I have previously posted comments about this paper, published in the Journal of Quaternary Science that provides evidence for the generally cooler period known as the Little Ice Age being a global phenomenon rather than being limited to the Northern Hemisphere:
Five centuries of climate change in Australia: the view from underground
Henry N. Pollack 1 *, Shaopeng Huang 1, Jason E. Smerdon 2
1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan, USA
2Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
Published Online: 27 Sep 2006
Keywords
palaeoclimate • borehole temperatures • Australia
Summary and conclusions
We have analysed 57 borehole temperature profiles from across Australia to reconstruct a ground surface temperature history for the past five centuries. The five-hundred-year reconstruction is characterised by a temperature increase of approximately 0.5 K, with most of the warming occurring in the 19th and 20th centuries. The 17th century was the coolest interval of the five-century reconstruction, perhaps representing a muted expression of the Little Ice Age widely observed in the Northern Hemisphere. Because most of the boreholes were logged prior to 1976, the observed subsurface temperatures do not show the strong warming experienced by Australia in the last two decades of the 20th century. Comparison of the geothermal reconstruction to the high-quality Australian annual SAT (Surface Air Temperature) time series in their period of overlap shows excellent agreement. The full geothermal reconstruction also shows excellent agreement with the low-frequency component of dendroclimatic reconstructions from Tasmania and NewZealand. The warming of Australia over the past five centuries has been about two-thirds that experienced by southern Africa, and only about half that experienced by the continents of the Northern Hemisphere in the same time interval.
This paper provides evidence for different regional responses to global climate change and illustrates the fact that the world has warmed since the end of the LIA, with half of the warming occurring in the 20th century.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Paul: Great choice! But how relevant is this reference in today’s debate on the more recent progress of warming?
“Because most of the boreholes were logged prior to 1976, the observed subsurface temperatures do not show the strong warming experienced by Australia in the last two decades of the 20th century”
Henry N Pollack’s book “Uncertain Science-Uncertain World” 2003 comes as highly recommended reading on “What’s Wrong With Still Waiting For Greenhouse?
The paper demonstrates the different regional responses to global climate change. It doesn’t tell us the causes of warming since the 17th century, but it does again demonstrate that the warming started before any significant man-made CO2 emissions. A point of argument is how much has man-made CO2 contributed to 19th and 20th century warming.
Unfortunately the industrial revolution was not global and hence could not affect a global anything, let alone a “global” climate.
Paul Biggs; ‘It doesn’t tell us the causes of warming since the 17th century…”
Alan Hunter: “Oh really Paul that seems to coincide with the start of the Industrial Revolution…”
Non sequitur.
Paul
Look at the current rate of change, in geological terms, it’s very quick, unlike the normal changes. This is reflected in the melting of the glaciers, they were slowly retreating, but not at the rate they are now. That rate has jumped sharply.
2+2=5
Not many glaciers in Oz. See the 18,000 year temp recon for NZ:
“evidence pointing to several millennia of MATs between 1.5 and 3.08C above those of the early 20th century. Given that there is considerable alarm about similar increases in MAT by the end of the current century, these results suggest that the early Holocene could profitably be used as an analogue to explore the consequences for biological change.”
SJT; the best heads from this country for tracking glaciers are in Tasmania where they have a good feel for the job, see
http://fcms.its.utas.edu.au/scieng/iasos/newsdetail.asp?lNewsEventId=1068
Apologies for using this link twice but it probably sums similar work in CSIRO
“The total cryospheric contribution to sea level rise between 1961 and 2003 was between 0.2 and 1.2 mm yr–1. Between 1993 and 2003 it increased to between 0.8 and 1.6 mm yr–1. The rate increased over the 1993 to 2003 period primarily due to increasing losses from mountain glaciers and ice caps, from increasing surface melt on the Greenland Ice Sheet and from faster flow of parts of the Greenland and Antarctic Ice Sheets. Model projections indicate that the ice sheets will continue to contribute to sea level rise. But the largest uncertainty in estimates of future sea level rise is from the potentially rapid dynamic response of the ice sheets to changes in conditions at their base. These are processes that are poorly understood, and are not incorporated into most ice sheet models”
Still one side of the coin only, from SJT and co.
They ignore the fact that many glaciers are again advancing. This, along with the main antarctic ice sheet, and the greenland ice sheet both thickening, is tieing more precipitation up in ice.
Which of these glaciers?
http://www.wgms.ch/mbb/mbb9/sum05.html
http://tamino.wordpress.com/2007/05/01/glaciers-al-gore-got-it-right/
Although maybe the anthropogenic greenhouse effect actually started 8000 years ago with our agrarian socialist ancestors (and Mottsa wants a credit for a 1927 tree stump – ha !)
http://courses.eas.ualberta.ca/eas457/Ruddiman2003.pdf
Yes, great choice of paper! There is absolutely nothing contentious about the Pollack paper. The various reconstructions show that temperatures started warming from before the industrial revolution. That has nothing to do with what caused the warming then, or now. It is a measure of climate change as represented by global temperature- as opposed to climate change represented by spatial fingerprints, which show the recent warming to be likely due to greenhouse gases. There have been a number of modelling studies that have attributed the past warming to natural forcing alone. No models were able to produce 20th C warming with natural forcing alone.
Pollack has presented this work in Australia for a number of years. He has never presented this result as some proof that AGW does not exist, because the paper simply does not show that. Then again, he did say that he was visited by IPCC goons one night and was scared to speak openly. We all get those visits periodically.
Actually, if you want to see borehole reconstructions in context you should check the Moberg nature paper.
http://www.nature.com/nature/journal/v433/n7026/fig_tab/nature03265_F2.html
If you believe the boreholes, then you would say that they validate the other Northern Hemisphere proxy reconstructions. And the naturally forced model runs. So I’m glad you have all jumped on the boreholes as reliable indicators of temperature variability.
If you are simply arguing that this natural variability in the past means that current warming is also natural- than that is a bizarre conclusion. I could say bushfires occurred naturally prior to human occupation of Australia therefore all current bushfires are not caused by humans- but I would rightfully be derided as a dunce.
The Moberg paper will also give you a chance to resume banging on about Mike Mann’s 98 NH temperature reconstruction- the reconstructions have moved on considerably, but I know don’t let this opportunity slip.
Thanks Space for bringing up the current warming vs past warmings.
So what happens when you get a current warming on top of one of your past warmings ??
The point about the Pollack is confirmation that the current warming, to the extent that valid temperature records might show a warming, is ENTIRELY WITHIN THE HISTORICAL RANGE OF VARIATION.
And no amount of spin will alter the fact that these past warmings have not been catastrophic. Indeed, they appear to have been unambiguously beneficial.
They have not been catastrophic for the very good reason that a warming involves mechanisms that return temperatures to basic equilibrium ranges.
We are told the sea ice will melt, but are not told that increased ocean surface will increase evaporation and, hence, increase cloud cover at the poles and return albedo to equilibrium ranges and produce a cyclical return of sea ice.
We are told that rising temperatures will produce more drought, but are not told that longer drought produces less ground cover which produces higher albedo and lower temperatures.
The Climate Crazies have been hanging out for a clear evidence of sustained warmer temperatures, And then it snows in buckets. Welcome to the real world, plodders.
errr – well they do seem to have coincided with extinction events – see PETM as one example – but why let facts intrude. Rant before you think.
Pity we’re not stopping at the current warming though eh?
“but are not told that longer drought produces less ground cover which produces higher albedo and lower temperatures.” – it does of late eh ? ROTFL
Why do we keep Ian here – “because we want to do him slowly”.
Ian- “They have not been catastrophic for the very good reason that a warming involves mechanisms that return temperatures to basic equilibrium ranges.”
Sounds like you’ve got a good understanding there- so what were the relevant climate forcings in the past, what was the self-adjusting mechanism involved and what is causing the current warming, and why will this episode self adjust?
Your point that the current warming is not statistically significant is marginal, and ignores model estimates of the variability in the absence of forcing. Your attribution is non-existent unless you can answer the above.
Space – let me predict a short circuit to the argument:
(1) You’ll get agreement that CO2 does something – but how much when you do the feedbacks so will end up at what is climate sensitivity
(2) A X amount of climate sensitivity what does that really mean for extreme events – droughts, floods, hurricanes
(3) Even if we agreed climate sensivity was 3C – they’d say it would all be a net benefit for agriculture and natural ecosystems
(4) What do we do with high end scenarios (a la Hansen) and ice sheet dynamics of which some papers did not make the IPCC cut. And known unknowns like biosphere feedbacks.
(5) Who agrees with Stern’s discount rate and the economics of acting or now or later.
(6) Is solar as a current warming hypothesis now deceased.
Biggsy could do well to lead us through a structured discussion. Lordy knows it might be revealing if you hang in and Ian keeps his turd-catapult at moderate levels. At the moment intelligent discourse is impossible so the blog has degenerated into simple derision, baiting and mocking with a bit of side science biffo to let them know we’re not frigging kidding.
I AM getting confused though Luke.
One minute Ian is posting that there is some certainty in the warming-evaporation-polarcloud-cooling feedback or the warming-drought-albedo-cooling feedback- such that it constrains climate to some ‘equilibrium’ temperature. I have to ask what this science is based on, some GCM modelling or close consideration of the physics or some broad guess?
But THEN, we are told that all the models are crap and that there is just no way we can attribute warming to CO2 or even figure out whether or not CO2 is a greenhouse gas.
There appear to be some Bats in the Belfry going on.
Sorry, guilty of baiting, can’t help it.
Models are useful diagnostic tools, but not good crystal balls.
CO2 ‘does something’ but doesn’t drive climate.
Climate sensitivity to CO2 is low. I have an as yet unpublished calculation based on IPCC AR4.
Hansen is an alramist who has completely lost the plot.
Stern concentrated on extreme high end computer models that bear no relation to reality.
Solar therory is alive and well, with a ‘low’ or ‘very low’ IPCC LOSU. Even Lockwood and Frohlich attribute much of the 20th century warming to solar. I’ll be doing a post on their paper sooner rather than later, and future solar activity.
Space – Ian’s like one of the scrub turkeys we have here. Diligently scraping all the bits he likes onto a big mound. Anything unpalatable is left. Turkeys are also rednecks (OK – I didn’t mean it Ian! – don’t hit me)
Pic for Biggsy: http://www.wettropics.gov.au/st/rainforest_explorer/Resources/Images/animals/birds/BrushTurkey.jpg
Well Biggsy – I tried – but you’ve just ticked and flicked. You could do something more innovative than Jen’s propagandista style you know.
Something useful would be to narrow the core issues of disagreement. Anyway la de dah.
OK guys back to derision, abuse and baiting.
Eighty five glaciers out of nearly seventy thousand, world wide?
What a sample, one wonders whether the usual cherry harvesting procedures were used.
Oh, and ONE NZ glacier quoted!! When 48 of the 50 recorded NZ glaciers are advancing and gaining in thickness… Oh. Cherry, Cherry, Cherry.
“CO2 ‘does something’ but doesn’t drive climate.”
Correct, to a certain extent. It is a driver of climate, and it does something. If the other drivers of climate are not changing, then CO2 is a likely culprit. Investigation has shown that in this particular case, it’s doing just that.
Well Sid make with the data/numbers then or be a big flake. And back up your assertion of cherry picking.
And BTW didn’t NIWA have something to say on NZ – you may like to remind us?
Don’t just drop and run Sid.
Paul, before you do your writeup on Lockwood and Frolich you might like to see what astrophysicist Nir Shaviv has to say about it:
http://motls.blogspot.com/2007/07/nir-shaviv-why-is-lockwood-and-frohlich.html
Today’s global warming has modified and distorted evidence of climate changes over the past 500 years. Global warming also causes diarrhea. There isn’t anything bad or any counter-proof that one can offer that global warming doesn’t affect.
Of course RC dismissed it at comment 194 – but of course they would.
Woody there is an exception – AGW has been unable to thaw the neo-con cranium frozen sold since the last ice age.
“L & F assume (like many others before) that there should be a one-to-one correspondence between the temperature variations and solar activity. However, there are two important effects which should be considered and which arise because of the climate’s heat capacity (predominantly the oceans). First, the response to short term variations in the radiative forcings are damped. This explains why the temperature variations in sync with the 11-year solar cycle are small (but they are present at the level which one expects from the observed cloud cover variations… about 0.1°C). Second, there is a lag between the response and the forcing.”
Hang on, one minute I’m being told there is close correlation between the sun and temperature, the next there is a lag? Which way do you sun guys want it?
Paul, another piece you might like to read reviewing Lockwood and Frolich:
http://icecap.us/images/uploads/Lockwood_and_Frolich_Review.pdf
Hi Carl – thanks – I’ve seen that and Nir Shaviv’s response. I’m busy doing my own response (amongst other things)which I will post on this blog, all in good time!
Instead of playing with yourselves and posting on blogs – get fair dinkum and get published in the serious literature. Or it’s simply lost to great void of blogspace as yet another whinge.
What’s fascinating to watch is the solar-o-philes turning themselves into pretzels trying to find a way out of this – so like the piece above we have a fatuous puff-piece of wandering prose that is a tiresome review that the Sun has had some historical impact on the Earth’s climate – as if that’s new?
And a theory of new solar that needs a string physicist to understand.
The IPCC are the ones with a ‘low’ LOSU for solar irradiance and ‘very low’ for other solar factors. Why isn’t the LOSU high?
Lockwood in the UK Daily Telegraph:
I am one of the authors of the Royal Society global warming paper that you say is simple and fundamentally flawed (Comment, July 15). Simple? The idea was to present a straightforward demonstration, without recourse to complex climate models. Flawed? None of the three academic referees the paper was subjected to found any flaws.
Climate change is by far the greatest threat to everyone’s standard of living. Unlike political parties, companies, media stars, works of art, consumer products and even social trends and national economies, a scientific reality is immune to spin.
(Prof) Mike Lockwood, Southampton University