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Discussion > Are Geological Paleo-Climate Records Relevant to The Climate Debate?

Alan Kendall, your Granddaughter has raised interesting concerns about the need to educate children/young adults about certain issues. With modern technology, it is good she is aware, and probably has a mischievous sense of humour too!

Grooming a dog or horse used to be a positive gesture of care and affection. Women had 'hair care' products, men had 'male grooming' products. I have never felt the need to ask for grooming products in a shop, particularly recently, as there is less to groom, but I suppose it is another word that will fall out of its traditional use.

Those offering 'Professional Grooming Services' may have to rethink their job description.

Mar 23, 2016 at 6:16 PM | Unregistered Commentergolf charlie

Michael hart

Your Holocene Optimum value is probably obsolete.

IIRC Marcott et Al(2013) estimated the optimum as 14.4C+/-0.2C.

The first GISS value above that mean was in 1995.

The critical value for passing the Optimum with 95% statistical significant is 14.69+/-0.09C. This has been exceeded in 2005, 2010,2014 and 2015

With the long term trend approaching 14.8C we have probably passed out of Holocene conditions into Eemian conditions, last seen 120,000 years ago.

Mar 23, 2016 at 7:09 PM | Unregistered CommenterEntropic man

Radical Rodent

Like skydiving with no parachute, the problem is not the fall, but the hard landing.

Consider the case of a farmer on a coastal plain. He gets a few years of increased yields from warming and increased CO2 and then has to watch increasing sea level turn his fields in a salt marsh.

Mar 23, 2016 at 7:19 PM | Unregistered CommenterEntropic man

EM , who seems to rely exclusively on Marcott et al ( 2013) says:-
The critical value for passing the Optimum with 95% statistical significant is 14.69+/-0.09C. This has been exceeded in 2005, 2010,2014 and 2015

The highest anomaly of the present period of recovery was 0.786 °C, and happened in 1998 . Since then, no anomalies have been registered that would indicate a continuous warming, given that the anomalies from 1999 to 2007 have all been much smaller than the anomaly registered in 1998. For example, in both 2000 and 2001 the anomaly was 0.34 °C ; in 2002 it was 0.27 °C, in 2003 it was 0.27 °C, in 2004 it was almost 0.19 °C, in 2005 the anomaly was no more than 0.48 °C, and in 2006 it did not exceed 0.38 °C.

By comparison, during the period of warming at the beginning of the Holocene known as the Holocene Climatic Optimum, the temperature anomalies were 12 times greater than the highest deviation registered in the last 156 year (the anomaly during the Holocene Climatic Optimum was 6 °C higher, while the anomaly in the current period has been no higher than 0.52 °C). (Koshkarova & Koshkarov. 2004).

Mar 23, 2016 at 7:28 PM | Unregistered CommenterSpectator

Spectator

I don't recognise those figures. Where did you get your anomalies, and what baseline do they relate to? Link, please.

"Regional signatures of changing landscape and climate of northern central Siberia in the Holocene". Koshkarova & Koshkarov. 2004 only covers Siberia, Their data is local, not global.

Mar 23, 2016 at 8:01 PM | Unregistered CommenterEntropic man

Entropic man: firstly, where is your evidence that sea-level rise is going to cause the sort of problem for farmers 1 metre above the present high water mark (please do not give us alarmist ideas that the rise is soon going to increase dramatically; let us work on the information we DO have)? Also, have you not heard of sea-walls? The Dutch are pretty knowledgeable about that sort of thing, as you might have heard, a knowledge that many parts of Cambridge are grateful for, and the sort of knowledge that the Romans used in the Somerset Levels, until modern governments decided that they knew better. Which do you trust – knowledge that has worked for centuries, or ideals that have not worked at all?

Mar 23, 2016 at 8:15 PM | Registered CommenterRadical Rodent

EM..... there is no such thing as global data - all data is specific to the site of acquisition. Global estimates are made by aggregating and averaging local data.

Mar 23, 2016 at 8:45 PM | Unregistered CommenterSpectator

Spectator: you mean to say that the 12 bristlecone pines that the hockey-stick is based on are not global?! I am shocked, I tell ya – shocked!

Mar 23, 2016 at 8:54 PM | Registered CommenterRadical Rodent

EM, I've noticed how enamoured you are of the 2013 Marcott et al proxy reconstruction. You quote temperatures from this for the Holocene and compare with 5 individual years data for the late 20th and early 21st century. This is not an appropriate comparison and your assertion that modern temperatures are somehow statistically above the Holocene optimum is a fallacy.
There are many issues with the Marcott et al study amongst which is their handling of errors and their Monte Carlo procedure. However the key issue relating to your comment is that their reconstruction for the most part does not capture any variability on time scales less than three to four hundred years. I think this point is even acknowledged by the authors.

Mar 23, 2016 at 9:25 PM | Unregistered CommenterPaul Dennis

Grafting recent rapid changes, from instrumental measurements, on to data obtained by proxies, where the temporal resolutiion is far far lower, and then stating that recent changes are therefore unprecedented seems to be an ingrained habit of so-called climate science.

And eagerly lapped up by its acolytes.

Mar 23, 2016 at 9:34 PM | Registered CommenterMartin A

EM seems to be a slow learner.

Mar 23, 2016 at 9:55 PM | Registered CommenterMartin A

Martin A, it seems such an obvious point. It is very difficult to unpack 'global' climate variability on centennial time scales from the proxy record and therefore difficult to impossible to make such unprecedented claims.

Mar 23, 2016 at 10:19 PM | Unregistered CommenterPaul Dennis

EM, where is this rapid sea level rise going to happen, and on what timescale?

The Bristol Channel Flood 1607 (See Wikip) remains an interesting area for further research, but there is no evidence to suggest a progressive or recurring problem.

Mar 23, 2016 at 10:44 PM | Unregistered Commentergolf charlie

Paul Dennis

It seems a simple question.

What was the global mean temperature during the Holocene Optimum and how do 21st global mean temperatures compare?

If my approach is wrong, how should one answer the question?

Mar 23, 2016 at 11:23 PM | Unregistered CommenterEntropic man

EM, did the Holocenii have a big carbon footprint? It seems a perfectly simple and irrelevant question.

Mar 24, 2016 at 1:27 AM | Unregistered Commentergolf charlie

EM, it's a simple question. The most profound ones often are. It doesn't have a simple answer. This should be very easy for you to understand but you seem blind to the point. I'll try one more time to explain. The temporal resolution of the Marcott et al study is at best three hundred years and possibly a lot worse during the early and mid Holocene. It doesn't capture variability of climate on a centennial time scale and so could miss decadal and century long warm and cold periods. You then make the statement that years 1995, 2005, 2010, 2014 and 2015 are 95% certain to be warmer than the Holocene optimum. Ergo the modern period is entering unprecedented territory which is a favoured theme of yours. What you need to compare is temperatures smoothed over the last three hundred years to even begin to approach any kind of rigour and validity.

The reductio ad absurdum is that I have data for the specific years 5995, 6005, 6010, 6014 and 6015 bp that show Holocene optimum annual temperatures that are 16.36 +/-0.2 degrees C. Therefore the Holocene optimum is statistically significant warmer than the present day.

Of course I don't have that data because it is not possible to capture the behaviour of the climate 6000 years ago with the required temporal resolution. However this is the basis of your argument. There is however, plenty of local evidence which often has greater temporal resolution that shows the Holocene optimum to be warmer than the present day. We've seen the example of Siberia. We could look closer to home and use tree lines in Scotland, or cave deposits in the Mendip Hills. There has been the recent multiproxy study on the Canadian Arctic. Of course we could find other sites that might show little warming, or even cooling. The point is that whilst global multiproxy studies try to incorporate these into a global mean one has to have the real faith of a believer to think that these are accurate and precise representations of global climate.

It is getting tiresome debating with you because you have no interest in seriously learning about the science of proxies, or entering a debate on one. You are just interested in drive by statements such as 'I've been reading this or that paper....etc.' I would call you a Cassandra but you are not because you don't have a correct vision of the future. You'r more like Senna the soothsayer. I'm sorry to be so harsh but as I said it has become tiresome now.

Mar 24, 2016 at 7:32 AM | Unregistered CommenterPaul Dennis

Paul.

Tried to remind myself of Senna.
Consulted Wikipedia, only links are to "Up Pompeii" and a "Carry On" film.
Unlikely to be applied to EM???

Wiki rubbish when you need it most!

Mar 24, 2016 at 8:34 AM | Unregistered CommenterAlan Kendall

Alan,

it shows how popular culture enters the psyche. I thought Senna the soothsayer simply applied to inveterate doom sayers and didn't realise it came from Up Pompeii!

Mar 24, 2016 at 8:38 AM | Unregistered CommenterPaul Dennis

Oh the shame!! Further intensive research reveals Senna was an Up Pompeii character. How could I have forgotten. But said research interestingly throws up link to Dame Julia Slingo. This line of inquiry continues....

Mar 24, 2016 at 8:47 AM | Unregistered CommenterAlan Kendall

Paul Dennis

".....whilst global multiproxy studies try to incorporate these into a global mean one has to have the real faith of a believer to think that these are accurate and precise representations of global climate".

EM Clearly does have the faith of a real believer - that is why discussing science with him is such a waste of time.

Mar 24, 2016 at 9:42 AM | Unregistered CommenterSpectator

" It seems a simple question.

What was the global mean temperature during the Holocene Optimum and how do 21st global mean temperatures compare?"

If it's a simple question, EM should start by explaining how "global mean temperature" is defined and what is the relation between that quantity and published data such as HadCRUT4.

Mar 24, 2016 at 10:00 AM | Registered CommenterMartin A

Could EM also explain how the Alaskan forest that is being revealed by melting ice got there, if temperatures now are higher than they have ever been?

“Woe, woe, and thrice woe!” was always Senna’s opening line. Maybe she should go online now, then we could have Senna Pods!

***crickets***

Perhaps EM is working on the simple premise that, if you tell someone every day that they will die tomorrow, you will eventually be right.

Mar 24, 2016 at 10:34 AM | Registered CommenterRadical Rodent

Paul,


However the key issue relating to your comment is that their reconstruction for the most part does not capture any variability on time scales less than three to four hundred years. I think this point is even acknowledged by the authors.

I think it is indeed acknowledged that the resolution of their proxies is a few hundred years. One might then assume that this would imply that their analysis would miss variability on scales less than this, but this isn't obvious. As I understand it, these proxies do not simply sample temperature (for example) at a specific time, but are more like some average of temperature over that timescale. Therefore it isn't clear that a large century-scale perturbation of similar magnitude to what we've experience in the last hundred years would be missed in their analysis. I'm certainly no expert, so am happy to be corrected if wrong, but it's not clear to me that your claim that it does not capture variability on time scales less than 3 to 4 hundred years is strictly correct

Mar 24, 2016 at 11:51 AM | Unregistered Commenter...and Then There's Physics

aTTP

I suggest working it out for yourself using, if you wish, an optical analogy where resolution is limited to, say, 350 units of length and bearing in mind that the signals are very noisy.

Mar 24, 2016 at 12:12 PM | Registered CommenterMartin A

ATTP, it's an interesting idea. An individual proxy, for example the Mg/Ca ratio of foraminifera has a record of the temperature and water composition at the time the organism lived. If a sample for measurement consists of forams collected over a depth interval of sediment corresponding to say three hundred years then the signal would record some form of time weighted average for this interval. If we then collect another sample from another sediment core over a similar interval of time but offset by 100 years, and so on and then we average these any signal is smeared out and reduced considerably in amplitude. This is before we begin any considerations as to wether or not the Mg/Ca ratio, d18O value, Uk37 or other proxy has sufficient resolution that an anomaly of say +0.5 degrees (similar to the average of the last centuries temperature rise) is anywhere other than amongst the noise.

Mar 24, 2016 at 12:24 PM | Unregistered CommenterPaul Dennis