Scientists unlock a 2000 year ice core climate record

Aurora Basin project overview

Video transcript

The Aurora Basin project was a major ice coring project in East Antarctica to deliver us a long, 2000 year detail climate record form a part of Antarctica where we really had little or no information about past climate.

We do need climate records that go one or two thousand years or in this ballpark because they are used to test climate models of the past. And 2000 years gives us a nice long period to look at the climate before human interference began with the emission of carbon dioxide into the atmosphere. So we end up with over a thousand years of natural variability, seeing how it responds to changes in the sun’s output, seeing it responds to volcanoes and how the natural system works and that really important for understanding the changes that we are seeing now.

The drilling was part of an international project; we’ve got partners from Europe and America helping. And providing various analyses and putting the whole project together was French traverse to deliver the camp to the site and to get it up and running, provided a very broad sweep of science.

We had a lot of international participation in the camp, we had scientists from Denmark, France, the US, as well of as course Australian scientists. We had scientists also from China, and we had some student participation which brought in people from NZ, and also Japan. So, a very international team at times.

We got about 500 metres of ice in the main ice cores and we also took some shallow cores which will be about 30-50 metres, and on the traverse with the French we also recovered some shallow cores to another 20 metres so ice core scientists in France, Australia, and the US  are going to be busy for the next few years really digesting what we are going to get out of Aurora Basin.

The cores in the field were progressively brought out in insulated boxes and stored in a refrigerated container which has come back to Australia and those ice cores will be processed. Some of them have already been cut and sectioned and ready for distribution to our partners. That job needs to be completed here in Hobart before we can ship all the cores.

Our specialty here in Hobart will be to look at the water isotopes which will give us a temperature signal from the main ice core. That’s the work we have already started with the spectrometer in the field and the other strand is to look at trace chemistry, things like seas salts, volcanic emissions, things that get deposited in the ice that we can measure with ion chromatography. So we’ll be part of the big team.

Co-operation is absolutely essential in any project like this where you have tight timelines, large logistics, complications with weather  require flexibility and AB was gem for a model of co-operation in that sense. We had a logistical field leader who understood the science need and facilitated that and made the camp run smoothly, we had science leadership in the camp that was making smart decisions about how to get the science done.

But we have long term view to what is an international priority and that’s to find the oldest ice in Antarctica  which we believe is over a million years old and that almost certainly in the deep heart of Antarctica, even further than Aurora Basin.

This is very much a stepping stone for us. It’s a chance to contribute to that big cooperative ice to understand where the oldest ice will be and in learning how to operate in a remote  deep field camp refining our skills we are also paving the way for ongoing Australian participation.

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Five scientists in a drill tent with one using the Eclipse drill and others processing ice cores
Dr Tas van Ommen monitors the Australian Eclipse drill, used to drill a 116 m core. (Photo: Tony Fleming)
Drilling the main ice core inside a tent.Dr Mark Curran holds up a one-metre length of ice core.Tractors in a traverse train heading for Aurora Basin.The Aurora Basin camp site from the air.Scientists monitor computer screens for firn airThe laser spectrometer used to measure past temperature.Dr Mark Curran with a pallet of ice cores in insulated boxes, ready to fly to Casey station.Chef Jenny Carlisle in the kitchen tent.

An international contingent of polar scientists is set to unlock a 2000 year climate history from Antarctic ice cores drilled from the heart of the Australian Antarctic Territory over summer.

About two tonnes of ice core sections drilled at Aurora Basin, 500 kilometres inland of Australia’s Casey station, is being distributed to Australian and international ice core laboratories.

The cores will be analysed for atmospheric gases, particles and other chemical elements that were trapped in snow as it fell and compacted to form ice.

Australian Antarctic Division glaciologist and Leader of the Aurora Basin project, Dr Mark Curran, said the cores will help fill a gap in the science community’s knowledge of climate records.

“Using a variety of scientific tests on each core, we’ll be able to obtain information about the temperature under which the ice formed, storm events, solar and volcanic activity, sea ice extent, and the concentration of different atmospheric gases over time,” Dr Mark Curran said.

The team used a Danish Hans Tausen drill to extract the main 303 metre long ice core, which will provide annual climate records for the past 2000 years.

“There are only a handful of records with comparable resolution that extend to 2000 years from the whole of Antarctica, and this is only the second one from this sector of East Antarctica.”

Additionally two smaller drills were used to extract 116 and 103 metre cores, spanning the past 800 to 1000 years.

“These shorter cores will provide extra ice for large volume chemical analyses,” Dr Curran said.

All the ice cores were drilled in one metre sections over the five week field project.

A highlight of the drilling team’s work was obtaining a 300 year temperature record from the main ice core using a field-based ‘laser spectrometer’.

“The spectrometer allowed us to see the summer and winter snowfall variations in the ice. This detailed seasonal information is exactly what we wanted,” he said.

The project paves the way for a more ambitious drilling expedition to collect a one million year old ice core in the future.

“Such an ice core would help us understand what caused a dramatic shift in the frequency of ice ages about 800 000 years ago, and further understand the role of carbon dioxide in climate change,” Dr Curran said.

The Aurora Basin project involves 15 partner organisations contributing from six nations: Australia, China, Denmark, France Germany and the United States of America.

Further background information is available on the Aurora Basin website.