Here, we present some preliminary results from a transient modeling work covering the last 22,000 years by using NCAR CCSM3, and compare our results with millennium reconstructions as well as centennial reanalysis. It is shown that AA is a solid and robust mode throughout the past 22,000 years with a typical ratio around 2.47, especially when the change of NH temperature is greater than 0.5 K/100a. Our findings suggest that AA can be linked to comprehensive air-sea-ice coupling process in polar areas as response to huge natural external forcing, like glacial-to-interglacial scale, rather than just minor anthropogenic forcing in the last century or even internal noise within climate system.
This study presents a more complete picture of AA’s long-term variability on the timescales far beyond anthropogenic influences, which broaden our views and improve our understanding of modern climate changes at high-latitudes and polar regions.