Not exactly any of the above although it can be approximated by (b). See http://...

		tim333 on Sept 29, 2016 \| parent \| context \| favorite \| on: Atmospheric carbon dioxide passes 400ppm Not exactly any of the above although it can be approximated by (b). See http://www.realclimate.org/index.php/archives/2007/06/a-satu... for some details