In case anyone is interested I thought I might point out that Ralph
Keeling will be one of the speakers at the Royal Society during their
discussion meeting on "Greenhouse gases in the Earth system: Setting
the agenda to 2030". His talk is at 11:10 on Monday 22nd Feb and
entitled "What Have We Learned from Carbon Isotopes and O2/N2?

Details of the full two day meeting are here.
http://royalsociety.org/Event.aspx?id=1958
Anyone can attend.

Cheers, Alastair.