From the University of Melbourne, I’m sure Julia and Flannery are thrilled at this paleo-reconstruction, and of course, the blame goes on Mann, er man. I find it interesting though that the lead author, Dr Joelle Gergis, thinks of her science work as a “guerrilla war”. From “Science Matters”:
Seems like just another angry Michael Mann clone to me.
At the outset of this project in 2010, they said:
Australian climate scientist Professor Chris Turney from the University of Exeter, UK says this meeting will allow us to place Australian records in a global context and gives us an opportunity to fully understand natural climate variability.
Yet in the current press release, the phrase “natural climate variability” is not mentioned. WUWT?
1,000 years of climate data confirms Australia’s warming
In the first study of its kind in Australasia, scientists have used 27 natural climate records to create the first large-scale temperature reconstruction for the region over the last 1000 years.
The study was led by researchers at the University of Melbourne and used a range of natural indicators including tree rings, corals and ice cores to study Australasian temperatures over the past millennium and compared them to climate model simulations.
Lead researcher, Dr Joelle Gergis from the University of Melbourne said the results show that there are no other warm periods in the last 1000 years that match the warming experienced in Australasia since 1950.
“Our study revealed that recent warming in a 1000 year context is highly unusual and cannot be explained by natural factors alone, suggesting a strong influence of human-caused climate change in the Australasian region,” she said.
The study published today in the Journal of Climate will form the Australasian region’s contribution to the 5th IPCC climate change assessment report chapter on past climate.
She said using what is known as ‘palaeoclimate’ or natural records, such as tree rings, corals and ice cores, are fundamental in evaluating regional and global climate variability over centuries before direct temperature records started in 1910.
Dr Gergis collated these natural records provided by decades of work by more than 30 researchers from Australia, New Zealand and around the world.
The reconstruction was developed using 27 natural climate records calculated in 3000 different ways to ensure that the results were robust.
She said reconstructions of regional temperature not only provide a climate picture of the past but also a significant platform to reduce uncertainties associated with future climate variability.
The study is part of a global collaboration, PAGES, Past Global Changes Regional 2K initiative, which is working to reconstruct the last 2000 years of climate across every region in the world in order to reduce uncertainties associated with future climate change projections.
Collaborators include the Climate Change Research Centre and the ARC Centre of Excellence for Climate System Science, University of New South Wales where the climate modeling was conducted.
###
The study was funded by the Australian Research Council, Federal Department of Climate Change and Energy Efficiency and Past Global Changes (PAGES).
Of course, in true Mannian form, the press release has no link to the actual paper. We aren’t supposed to look to closely at this things don’t you know?
And, searching the JoC journal index of the most recent issue shows no mention of this paper, so it must have just been accepted. Does anybody have a copy of this in part or full?
UPDATE: via Marc Hendrickx, thanks.
Briefing powerpoint presentation (PDF)
I find it interesting though that the lead author, Dr Joelle Gergis, thinks of her science work as a “guerrilla war”.
I’ll bet she hasn’t got the slightest notion of how to set up a good L-shaped ambush.
Aynsley Kellow says:
May 19, 2012 at 12:19 am
I have never known Graham Farquhar to indulge in ‘political’ science — in either direction. Tells it as he sees it. Old fashioned. But admirable.
_____________________________________
Very admirable. He is a true scientist. I do not want a scientist who is “political” I want a scientist who is unbiased and reports what he finds with out any twists.
@- davidmhoffer says:
“I call bs.
A considerable portion of their study is based on tree rings, possibly the most discredited proxy there is. Using tree growth as a proxy for temperature ignores natural factors in spades, including (but not limited to) –
rainfall
pestilence
disease ….
Tree rings as a proxy for temperature is a total load of animal excrement, male bovine to be specific. Once one sees those words in a “temperature reconstruction” the paper can safely be assumed to be bullarky.”
You are right that tree rings indicate responses to much more than temperature, water and nitrogen are major influences. But those are also influenced by the temperature…
Commercial growers know that the temperature history of a forest can be a good guide to its productivity and therefore its commercial profitability. They do not regard tree growth and temperature to be so distantly related that it is bullarky to use one to project the other.
The ENSO cyclic variations can be clearly derived from tree ring data from NZ. That may be a response to much more than just a temperature variation, but it is a clear response to a change in the climate, derivable from the tree ring data.
Historical proxy records like tree rings can never give you specific measurements of the actual temperature, rainfall or other factors at some past time that are comparable with present conditions in any direct way.
But what is often overlooked is that while they may fail to provide a precise number for past temperature, they DO provide an very accurate inter-annual comparison of past variation. It may not be possible to ascribe a numerical value to a year, but it is straightforward, and unambiguous to ascribe a ranking to a year based on its tree ring width because that WILL be explicitly recorded in the physical measurement.
Tree rings provide a record of the anomalies, the variation without providing an easily determinable value for the baseline around which these anomalies scatter. Dismissing that information because you dislike the message promoted by some researchers using the data is foolish. If you expect to refute research claims, then rejecting valid data on the anomalies because it fails to include the absolute temperature values, just a record of the integrated variation of the climate, seems counterproductive.
Unless you think all of the data is against you and supports those you oppose?
@- el gordo says:
“The university of NSW has been quick off the mark with a graph and would you believe it, they have found a southern hemisphere hockey stick. -[link]-
One with VERY spiky handle !
Obviously some of that much greater apparent variation in the past could be an artifact of uncertainty in ascribing an absolute value to proxy indicators.
But it could also be real to some extent. During the MWP temperatures reached levels – according to this research – comparable to today around 1320 and 1490. But within decades it appears to have experienced temperatures considerably colder than any recent temperatures in the last century.
This greater variability at higher temperatures is seen in most historical records. The LIA when it was ~1degC colder was much less variable from year to year, weather extremes were less.
It is possible that as the climate returns to conditions – for whatever anthropogenic or ‘natural cycle’ reason – similar to the MWP the same pattern of much more extreme shifts between hot/cold wet/dry will also return.
@- Aynsley Kellow
“I have never known Graham Farquhar to indulge in ‘political’ science — in either direction. Tells it as he sees it. Old fashioned. But admirable.”
This Graham Farquhar ? –
http://lwa.gov.au/projects/3231
Professor Farquhar is Professor of Environmental Biology at the Research School of Biological Sciences, ANU . He is a world leader in researching and modelling the interactions between plants and their environment. As a member of the Intergovernmental Panel on Climate Change, Professor Farquhar shared the 2008 Nobel Peace Prize with other IPCC scientists.
With research papers –
‘Hydroclimatic projections for the Murray-Darling Basin based on an ensemble derived from Intergovernmental Panel on Climate Change AR4 climate models’,
‘Effects of rising temperatures and [CO2] on the physiology of tropical forest trees’,
‘Evaporative demand: Does it increase with global warming?’,
‘On the attribution of changing pan evaporation’,
‘Tropical rainforest canopies and climate change’,
As one of these papers indicates he was also involved in revealing the role of global dimming in mitigating AGW as detected in changes in pan evaporation rates.
http://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_trans.shtml
‘The authors dismiss this concern. Karoly says that nothing is certain in science, but the results draw from a range of sites and using state-of-the-art statistical methods can be accepted with high confidence: ”It is reinforcing that barrage of scientific information that confirms that the climate is warming and increasing greenhouse gases are the major cause.” ‘
——————————————————————————————
I really hope that someone like Steve McIntyre gets a chance to run the ruler over their ‘state of the art’ statistical methods. Even to my uneducated eye, the weighting of the respective proxies, and of samples within the proxies, is murky at best – and we all know the problems with treemometers.
And, the use of ‘reinforcing the barrage of scientific information’ is interesting. What’s with all the war metaphors we have been hearing lately? Does he genuinely believe that anyone who disagrees with him is a barbarian at the gate? Coming soon: ‘this study pours boiling oil on the heads of those who ‘deny’ CAGW’.
Quoting from page 7 of the Briefing powerpoint presentation pdf ( http://www.smc.org.au/wp-content/uploads/2012/05/Aus2K_AusSMC_briefing_May_2012.pdf )
“- Issue of Northern Hemisphere-described tree ring ‘divergence’ (inability of tree rings to
track recent temperatures) was assessed and is not present in the data network”
Forgive me if I’m asking a stupid question, but what is so special about Australian trees that they do not suffer from the tree ring divergence problem? Or, do they mean that tree-ring data was not used in their temperature reconstruction? Or did they omit the divergent data only and replace it with modelling from non-divergent data or other sources? Or, …?
Can anyone enlighten me?
sunshinehours1 says:
May 17, 2012 at 6:54 pm
“Only records that were significantly (p<0.05) correlated with the
226 detrended instrumental target over the 1921–1990 period were selected for analysis."
—————————
It is pretty easy to demonstrate that this is poor science and generates a hockey stick.
Assume there was a medieval warm period and a present warm period. Then proxy records may be attributed to one of the following 4 compositions:
1. Proxy shows both warm periods.
2. Proxy shows only modern warm period but not MWP.
3. Proxy shows only MWP but not modern warm period.
4. Proxy shows none of both warm period.
Now assume (just to keep the thought experiment simple) that both warm periods would be about the same and show up in the same number of proxies.
By above selection citeria only 1+2 would be selected. Discarding 3 leads to an overrepresentation of the modern warm period relative to the MWP.
q.e.d.
It would help if the paper’s authors commented on the following statement by Blair Trewin of the BoM Australia. Is the passage relevant to the temperatures used for calibration of proxies? If so, was a correction made for the error?
> Up until 1994 CLIMAT mean temperatures for Australia used (Tx+Tn)/2. In
> 1994, apparently as part of a shift to generating CLIMAT messages
> automatically from what was then the new database (previously they were
> calculated on-station), a change was made to calculating as the mean of
> all available three-hourly observations (apparently without regard to
> data completeness, which made for some interesting results in a couple
> of months when one station wasn’t staffed overnight).
>
> What was supposed to happen (once we noticed this problem in 2003 or
> thereabouts) was that we were going to revert to (tx+Tn)/2, for
> historical consistency, and resend values from the 1994-2003 period. I
> have, however, discovered that the reversion never happened.
>
> In a 2004 paper I found that using the mean of all three-hourly
> observations rather than (Tx+Tn)/2 produced a bias of approximately
> -0.15 C in mean temperatures averaged over Australia (at individual
> stations the bias is quite station-specific, being a function of the
> position of stations (and local sunrise/sunset times) within their time
> zone.
Geoff Sherrington says:
May 21, 2012 at 3:13 am
It would help if the paper’s authors commented on the following statement by Blair Trewin of the BoM Australia. Is the passage relevant to the temperatures used for calibration of proxies? If so, was a correction made for the error?…..
________________________________
Geoff, You might want to check out an article on Joanne nova’s website on the subject:
Australian temperature records shoddy, inaccurate, unreliable. Surprise! http://joannenova.com.au/2012/03/australian-temperature-records-shoddy-inaccurate-unreliable-surprise/
Thanks, Gail. I helped write that article for Jo. Geoff.