Climate amelioration during the Last Glacial Maximum recorded by a sensitive mountain glacier in New Zealand

Shaun R. Eaves, Andrew N. Mackintosh, Brian M. Anderson

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Well-dated moraine chronologies indicate that New Zealand glaciers retreated between the onset and the peak of the global Last Glacial Maximum (30-18 ka). The cause of New Zealand net glacier decline during what is thought to have been a ubiquitously cold climate is not known. Here we use a glacier modeling approach to explain the remarkable demise of a former glacier in the Cobb River valley (South Island), which retreated by > 50% prior to 20 ka, and may have melted completely by 18 ka-prior to the onset of rapid deglaciation evident across the southern mid-latitudes during Heinrich Stadial 1. Modeling experiments show that this glacier had an amplified response to modest climate forcing, requiring only a minor atmospheric warming (+0.5 °C) or precipitation reduction ( > 15%) to force retreat. Our results, when considered alongside pollen and speleothem evidence from the region, indicate that minor interstadial warming and/or drying of the atmosphere in New Zealand drove regional glacier retreat prior to 20 ka. Our results reinforce that mountain glaciers are sensitive indicators of climate change-but highlight that some are more sensitive than others. This high-sensitivity glacier record provides quantitative constraint of low-magnitude climate forcing that immediately preceded the abrupt Southern Hemisphere transition out of the Last Glacial Maximum.

Original languageEnglish
Pages (from-to)299-302
Number of pages4
JournalGeology
Volume47
Issue number4
DOIs
Publication statusPublished - 1 Apr 2019
Externally publishedYes

Keywords

  • Geothermal fields
  • Volcanoes
  • geothermal system

Cite this

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abstract = "Well-dated moraine chronologies indicate that New Zealand glaciers retreated between the onset and the peak of the global Last Glacial Maximum (30-18 ka). The cause of New Zealand net glacier decline during what is thought to have been a ubiquitously cold climate is not known. Here we use a glacier modeling approach to explain the remarkable demise of a former glacier in the Cobb River valley (South Island), which retreated by > 50{\%} prior to 20 ka, and may have melted completely by 18 ka-prior to the onset of rapid deglaciation evident across the southern mid-latitudes during Heinrich Stadial 1. Modeling experiments show that this glacier had an amplified response to modest climate forcing, requiring only a minor atmospheric warming (+0.5 °C) or precipitation reduction ( > 15{\%}) to force retreat. Our results, when considered alongside pollen and speleothem evidence from the region, indicate that minor interstadial warming and/or drying of the atmosphere in New Zealand drove regional glacier retreat prior to 20 ka. Our results reinforce that mountain glaciers are sensitive indicators of climate change-but highlight that some are more sensitive than others. This high-sensitivity glacier record provides quantitative constraint of low-magnitude climate forcing that immediately preceded the abrupt Southern Hemisphere transition out of the Last Glacial Maximum.",
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Climate amelioration during the Last Glacial Maximum recorded by a sensitive mountain glacier in New Zealand. / Eaves, Shaun R.; Mackintosh, Andrew N.; Anderson, Brian M.

In: Geology, Vol. 47, No. 4, 01.04.2019, p. 299-302.

Research output: Contribution to journalArticleResearchpeer-review

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