A Few Things Ill Considered

A layman's take on the science of Global Warming featuring a guide on How to Talk to a Climate Sceptic.

Tuesday, September 05, 2006

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CO2 Highest in At Least 800,000 Years

As analysis of ice cores from the Antarctic continue, we have moved from the finding that GHG's in the atmosphere are at their highest concentration in 450,000 years to 650,000 years and now to 800,000 years. I believe the limit to this record is supposed to be around 900,000 years. Even though the antarctic ice sheet is older than that, the continent has been mostly ice covered for the last 15 million years, the usable record is limited by melting from the bottom and corruption of the record due to motion and pressure.

What this new result reconfirms is that humanity is really taking us off the charts in terms of the atmosphere/ocean climate system that has existed for longer than the entire history of the human species. (NB - other indicators such as ocean sediments suggest we may be at a 20 million year high, though the time resolution is not as fine nor the measurement as direct),

And we have done this is about one century.

It doesn't take a computer model to tell a sincere and intelligent person that this is folly on a monstrous scale. There is nothing in geological history that tells us this is nothing to worry about, in fact, quite to the contrary.

Here are a few guide entries that relate to this paleo-climate record.

Complete listing of guide entries here.

Wikipedia has a fascinating article on ice cores.



  • At September 05, 2006 4:49 PM, Anonymous Tim Burrows said…

    The discovery was interesting because it confirmed that CO2 concentrations are at an 800,000 year peak, as you say. However they were all the more remarkable because the guys were able to carry out isotopic analysis on the air samples. This proved that the increased CO2 concentration over the last century was due to fossil fuel combustion, not volcanic activity or an other source. I suspect that this done using a mass spectrometer similar. This instrument can identify the chemical composition of materials, so traces of chemicals that only come from fossil fuel combustion would leave a kind of fingerprint.
    Here's another link:

  • At September 08, 2006 2:10 AM, Blogger Heiko said…

    Isn't it millions of years, based on other indicators?

  • At September 08, 2006 3:26 AM, Blogger Heiko said…


    Just did a quick google to refresh my memory. It seems it's at least 20 million years.

  • At September 08, 2006 8:12 AM, Blogger coby said…

    Hi Heiko,

    I added that information, as well as the correct figure for the age of Antarctica's ice cover. I think the ice core is considered the most reliable, especially in terms of better temporal resolution, than the other proxies from ocean sediment.

  • At September 08, 2006 4:28 PM, Blogger Heiko said…

    Thanks for the clarification. I suppose I'd interpret these facts somewhat differently, as you know. At least, I'll draw the conclusion that little in terms of CO2 taxes is justified today, and am rather glad that politicians are by and large doing what is (hmm what consider to be) right in that regard.



    Jeff Masters, a well known hurricane expert, has an interesting posting up.

    'Since 1976, El Niño events have been approximately twice as frequent as La Niña events, with ten El Niño events and only six La Niñas. Some researchers have speculated that this is due to the effects of global warming causing a new "resonance" in the climate system. If so, this is one way in which global warming may end up causing a decrease in Atlantic hurricane activity over the coming decades, since the increased wind shear over the Atlantic during El Niño events greatly reduces the number and intensity of these storms.'

    My understanding of the hurricane debate is as follows:

    SST's ought to rise with global warming and all else equal that ought to mean greater hurricane reach/activity, but we don't really understand the "all else" yet. So, if "all else" is not materially affected, theory has it that Katrina say was made 5% stronger or so, but "all else" may also mean that actually anthropogenic global warming has made it say 15% stronger or 5% weaker.

    And as you know, I also consider revealed preference quite strongly (ie people want to live in Florida close to the beach, full well knowing that that means being exposed to hurricanes - presumably indicating that the benefits they derive from warms SST's outweigh the negatives)

  • At September 08, 2006 6:00 PM, Blogger coby said…

    I think misguided policy plays a role in that cost-benefit judgement that coastal populations make: ie gov't compensation for losses and insurance premiums underwritten by everyone's else's.

    If people had to bear the true costs, they might not find the benefits worth it. Then again, better construction and emergency preparedness would make huge strides in ameliorating the costs of any paricular storm.

    I don't actually think the hurricane issue is a particularily compelling one in the GW debate, it is however remarkably influential in the public's mind. Big storms are scary.

    It also goes without saying that Atlantic hurricanes are only one part of global cyclones, so even if more wind shear from El Nino's counter rising SST there, what about typhoons in Japan and China and India. Hurricane Ioke for example was a very remarkable storm, except that it did not happen in the Gulf Coast!

  • At September 09, 2006 3:26 AM, Blogger Heiko said…

    It is always a pleasure to discuss things with you.

    I am well aware of the argument that the cost benefit analysis is impacted by bad insurance policies, I just don't think that's responsible for that large a fraction of the movement, ie even with ideal insurance policies I think people would be heading for Florida rather than Chicago.

    On your other point, I completely agree the Atlantic basin isn't the only one that counts (and besides Jeff Masters is discussing a possible mechanism of why global warming might not actually lead to an increase there, this is far away from proof that that'll actually be the case).

    Roger Pielke's point about Iraq and Katrina is an interesting one. Of course, analogies are always faulty in some respects.

    But, let me quickly give you my perspective on Iraq. I never thought that Saddam had ordered 9/11 or had had direct involvement, and whether he had WMD's left over from the first Gulf War or not, I wasn't too bothered about. They didn't exactly do him much good then, when he did have them and he actually chose not to use them.

    I favoured the intervention largely on humanitarian grounds, and did in fact take a very similar approach to the WMD and 9/11 arguments as you. I'd defend the notion that there was no proof he had destroyed them, and that as far as weapons of mass destruction and terrorism are concerned 9/11 was a wake-up call to what could potentially be.

    But I didn't go out of my way to make the case that Saddam might have destroyed all his WMD's (or most of them) that they were pretty useless anyway and that any and all connections to 9/11 were rather indirect.

    In retrospect, I think the biggest issue with Iraq is that it was partially motivated by a desire for revenge and even more widely perceived as such among Muslims, even moderate ones. That I think is a major reason for the amount of violence there is in Iraq today, because the "resistance" needs support and such is much more forthcoming when the cause is widely regarded as just.

    In Iraq, I therefore think the wrong emphasis in communication was a big issue.

    For Katrina it may be less so I think. Global warming initially got a lot of publicity from a minor drought at the end of the 80's I believe (minor compared to the dust bowl years), since then there hasn't been much unusual drought wise in the US (ie the droughts that have happened have been even less serious than the end of 80's situtation, let alone by comparison with the dust bowl years), but this hasn't exactly caused any problems.

    So, suppose that beween 2006 and 2100 it turns out there's no upward trend in Atlantic hurricanes, what damage would that cause?

    Or suppose there are no major Atlantic hurricanes this year and no hurricanes at all next year, are there gonna be hearings on that? People going onto the street holding up placards "Gore lied, people died"?

    It's not as if the faulty information got people to flee Florida in droves (and got many killed in the process), or got people not to build flood defenses to save the money for hybrid incentives.

    So, I accept your point, it's not that important to go out and correct the misperception, on the other hand, I also accept Roger Pielke's point, you should make sure that people are correctly informed and make the right decisions for the right reasons.

  • At September 09, 2006 10:42 AM, Blogger coby said…

    Yes, I can accept Roger's point and agree with it. What I have a problem with is his choice of examples to prove it. I think he chooses poorly and thus weakens his own argument.

    And unlike you he doesn't see my point, that there are legitimate value systems that do not require actively addressing this particular public misconception.

    BTW, your framing of the Iraq/9-11 issue is a much more correct analogy, I had started to state it in a similar way in one of my comments over on Prometheus but decided not to spend the time going down yet another road. If I believed for a second that Cheney gave a damn about anything humanitarian and if he had not actively participated in creating and promulgating the Saddam-9/11 falsehood, then it would be exactly the same as my view of public acceptance of GW because of Katrina.

    I also refrained from raising the question as to whether or not the ends can indeed sometimes justify the means. We all clearly live our lives that way, and politics is almost entirely based on that, (what is a war, if not the ultimate expression of that sentiment) but Roger tends to wave that phrase around, "the ends do not justify the means", like some moral light sabre.

  • At October 04, 2006 11:55 PM, Blogger Glen said…

    It actually does require some kind of a model - not necessarily a computer model, but a model nonetheless - to jump from "X is unprecedented in Y years and due to recent human activity" to "this is folly". I found the idea of making such a leap without any model amusing, which inspired me to try writing an Onion-style version of the same story here.

  • At October 05, 2006 7:54 AM, Blogger coby said…

    Hi Glen,

    Well, they say that imitation is the sincerest form of flattery, so perhpas satire is up there too...thanks!

    Of course, your point is misguided, though.

    While we could quibble about just what exactly constitutes a "model", I don't think it takes one more sophisticated than "CO2 is a GHG that effects the earth's climate" to understand my article.

    Thanks for the comment!


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