|Title:||Ice Core Evidence to support a Paleo Global Monsoon|
|Periodical:||American Geophysical Union, Spring Meeting 2013, abstract #U23A-04|
The notion that many of the monsoon regions are teleconnected over long timescales has gained traction recently. Numerous high resolution climate records from speleothem coral sites, high accumulation rate deep sea sediments, and ice cores tend to support the general notion of a global paleo-monsoon system that appears to be driven by changes in the latitudinal distribution of incident radiation. In particular, the atmospheric CH4 record from ice cores has been shown to follow tropical insolation variations with a strong precession index. High CH4 levels occur during periods of elevated summer insolation presumably related to enhanced tropical emissions from a growth in the areal extent of wetlands and elevated summer temperatures. Here we present a new ultra-high resolution atmospheric CH4 record from the recently completed WAIS divide Antarctic ice core (79S, 112W). Using a new automated CH4 analytical system, we have measured 2632 discrete samples throughout the entire core. The vast majority of the samples were taken from the glacial portion of the core (N=1706) with gas ages between 20 and 68ka, corresponding to roughly one sample every 30 years. Comparisons between our new CH4 record, the isotopic temperature record from the NGRIP ice core in Greenland, and various speleothem d18O records illustrates rather convincingly that all three proxies are responding to the same forcing. The phasing between the abrupt climatic events in all three records is not easily deciphered due to uncertainties in the independent timescales. However, the amazing covariation between these three proxy records is most easily explained by invoking strong teleconnections within the global hydrologic cycle that are paced by changes in incident radiation.