title: Regional cooling caused recent New Zealand glacier advances in a period of global warming.
abstract: Glaciers experienced worldwide retreat during the twentieth and early twenty first centuries, and the negative trend in global glacier mass balance since the early 1990s is predominantly a response to anthropogenic climate warming. The exceptional terminus advance of some glaciers during recent global warming is thought to relate to locally specific climate conditions, such as increased precipitation. In New Zealand, at least 58 glaciers advanced between 1983 and 2008, and Franz Josef and Fox glaciers advanced nearly continuously during this time. Here we show that the glacier advance phase resulted predominantly from discrete periods of reduced air temperature, rather than increased precipitation. The lower temperatures were associated with anomalous southerly winds and low sea surface temperature in the Tasman Sea region. These conditions result from variability in the structure of the extratropical atmospheric circulation over the South Pacific. While this sequence of climate variability and its effect on New Zealand glaciers is unusual on a global scale, it remains consistent with a climate system that is being modified by humans.
authors.affiliation: Antarctic Research Centre, Victoria University of Wellington, Wellington 6140, New Zealand.|School of Geography, Environment and Earth Sciences, Victoria University of Wellington, Wellington 6140, New Zealand.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Mackintosh
authors.affiliation: Antarctic Research Centre, Victoria University of Wellington, Wellington 6140, New Zealand.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Anderson
authors.affiliation: National Institute of Water and Atmospheric Research, Auckland 1010, New Zealand.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Lorrey
authors.affiliation: School of Geography, Environment and Earth Sciences, Victoria University of Wellington, Wellington 6140, New Zealand.
authors.forename: James A
authors.initials: JA
authors.lastname: Renwick
authors.affiliation: Antarctic Research Centre, Victoria University of Wellington, Wellington 6140, New Zealand.
authors.forename: Prisco
authors.initials: P
authors.lastname: Frei
authors.affiliation: National Institute of Water and Atmospheric Research, Wellington 6021, New Zealand.
authors.forename: Sam M
authors.initials: SM
authors.lastname: Dean