New ice core record of atmospheric methane

Abstract

Atmospheric concentrations of methane, an important greenhouse gas, have varied in the past on time scales ranging from seasons to hundreds of thousands of years. Understanding past variations is important to interpreting current natural and anthropogenic changes. Mitchell et al. present a new high‐precision, high‐resolution atmospheric methane record covering 1000–1800 C.E. from an ice core from the West Antarctic Ice Sheet Divide project that has confirmed the existence of multidecadal‐scale variability during this time period. The new record, which complements other existing ice core methane records, shows that multidecadal‐scale methane variability is only weakly correlated or uncorrelated with reconstructed temperature and precipitation variations. The authors also found that time periods when war or plague resulted in population declines are coincident with global atmospheric methane decreases. (Journal of Geophysical Research‐Biogeosciences, doi:10.1029/2010JG001441, 2011)