A Global Temperature History of the Past Two Millennia [PEER-REVIEWED!!! WITH SOURCE!!!]

Energy and Environment 18: 1049-1058. ^ | November 2007 | Loehle, C., and J.H. McCulloch

[M. Dodge Thomas]

So, CO2 drives the Climate. So you are putting your faith in a playstation GHG models? Of course the GHG models, for the past 30 years, have never been peer-reviewed or validated! CO2 induced global warming, rename to CO2 climate change, rename climate change is a scam. I wonder how the GHG models will play out against the DATA QUALITY ACT.

You can stand there and stamp your foot as long as you want, but that does not change the fact that the physics and chemistry of "greenhouse effects" are well understood, and that if you want to argue that AGW cannot be happening, you have to come up with some way to explain why greenhouse processes are not operating to increase global temperatures.

This this is exactly what skeptics of AGW have been unable to do - it's not enough just to argue that some other process is operating to retard or accelerate the observed warming, you need to be be to explain why the "greenhouse effects" resulting from the steady increase in AGGs have not done so irrespective of whatever other "natural" background processes also affect climate.

[stormer]

Before anyone gets too excited, they probably should read this:

http://pubs.acs.org/subscribe/journals/esthag-w/2005/aug/policy/pt_skeptics.html

“...When von Storch, who was then the journal’s editor, read Mann’s critique, he recalls that he realized his journal should never have accepted the study. “If it would have been properly reviewed, it would have been rejected on the basis of methodological flaws,” von Storch admits...”

[cogitator]

Thus whatever value your prior observation had, which probably isn't much, it would seem detrimental rather then helpful to the anthropological doctrine of the current trend.

Not really. "Polar amplification", particularly in the Arctic, is a common observation in anthropogenic CO2-driven climate models.

[cogitator]

What data type is the “solar activity” data shown in the figure? Possibilities are sunspot number, solar cycle length, estimated solar irradiance, or something else.

[JPJones]

This this is exactly what skeptics of AGW have been unable to do - it's not enough just to argue that some other process is operating to retard or accelerate the observed warming, you need to be be to explain why the "greenhouse effects" resulting from the steady increase in AGGs have not done so irrespective of whatever other "natural" background processes also affect climate.

Or one could argue that while the "greenhouse effects" are acknowledged, their effects on global temperature are so minimal in comparison to say, sunspots, that any political movement to abate emissions of Co2, would not only be futile in effecting global temperature, but catastrophic to economies and quality of life.

[savedbygrace]

A bit more than a henway.

What’s a henway? Oh, about three-and-a-half pounds.

[M. Dodge Thomas]

Or one could argue that while the "greenhouse effects" are acknowledged, their effects on global temperature are so minimal in comparison to say, sunspots, that any political movement to abate emissions of Co2, would not only be futile in effecting global temperature, but catastrophic to economies and quality of life.

Well, that's one position in a group of reasonable arguments, and IMO it's where the debate is headed - meanwhile the people attempting to explain away the portion of current GW attributable to AGW have sort of missed the boat in this reguard.

[AndyTheBear]

Not really. "Polar amplification", particularly in the Arctic, is a common observation in anthropogenic CO2-driven climate models.

And I'm sure one could also construct a "polar amplification" model without the anthropogenic component. Why heck, if the Medieval Warm Period was indeed hemispherical, then Earth itself may already have served as such a "model".

Its funny, science is supposed to be about looking for evidence to falsify a theory. But in pop "climate science" it seems to be about looking for a theory to falsify the evidence.

[cogitator]

And I'm sure one could also construct a "polar amplification" model without the anthropogenic component. Why heck, if the Medieval Warm Period was indeed hemispherical, then Earth itself may already have served as such a "model".

Frankly, I don't know. So I will Google "polar amplification":

Polar Amplification

And yes, you're right. Any global forcing (greenhouse gases, increase in solar activity) will usually produce polar amplification in climate models. I'm going to post this and then go back and see what I said before again.

[cogitator]

Here's a reprise. I said:

Why is this important? Because previous work on the Medieval Warm Period has indicated that it was primarily a Northern Hemisphere event strongest in North America and Europe. (The LIA was more global.) So seeing it (a warming event occurring over about 400 years) in this data is not surprising.

And you (AndytheBear) replied: Is not the current warming trend also more pronounced in the Northern Hemisphere?

The reason that I stated the initial observation is that there appears to be an over-representation of the Northern Hemisphere, specifically North America and Europe, in the Loehle data sets. So, if this area is over-represented when examining the peak temperatures of the Medieval Warm Period (even though there is data from other areas) the signal "strength" will be stronger because there are more datasets from the region where the temperatures were highest.

So comparing the peak temperatures of the MWP based on this paper to current GLOBAL temperatures (which is what is done) may be a mismatch leading to erroneous interpretation of the significance of the observations. ClimateAudit had a figure in the discussion that showed all of the datasets, but they weren't labeled. What would be interesting would be to see individual plots of each dataset to see if there are comparably strong temperature signals in the data from regions other than North America and Europe.

Which is to say that the current global temperature instrumental record (land-ocean) should not have more data from North America and Europe, even if the warming is strongest there. If Loehle's datasets were roughly equally distributed around the world, then the comparison of MWP to current global temperatures would be more valid.

Figure:
Red is NH, blue is SH.

Acquired from: A tale of two hemispheres

[Dan Evans]

How can we put these presumptions to the test? Could not the carbon have been high for some other reason?

Yes. The width of tree rings vary for many reasons, that's why tree rings are not a good proxy for global temperature. However the ratio of carbon-14 to carbon-12 in those tree rings tells you the level of cosmic rays hitting the atmosphere.

The way to test this? Compare these carbon-14 measurements with known fluctuations in solar activity via sunspot counts.

[I got the rope]

From the paper:

Arctic surface air temperature compared with total solar irradiance as measured by sun spot cycle amplitude, sunspot cycle length, solar equatorial rotation rate, fraction of penumbral spots, and decay rate of the 11-year sunspot cycle. Solar irradiance correlates well with Arctic temperature, while hydrocarbon use does not correlate.

[I got the rope]

http://scienceandpublicpolicy.org/images/stories/papers/other/Robinson_Soon.pdf

[Dan Evans]

Now that the temperature record is being politically rehabilitated, what do you think of the “Hockey Stick”? Do you think it was simply bad science or was there a more insidious motive?

[Dan Evans]

What is significant? The warming rate. Reading Figure 1 roughly, the temperature increase is about 0.6 C in 400 years (I put the peak at about 900 AD). The warming rate in the 20th century was 0.6 C in 100 years

Not unprecedented though. The 100 years before the Little Ice Age had a temperature plunge about the same.

[justa-hairyape]

What data type is the “solar activity” data shown in the figure? Possibilities are sunspot number, solar cycle length, estimated solar irradiance, or something else.

Solar Activity generally refers to all three. Increased sunspot activity defines active cycles which tend to have shorter lengths and tend to emit more solar radiance. Solar Activity in laymen terms is Solar Weather. Once that weather escapes the sun, NASA refers to it as Space Weather and surprisingly they watch it like a hawk. After gravitational field strength, it is probably the most important metric in our solar system.

[AndyTheBear]

So comparing the peak temperatures of the MWP based on this paper to current GLOBAL temperatures (which is what is done) may be a mismatch leading to erroneous interpretation of the significance of the observations.

Well, heck I have to agree with you, somewhat, on that point.

As a kind of by standing layman (albeit one with an opinion) I am impressed there may be many ways folks have chosen to aggregate global temperature. But if some statistic of "global temperature" is to have the significance you desire, it best be done from a very even handed way indeed. It should cover the whole Earth evenly, and average the entire cycle of seasons (yearly, or preferably longer for other known cycles such as La Nina etc).

Just makes sense to me that the only data passing your test of significance would be comparing current satellite data with the satellite data from the MWP.

[RogerFGay]

"McCain’s co-sponsorship with Sen. Joe Lieberman (I-Conn.) of legislation to prevent global warming, ..."

http://thehill.com/dick-morris/mccain-may-win-romney-cant-2008-01-30.html

[cogitator]

total solar irradiance as measured by sun spot cycle amplitude, sunspot cycle length, solar equatorial rotation rate, fraction of penumbral spots, and decay rate of the 11-year sunspot cycle.

I actually found the Robinson-Soon paper and read the caption (reproduced above). There's no description of this five-parameter index other than that, and two references which may talk about it. When various measures of solar activity are compared individually to global temperature (which has been similar in direction but smaller in magnitude than Arctic warming), they show a distinct separation starting in the 1970s. Here's an example.

This is from: The Role of the Sun in 20th Century Climate Change

All of the solar activity parameters shown on this Web page demonstrate a plateau or decrease starting roughly in the 1970s while temperature is increasing. This is not as clear in the figure in post 70 from the linked paper. Plus the figure in post 70 shows a much bigger decline (~2.5 W/m2) from the 1940s to the 1980s than in the figure above, which has a roughly constant value for that period.

Obviously different groups are performing independent analyses, but some of the data they're analyzing is the same! I'd also like to know why the estimated solar irradiance is roughly 1366 W/m2 in the figure above and about 1372 W/m2 in the figure in post 70.

So there's some discrepancies here. And you could also take a look at point #6 in my profile for some background on the first author of the Robinson-Soon paper. Willie Soon can be Googled.

[cogitator]

Now that the temperature record is being politically rehabilitated

To which temperature record are you referring, and what is the rehabilitation process?

what do you think of the “Hockey Stick”? Do you think it was simply bad science or was there a more insidious motive?

Here's what I think of the Hockey Stick:

The full page describes the "author" of each of the illustrated reconstruction curves (and has bigger images):

2000 Year Temperature Comparison.png

So what do you think my answer to your second question would be?