The Role of the Sun in 20th Century Climate Change
Posted on 12/17/2004 2:27:50 AM PST by Exton1
A 1240-Year Record of Arctic Temperatures
Reference
Moore, J.J., Hughen, K.A., Miller, G.H. and Overpeck, J.T. 2001. Little Ice Age recorded in summer temperature reconstruction from varved sediments of Donard Lake, Baffin Island, Canada. Journal of Paleolimnology 25: 503-517.
What was done
Lake sediment cores from Donard Lake, Baffin Island, Canada (approximately 66.25°N, 62°W), were analyzed to produce a 1240-year record of average summer temperatures for this region.
What was learned
Over the entire 1240-year period from 750-1990 A.D., summer temperatures averaged
2.9°C. Anomalously warm decades with summer temperatures as high as 4°C occurred around 1000 and 1100 A.D. At the beginning of the 13th century, Donard Lake witnessed "one of the largest climatic transitions in over a millennium," as "average summer temperatures rose rapidly by nearly 2°C from 1195-1220 A.D., ending in the warmest decade in the record" with temperatures near 4.5°C.
The rapid warming of the 13th century was followed by a period of extended warmth that lasted until an abrupt cooling event occurred around 1375 A.D. The decade following 1375 A.D. was one of the coldest in the record and represented the onset of the Little Ice Age on Baffin Island, which lasted for 400 years. At the modern end of the record, a gradual warming trend occurred over the period 1800-1900 A.D., followed by a dramatic cooling event in 1900 that brought temperatures back to levels consistent with the Little Ice Age, which lasted until about 1950. Temperatures warmed during the 1950s and 1960s, whereupon they have trended toward cooler conditions to the present.
What it means
Large abrupt swings in temperature appear to be a consistent feature of climate in this region of the world, with temperatures rising and falling by as much as 2°C in as short a time period as a decade. Such natural temperature variability demonstrates the high degree of difficulty associated with attempting to separate effects of anthropogenic climatic forcing from those of natural causes.
In contradiction of politically-correct climatology, the study also demonstrates the existence of both the Medieval Warm Period and Little Ice Age on Baffin Island. And it stands in stark contrast to the climate alarmist claim that the latter part of the 20th century experienced "unprecedented" warming, at least in this part of the world, which is, however, where such anthropogenic phenomena are supposed to be most evident.
Page printed from: http://www.co2science.org/journal/2001/v4n32c1.htm
That is too funny. And yet you would never suggest the IPCC is an advocacy group, despite the fact their very name suggests otherwise. The sad fact is most 'science' publications today are advocacy groups especially in this area of global warming.
That should answer your question. I will be watching the journals quite closely.
I'm most interested in what Working Group I of the IPCC does. Working Groups II and III have socio-political foci, and that makes them more prone to advocacy forces and advocacy positions.
The sad fact is most 'science' publications today are advocacy groups especially in this area of global warming.
Approaching this scientifically, the preponderance of current data analyses indicate an anthropogenic influence on climate. If the journals have a preponderance of papers indicating same, that's not the fault of the journal -- blame the data for being so inconveniently biased.
Sorry; "Always Right" asked the question to which I responded, and which you followed up on.
The sad part about your Antarctic Ice Core Data Chart is that it doesn't even support global warming. For one thing, temperature increases lead CO2 increases, suggesting an alternative relationship. And the recent sharp rise in CO2 has not lead to a coorespondingly high rise in temperature. The current rise in temperature is within the noise level of what we have been seeing for the last 10,000 years. If they were related as suggested, one would have expected a much sharper rise in temperature over the last 100 years.
I agree, the preponderance of analysis does in fact indicate anthropogenic influence, but the actual data does not. And that is the problem, I see a huge divergence in the data and the analysis.
According to the alledged correlation of your chart, we should of had a 6 degree rise in tempreture over the last hundred years instead of a 0.6.
Maybe that's not why I posted it.
There are a whole lot of things that I could try to explain. Whether or not you know it, I've been over this ground before. So what I'll do is provide a brief summary, and you can ask all the questions you want.
Over the past 420,000 years, the primary cause of glacial-interglacial cycles is orbital and rotational (astronomical) forcing -- Milankovitch cycles. Because climate is complex, there are numerous feedbacks that complicate a simple cause-and-effect response. I recently posted -- it may have been to you -- a number of links that provided detailed information about this. (Do you remember if I posted them to you? Since I'm not sure, I'll check after finishing this and provide a link to that thread and the post number.)
When the world warms, there is a response in the climate system, notably in the atmosphere and ocean. Warming oceans release CO2 -- there's a lot of complexity as to why, but they do. That's why CO2 increase/decrease responds to insolation changes driven by Milankovitch cycles. All paleoclimate models indicate that CO2 is a major factor in maintaining warm or cold climate conditions, requiring a substantial "push" to change them.
The reason I posted the ice core graph is that it shows that CO2 has not varied appreciably since the end of the last glacial period -- UNTIL the last 150 years. That means that the Earth has been in a remarkably stable climate period over that time. The perturbation that is occurring now is a marked increase in CO2 without any other notable climate forcing factors. Because there are feedbacks both positive and negative in the climate system, there is very likely a "damped" response in the climate system to rising CO2. Also, other factors come into play: natural (volcanic eruptions) and anthropogenic (SO2 aerosols).
That's the brief summary. Now ask whatever you feel like asking, but you may want to wait until I get that link and post it.
Massive air pollution casts Asian haze over global climate
Post 35 -- which was a reply to you. And looking at that thread, in post 32 I said virtually the same thing that I just posted in the reply above this.
I hope that you are intellectually engaged on this subject. If you're not, we can oscillate on the same points and never make any headway toward resolution. I don't enjoy that kind of situation. I am attempting in good faith to provide information in response to your statements.
The perturbation is still not outside of what we have been seeing for the last 10,000 years. There are several spikes that are nearly identical to what we are seeing today. And I never see global warmers talking about posible negative feedback systems that is possibly damping the temperature response. If this is true, it is silly to talk about the exponential growth in temperature that global alarmists keep warning us about.
Repeat after me:
Man-made Global Warming is a MYTH!
Man-made Global Warming is a MYTH!
Man-made Global Warming is a MYTH!
No. Do you have a source for more info?
Bush's fault!
Global Cooling is the first sign of Global Warming!
Yea in the 13th century...wasn't that when they invented those Zippo lighters???
Everyone knows that....
;-)
It's true, the world was smaller a long time ago. I personally remember when "It's A Small Small World" was a popular song and old acquaintances used to greet each other by saying "Well, it's a small world, isn't it?"
Gavin Schmidt wrote this, as part of a response to Michael Crichton's "State of Fear", far better than I could have done and it's quicker to post what he said than write it myself:
"The first set of comments relate to the attribution of the recent warming trend to increasing CO2. One character suggests that “if CO2 didn’t cause the global cooling between 1940 and 1970, how can you be sure it is responsible for the recent warming?” (paraphrased from p86) . Northern Hemisphere mean temperatures do appear to have cooled over that period, and that contrasts with a continuing increase in CO2, which if all else had been equal, should have led to warming. But were all things equal? Actually no. In the real world, there is both internal variability and other factors that affect climate (i.e. other than CO2). Some of those other forcings (sulphate and nitrate aerosols, land use changes, solar irradiance, volcanic aerosols, for instance) can cause cooling. Matching up the real world with what we might expect to have happened depends on including ALL of the forcings (as best as we can). Even then any discrepancy might be due to internal variability (related principally to the ocean on multi-decadal time scales). Our current ‘best guess’ is that the global mean changes in temperature (including the 1940-1970 cooling) are actually quite closely related to the forcings. Regional patterns of change appear to be linked more closely to internal variability (particularly the 1930’s warming in the North Atlantic). However, in no case has anyone managed to show that the recent warming can be matched without the increases in CO2 (and other GHGs like CH4)."
With respect to the bolded emphasis on solar irradiance, refer to the solar cycle length vs. temperature plot that I posted earlier.
As for your other links, I already responded briefly, because I certainly don't have unlimited time to address all the errors that I saw when I examined them. (And I'm only an amateur.) If you were willing to let me deal with one link a week after the holidays, I might be able to.
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