FACT SHEETS

Looking at past climates to understand the present — and predict the future

20.02.20 by By Zoë Taylor

As we grapple with the reality of climate change and imagine what it will be like to live in a warmer world, CABAH researchers are looking for answers to some big questions in some surprising places.

For the past hundred thousand years or so, the continent has been much cooler than it is at present. If we want to know what Australia will be like as the climate warms — and to plan for it — it’s important to understand what drives the region’s climate. We need to look into past patterns of climate extremes and how people and the environment responded to them.

But how can we investigate climate patterns from thousands of years ago? Written records of climate indicators, like rainfall, only stretch back 50 to 100 years or so. That’s why CABAH researchers, working in our Climate research theme, are searching for evidence of past climates in the current landscape. 

Surveying an archaeological site at Lake Woods, Northern Territory. Image credit: Aara Welz
Reconstructing past climate patterns
can help us answer questions like: Will the continent become wetter or dryer as the climate warms?
We can find evidence of past climates in the current landscapes
by looking for clues hidden in the natural world, like lakes and trees.

Reconstructing past landscapes

They are working to understand climate extremes in Australia’s past — and links to deep time. The multidisciplinary research team wants to answer questions like; ‘Are droughts becoming more frequent?’ or “Will the continent become wetter or dryer as the climate warms?’

And they are using sophisticated methods to retrieve and analyse geological data to reconstruct past climates and landscapes. Sometimes the clues to fill gaps in our climate history come in the form of metres of mud extracted from the beds of former lakes, sometimes from looking at the rings hidden in trees and sometimes from traces of microscopic pollen and charcoal.

CABAH researcher Jonathan Palmer explains his work studying past climates through tree rings.

Claudette Albert looking at surface artefacts at Lake Woods, Northern Territory. Image credit: Aara Welz

Each puzzle piece — along with knowledge from Traditional Owners — helps to paint a clearer picture of the region’s patterns of past climate change, and how people and the environment changed and adapted.

Climate research theme leader Associate Professor Tim Cohen explains: “We want to understand when Australia experienced wet and dry periods and how the environment responded to it. We are trying to understand how it happened and when it happened. Did it happen everywhere at the same time or did it happen in certain parts of the continent at different times?

Each puzzle piece — along with knowledge from Traditional Owners — helps to paint a clearer picture of the region’s patterns of past climate change, and how people and the environment changed and adapted.

Climate research theme leader Associate Professor Tim Cohen explains: “We want to understand when Australia experienced wet and dry periods and how the environment responded to it. We are trying to understand how it happened and when it happened. Did it happen everywhere at the same time or did it happen in certain parts of the continent at different times?

Tim Cohen collecting samples at the Lake Woods, Northern Territory. Image credit Aara Welz

 

“Understanding when in history we had past periods of drought or wet will give us an insight and a capacity to improve our predictions for what is going to happen as the planet warms.”

 

Cohen, a geomorphologist and Quaternary scientist at the University of Wollongong, and his team are working on lakes across Australia — and in Eastern Indonesia — and extracting the sediment contained in them.

 

Students learning about collecting and analysing lake sediment cores.
A sediment core from Thirlmere Lake, NSW.

“Our work involves digging holes, taking cores, and analysing the sediments within them. Those sediments are more or less layered like a cake and the internal structure of the cake tells us a story about the history of the climate for that region.”

These geological findings are not considered in isolation.  At CABAH, researchers from a range of disciplines, including ecologists, archaeologists and geneticists work together.

“That allows us to answer some very broad and important questions — from whether the climate is getting warmer and wetter or dryer, to understanding how people have responded to that, and how Aboriginal and Torres Strait Islanders have managed those landscapes and responded to these climate fluctuations over time,” Cohen says.

CABAH and University of Wollongong students learning about collecting and analysing lake sediment cores, which can be used to provide a window back thousands of years to help reconstruct past climates and landscapes.

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