New Zealand climate in the Neogene and implications for global atmospheric circulation

Pole, Mike (2003) New Zealand climate in the Neogene and implications for global atmospheric circulation. Palaeogeography Palaeoclimatology Palaeoecology, 193 2: 269-284. doi:10.1016/S0031-0182(03)00232-3


Author Pole, Mike
Title New Zealand climate in the Neogene and implications for global atmospheric circulation
Journal name Palaeogeography Palaeoclimatology Palaeoecology   Check publisher's open access policy
ISSN 0031-0182
Publication date 2003-04-15
Sub-type Article (original research)
DOI 10.1016/S0031-0182(03)00232-3
Volume 193
Issue 2
Start page 269
End page 284
Total pages 16
Place of publication Amsterdam, The Netherlands
Publisher Elesevier Science BV
Language eng
Subject C1
260602 Climatology (incl. Palaeoclimatology)
770101 Climate change
780104 Earth sciences
260112 Palaeontology
Abstract New Zealand has a good Neogene plant fossil record. During the Miocene it was without high topography and it was highly maritime, meaning that its climate, and the resulting vegetation, would be controlled dominantly by zonal climate conditions. Its vegetation record during this time suggests the climate passed from an ever-wet and cool but frostless phase in the Early Miocene in which Nothofagus subgenus Brassospora was prominent. Then it became seasonally dry, with vegetation in which palms and Eucalyptus were prominent and fires were frequent, and in the mid-Miocene, it developed a dry-climate vegetation dominated by Casuarinaceae. These changes are reflected in a sedimentological change from acidic to alkaline chemistry and the appearance of regular charcoal in the record. The vegetation then changed again to include a prominent herb component including Chenopodiaceae and Asteraceae. Sphagnum became prominent, and Nothofagus returned, but mainly as the subgenus Fuscospora (presently restricted to temperate climates). This is interpreted as a return to a generally wet, but now cold climate, in which outbreaks of cold polar air and frost were frequent. The transient drying out of a small maritime island and the accompanying vegetation/climate sequence could be explained by a higher frequency of the Sub-Tropical High Pressure (STHP) cells (the descending limbs of the Hadley cells) over New Zealand during the Miocene. This may have resulted from an increased frequency of 'blocking', a synoptic situation which occurs in the region today. An alternative hypothesis, that the global STHP belt lay at a significantly higher latitude in the early Neogene (perhaps 55degreesS) than today (about 30degreesS), is considered less likely because of physical constraints on STHP belt latitude. In either case, the difference between the early Neogene and present situation may have been a response to an increased polar-equatorial temperature gradient. This contrasts with current climate models for the geological past in which the latitude of the High Pressure belt impact is held invariant though geological time. (C) 2003 Elsevier Science B.V. All rights reserved.
Keyword Geography, Physical
Geosciences, Multidisciplinary
Paleontology
Atmosphere
Circulation
New Zealand
Miocene
Palaeoclimatology
Early Miocene Flora
Australia-pacific Boundary
New-south-wales
Manuherikia Group
Southeastern Australia
Ocean Circulation
Central-otago
Vegetation
Pollen
History
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2004 Higher Education Research Data Collection
School of Biological Sciences Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 18 times in Thomson Reuters Web of Science Article | Citations
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Created: Wed, 15 Aug 2007, 05:14:37 EST