Abstract
AbstractThe continuous growth of atmospheric nitrous oxide (N2O) is of concern for its potential role in global warming and future stratospheric ozone destruction. Climate feedbacks that enhance N2O emissions in response to global warming are not well understood, and past records of N2O from ice cores are not sufficiently well resolved to examine the underlying climate‐N2O feedbacks on societally relevant time scales. Here, we present a new high‐resolution and high‐precision N2O reconstruction obtained from the Greenland NEEM (North Greenland Eemian Ice Drilling) and the Antarctic Styx Glacier ice cores. Covering the N2O 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 N2O with changes in tropical and subtropical land hydrology and marine productivity.
Highlights
Improved knowledge of greenhouse gas‐climate feedbacks is required to understand past and future climate changes
We report new, high‐quality N2O records covering the last two millennia using ice cores obtained from Greenland and Antarctica
The 600 CE minimum was previously observed in the Law Dome ice core N2O record, the uncertainty of the N2O data (± 6.5 ppb) was not sufficient to resolve the magnitude of the N2O decrease (MacFarling Meure et al, 2006)
Summary
Improved knowledge of greenhouse gas‐climate feedbacks is required to understand past and future climate changes. With the regulation of chlorofluorocarbon emissions, N2O is becoming the most important ozone‐destroying substance in the stratosphere (Ravishankara et al, 2009). The atmospheric N2O concentration is primarily regulated by the balance of these terrestrial and oceanic sources (Freing et al, 2012) with the tropical stratospheric upwelling and photolysis in the stratosphere (Khosrawi et al, 2013; Olsen et al, 2001; Prather et al, 2015). Natural emissions are thought to be sensitive to future climate change (Battaglia & Joos, 2018; Denman et al, 2007; Martinez‐Rey et al, 2015; Voigt et al, 2017)
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