Aaron Bunch Journalist with Australian Associated Press | Collection of published work | + 61 484 008 119 | abunch@aap.com.au

Aaron Bunch
Ice age sea level drops not linked to CO2

Climate scientists studying the Great Barrier Reef were surprised to discover that ice age sea levels dropped instead of rose as previously thought.

July 26, 2018

Climate change scientists have been surprised to learn that ice-age sea levels dropped instead of rose, and that they weren’t linked to carbon dioxide increasing in the atmosphere.

An abrupt 20-metre drop 20,000 years ago, which brought sea levels 130 metres below the present level, challenges all previous scientific assumptions about the last ice age.

“Our study is unique and completely rewrites the history of this period,” Australian National University climate specialist Dr Tezer Esat said in a statement on Thursday.

The international team studied more than 900 coral samples from the Great Barrier Reef and found there were rapid sea-level drops during the last ice age and corresponding increases in ice volumes globally.

Scientists also discovered the abrupt changes were not linked to any concrete climate indicators, such as changes in carbon dioxide levels or temperature.

Rather, it was discovered that climate could flip in just decades with small localised disruptions, such as the discharge of huge masses of ice.

“Transitions appear to have occurred spontaneously,” Dr Esat said.

After this period of sea-level drops, evidence indicates the ocean rose at an average rate of 1.6mm per year over 4000 years and it has continued rising to the present day.

Dr Esat said it was important to note that although the rapid ice-age changes were not caused by carbon dioxide concentrations, the gas is expected to contribute to future sea levels.

“Human activity is affecting the present climate and is expected to contribute to future sea-level rises,” he said.

Dr Esat said the Great Barrier Reef was an ideal location because corals found more 120 metres below the present sea level on the continental shelf reveal the dramatic changes of the period.

The research was published in the British journal Nature.


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