Global Warming - A review of a paper by James Hansen, et al.

This page discusses Climate change and trace gases by James Hansen, et al., 2007. (abstract)

I don't make it a point to simply read and criticize Hansen's work ... but this paper begged for it.

In this paper, Hansen admits and then proves, beyond a reasonable doubt, that the ice core data shows that CO2 will NOT have any effect on temperature. That's right, in an effort to prove that CO2 is a greenhouse gas, Dr. Hansen provides all the evidence that anyone should need to actually prove the contrary position.

But, then he provides the solution - Just fudge the data so that it matches his theory.

Below, the indented, italicized quotes are from Hansen's document - the page numbers are the ones shown in Adobe Reader (Acrobat).

As usual, please don't just read my quotes from the paper - please be sure to read them in context.

Ice Core Data | Positive Feedbacks | Justification for Modifying Data | Additional Observations | Final Comments

Ice Core Data

The same Vostok ice core that defines past Antarctic temperature also reveals the history of long-lived atmospheric gases. Bubbles of air are trapped as annual snowfalls pile up and compress gradually into ice. page 3
The temperature change appears to usually lead the gas changes by typically several hundred years, as discussed below and indicated in figure 1b. This suggests that warming climate causes a net release of these GHGs by the ocean, soils and biosphere. page 4
The temperature–GHG lag is imprecise because the time required for snow to pile high enough (approx. 100 m) to seal off air bubbles is typically a few thousand years in central Antarctica. ....

Despite multiple careful studies, uncertainties in the ice–gas age differences for the Vostok ice core remain of the order of 1 kyr. ....

Data from a different Antarctic (Dome C) ice core with slightly higher snow accumulation rate ... support temperature leading GHGs by ca 600–800 years. page 4

Basically, this says that temperature change causes a change in CO2. And when you look at the plots in other sources, it is obvious that the CO2 increase did not cause any additional temperature increase. In fact, in almost all cases, an increase in CO2 is correlated with a significant temperature decrease.

You can not tell that from the graphs in Dr. Hansen's paper because he has adjusted them so that most of the major CO2 increases coincide with temperature increases - that's right, he changed the data to fit the theory. In fact, that is the purpose of his paper - to explain why he thinks he is correct in changing the data in this way.

That's right, the data proves his theory wrong, so he changes the data.

Just so you'll know that I have a clue, many great discoveries required manipulating the data. And Dr. Hansen should be credited for at least explaining why he is doing it. It is the fact that it took him so many years to see what has been totally obvious to everyone else and his insistence that his is the only possible interpretation of the data that bothers me.

Positive Feedbacks

Talking about the beginnings of the last 4 interglacials (including the current one), Hansen says
Such huge rapid climate change had to involve large positive feedbacks. page 7
Really? There was no possible change in external forcings? No space dust, no volcano explosions, no asteroid? The ONLY possible explanation is positive feedbacks?

Sorry, but I am not buying that ... unless you can prove that no external forcings occurred.

My personal preference is for asteroids.

Dust from the moon, or even from an impact on the Earth, could account for the very fast 'start' of an ice age.

Once the dust settles, then the Earth is able to warm up again.

Granted, there is not enough dust in the ice cores to support this theory ... but it is plausible and it does not require any positive feedbacks.

Actually, the fact that there is so little volcanic, lunar, and other dust in the ice cores raises an interesting question. I think that there should be more. Perhaps a dust cloud around the moon would eventually return to the moon and leave little trace here on Earth ... and a large enough cloud would definitely cool the Earth.

As soon as the sun is bright enough, the ice would start to melt and an albedo feedback could make it melt very fast. Another possibility is that dark volcanic (or impact) dust falling on an ice desert (little or no fresh show) can melt a lot of snow very fast.

Justification for Modifying Data

This paragraph is immediately after the one that suggested that only positive feedbacks could account for the end of an ice age.
Note first that ‘minor’ mismatches in timing of observed and calculated temperatures in figure 2c are due to dating errors and, to a lesser degree, limitations of a local thermometer. Proof is obtained by considering the contrary: ice sheet forcing approximately 3 W m-2 and a 5 kyr timing gap between forcing and response, as appears to be the case at Termination IV (figure 2c), is 15,000 W yr m-2, enough to warm the upper kilometre of the ocean by approximately 160 C (see table S1 in Hansen et al. (2005b)). Obviously, no such warming occurred, nor did warming more than approximately 1/100th of that amount. Forcing and temperature change had to be synchronous within a few centuries, at most, for the large global climate change at terminations. page 7
As mentioned before, Hansen has admitted that, based on the ice cores, the change in CO2 (and other greenhouse gases) occurs within about one thousand years of the change in temperature - sometimes before and sometimes after.

In this paragraph, Dr. Hansen is arguing that if the changes were not at exactly the same time, then the powerful greenhouse gases would have boiled the oceans. As a result, all the existing graphs must be adjusted to fix this error.

Specifically, he thinks that the fact that the earliest ice age ended 5,000 years BEFORE the CO2 increased means that the people analyzing the ice core data made a 5,000 year mistake - on more than one ice core.

Maybe a better interpretation of the data is

When the oceans warm more CO2 is released to the atmosphere
CO2 does not cause the temperature of the Earth to increase

Additional Observations

Most of the paper's graphs show very clearly that previous interglacials were 1 to 5 degrees C warmer than today ... without the help of humans.

The paper argues (page 12) that the IPCC reports are too conservative. To some extent, I actually agree with Dr. Hansen on this point, additional global warming would cause an albedo change - I just disagree that CO2 would have any affect.

Final Comments

I had always planned to write a paper explaining that, in the ice cores, the change in temperature frequently occurs before changes in CO2 ... but Dr. Hansen has already admitted that this is a serious issue.

His solution to the problem is to adjust the data.

I don't agree, I think that the theory needs adjusting.

Without the adjustments suggested by Dr. Hansen, it is obvious that increasing the amount of carbon dioxide in the atmosphere will not cause Global Warming. Instead, the CO2 concentration is actually a global temperature indicator ... a type of thermometer.

Author: Robert Clemenzi
URL: http:// / Global_Warming / Papers / Hansen_2007.html