Well, after numerous attempts to kill off the Warming period circa 1000AD, it has bounced back again in New Zealand. But wait a minute, wasn't it a NH phenomenon only?

The puzzle continues to come together nicely. Another thread tugged in the fabric of dominant AGW.

"Lorrey, A., Williams, P., Salinger, J., Martin, T., Palmer, J., Fowler, A., Zhao, J.-X. and Neil, H. 2008. Speleothem stable isotope records interpreted within a multi-proxy framework and implications for New Zealand palaeoclimate reconstruction. Quaternary International 187: 52-75."

http://wattsupwiththat.com/2009/01/03/4000-year-o18-histories-of-new-zealands-north-and-south-islands/#more-4791

"Not wanting to acknowledge that the earth was likely as warm as, or even warmer than, it is currently a thousand or so years ago (when the atmosphere’s CO2 concentration was much lower than it is today), the world’s climate alarmists have been loath to admit there was an MWP or Medieval Warm Period anywhere other than in countries surrounding the North Atlantic Ocean. Consequently, the seven independent speleothem records that produced the results reported by Lorrey et al. are of great importance to the ongoing global warming debate, as they greatly advance the thesis that the MWP was indeed a global phenomenon, and that there is thus nothing unusual, unnatural or unprecedented about earth’s current warmth, and that it therefore need not be attributed to the historical increase in the air’s CO2 content."

Now come on WS, Stephen spent such a long time the other day telling us how you couldn't imply anything from isotopic analysis and here you are telling us that it completely rewrites history

Ulric:

Now come on WS, Stephen spent such a long time the other day telling us how you couldn't imply anything from isotopic analysis and here you are telling us that it completely rewrites history

I don't see the connection between something Stephen said (that I ain't even read!) and this new study and myself? To You Too!

Abstract:

A primary step in the interpretation of speleothem stable isotope records (¹⁸O/¹⁶O and ¹³C/¹²C) is to conduct a comparison with other local palaeoclimate proxies. Here, two new master speleothem δ¹⁸O and δ¹³C records (one from eastern North Island, and the other from western/southern South Island, New Zealand) are evaluated against independent precipitation and temperature proxy information to assess their palaeoclimate reconstruction potential. This comparison also resulted in a serendipitous opportunity to reconstruct past circulation using climate regime classification [Lorrey, A.M., Fowler, A.M., Salinger, J., 2007a. Regional climate regime classification as a qualitative tool for interpreting multi-proxy palaeoclimate data spatial patterns: a New Zealand case study. Palaeo-3, in press], specifically because these two regional climate districts are hyper-sensitive to westerly circulation changes, and in many cases, exhibit contrasting climate character in response to circulation anomalies.

For both the western South Island and the eastern North Island master speleothem δ¹³C records, variations tracked changes in relative regional precipitation. The δ¹⁸O master speleothem record for both regions varied with temperature change. Both records contain strong regional climate signals that suggest they have good value for palaeoclimate reconstruction. The ensuing attempt at a multi-proxy reconstruction of regional climate regimes from the compiled proxies indicates past circulation in the New Zealand sector has varied considerably during the past four millennia. Centennial-scale circulation changes for the past 4000 years are evident, and are analogous to modern Blocking, Zonal and Trough regime types [Kidson J. W., 2000. An analysis of New Zealand synoptic types and their use in defining weather regimes. International Journal of Climatology 20, 299–316] that characterise changes in present-day (prevailing) westerly circulation. This palaeoclimate reconstruction indicates modern regional climate regime classification can be extended at least as far back as the temporal coverage of the records presented here, and it can likely be improved on with better dating control and the addition of new records with higher resolution. It is also anticipated that future work will expand to include more proxy data from across New Zealand to improve the clarity of past climate regime occurrence for the Late Holocene.

Doesn't give the impression to me that there's likely to be anything new in the paper to "greatly advance the thesis that the MWP was a global phenomenon"  Anyone able to access a copy to check?

(I never trust anything I read in the media )

Waterspout:

I don't see the connection ...

The conversation was about the source of the additional CO2 in the atmosphere and I quoted a paper which shows by isotopic analysis that the additional CO2 is of fossil origin. Don't get me wrong, I think isotopic analysis works and provides valid results but it seemed to me there was an inconsistency that needed to be cleared up.

I think Ulric is suggesting that you and Stephen are in cohorts WS! You should read the thread though, it's called 'The global energy balance' and was started by Ulric, and went predictably off topic. In fact, so off topic it contains a three page argument between me and Stephen where he claimed that even if anthropogenic CO2 makes up only 1% of all CO2 input, eventually 50% of the CO2 in the atmosphere will be anthropogenic, rendering isotopic analysis useless. I of course knew this was wrong. Anyway the general consensus is that isotopic analysis is reliable enough, unless you're Stephen Wilde. He did promise to expand upon his ideas why soon though.

So, isotopic analysis shows that New Zealand was warm eh? Interesting, I'll have to have a good read of that post and see what I think.  

Essan:

Abstract:

A primary step in the interpretation of speleothem stable isotope records (¹⁸O/¹⁶O and ¹³C/¹²C) is to conduct a comparison with other local palaeoclimate proxies. Here, two new master speleothem δ¹⁸O and δ¹³C records (one from eastern North Island, and the other from western/southern South Island, New Zealand) are evaluated against independent precipitation and temperature proxy information to assess their palaeoclimate reconstruction potential. This comparison also resulted in a serendipitous opportunity to reconstruct past circulation using climate regime classification [Lorrey, A.M., Fowler, A.M., Salinger, J., 2007a. Regional climate regime classification as a qualitative tool for interpreting multi-proxy palaeoclimate data spatial patterns: a New Zealand case study. Palaeo-3, in press], specifically because these two regional climate districts are hyper-sensitive to westerly circulation changes, and in many cases, exhibit contrasting climate character in response to circulation anomalies.

For both the western South Island and the eastern North Island master speleothem δ¹³C records, variations tracked changes in relative regional precipitation. The δ¹⁸O master speleothem record for both regions varied with temperature change. Both records contain strong regional climate signals that suggest they have good value for palaeoclimate reconstruction. The ensuing attempt at a multi-proxy reconstruction of regional climate regimes from the compiled proxies indicates past circulation in the New Zealand sector has varied considerably during the past four millennia. Centennial-scale circulation changes for the past 4000 years are evident, and are analogous to modern Blocking, Zonal and Trough regime types [Kidson J. W., 2000. An analysis of New Zealand synoptic types and their use in defining weather regimes. International Journal of Climatology 20, 299–316] that characterise changes in present-day (prevailing) westerly circulation. This palaeoclimate reconstruction indicates modern regional climate regime classification can be extended at least as far back as the temporal coverage of the records presented here, and it can likely be improved on with better dating control and the addition of new records with higher resolution. It is also anticipated that future work will expand to include more proxy data from across New Zealand to improve the clarity of past climate regime occurrence for the Late Holocene.

 

Doesn't give the impression to me that there's likely to be anything new in the paper to "greatly advance the thesis that the MWP was a global phenomenon"  Anyone able to access a copy to check?

 

(I never trust anything I read in the media )

...or CO2science....

Devonian:

...or CO2science....

Oh yes, thats the Idso family lobbying business which gets direct funding from Exxon isn't it?

Yes, I can access the full paper, most paleoclimate reconstructions do have a warm period in global reconstructions around this time but in all cases (except 1) the warm period is significantly cooler than today, this paper does not change that WUWT have got it wrong as usual.

but in all cases the warm period is significantly cooler than today

Thanks for touching on the divergence problem there. What happens if you look at a lot of "proxies" is that they do not represent the late 20th century warming period. So this comments seems to be comparing apples and oranges, by comparing the thermometer-measured temperature record with a derived temperature from the proxies. If you use the proxies in question up to the current period without reference to the temperature record, you find a warmer MWP.

What this suggests is either one of two things:

1) The current period isn't as warm as thermometers suggest (UHI where sensors are located, site placement, biased adjustments and algorithms)

2) The proxies are not linearly linked to temperature but instead display a quadratic response whereby higher temperatures are not represented by increased growth. So shouldn't be used as proxies without extraordinary caveats about their response - they won't show past warm periods correctly.

If however your quote does not refer to a comparison of apples and oranges I'd like to know how the comparison of current temperatures and proxy-derived ones is done.

WUWT is a very good site for the science.

It suggests a third thing also. It suggests that you don't read any treatment of the subject that doesn't appear on websites published by hair on fire climate troofers. If you reviewed the available material, you would find articles like this:

On the ‘Divergence Problem’ in Northern Forests: A review of the tree-ring evidence and possible causes
Rosanne D'Arrigo a,⁎, Rob Wilson a,b, Beate Liepert a, Paolo Cherubini a,c

Abstract
An anomalous reduction in forest growth indices and temperature sensitivity has been detected in tree-ring width and density records from many circumpolar northern latitude sites since around the middle 20th century. This phenomenon, also known as the “divergence problem”, is expressed as an offset between warmer instrumental temperatures and their underestimation in reconstruction models based on tree rings. The divergence problem has potentially significant implications for large-scale patterns of forest growth, the development of paleoclimatic reconstructions based on tree-ring records from northern forests, and the global carbon cycle. Herein we review the current literature published on the divergence problem to date, and assess its possible causes and implications. The causes, however, are not well understood and are difficult to test due to the existence of a number of covarying environmental factors that may potentially impact recent tree growth. These possible causes include temperature-induced drought stress, nonlinear thresholds or time-dependent responses to recent warming, delayed snowmelt and related changes in seasonality, and differential growth/climate relationships inferred for maximum, minimum and mean temperatures. Another possible cause of the divergence described briefly herein is ‘global dimming’, a phenomenon that has appeared, in recent decades, to decrease the amount of solar radiation available for photosynthesis and plant growth on a large scale. It is theorized that the dimming phenomenon should have a relatively greater impact on tree growth at higher northern latitudes, consistent with what has been observed from the tree-ring record. Additional potential causes include “end effects” and other methodological issues that can emerge in standardization and chronology development, and biases in instrumental target data and its modeling. Although limited evidence suggests that the divergence may be anthropogenic in nature and restricted to the recent decades of the 20th century, more research is needed to confirm these observations.

http://www.st-andrews.ac.uk/~rjsw/all%20pdfs/D'Arrigoetal2008.pdf

Ulric:

It suggests a third thing also. It suggests that you don't read any treatment of the subject that doesn't appear on websites published by hair on fire climate troofers. If you reviewed the available material, you would find articles like this:

On the ‘Divergence Problem’ in Northern Forests: A review of the tree-ring evidence and possible causes
Rosanne D'Arrigo a,⁎, Rob Wilson a,b, Beate Liepert a, Paolo Cherubini a,c

Abstract
An anomalous reduction in forest growth indices and temperature sensitivity has been detected in tree-ring width and density records from many circumpolar northern latitude sites since around the middle 20th century. This phenomenon, also known as the “divergence problem”, is expressed as an offset between warmer instrumental temperatures and their underestimation in reconstruction models based on tree rings. The divergence problem has potentially significant implications for large-scale patterns of forest growth, the development of paleoclimatic reconstructions based on tree-ring records from northern forests, and the global carbon cycle. Herein we review the current literature published on the divergence problem to date, and assess its possible causes and implications. The causes, however, are not well understood and are difficult to test due to the existence of a number of covarying environmental factors that may potentially impact recent tree growth. These possible causes include temperature-induced drought stress, nonlinear thresholds or time-dependent responses to recent warming, delayed snowmelt and related changes in seasonality, and differential growth/climate relationships inferred for maximum, minimum and mean temperatures. Another possible cause of the divergence described briefly herein is ‘global dimming’, a phenomenon that has appeared, in recent decades, to decrease the amount of solar radiation available for photosynthesis and plant growth on a large scale. It is theorized that the dimming phenomenon should have a relatively greater impact on tree growth at higher northern latitudes, consistent with what has been observed from the tree-ring record. Additional potential causes include “end effects” and other methodological issues that can emerge in standardization and chronology development, and biases in instrumental target data and its modeling. Although limited evidence suggests that the divergence may be anthropogenic in nature and restricted to the recent decades of the 20th century, more research is needed to confirm these observations.

http://www.st-andrews.ac.uk/~rjsw/all%20pdfs/D'Arrigoetal2008.pdf

I'm aware of that paper and the abstract simply puts in longer words what I spelt out earlier in this thread (bold and underlined). It also has some wild speculation that I wouldn't call science (left as is).

Pingo:

It also has some wild speculation that I wouldn't call science (left as is).

Which presumably is why you couldn't point us at this rather even handed discussion of the subject. You see it contains references to all of the important work written on this subject by real scientists and then discusses the synthesis of those ideas calmly and rationally without inflicting a social policy agenda on the reader. I can go and search out the papers, read the references and make my own mind up. I like this piece a lot. Especially where it says, "limited evidence suggests that the divergence may be anthropogenic in nature and restricted to the recent decades of the 20th century". You pointed that out so clearly in your previous post that I thought it was worth repeating

Ulric:

Pingo:

It also has some wild speculation that I wouldn't call science (left as is).

Which presumably is why you couldn't point us at this rather even handed discussion of the subject. You see it contains references to all of the important work written on this subject by real scientists and then discusses the synthesis of those ideas calmly and rationally without inflicting a social policy agenda on the reader. I can go and search out the papers, read the references and make my own mind up. I like this piece a lot. Especially where it says, "limited evidence suggests that the divergence may be anthropogenic in nature and restricted to the recent decades of the 20th century". You pointed that out so clearly in your previous post that I thought it was worth repeating

That was the most shambolic comment in the abstract. It doesn't surprise me you've picked it out.

Pingo:

Ulric:

Pingo:

It also has some wild speculation that I wouldn't call science (left as is).

Which presumably is why you couldn't point us at this rather even handed discussion of the subject. You see it contains references to all of the important work written on this subject by real scientists and then discusses the synthesis of those ideas calmly and rationally without inflicting a social policy agenda on the reader. I can go and search out the papers, read the references and make my own mind up. I like this piece a lot. Especially where it says, "limited evidence suggests that the divergence may be anthropogenic in nature and restricted to the recent decades of the 20th century". You pointed that out so clearly in your previous post that I thought it was worth repeating

That was the most shambolic comment in the abstract. It doesn't surprise me you've picked it out.

Why is it shambolic?