"bill" wrote in message
oups.com...
Methane in the atmosphere has a 5 year half-life.

Don't listen to the borg, get the facts :

"Methane has an atmospheric lifetime of 12 +/- 3 years and a GWP of 62
over 20 years, 23 over 100 years and 7 over 500 years. The decrease in
GWP associated with longer times is associated with the fact that the
methane is degraded to water and CO2 by chemical reactions in the
atmosphere."

http://cosmic.lifeform.org

Okay, I was wrong by a small amount in my half-life statement, I
read it last year.
However, Your citation is also wrong. the proportion of the
methane which degrades to co2 remains in the atmosphere for milennia,
correct, but the water vapor precipitates out.

And then evaporates back into the atmosphere. The call it the hydrologic
cycle. It is a continuous cycle.

George