The ice-core recordSlide 14
- Their argument:
- CO2 and T clearly linked in the ice core record
- Either CO2 is driving a change in T, or T is driving a change in CO2
- Since, at the end of glaciations, T increases first, T must drive CO2
- Further implication
- Since CO2 didn't drive temperature change in the past, it won't do so now
False dichotomyMerchant states that both temperature and CO2 are driven by orbit changes. But this statement is a tacit agreement that Gore's proof is invalid. The program's point does not prove that CO2 can't drive temperature and I'm not sure this is what the presenters are saying. What they are saying is that Gore's chief proof is not true because the temperature changes precede the CO2 changes and do not follow it. One can go with the program or with the Merchant but either way, both show Gore's presentation to be a logically invalid argument.
- T drive CO2 or vice versa
- No! The driver is the variation in Earth's orbit (Milankovitch cycles)
- T and CO2 respond to this driver, T first
- Third possibility: feedback relationship
- Does not follow CO2 has no effect on T
- ~Half T change from CO2 feedback
He states this doesn't necessarily prove CO2 is not important now (I agree). But if your major proof is shown to be invalid you can no longer rely on it.
Further, in terms of logic disproving A does not prove B (unless B equals not A), but it may support it.
His option C is just a story. Stories can be true or untrue, but coming up with a plausible explanation allows for a scenario, it does not prove it. Frankly, causes of repeat ice-ages just are not understood. I think there is evidence for a single ice-age which, in some ways, we are still coming out of.
No guide to future performanceLine 3 does not follow, just because we are producing CO2 does not mean we are changing the amounts in the atmosphere significantly. And the argument that CO2 is forcing the change in T rather than responding to the change in CO2 is an assumption.
- CO2 did not "drive" T in the last 600kyr
- CO2 still affected T (greenhouse effect)
- We are now changing CO2 directly, independently of T
- In this (completely different) forced situation, CO2 changes can (and will) "drive T changes
Changes in gases in the atmosphere are considered to follow or force temperature. Following temperature means that the amounts in the atmosphere are a reflection of the temperature of the atmosphere. Forcing temperature means that the gases are changing the temperature of the atmosphere. A gas can potentially follow, force or do both. Asserting which is based on theory as much (or more so than) as data. Water vapour and clouds have a far greater effect on greenhouse effect but the proponents of anthropomorphic global warming suggest that ongoing changes of water follow rather than force. This allows them to effectively ignore a potentially larger cause.
Ice cores not fundamentalWell maybe someone should tell Al Gore this!
- The T and CO2 inter-relationship in the ice cores is not the main theory under-pinning global warming
- The fundamental theory is the physics of the greenhouse effect, dating back to Faraday, Tyndall and Arhennius in the 19th century