Atmospheric Nitrous Oxide Variations on Centennial Time Scales During the Past Two Millennia

The continuous growth of atmospheric nitrous oxide (N 2 O) is of concern for its potential role in global warming and future stratospheric ozone destruction. Climate feedbacks that enhance N 2 O emissions in response to global warming are not well understood, and past records of N 2 O from ice cores are not sufficiently well resolved to examine the underlying climate‐N 2 O feedbacks on societally relevant time scales. Here, we present a new high‐resolution and high‐precision N 2 O reconstruction obtained from the Greenland NEEM (North Greenland Eemian Ice Drilling) and the Antarctic Styx Glacier ice cores. Covering the N 2 O history of the past two millennia, our reconstruction shows a centennial‐scale variability of ~10 ppb. A pronounced minimum at ~600 CE coincides with the reorganizations of tropical hydroclimate and ocean productivity changes. Comparisons with proxy records suggest association of centennial‐ to millennial‐scale variations in N 2 O with changes in tropical and subtropical land hydrology and marine productivity.