Antarctica-New Zealand Interglacial Climate Extremes sought to understand the likely response of the New Zealand-Antarctic region to a warmer world.
ANZICE (Antarctica-New Zealand Interglacial Climate Extremes) was a scientific research programme funded by the New Zealand Foundation for Research Science and Technology operated from the Antarctic Research Centre at Victoria University. It was closely aligned with the FRST-funded Global Change Through Time programme at GNS Science and linked with the ice core, gas analysis group at NIWA.
The programme sought to understand the likely response of the New Zealand-Antarctic region to a warmer world. To achieve this aim, the project focused on environmental changes that occurred during peak warm periods in the past when the atmosphere and surface ocean were up to 3 degrees Celcius warmer than now.
Such temperature increases are in line with those indicated for the next century by the Intergovernmental Panel on Climate Change (IPCC). We believe that by deciphering detailed environmental records of the previous warm periods, we can provide a template for the future.
By evaluating past warm phases (ANZICE) aimed to:
- provide reconstructions of environment responses to rises in temperature
- develop the reconstructions into models to help identify potential changes and consequences for a projected warmer world
- apply model results to guide policy for New Zealand’s future.
To achieve these goals, ANZICE took a three pronged approach:
- Antarctic drivers of ocean-climate used new and existing records from ice cores to determine how Antarctica’s climate and ocean behaved during past warm phases such as occurred around 7,000-9,000 years ago (Holocene Climatic Optimum) and 125,000 years ago (Last Interglacial Period or Stage 5e).
- Southern Ocean-NZ responses relied on environmental data contained within sediment cores from the Southern Ocean to identify past responses of ocean waters and currents. The impact of such changes on New Zealand were gauged from glacial and lake records preserved onshore.
- Analogue and computer models drew on the above research results to develop models that help clarify our view of the future.
ANZICE introduced new techniques that greatly improved the ability to analyse, interpret and apply records of previous warmer climates.
Ice cores, collected from coastal sites, contain information with annual detail similar to tree rings. The cores were expected to recover ice at least 10,000 years old, and so included the Holocene Climatic Optimum.
Contained within the ice are a host of environmental clues:
- gases reveal the composition of the atmosphere
- isotopes of hydrogen and oxygen fingerprint atmospheric temperatures
- major and trace chemical elements reflect changes in the atmospheric circulation and storminess
- dust contents permit the study of winds, and the state of lands bordering Antarctic continent
- sulphates, fluoride and chloride identify volcanic activity
- the compound methylsuphonate can be used to measure sea-ice concentration.
Ice cores and samples are stored and processed at the state of the art New Zealand Ice Core Research Laboratory at the National Isotope Centre in Lower Hutt. This laboratory is a joint venture between GNS Science and Victoria University of Wellington, with assistance from NIWA.
The ice is analysed in laboratories at GNS Science, Victoria University, NIWA, the Universities of Maine and Hawai'i (USA) and the Alfred Wegener Institute (Germany).
Sediment cores from the ocean also hold a wealth of environmental information, much of which is tied up in the remains of plankton, in particular foraminifers.
As these animals form their sand-sized shell, they incorporate chemical elements and isotopes from the ocean. For example, the ratio of magnesium to calcium (Mg/Ca) relates to ocean temperature, and the ratio of barium to aluminium (Ba/Al) gives an insight into ocean fertility that involves the production of plant and animal plankton – the foundation of the marine food chain.
To unravel these chemical fingerprints ANZICE used Victoria University's laser ablation, inductively coupled plasma, mass spectrometer. This analytical system deploys a laser beam to “drill” through minute objects, measuring liberated elements en route.
The use of observation-based and computer-based models was another feature of ANZICE.
Information from the ice and sediment core studies was compiled to form observational models to help answer basic research questions, for example: how did the Antarctic environment appear during the Last Interglacial period, 125,000 years ago, and what was the impact on the Southern Ocean and New Zealand?
Answers to such questions helped guide and verify the computer models to give a measure of confidence in their results. Once operational, the computer models improved our ability to understand how an environment may change under various warmer world conditions.
By changing the drivers that control a model such as ocean and air temperatures, greenhouse gas concentrations, wind strength and other factors, it becomes possible to gain an insight into potential environmental responses, while checking the results with observations of the past.
As research results and computer models took shape, ANZICE turned to communicating the information to the public and governmental agencies involved with climate change. This initiative was not only to inform, but to help shape policy.