The New Chart at the Top of the Page

My last article about the chart I use in the header generated some interesting discussion. You can look back to see the types of comments that were made about it. The two headers can be seen here. For all the discussion about it, the charts didn’t change very much. That is because they both reflect the type of temperature behavior that the Northern Hemisphere (NH) has experienced for the past few thousand years.

The Inconvenient Skeptic

GISP2 (Greenland) Header (Old)

The Inconvenient Skeptic

Penny Glacier Header (New One)

The new chart is from the Penny Glacier on Baffin Island in northern Canada. The last data point from this core is a 25 year average from 1967-1992. One interesting fact about Baffin Island is that it contains the last remnants of the Laurentide Ice Sheet that once covered large parts of North America.

Perhaps the biggest difference between Penny Glacier and the GISP2 ice core is that Penny isn’t impacted by the Gulf Stream in the same way Greenland is. The Gulf Stream goes to the east of Greenland and Baffin Island is north of Hudson Bay to the west of Greenland. As a result there is less overall variation in the temperature record.

This likely makes the Penny Glacier ice core a better indicator of overall Arctic conditions for the past 6,000 years than the GISP2 because the Gulf Stream has less of an impact. This indicates that the current conditions in the Arctic are less unusual than what is commonly believed by many. While this may be a surprise to many, it is very comparable to the other Northern Hemisphere ice cores.

On time scales that are less than a few hundred years, it is impossible to tell if the overall trend is cooling or warming because it is almost always doing one or the other. Trends in the Earth’s climate are visible on the scale of thousands of years, not dozens of years. The trend for the past 6,000 years is cooling. The Penny records show this more clearly.

Any honest analysis of the isotope record will show that the current warming is nothing unusual. In fact, the warmest part of the past 200 years is not the current temperature, but 25 year average from 1892-1917. The record from Baffin Island is pretty straightforward in one respect. The current warming is nothing special in the history of the Arctic.

Anyone truly concerned about the Polar Bears should take heart from that. They have survived much warmer Arctic conditions than those that currently exist.


Posted in Skeptic by inconvenientskeptic on October 31st, 2010 at 4:35 pm.


This post has 7 comments

  1. Rob Honeycutt Nov 1st 2010

    John… I would suggest that you are still using a single line of evidence to portray a broad conclusion on the topic. I would challenge you to plot the data from all the 30-some-odd ice core projects together and see what results you get.

    Already, just looking at these two charts plotted side-by-side questions come to mind. The peak of the GISP2 chart is at about 3500 year ago. But the peak of the Penny glacier is at 6000 year ago. That’s a pretty dramatic difference for two ice cores that you suggest are indicators of global temperature during the holocene.

    What do those two charts look like on top of one another? What is similar about them? What is different about them? Why?

  2. inconvenientskeptic Nov 1st 2010


    The Penny Glacier data is in raw isotope data. I could calibrate it to temperature, but I preferred to keep it in the isotope data.

    All the NH ice cores show the same behavior. Today’s post uses the NGRIP that has the same thing. It also links to a journal article that points out that the early Holocene was Arctic ice free during the summer.

    That is sufficient to show that the early Holocene was warmer while the CO2 levels were also much lower.

  3. Rob Honeycutt Nov 1st 2010

    John… The NSIDC states here that the last time scientists can confidently say that the Arctic was ice free in summer was 125,000 years ago.

  4. Rob Honeycutt Nov 1st 2010

    Richard Alley also clearly states here that ice core records are local records. Thus, all you are doing is presenting another localized record that you believe supports the conclusion you are trying to peddle.

  5. inconvenientskeptic Nov 1st 2010


    The Arctic was also ice free in the early Holocene which was 10,000 years ago. An ice free arctic is pretty indicative of warmer climate in the region.

  6. Rob Honeycutt Nov 2nd 2010

    John… Are you clear what Jakobsson means by the central Arctic ocean? When I read Jakobsson the wording is less conclusive than you are making it out to be.

  7. I had been looking for a visual representation of the penny ice cap data to put the current warming in the region in historical context (see here Much appreciated!

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