GLOBAL HOLOCENE CLIMATE FLUCTUATIONS EMPHASIED BY NEW ZEALAND PEATLANDS

• Main Author: Jack, Simon Andrew
• Format: Thesis
• Language: unknown
• Published: 2010
• Subjects: Greenland; New Zealand; Greenland ice cores; North Atlantic
• Online Access: http://hdl.handle.net/10026.2/926

The driving force behind centennial and millennial-scale periodicities in Greenland ice cores and North Atlantic sediments is open to debate. Comparable periodicities have been found in northwest European peat bogs but similar studies elsewhere are sparse. Here it is argued that the detection of comparable centennial and millennial-scale periodicities in a New Zealand peat humification profile suggests that the same forcing mechanism has been dominant during much of the Holocene. A number of mechanisms exist that might induce such periodicities in climate: changes in ocean circulation; inherent noise within the climate system; long-term tidal-cycles; variability in volcanic aerosol loading of the atmosphere and variation in solar irradiance. The latter is proposed as the prominent Holocene forcing mechanism and strength is given to this hypothesis by detection of coherent climatic shifts between two New Zealand peat bogs and bogs throughout Europe. Similarly, high-resolution pollen analysis provides evidence of a vegetation response coinciding with shifts to inferred wetter bog conditions in humification data at around 2800 cal. yrs BP and 4400 cal. yrs BP; two prominent episodes of increased bog surface wetness in northwest Europe. The recognition of the possible global dominance of solar forcing during the Holocene has important significance for the prediction of fiiture climate. Faculty of Science