Summary

Measurements of atmospheric trace gas composition from times before reliable direct observations began in the late 20th century come from air enclosed in polar ice and firn. This presentation will review the evidence for changes in atmospheric CO2, CH4 and their isotopes over the past 2000 years found from this archive. This period is dominated by concentration growth due to industrial and agricultural emissions over the past 200 years causing trace gas radiative forcing to increase at unprecedented rates. It also contains evidence for early natural and anthropogenic causes of CO2 and CH4 variations and for climate-carbon feedbacks.

Authors:Etheridge D. Steele P. MacFarling Meure C. Langenfelds R. Trudinger C. Francey R. Allison I. Lassey K. Ferretti D. Enting I. van Ommen T. Smith A. Published in: 2008 Category 3: Conference paper Program area: Ice, Ocean, Atmosphere and Climate
Etheridge D., Steele P., MacFarling Meure C., Langenfelds R., Trudinger C., Francey R., Allison I., Lassey K., Ferretti D., Enting I., van Ommen T., Smith A. (2008) Carbon dioxide and methane changes over recent millennia from the ice core record: causes, climate forcing and feedbacks, Carbon Workshop 2008: Global Cycle to Regional Budget, Wellington, NZ, April 14-15 .;

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