Apr 15, 2015
Icebergs not the trigger for North Atlantic cold events
- Results reveal the intimate association between ice rafting and high-latitude temperature variability over the last four glacial cycles with unprecedented detail
- Cites previous studies that identified an apparent lag between North Atlantic cooling events and the appearance of ice-rafted debris over the last glacial cycle, leading to the hypothesis that iceberg discharge may be a consequence of stadial conditions rather than the cause
- Further establishes this relationship and demonstrates a systematic delay between pronounced surface cooling and the arrival of ice-rafted debris at a site southwest of Iceland over the past four glacial cycles, implying that in general icebergs arrived too late to have triggered cooling
- Suggests abrupt transitions to stadial conditions should be considered as a nonlinear response to more gradual cooling across the North Atlantic
- Finds that although the freshwater derived from melting icebergs may provide a positive feedback for enhancing and or prolonging stadial conditions, it does not trigger northern stadial events.
- Findings suggest that stadial transitions may occur as a nonlinear response to more gradual cooling, implying the existence of a threshold beyond which the transition to a stadial state becomes inevitable