Atmospheric methane control mechanisms during the early Holocene

Ji-Woong Yang, Jinho Ahn, Edward J. Brook, Yeongjun Ryu
2017 Climate of the Past  
<p><strong>Abstract.</strong> Understanding processes controlling the atmospheric methane (CH<sub>4</sub>) mixing ratio is crucial to predict and mitigate future climate changes in this gas. Despite recent detailed studies of the last ∼ <span class="thinspace"></span>1000 to 2000 years, the mechanisms that control atmospheric CH<sub>4</sub> still remain unclear, partly because the late Holocene CH<sub>4</sub> budget may be comprised of both natural and anthropogenic emissions. In contrast, the
more » ... arly Holocene was a period when human influence was substantially smaller, allowing us to elucidate more clearly the natural controls under interglacial conditions more clearly. Here we present new high-resolution CH<sub>4</sub> records from Siple Dome, Antarctica, covering from 11.6 to 7.7 thousands of years before 1950<span class="thinspace"></span>AD (ka). We observe four local CH<sub>4</sub> minima on a roughly 1000-year spacing, which correspond to cool periods in Greenland. We hypothesize that the cooling in Greenland forced the Intertropical Convergence Zone (ITCZ) to migrate southward, reducing rainfall in northern tropical wetlands. The inter-polar difference (IPD) of CH<sub>4</sub> shows a gradual increase from the onset of the Holocene to ∼ <span class="thinspace"></span>9.5<span class="thinspace"></span>ka, which implies growth of boreal source strength following the climate warming in the northern extratropics during that period.</p>
doi:10.5194/cp-13-1227-2017 fatcat:sqce3b54irg3vjegfxr2c5x6pq