A Last Interglacial cooling event in New Zealand and its regional teleconnections

Abstract:

The Last Interglacial (LIG) was the last time that temperatures were warmer than present, making it an interesting target for better understanding the consequences of global warming. Of particular interest is the smaller global ice volume which, in combination with ocean thermal expansion, contributed to sea levels reaching 6 to 9 metres above present. The ice-sheet source of the meltwater that contributed to this higher sea level is hotly debated. One way of addressing this issue to examine proxy records from the middle latitudes that should record a local climatic response to a high-latitude meltwater pulse.

In this presentation we report a new, precisely dated speleothem record from New Zealand’s South Island that preserves evidence a cooling event between 127.5 and 124. 5 ka. The event is consistent with cooling recorded in regional proxy records, and is broadly synchronous with cooling over Antarctica immediately following the Last Interglacial thermal optimum. We explore the links between the NZ speleothem record and proxy data from the high latitudes of both hemispheres. We then combine this information with climate-model simulations to determine whether the cooling over NZ could be in response to an Antarctic melt event, or if it represents a local response to AMOC recovery following a melting event in the northern high latitudes.