On Jan 28, 2:00 pm, Dick Lovett wrote:
On Jan 28, 1:07�pm, Stewart Robert Hinsley

wrote:
In message , Ron Button
writes
I don't have the literature to hand, but supposedly carbon isotope
ratios demonstrate the anthropogenic source of the additional
atmospheric carbon dioxide.
--
Stewart Robert Hinsley

As far as I am aware - source Hadley Centre - it has not been possible
to measure the isotopic signal of anthropgenic CO2
since 1945 due to atomic bomb contamination of the atmospheric.

Dick Lovett
Charlbury

Do you have an exact source for this? I would expect atomic bomb
explosions to affect the amount of Carbon-14 in the atmosphere but not
the ratio of Carbon-13 to Carbon-12, which is what is used as an
indicator of combustion of plant-derived carbon.

The most recent IPCC report gives no hint of any difficulty in using
the 13C/12C ratio as an indicator of increased inputs of plant-
material carbon into the atmosphere - see
http://www.ipcc.ch/pdf/assessment-re...1-chapter2.pdf
page 139 and references.

Cheers,

Richard Stamper