The contemporary and historical budget of atmospheric CO21This article is part of a Special Issue that honours the work of Dr. Donald M. Hunten FRSC who passed away in December 2010 after a very illustrious career.

Abstract

Observations of CO2 and O2 are interpreted to develop an understanding of the changes in the abundance of atmospheric CO2 that have arisen over the period 1995–2007. Fossil fuels accounted for an addition of 89.3 Gt of carbon to the atmosphere over this time period, 29% of which was transferred to the ocean, 15% to the global biosphere, with the balance (57%) retained by the atmosphere. Analysis of historical data for CO2 derived from studies of gases trapped in ice at Law Dome in Antarctica indicate that the biosphere represented a net source of atmospheric CO2 prior to 1940, switching subsequently to a net sink.