And now brace yourself for an ice age

DPinBucks

No it hasn't. The original MBH98/99 papers showed a clear hockey stick effect pointing to highly anomalous recent warming.

This was contested in later papers by McIntyre, McKitrick and others, whose results (the Reconstructed Graph) tended to show a dip over the past millennium, followed again by a recent rise. This was interpreted as indicating that the hockey stick rise is not anomalous.

The net result of all the controversy is that two highly authoritative studies, by the American National Research Council and National Academy of Sciences, supported the original MBH findings. On the other hand, another study by the Committee on Energy and Commerce (the Wegman report) supported the reconstruction. However, whilst all other relevant papers were peer-reviewed, the Wegman was not, and there are severe doubts. And whatever interpretation of the MBH data you use, they unequivocally show that the last few decades have been the warmest on record.

I can find no mention of dendrochronology being used to interpret the data of the past 150 years. From then, as I have said, meteorological data has been used to provide instrumental measurements. Before then, proxy measurements were taken, that is secondary inferences made as a result of other observations, such as tree rings, reports of harvest yields, contemporary if subjective writings, etc.

The seemingly-anomalous recent tree ring data were not part of the MBH paper, nor its reconstruction. Unfortunately, they are in the not-uncommon situation of seeming to both rebut and support recent climate change. Until the matter clarifies, it is safest to exclude them from the debate.

DPinBucks

It’s a tricky question. Firstly, the issue is not global: it is more pronounced in the northern hemisphere and at higher latitudes, so global inferences are invalid.

Secondly, it’s quite possibly a simple matter of calibration. It’s only in the past 150 years that we have had any real quantitative instrument measurements to compare with tree ring growth, and so we don’t know how accurate our inferences from earlier periods have been.

Thirdly, our understanding of tree growth itself is very imprecise: it’s not easy to observe the ups and downs of ring deposition against climate in species with lifetimes measured in decades. What is clear is that CO2 is only one factor in determining growth patterns. Others are temperature, seasonal variation, drought, etc. It is quite possible that too much CO2 can overstress the tree to the extent that its development is disrupted. Living things are generally in balance with their environment; change the environment and the response is unpredictable. A comparison is with mammals and oxygen: a too-rich O2 environment over too long a period is very damaging.

As I say, it boils down to not proven, either way.

GasDad

However isn't the tree ring data the only data used for the early centuries of the 'Hockey Stick'. ie it was the tree ring data that was used to demonstrate that the Medieval Warm Period was not a global phenomenon.

If the tree ring data is really that unreliable, where does that leave the 'Hockey Stick?'

Lee

If you can't be civil with your posts then I suggest you don't post in this section.

richardb70

Sorry Jenn, my apologies, I let my 3  hour snow commute to work get the better of me.

What I *should* have said in a much more polite manner is:

a) there's a much better thread in this same section with lots of interesting viewpoints and links.
b) creating new threads focussing on things like "tree rings" is slightly bizarre. Do you think the scientists have missed anything you and I have to offer?

Ultimately we're armchair scientists here. Yes, I dispassionately looked at the "digestible" information I've seen and I believe that if the scientists who are experts in this area say that there's a problem, and we're causing it, then there's a problem, and we're causing it.

I don't have the time or knowledge to sift through all the masses of raw data that's been collected. So I have to trust the authority figures I've selected on this - namely the scientific experts in the field. Not the Daily Mail. Not Jeremy Clarkson. Not the politicians.

As I've mentioned on the main thread, I have climate deniers in the family and it's just plain exasperating talking to them. They don't bother to look beyond their energy company-sponsored websites, and they think it's all some giant conspiracy between scientists and politicians to raise taxes and so on. Is it easier to think that, than think that humans might just be affecting their own environment adversely? Shrug.

Jenn

To be fair the thread was originally about the mail article about some IPCC scientists now saying we're at the start of a 30 years ice age due to multi decadal occillations.

The problem with man made global warming "science" is that it's all speculation and "predictions" and certainly not a proven fact.
First you're told the antartic ice will disappear in 30 years, then it's at its highest level since records began, then we use tree rings to draw a graph for the last 1000 years but when it suddenly goes down it's just that tree rings aren't reliable anymore, and other things I can't remember as I type it now.
It's nearly as much a fact as the existence of a God.

The thing is the earth isn't stuck in an equilibrium and the climate we know only because that's the only one we can "remember" isn't necessarily the right one if there is one.
At the time of the vickings which isn't that long ago, Greenland wasn't covered with ice, it was lush and green (hence the name) and the Vickings used the land for food.
Species have died out and others have started throughout the ages because of the earth going through hot and cold periods, and we certainly aren't at the hottest now.

Anyway I'm rambling on now.

deckingman

I'm curious to know which of the "scientific experts" you choose to trust. Obviously not the guy who said this.

“The fact that the developed world went into hysterics over changes in global mean temperature anomaly of a few tenths of a degree will astound future generations. Such hysteria simply represents the scientific illiteracy of much of the public, their susceptibility to substitution of
repetition for truth, and the exploitation of these weaknesses by politicians, environmental
promoters, and, after 20 years of media drum-beating, many others as well. Climate is always​changing.”

That was from Dr. Richard Lindzen, Alfred P. Sloan Professor of Meteorology at Massachusetts Institute of Technology, in Boston - one of the most credible climate researchers in the academic world and a tenured professor who need not fear for his funding or career.

So, if not him or anyone who holds similar beliefs, who then?

NikB

There is a growing voice in the scientific community that does not believe in agw such as Dr Lindzen (though information in his recent paper may about to be challenged). We so called denialists are often accused of just being Daily Mail readers or listen to the gospel according to Clarkson. The truth is that we don't just believe information because we're told to. If incontrovertible evidence of agw does prove the theory beyond all reasonable doubt then I and no doubt others will accept it. Until then I will continue to live my life normally and sensibly.

DPinBucks

Fair enough. Where does the heat go?

GasDad

That assumes there is more heat !

If other forces are at work (that sounds sinister lol) , that are affecting the climate on a large scale, any of the theoretical heat associated with MMGW, may be totally offset and more by increases in cloud cover, increased plant growth etc etc.