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.

The perturbation is still not outside of what we have been seeing for the last 10,000 years.

The perturbation in CO2 concentration in the atmosphere is obviously well outside the range of what has happend to atmospheric CO2 concentrations since the end of the last glacial period.

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.

The chief unknown -- and still hard to figure out -- is cloud feedbacks. If warming increases clouds sufficiently, the extra cloud cover would counteract the warming influence. Most "global warmers" will mention that. As for that exponential growth in temperature, I've only seen that in the high-end predictions from models in which some of the negative feedbacks have been removed or modified. It gives the predictions an error range, and the media loves the high end, but because it's the high end it's not as likely as the mid-range, and far less likely than the low end predictions.

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).

It appears to me, from your chart, that these "other factors" are much more powerful than that of atmospheric CO2 levels. If not, we return to a modified version of the original question: Why did these other factors have such sway over global temperatures up until the last 10-20 years? Are CO2 levels suddenly shooting off the charts and only now capable of overwhelming all these other factors? It appears that CO2 has magically become quite a powerhouse in a very short period of time.

Also, didn't this link, posted previously by another FReeper, indicate that there are much greater forces at work in the production of atmostpheric CO2 than man? This fact, when combined with the fact that CO2 levels themselves are only a small piece of the global temperature puzzle, should cause the alarm over anthropogenic CO2 production to decrease to approximately zero. Worthy of some scientific attention, but hardly any alarm, and certainly not a treaty or policy change.

Man has little to do with atmospheric CO2 levels. Atmospheric CO2 levels have little to do with global temperature change. What changes do occur in our planet's temperatures, I'm quite satisfied, are far, far out of our control.

It appears to me, from your chart, that these "other factors" are much more powerful than that of atmospheric CO2 levels.

The temperature vs. solar cycle chart?

If so, up until the 1990s, the climate scientists say that solar effects accounted for 1/3 to 1/2 of the warming since the late 1800s -- i.e., up to the mid-1940s, when it appears other effects kicked in to cause the slight cooling over the next couple of decades. I.e., the CO2 effect wasn't as strong as now, and there is a lag time in response, too (probably).

Why did these other factors have such sway over global temperatures up until the last 10-20 years? Are CO2 levels suddenly shooting off the charts and only now capable of overwhelming all these other factors?

What the Sun does is out of our control. SO2 aerosols in industrialized countries were markedly reduced in the 1970s due to clean air and acid rain concerns. Same with a lot of plain ol' smoke (black soot). And, CO2 is significantly higher in concentration in the atmosphere now than 20 years ago. It's not "shooting off the charts", but any effect that it's creating is increasing, too.

Mankind is the primary source of the imbalance between input and output from the atmosphere. The imbalance is the cause of the increase in atmospheric CO2 concentration (and we are indebted to the oceans, which have absorbed about 50% of the CO2 that has been produced by fossil fuel burning). This can be easily proven by the Suess effect (isotopic dilution).

Water vapor is a GHG, and the most important, but water vapor responds to radiative forcing -- it is so big a constituent in the atmosphere that mankind has no appreciable effect on water vapor input/output. But radiative forcing does have an effect, a positive feedback. In an interesting paper (subject of a FR thread in the past year, I think), a study confirmed that the water vapor feedback is positive -- which hadn't been conclusively shown before that -- and also showed that the modeling assumption of the mathematical expression of the positive feedback probably overestimated it. I bet the modelers are still working on an improved formulation of this aspect.

Man has little to do with atmospheric CO2 levels.

But... man has everything to do with the increase in atmospheric CO2 levels from 280 ppm to the current level. That's a rock-solid inescapable certainty. Below 280 (and sometimes a lot lower, in glacial periods) -- that's the natural climate system.

Atmospheric CO2 levels have little to do with global temperature change.

That's the subject of our discussion now -- how much of a global temperature increase will be induced by rising atmospheric CO2 concentrations. Only the most diehard, ardent skeptics maintain that there will be a zero effect. In case you hadn't noticed, there has a been a change in the tenor of argument from the notable skeptics, people like Patrick Michaels, Richard Lindzen, and Roy Spencer. They are basically saying two things: the temperature increase in the next century will be on the low-end of the predictions, and mankind should have nothing to fear from that.

I would heartily wish them to be right. But I've been tuned into this issue for awhile, and I just can't give them the benefit of the doubt.

I would heartily wish them to be right. But I've been tuned into this issue for awhile, and I just can't give them the benefit of the doubt.

Personally, I'm not concerned. I have a great trust in the fact that the various forces on and around earth are quite capable of recovering from and adjusting to any activities engaged in by mankind. A volcano erupting or tectonic plate moving has a far more profound effect on our planet than anthropogenic CO2 levels.

I predict that the Global Warming hype will eventually become something like the "flat earth" maps of years gone by with the "There be dragons here" warnings at the edges. It will be seen historically as another in a long line of fear-based overreactions to the unknown.

I appreciate your thoughtful and well-researched answers, both marks of an intelligent gentleman. However, I remain unconvinced.

Hi Larry E:
Sorry, not a ghost of a chance. The earth is only c. 6010 years old. Also, the globe is the same size. Were it not, the magnetic pull would not be an accurate indicator. The magnetic pull is one of literally millions of things that the LORD has magnificently set up to show the sick, sick lie and fantastic pagan myth of evilution. The earth’s magnetic field is in constant change. Every 1400 years, the half life decreases by one-half. Therefore, were the earth much older than 6000 years, the earth would’ve ripped apart.
There’s a tremendous amount of books, treatises, tapes and websites on the subject. I haven’t taken the time to type exposes of the fantastic pagan myth of evilution because I have an awful lot going on. Best point to start far and away no contest: Genesis One and Two. Also, you will see great nuggets in Isaiah 51:6, 40:22, Deuteronomy 29:29, Psalm 103:12, 1Timothy 6:20 ~ like that. Jack Chick’s got some stuff on the hopelessness of evilution. Also, were you to type in av1611.com, .org, kjv1611.com, .org, biblebelievers.com: like that.
E R Rocky Drake
www.1040.com/consultant

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