Reading Climate Change in Rocks: The Ice Age debate in New Zealand, 1860-1880

Abstract: The first wave of debate about the Ice Age in New Zealand occurred between 1860 and 1880. The pioneering geological surveys of Julius von Haast demonstrated that the glaciers of the Southern Alps of the South Island of New Zealand had been much more extensive in the past. Haast initially explained the geological evidence using Charles Lyell’s drift theory involving debris-laden icebergs, but he quickly abandoned this for a version of Louis Agassiz’s hypothesis of widespread terrestrial glaciation. Haast’s arguments set off a heated debate amongst New Zealand scientists. Haast and his interlocuters recognized that climate change could explain the evidence, but ultimately their consensus went against that view in favour of land elevation. Nevertheless, within this consensus there was considerable disagreement over how the sequence of events played out. Furthermore, around the edges of the main debate other figures argued that climate change had in fact occurred and they put forward a range of possible explanations for this from the role of a now-submerged “southern continent” to James Croll’s theory of climate change due to variations in the earth’s orbit. I contend that the resistance amongst leading New Zealand scientists to the notion of climate change stemmed primarily from their interpretation of Lyell’s uniformitarianism. However, geographically specific factors may have also contributed to their perspective: New Zealand is a chain of islands in the temperate belt, it is a tectonically active country, and its isolation entails a less variable fossil record than continental environments.

Biography: Ciaran is a PhD candidate in history of science at the School of Science in Society at Te Herenga Waka – Victoria University of Wellington. He is also a meteorologist at Te Ratonga Tirorangi – Meteorological Service of New Zealand and has taught meteorology to graduate students at Victoria University of Wellington.