[quote="Falco, post:13, topic:326976"]
In New Zealand recently they were concerned about the effect of farting animals on the ozone layer - it is a great farming country, and the methane levels were measurable and causing concern.
Perhaps the ice age was caused by the dinosaurs eating too many beans?
I'm starting to read a book "Clean Energy, Climate and Carbon" by Peter J. Cook (CSIRO Publishing).
He allocated the following "global warming potential" over 100 years on a per molecule basis as follows -
Carbon Dioxide 1
Nitrous Oxide 298
HFC Refrigerants 1430
Carbon Tetrachloride 1400
CFC Refrigerant 10900
Suphur Hexafluoride 22800
Which means that Methane has 25 times the potential as a Greenhouse Gas (GHG) compared to Carbon Dioxide on a molecule to molecule basis.
When sunlight hits the earth, a lot is reflected back out into space.as infrared radiation, much like a radiator used to heat a home. The net energy supplied by the sun is therefore the solar input less the reflected radiation.
What GHG's do is to trap this reflected energy, and retain it in the atmosphere. The biggest contributor to the Greenhouse effect is water vapour in the atmosphere, but there is no evidence that mankind has contributed to any significant increase in water vapour.
But while Methane has 25 times the inherent GHG ability of carbon dioxide, it is at significantly lower concentrations (about .45% compared to CO2, if my interpretation of a graph in the book is correct) which would equal about 11.25% of the effect of carbon dioxide.
We are pumping increasing amounts of CO2 into the atmosphere, and I think it is having a gradual greenhouse effect. That's why the debate tends to focus on CO2 and not the other gases or water vapour. The water vapour does not appear to be changing (at least not by man's efforts) and the other GHG gases are in small concentrations.