 350 miles south of York. So warmer back then.

SteveW

If you follow the H/T to Tory Aardvark, the link from there works fine, it’s here:
http://www.wsl.ch/fe/landschaftsdynamik/dendroclimatology/Publikationen/Esper_etal.2012_GPC

ob

working link to paper to be found on Esper’s homepage

Espen

I remain skeptical that it’s possible to tease a sensible “temperature signal” out of tree rings at all, and the large error span (see dashed lines) support my position. However, it’s so refreshing to read “We conclude that the temperature history of the last millennium is much less understood than often suggested, and that the regional and particularly the hemispheric scale pre-1400 temperature variance is largely unknown.” Applause!

schnurrp

Uchiha says:
October 18, 2012 at 1:35 am
No doubt these findings advocate that we need to research more on the causes of global warming i.e. is it human or naturally induced?. However, which ever side your bread is buttered with regards to climate change, there are increases in global temperatures and burning fossil fuel is only adding to the problem. The problem is that there is competition amongst the economies of the world, and it is compromising the world of the future generations. I seriously think we need to start acting and as soon as possible to prevent further damage.
Are you implying that we need to stop competing in the world economy? Why wait for AGW? Let’s just commit suicide now and get it over with!

kadaka (KD Knoebel)
luval

Earth has gone through cycles of cooling and warming throughout its history but this does not imply that what we are experiencing the same situation. The increase of CO2 in the atmosphere is a fact and studies show that this increase represents the best fit to the increase in temperatures as it correspond in terms of trend and magnitude. Prediction for climate changes in the next 30 years are quite accurate and the intensifying of events as storms and drought should encourage not only further studies but also adaptation measures as, even if naturally caused, climate changes are going to affect food production, water availability etc. Moreover fossil fuels production is not sustainable anymore since not only pollution levels are increasing and so health is endangered, but also as resources are becoming scarcer and scarcer the price is increasing and so it is becoming not economically feasible to continue this sort of production.

richardscourtney

Uchiha:
At October 18, 2012 at 1:35 am you say

No doubt these findings advocate that we need to research more on the causes of global warming i.e. is it human or naturally induced?. However, which ever side your bread is buttered with regards to climate change, there are increases in global temperatures and burning fossil fuel is only adding to the problem.

Please explain what you think is a “problem” in longer growing seasons and cheap energy.
Richard

mwhite

I wonder what would happen if Mikes “NATURE TRICK” was applied to the graph????

Uchiha (01:35 am) writes “there are increases in global temperatures and burning fossil fuel is only adding to the problem”
If you had written “temperature are varying entierely within the historical range, and there is no problem” I’d have agreed with you.

Marcel Terblanche

This article puts and interesting spin on our current fixation with human induced climate change. If we look back into ‘deep time’ the geological climate is ever changing and highly variable. Even though this article isn’t necessarily representative of global climate change, it points to some very valid and worthwhile ideas regarding climate change over much longer periods of time. What about a million years ago? What kind of change have we experienced over that period? As humans we tend to live in a very self centered, short term reality and it is important to step back and analyse climate change from a longer time period, as this can point to the extent to which we are actually changing the climate and thus the environment. It is inarguable that we have had an effect on the increased temperatures in the past century, but these kinds of papers help us realise that we may not be the climate ‘hell spawn’ that the media likes to imply.
Marcel Terblanche
Cape Town

Paul Matthews

Memo to people saying the link doesnt work – it might be more helpful to google the paper and post the correct link
http://www.geo.uni-mainz.de/Dateien/Esper_2012_GPC.pdf

Byron

Yet another stake through the heart of the CAGW monster , any normal scientific hypothesis would be long dead with this many holes in it but CAGW keeps lurching around making groaning noises and sucking the fiscal life out of the world like some sort of vampire/zombie hybrid . I shouldn`t be be surprised at the similarities though , the post-normal science of CAGW , zombies and vampires have two things in common , they`re all fictional terrors designed to frighten Us and being undead they need to feed on the living , be it brains , blood or economies

Uchiha says:
October 18, 2012 at 1:35 am
“there are increases in global temperatures and burning fossil fuel is only adding to the problem”
—————————————————————————————
Not only did the Romans have better weather, they also had more intelligent superstitions.

Warren in Minnesota
KevinM

http://www.pannelldiscussions.net/2012/10/226-modelling-versus-science/
Interesting link for WUWT readers. Modeling issues discussed.

The Medieval,Roman and Minoan periods are approximately 1,000 year apart at peak and this MODERN warm period is also around a 1,000 years from the MWP peak.

RobW

Who knew chariots produced so much CO2. 😉

Pamela Gray

Ah, the ending.
“Expert teams are needed to assess existing records, and to reduce uncertainties associated with millennium-length temperature reconstructions, before we can usefully constrain future climate scenarios.”
I have memorized the ending. We get the ending served up morning, noon, and night. If a midnight snack is wanted, you will be served another helping of the ending. This one comes with plating artistry.
If you are a foodie you know what plating means. The only differences between meat, potatoes, and gravy served on a kitchen plate, and meat, potatoes, and gravy plated up is that the former has the gravy spooned over the top of the food, hold the sprig, whereas the latter has the gravy artistically swirled under the food with a sprig of green something stuck somewhere into it.
Regarding this particularly subtle but still necessary-for-funding ending reference to anthropogenic scary climate scenarios, four marks for plating.

TeddySlayerZA

The paper seems well researched, and I’m not going to pretend I’m enough of a scientist to dispute it. I do however think that this does not in any way rule out the anthropogenic role in our present day Climate Change. This may be simply another contributing factor, and by all means the IPCC should review this, but it doesn’t mean we can ignore all other factors.
@Brian H. You haven’t really explained why this ‘fudge-proof’ paper is a disaster for CAGW. Nobody claims that climate change is purely anthropogenic, whats so strange of the idea about a natural process taking place alongside our own contributions? As you clearly state, atmospheric CO2 was much lower in the past warming periods, but today it isn’t and we can see this manifesting itself in ocean acidification, a process this paper in no way ‘explains away’, and this is indisputably mans doing.
Finally, warming periods in the past may have been better then, when the world did not have 7 billion mouths to feed and ecosystems were not already on the point of collapse from various other influences. How would we cope with this now? Entire countries can’t simply migrate their agricultural sectors to higher latitudes at will. Natural or not, these are issues that we need to address, not just ignore.

Pamela Gray

I’ve noticed recently an uptick in canned AGW proponent responses to debate on WUWT. These responses usually have little to do with the particular thread topic they appear in. In terms of debate science, this tactic is considered to be very poor debate form for numerous reasons. My recommendation is to debate the style and/or content of the article or face debate dismissal of your comment due to lack of substance. Humor is always an exception to debate tactics as long as it is light hearted.
And yes, I have violated my own recommendation but am reminded by these canned blurbs how poor my comment must have looked.

Grant

Now another paper, by Esper et al published in the Journal of Global and Planetary Change, shows that not only was the summers of the MWP equal or greater than our current warmth, but that the summers of the Roman Warm Period of 2000 years ago was significantly warmer than today.
Should be “were” not “was” in both cases.

Peter Miller

R Taylor says: “Not only did the Romans have better weather, they also had more intelligent superstitions.”
I have always thought of CAGW in terms of bad science or cultish beliefs, but the concept of it being a superstition is equally appropriate..

richardscourtney

luval:
WUWT really does have a bad troll infestation today.
Your post at October 18, 2012 at 3:02 am says in total

Earth has gone through cycles of cooling and warming throughout its history but this does not imply that what we are experiencing the same situation. The increase of CO2 in the atmosphere is a fact and studies show that this increase represents the best fit to the increase in temperatures as it correspond in terms of trend and magnitude. Prediction for climate changes in the next 30 years are quite accurate and the intensifying of events as storms and drought should encourage not only further studies but also adaptation measures as, even if naturally caused, climate changes are going to affect food production, water availability etc. Moreover fossil fuels production is not sustainable anymore since not only pollution levels are increasing and so health is endangered, but also as resources are becoming scarcer and scarcer the price is increasing and so it is becoming not economically feasible to continue this sort of production.

That is so wrong it is astonishing. Every statement in it is plain wrong.
“Earth has gone through cycles of cooling and warming throughout its history but this does not imply that what we are experiencing the same situation.”
It does according to science. Read up on the Null Hypothesis which is a fundamental scientific principle.
“The increase of CO2 in the atmosphere is a fact and studies show that this increase represents the best fit to the increase in temperatures as it correspond in terms of trend and magnitude.”
The increase of CO2 in the atmosphere has no relationship to the increase in temperatures. Indeed, the global temperature stopped rising 16 years ago but the increase to CO2 in the atmosphere has not stopped.
“Prediction for climate changes in the next 30 years are quite accurate”
No! They are completely wrong!
The IPCC AR4 predicted (n.b. predicted and not projected) that global temperature would rise at an average rate of 0.2 deg.C/decade +/-20% over the period from 2000 to 2020. This was “committed warming” which was certain because of GHGs already in the system. And the rise would be double that if emissions continued as they have. To date there has been negligible rise in global temperature since 2000. Therefore, for the minimum temperature rise of this prediction to be true then a rise of 0.64 deg.C must occur over the next nine years. This is extremely implausible: the entire rise over the last century was only about 0.8 deg.C. And if this jump in temperature were to occur then it would not explain where the “committed warming” has been hiding since 2000.
Those are only the first three statements in your post. I could refute the rest of the statements in your post, too. But it is not worth the bother spending time on such bunkum.
Richard

Donald Mitchell

pat says:
October 18, 2012 at 1:49 am
what’s 1,000 or 2,000 years when climate models for mars prove CAGW climate models for earth are valid?
I suspect four major reasons for climate models working better for mars.
1 Cloud cover and oceanic contributions may be easier to model for mars.
2 The number of available proxies may be significantly smaller for mars.
3 Data does not have to be massaged to fit anthropogenic forcing.
4 There may be a much less active group scrutinizing their findings.

thingadonta

Yes but according to the Australian Acaedmy of science the distant geological past has nothing to do with the causes of global warming, (unless of course it shows that temperatures were less than the current warming caused by humans).

Gras Albert

Luval
The increase of CO2 in the atmosphere is a fact and studies show that this increase represents the best fit to the increase in temperatures as it correspond in terms of trend and magnitude. Prediction for climate changes in the next 30 years are quite accurate and the intensifying of events as storms and drought should encourage not only further studies
This statement is wholly false, all AR4 models are biased high showing no skill, see
http://tinyurl.com/8lkyj5b
they were tuned to hindcast correctly, as a result their collective projections have failed at 95% confidence or will fail by mid 2013
a 10 year rolling trend analysis arguably suggests an inverse relationship between increasing CO2 and land/ocean temperatures over the past 20 years
http://tinyurl.com/hadcrut4hadsst2co2decadal1990

There are two points made by warmist re the modern warming: 1) that the temps are higher than any (sustained) in the last 1000 or 10,000 years, and 2) that the rate of warming since the mid-60s is “unprecedented”, i.e. greatest in the last etc.
The proxy reconstructions put the lie to both. That is good. The warmists say that yesterday is not pertinent to today because warming may be caused by solar changes yesterday, while they are caused by CO2 today. Based on circular reasoning, but a reasonable starting point. The clincher is the rate of warming, which is tied to the date of fossil-fuel CO2 injection, and (circular reasoning again, considering the assumptions) the “empirical” mathematics of CO2-forcing.
Having warming rates similar in the past to those today makes two coincidences for CAGW theory to deal with. Occam’s Razor puts the doubt it, or should.
If Mann publicly accepts any of these reconstructions, Gore is in trouble. And once Gore is in trouble – as he is the “prophet” of Global Warning, the whole Church is in trouble.
My bet: Mann will brush them off.

Dan in Nevada

Lots of (very polite) comments maintaining that CAGW is still a fact. Are these from the “Crusher Krew”?

luval says:
October 18, 2012 at 3:02 am
Moreover fossil fuels production is not sustainable anymore since not only pollution levels are increasing and so health is endangered, but also as resources are becoming scarcer and scarcer the price is increasing and so it is becoming not economically feasible to continue this sort of production.
=========
actually, in the first world at least, pollution levels are much decreased over what they were 50 or 100 years ago.
what solution do you propose? the earth is currently supporting more people in greater prosperity and health than in any age previously. low cost energy derived from fossil fuel is the driving engine behind this prosperity. to change this, market forces require that you must come up with a lower cost alternative, or you must reduce the prosperity of the people of the earth.
if for example we were to return to burning wood for energy, which was common in the past, the forests of the earth would need to be burned within a decade or two to supply our current energy needs. This can be seen in the US, where many of the forests cut down 200-300 years ago to supply firewood have now regrown.
I personally would like to see an end to burning fossil fuel as an energy source. I would prefer to have a low powered fusion reactor in my house that ran off tap water, so that I didn’t need to send my hard earned money to the power and gas companies each month. However, until the Mr Fusion units go on sale at Walmart and Costco, I’m pretty much stuck.
I would certainly appreciate it if the government would pay me to replace my roof with $100,000 worth of solar panels. My only question is, where is the government going to get this $100,000? If they are giving me $100,000 and my neighbors $100,000, then I suspect they are going to have to raise my taxes by $150,000 to pay for my roof. $50,000 to pay the government officials, who approve my roof, and the $100,000 to pay for my roof.
On that basis I would rather keep the $150,000 in my pocket.

Zinzi

The paper seems well researched and points out some valid points; however the paper appears as though they are against the whole idea that the world’s warming periods have been increasing drasticaly in the 21st century and the scarry part is the after effects of this increase in temperatures in the next decade/century. The increase in these temperatures is partially anthropogenetic and also natural variabilities, but anthropogenetic activities are the main drivers of warming in this 21st century, and that is not a factor that one can be ignorant of. It is inarguable that temperatures indeed have been increasing for past millenium,and no one disputes the fact that some temperature increases where higher than the recent temperature increases, but the focus is how the increase was in the last 2000 years ago, was it is increasing rapidly like it is recently or it was gradually increasing with time?. it is inevitably that today the warming preiod is increasing drastically due to human activities. Borrowing the last statement of the paper that “the temperature history of the last millennium is much less understood than often suggested. Indeed it is less understood, because going back to thise times there were not many stresses affecting the warming of the world, human population at that time was far less than 7billion, and the activities at that time were not as intense as they are today. Hence it is better to start teaching people about adaptation and mitigation and not advice them to be ignorant about this matter that our climate is changing, and that the warming periods are increasing at a high rate.

There is a lot of uncertainty when it comes to projections of future climate, we need to take into consideration that this issue is not only a direct result of human activity; it is also coupled by natural forces and feedback mechanism. The temperatures in the past were once higher than what we claim to be global warming today, what we still don’t know is the rate that the temperature increased by. In this case we don’t know the magnitude of the effect that human activities play in amplifying the effect of increase in temperatures. Whether we like it or not the symptoms of what seems to be global warming are out there and affecting each and every one of us at different scales, social or economic aspects of life.

On that basis I would rather keep the $150,000 in my pocket.
==========
Invested that $150,000 will bring an income of $500+ a month. About what I spend on fossil fuel energy each month. So, if I don’t put up solar panels, my energy is free.

Alan the Brit

TeddyslayerZA
@Brian H. You haven’t really explained why this ‘fudge-proof’ paper is a disaster for CAGW. Nobody claims that climate change is purely anthropogenic, whats so strange of the idea about a natural process taking place alongside our own contributions? As you clearly state, atmospheric CO2 was much lower in the past warming periods, but today it isn’t and we can see this manifesting itself in ocean acidification, a process this paper in no way ‘explains away’, and this is indisputably mans doing
Sorry to disillusion you, but that is precisely what Warmistas have been saying, that there is no natural variation going on just AGW because of man’s emissions of CO2. We don’t know for certain that there was less CO2 in the atmosphere in the previous warm periods, CO2 dissolves in ice in such a way that losses are incurred, & losses are also incurred in the CO2 extraction process, so in fact they could have been higher. Danish research on fossilized plant stomata from the bottom of prehistoric lakes have shown that over Denmark at least, atmospheric concentrations were at about 320-330ppm some 9500 YBP, therefore it is hightly unlikely that this was just located over Denmark only, & not over much more of Europe (certainly there is currently more over Brussels & Strassbourg at the EU HQ)! The IPCC arbitrarily ignored thousands of well measured levels of atmospheric CO2 taken pre 1958 Mauna Loa measurements that demonstrated variations of Northern Europe of betyween 320-450ppm, many taken before the Industrial Revolution could have had any significant effects from fossil fuel burnng! It has also been noted that due to the way CO2 is dissolved in ice today’s blip of 390ppm would not be seen in core samples in another thousand years time! Taking this into consideration, therefore instead of assuming that CO2 increases were from 270ppm to 390ppm (44%), they could have been 330ppm to 390ppm, (18%) much less than claimed! The warming of today in not unprecedented as claimed, & if you actually look at the ice core records, going back the last few hundred thousand years, they show clearly that temperatures have risen & fallen wit ice-ages, & that when warming the temp plots look rather like a central heating overshoot graph before settling to the desired temperature, on top of which it was warmer 11500 YBP & that the Earth has been cooling off pretty muh ever since, inaccordance withh previous Inter-glacials!

Max Roberts

What the AGW proponents are missing in this debate is that the reason they want us to be so frightened is that they believe we are approaching some sort of horrible tipping point in which an irreversible positive feedback loop commences and we are all boiled.
They now should explain why the warmer warming in the past did not lead to a feedback loop, but today’s cooler warming will lead to a feedback loop.

Cam_S

Anybody notice K.R Briffa and tree-rings in the references?

Geof B.

RichardS, Schnurrp, Brent, Pamela…
Today’s trolls (Uval, Uchiha, etc) could very well have been directed here by something like the “Campaign Against Climate Change Aggregator” (which is what I use as a convenient way to make sure I don’t miss anything by Bishop Hill). With that in mind, I kind of enjoy their very silly (mostly) canned responses.