Cooling and changing seasonality in the Southern Alps, New Zealand during the Antarctic Cold Reversal

Abstract

A comprehensively 14 C AMS dated pollen and chironomid record from Boundary Stream Tarn provides the first chironomid-derived temperature reconstruction to quantify temperature change during Lateglacial times (17,500-10,000 cal yr BP) in the Southern Alps, New Zealand. The records indicate a ca 1000-year disruption to the Lateglacial warming trend and an overall cooling consistent with the Antarctic Cold Reversal (ACR). The main interval of chironomid-inferred summer temperature depression ($2-3 1C) lasted about 700 years during the ACR. Following this cooling event, both proxies indicate a warming step to temperatures slightly cooler than present during the Younger Dryas chronozone (12,900-11,500 cal yr BP). These results highlight a direct linkage between Antarctica and midlatitude terrestrial climate systems and the largely asynchronous nature of the interhemispheric climate system during the last glacial transition. The greater magnitude of temperature changes shown by the chironomid record is attributed to the response of the proxies to differences in seasonal climate with chironomids reflecting summer temperature and vegetation more strongly controlled by duration of winter or by minimum temperatures. These differences imply stronger seasonality at times during the Lateglacial, which may explain some of the variability between other paleoclimate records from New Zealand and have wider implications for understanding differences between proxy records for abrupt climate change. r

Glacier‐based climate reconstructions for the last glacial–interglacial transition: Arthur's Pass, New Zealand (43°S)

“…2010a). The magnitude of climate change indicated by our Misery moraine simulations shows good agreement with other proxy-based temperature estimates for the Antarctic Cold Reversal (Vandergoes et al, 2008;Doughty et al, 2013). Thus, it is possible that the Misery moraines may represent a glacier advance in the Arthur's Pass region during the Antarctic Cold Reversal.…”

“…Glacier advance during the Antarctic Cold Reversal followed by retreat during the Younger Dryas appears to be a common occurrence across the central Southern Alps (Kaplan et al ., ; Putnam et al ., ). The magnitude of climate change indicated by our Misery moraine simulations shows good agreement with other proxy‐based temperature estimates for the Antarctic Cold Reversal (Vandergoes et al ., ; Doughty et al ., ). Thus, it is possible that the Misery moraines may represent a glacier advance in the Arthur's Pass region during the Antarctic Cold Reversal.…”

A refined paleotemperature calibration for New Zealand limnic environments using differentiation of branched glycerol dialkyl glycerol tetraether (brGDGT) sources

“…The MAT values between 7.2 and 4.0 °C are in a similar range as previously inferred for the region and time interval (e.g. Vandergoes et al ., ; Jara et al ., ). This observed cooling trend, which probably reaches the Antarctic cold reversal, corresponds to the record derived from high‐resolution pollen data expressed as qualitative pollen–temperature proxy reconstruction from this lake over the last 16 000 years by Jara et al .…”

Low-resolution Australasian palaeoclimate records of the last 2000 years

“…A range of proxies have been used in other regions of the world to reconstruct terrestrial palaeotemperatures in low-resolution records (Marcott et al, 2013); however, they have not yet been applied to Australasian sites on the timescales examined here. Lake temperatures have been reconstructed through chironomid transfer functions on the east coast of Australia (Chang et al, 2015), Tasmania (Rees and Cwynar, 2010) and the South Island of New Zealand (Vandergoes et al, 2008;Woodward and Shulmeister, 2007) on timescales beyond the Common Era. Modern training sets exist for additional locations in Tasmania (Rees et al, 2008) and an additional location on the South Island, New Zealand (Dieffenbacher-Krall et al, 2007).…”