Bob Martin wrote:
in 221785 20070309 124614 Gianna wrote:

As the proportions of atmospheric gases vary over time, the term 'excess' is
subjective. They stated that temperatures, and CO2 levels, have been higher
than they presently are, and that was long before industrialisation etc..

Other sources claim that CO2 today is higher than at any time in the last 600,000 years.

Yes, they do.
As in any scientific debate, each camp is producing evidence in support of their
conclusions. I would have no idea which set of evidence is true in some
theoretical absolute sense. Unless someone on this group is a qualified climate
scientist with access to the primary source raw data (somewhat unlikely), then
none of us will know which side is 'correct' (if any).

From the posts I have read here, we are all reliant on the secondary sources
(or worse). So, we weigh up each case and decide which we think the most plausible.
We may then state which body of evidence and conclusion we believe - we may not
state which body of evidence is 'true' or 'correct' as we cannot know.


If the person(s) you quote is not disputing that then he must be referring to an earlier
period - in which case how does he know?


I rather had the impression that the climate scientist(s) on the programme were
disputing that. If you want more detail than was provided in the programme, you
would have to ask those who took part. I can only report what I saw/heard.

I seem to recall that they suggested that CO2 from decaying vegetable matter,
including autumn leaves, was greater in volume than that generated my human
activity. I have not sought to check that.


--
Gianna

http://www.buchan-meteo.org.uk
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