Climate science: timing is everything during deglaciations.

Abstract

Links between various climate records for the North Atlantic Ocean and the Mediterranean Sea have helped to identify a potential mechanism that enhanced sea-level rise during the last interglacial time interval. See Letter p.197 A central goal of palaeoclimate research is that of deciphering the mechanisms responsible for major state shifts in the Earth system, such as between glacial and interglacial conditions. This has proven difficult enough even for the last glacial termination (T-I), much less termination II (T-II), which ended glacial conditions about 130,000 years ago. Gianluca Marino et al. use new and existing data to demonstrate a link, within uncertainties, between Heinrich Stadial 11 (HS11) — a prominent Northern Hemisphere cold event — and the timing of peak sea level rise during T-II. A strong Southern Hemisphere warming also occurred during HS11, consistent with the idea of a bipolar seesaw that would probably have promoted Antarctic ice sheet melting. In contrast, rapid sea level rise in T-1 clearly postdated Heinrich Stadial 1. Possibly in response to differing CO2 and insolation conditions during T-I and T-II, fundamentally different mechanisms seem to be at work in triggering glacial terminations.