Anthropogenic impacts on atmospheric carbonyl sulfide since the 19th
century inferred from polar firn air and ice core measurements
Abstract
Carbonyl sulfide (COS) was measured in firn air collected during seven
different field campaigns carried out at four different sites in
Greenland and Antarctica between 2001 and 2015. A Bayesian probabilistic
statistical model is used to conduct multi-site inversions and to
reconstruct separate atmospheric histories for Greenland and Antarctica.
The firn air inversions cover most of the 20 century over Greenland and
extend back to the 19 century over Antarctica. The derived atmospheric
histories are consistent with independent surface air time-series data
from the corresponding sites and the Antarctic ice core COS records
during periods of overlap. Atmospheric COS levels began to increase over
preindustrial levels starting in the 19 century and the increase
continued for much of the 20 century. Atmospheric COS peaked at higher
than present-day levels around 1975 CE over Greenland and around 1987 CE
over Antarctica. An atmosphere/surface ocean box model is used to
investigate the possible causes of observed variability. The results
suggest that changes in the magnitude and location of anthropogenic
sources have had a strong influence on the observed atmospheric COS
variability.