C3W researcher Dr Ann Rowan of Aberystwyth University has used the debris left behind by past glaciers to reconstruct how the climate changed during the last ice age.
Mountain ranges in the temperate middle latitudes, such as the Southern Alps of New Zealand, the Rockies and the European Alps, contain large numbers of glaciers. At the end of the last ice age, around 20,000 years ago, these glaciers rapidly receded as climate warmed from glacial conditions to the present-day. While these mountain glaciers advanced during the ice age and receded afterwards they moved sediment around to create moraines, and these moraines form a geological record of past climate change.
Dr Rowan and colleagues used the geological evidence of glaciation as the starting point for computer model simulations of these extinct glaciers to discover why glaciers advanced or receded and how fast climate changed over the last 30,000 years. They found that large glaciers in the Southern Alps including the Rakaia and Rangitata Glaciers receded very rapidly from their ice age maxima driven by warming temperatures. At the same time, glaciers in the Northern Hemisphere were advancing, suggesting that glaciations alternate between the hemispheres, and that the global climate system responds rapidly to changes in atmospheric temperatures.
Rowan, A V, Brocklehurst, S H, Schultz, D M, Plummer, M A, Anderson, L S, Glasser, N F, 2014. Late Quaternary glacier sensitivity to temperature and precipitation distribution in the Southern Alps of New Zealand. Journal of Geophysical Research: Earth Surface, 119, 1064-1081