Soren wrote on Oct 22
nd, 2008 at 9:35am:
Letter in yesterday's Oz:
ATMOSPHERIC CO2 is currently 382 parts per million. The Ordovician-Silurian (450-420 million years ago) and Jurassic-Cretaceous (151-132 million years ago) glaciations occurred when the atmospheric CO2 content was more than 4000 and at least 2000 parts per million respectively.
If CO2 drives climate, why was there glaciation and not a runaway greenhouse?
Professor Ian Plimer
School of Earth & Environmental Sciences,
The Mawson Laboratories,
The University of Adelaide, SA
- because things have changed since the Silurian. The laughable thing about that post is that a geologist should know exactly how inaccurate CO2 proxies are from around 450 million years.
Also - think about my earlier question about the natural log relationship and you might be able to answer the question yourself.
(Oh I forgot - you prefer to cut and paste rather than think independently. )
Apart from that, the periods where CO2 concentration was high coincided with periods where the earth had extensive and dense rainforests. Compare that to today and it's obvious that we're dealing with chalk and cheese. Biota provides buffering capacity.
Our proxies for CO2 are about as inaccurate as our proxies for solar irradiance during that period.
CO2 and temperature are inter-related, as I have explained, increase one and the other increases, but hey, let's compare apples with apples.