Atmospheric N2O during the last two millennia

Atmospheric nitrous oxide (N2O) is an important long-lived greenhouse gas and effective stratospheric ozone destroyer. Despite its essential roles in climate, the control mechanisms of atmospheric N2O remain poorly understood. In order to reconstruct atmospheric N2O during pre-industrial era, we precisely analyzed ice core samples from NEEM site in North Greenland and Styx glacier in East Antarctica. The N2O records cover the last two millennia with a precision better than 1.3 ppb and averaged temporal resolution of 10 years, sufficient to constrain centennial-scale variations. The N2O records from Styx and NEEM ice commonly show distinctive centennial-scale variations. The timings of rapid N2O changes are coincident each other. The rates of rapid N2O changes are comparable to current ones which is strongly affected by anthropogenic sources. Our findings suggest that there was significant natural and/or anthropogenic variability of atmospheric N2O during pre-industrial era. Further studies will include discussion about relationship between N2O and other paleoclimate records to better understand the underlying control mechanism of atmospheric N2O.