Interesting global cooling story.

[Aaron Kennedy]

Dennis,

Excellent question. Any reasonable graph of temperature over time includes a uncertainty range. Here's quick example: http://stephenschneider.stanford.edu/Graphics/tn_VariationsSurfaceTemp.jpg

If you only have one measure for determining temperature, then of course I'd be very suspect. We gain credibility when we see the same trends in a variety of datasets such as ice cores, fossil records, tree rings, etc.

http://en.wikipedia.org/wiki/Paleoclimatology

 

[Dennis Sherrod]

Thanks for the charts Aaron.
It may be me trying to read them, but I see no dramatic changes % wise from what we are seeing now. Example at approximately years 1250-1260 there appears to be a temperature variance upward of approximately .50 - .90 F. and then the temperatures seems to stabilize according to the charts.
A temperature change of + or - 1/2 - almost 1 degree appears to have been the norm for about a 1000 years according to the charts. The up-slide past the median 0.0 only occurs in the past 60 - 75 years.
What I do see as interesting in the bottom chart is, that the data referred to is coming from various sources "other" than thermometers.
Yet, thermometers are primarily referred to in data as being used in the past 100- 120 years and as that method is used, the others used are not shown as predominantly.
Now, my thought also includes.... As science and technology is advancing, the temperature recording devices are more accurate thus contributing to a higher temperature reading. Does this temperature rise not coincide with the time frame of advancing technology? If this is so, does this not give rise as to the previous methodology to measure being flawed as the science was not as advanced? Or is all of that taken into consideration as the latest data is published or has all of the other aging and measuring been re-evaluated and adjusted for this advance in science and accuracy?
I know, this may seem to be strange questions for some, but the topic was here.

 

[Aaron Kennedy]

It may be me trying to read them

Actually, I just grabbed the first graph I saw with temperature and uncertainty on google images search. Depending on how you take the mean and define the anomaly, you'll see everything shifted up or down above the mean. Depending on the study, you can either come up with present times being warmer than the medieval warm period or colder. Other issues include were the temperatures representative of the globe or regional variations?

Now, my thought also includes.... As science and technology is advancing, the temperature recording devices are more accurate thus contributing to a higher temperature reading. Does this temperature rise not coincide with the time frame of advancing technology? If this is so, does this not give rise as to the previous methodology to measure being flawed as the science was not as advanced? Or is all of that taken into consideration as the latest data is published or has all of the other aging and measuring been re-evaluated and adjusted for this advance in science and accuracy?

Yep... coming up with temperature averages and paleoclimatological reconstructions are two different processes. If they don't match at the present time, then uh oh! I believe many of these proxies need a time lag before you can actually analyze them... hence why the blue line doesn't go up to 2000. It still looks like you can see an increase corresponding with our observational record, however.

 

[Dennis Sherrod]

Thanks Aaron for your input. Interesting topic to me to discuss. But this forum may not be the place to go on with this much indepth discussion.
But again, interesting thoughts to ponder.