dehammer, I again agree with you for the most part.
I remember a study of the Arctic tundra that in its sample found bumble bees. From that it was concluded that the climate at the time that the ice froze was warmer than it really was. No on ehad thought to come up with another explanation until other evidence very much contradicted the proposition that the climate was warmer. The bumble bees' presence was almost certainly been caused by a storm that blew them into a frigid region from well to the south.
That's the trouble when you have only fragments of anything, extrapolation can be quite dangerous. So it is for plants. Just because you find a certain plant in sediment or trapped in a glacier or wherever does not mean anything but that plant was in a local area at that time. There are tropical rainforest plants today in the middle of the Australian deserts. That does not mean that the centre of Australia is currently experiencing tropical climate, only that there is a tiny pocket of those plants that have survived many thousands of years after the climate changed. Now if you found evidence of these plants in sediment for instance, in 100,000 years from now you would quite wrongly conclude that Central Australia had a tropical climate with a certain CO2 output.
To get any real idea you need to find evidence world wide and in various areas within each region for exactly the same time period. That very rarely happens.
This is what I was trying to get at. The evidence we have on which so much of earth's history, especially its climate, is based is extremely sketchy. It is my view that it is useful for trends but not for even a remote guess at what was the world's average temperature in the past or what was the actual CO2 concentration.
That said, the evidence does suggest that our current age has a very low CO2 atmospheric level, many times lower than in the past and during those times there has been periods both a little hotter and considerably colder than now despite the much higher CO2 levels.
As to trapped gases in ice cores, the science that calculates the atmospheric concentrations from these ice cores is by no means settled. It is my understanding that there are arguments relating to almost everything to do with such correlations, including just how well are gases trapped, things such as slight melting and refreezing of the cores as they are laid down (something dehammer mentioned).
Once again, the newspaper article seems to have taken the figures completely on face value without looking at what issues remain in contention relating to just how these figures were arrived at.
And 27% higher is suposed to be a big deal, even if perfectly accurate? Go back to another cold period a few million years back and the best estimate is that the CO2 concentrations where perhaps 1000% higher than an present yet the place was colder, with the world in relation to the sun being in similar positions. It would seem that such massive changes in CO2 levels are not necessarily related to whether the world is hotter or colder and that particular statement is not controversial at all. Pretty much every paleoclimatologist will agree with it.
Richard
