Heat waves connect abrupt polar climate changes during the past 67ka: evidence from sediment core GeoB3912-1

Monday, 15 December 2014
Xiao Yang and Jose A Rial, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
According to the hypothesis of polar synchronization, climate variations of Earth’s poles are connected with a persistent phase lock of π/2 throughout the last glacial period. However, it is not clear yet how the Earth’s two poles communicate with each other, the Thermohaline circulation (THC) being a possible candidate for signal carrier. Here we present a possible way of climate variation propagation through the Atlantic Ocean - likely in the form of heat or thermal wave (Cattaneo’s solution) - based on lagged correlation between an organic carbon climate proxy record from the tropical Atlantic and the south-north polar temperature gradient. We further demonstrate that the speed of such propagation is frequency dependent, of which the wave of the longest period travels the fastest at the speed of ~32 km/year consistent with the estimated speed of the THC. The observed speed – frequency relationship can be successfully modeled as resulting from a propagating dispersive thermal wave initiated by the polar temperature gradient maximum. We show that such heat wave propagation is a potential mechanism to couple and synchronize the polar climates during the last glacial period and to force the occurrence of Heinrich events. To summarize, the polar temperature gradient anomalies are consequence of the π/2 phase lock between the polar climates, which is caused by polar synchronization maintained by the coupling, which is, as the data suggest, in the form of thermal waves. The spikes in organic carbon and the Fe/Ca ratio records in the core GeoB3912-1 can be thought of as snapshots of the passage of strong meteorological wavefronts through the equatorial region. The results strongly suggest that each peak in the organic carbon recorded a half-hemisphere-delayed passage of a wave-like disturbance through the equator carrying the south-north temperature gradient maxima. And each of these occurs within timing error of the Heinrich events H0-H6.