Can a little ice age climate signal be detected in the southern alps of New Zealand?
The Little Ice Age (LIA) was a late Holocene interval of climate cooling registered in the North Atlantic region by expansion of alpine glaciers and sea ice (Grove, 1988). Here the LIA includes an early phase from about AD 1280 to AD 1390, along with a main phase from about AD 1556 to AD 1860, follo...
| Main Author: | |
|---|---|
| Format: | Text |
| Language: | unknown |
| Published: |
DigitalCommons@UMaine
2001
|
| Subjects: | |
| Online Access: | https://digitalcommons.library.umaine.edu/etd/523 https://digitalcommons.library.umaine.edu/context/etd/article/1547/viewcontent/BlackJL2001.pdf |
| Summary: | The Little Ice Age (LIA) was a late Holocene interval of climate cooling registered in the North Atlantic region by expansion of alpine glaciers and sea ice (Grove, 1988). Here the LIA includes an early phase from about AD 1280 to AD 1390, along with a main phase from about AD 1556 to AD 1860, followed by warming and ice retreat (Holzhauser and Zumbiihl, 1999a). It has recently been demonstrated from records of North Atlantic ice-rafted debris that the LIA is the latest cooling episode in a pervasive 1500-year cycle of the climate system that may lie at the heart of abrupt climate change (Bond et al., 1999). This raises the question of whether the LIA climate signal is globally synchronous (implying atmospheric transfer of the climate signal) or out of phase between the polar hemispheres (implying ocean transfer of the climate signal by a bipolar seesaw of thennohaline circulation) (Broecker, 1998). New Zealand is ideally situated to address this problem as it is located on the opposite side of the planet from the North Atlantic region where the classic LIA signal is registered so clearly. Due to high precipitation and ablative activity gradients, glaciers in the Southern Alps of New Zealand respond to climate change on a decadal timescale (Chinn, 1996). Therefore, moraine sequences deposited during oscillations of these glaciers are ideal for determining the character of the LIA signal in this portion of the Southern Hemisphere. The chronology of the late Holocene moraine sequences fronting Hooker and Mueller Glaciers in the Southern Alps is controversial. Initial dating of these moraines from historical records, as well as from lichenometric and tree-ring analyses (Lawrence and Lawrence, 1965; Burrows, 1973), pointed to deposition in the LIA, indicating a global near-synchronous climate signal. In contrast, a subsequent chronology based on weathering rinds of surface clasts suggested that most of the late Holocene moraines antedate the LIA (Gellatly, 1984), implying lack of a classic LIA climate signal in this ... |
|---|