Studying elements archived within ice cores offers scientists valuable information on climate variability. Sea-level rises, global warming, extreme weather changes. These are just some of the signals used by scientists to show that the earth's climate has altered.
But while mounting evidence points to the detrimental impact this has on the Earth exactly what triggers those changes is still being debated.
So how can scientists understand what influences climate?
Among a number of techniques being used to study past climate history and how this might shed light on future impacts, scientists have been studying ice cores.
Tiny bubbles and elements trapped in ice are telling us a great deal about past climate and the dramatic impact humans may have on future climate.
Dr Tas van Ommen, Principal Research Scientist with the Australian Antarctic Division in Hobart, is one of the leading experts in ice core studies and gave some insight into this science at a recent visit to ANSTO.
Speaking as part of a Distinguished Lecture series hosted by ANSTO, Dr van Ommen said that ice cores in the Antarctic are arguably the richest source of past climate information from recent times, and he feared that this record is backing up a famous quotation by climatologist, Dr Wally Broecker that, “The climate system is an angry beast and we are poking it with sticks.”
Ice cores and climate variability
According to the Australian Antartic Division's website, ice cores hold climate records from specific geographical locations dating back hundreds of thousands of years.
Polar regions, and some alpine areas, are sufficiently cold that snowfall accumulates from year to year, building up as glaciers.
As snow at the surface gets buried with time it gets compressed to form solid ice and this ice carries with it information about the climate when the snow originally fell.
By drilling down into a glacier and recovering this old ice, the information can be extracted to help understand past climate.
As part of the Australian Antarctic Program, Dr van Ommen has been closely involved with studies into ice cores gathered from Law Dome, which provide a record going as far back as 80,000 years.
“Ice cores capture tracers for the major climate forcings and feedbacks. These include atmospheric concentrations of CO2 and other active gases (from trapped bubbles), aerosols (from dissolved chemicals) and solar variability (from beryllium-10),” Dr Van Ommen said.
“Ice cores record the climate response in temperature, precipitation, atmospheric circulation, and even biogenic responses.
“Our studies of ice cores provide a record of relatively recent changes and anthropogenic influence. When compared with meteorological records, this makes ice core records a valuable adjunct to direct observation to characterise natural variability and in climate studies.”
Australian impact
Dr van Ommen noted that the ice core record from the northern and southern hemispheres shows that climate variability has not been uniform something that is put down to enormous changes in water circulation in the world’s oceans.
One of the interesting findings of these Antarctic studies is that high snowfall in some areas of the Antarctic appears to have a correlation with low rainfall in south-western Australia, and more snow in Antarctica since 1970 has corresponded with drier conditions around Perth.
There are still many questions to be answered, which Dr van Ommen hopes further research will help piece together the past climate puzzle both here in Australia and further abroad.
The future of these studies will include investigating what determines the end of an ice age, and to finding deeper ice cores to provide records older than 800,000 years.
“Data from these records is vital for building models about the likely outcomes of climate variability,” Dr van Ommen said.
Published: 01/12/2011