2020 Fellow - Adele Morrison, Australian National University

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12 October 2020

How long do we have until our cities will be under sea level?

As climate change continues to progress at a rapid rate, researchers are trying to understand how much, and how quickly, Earth's glaciers will melt.  

There are multiple factors causing sea level to rise, including water expansion as the ocean warms and the melting of Greenland, however the biggest uncertainty in predicting future sea level rise comes from Antarctica. The main way Antarctica melts is from warm waters flowing underneath and over time, due to effects of climate change, the ocean around Antarctica has been warming.

“If all of Antarctica was to melt, it would increase sea level by almost 60m - that would see cities like Sydney disappear.”

As the scientific community work to better constrain future rates of Antarctic ice melt, Physical Oceanographer, Dr Adele Morrison looks to better understand the ocean circulation, its dynamics, and feedbacks relating to warm water intrusion onto the Antarctic continental shelf. Adele’s research looks to understand the processes underpinning ocean variability and change around the Antarctic margin, which are fundamental to predicting future sea-level rise.

Many cities are positioned just above sea level, therefore rising sea level will mean we have to move or protect these cities in the future. Adele’s research will help in understanding how quickly this will have to occur.

“At the moment the best estimate, assuming continued emissions, is up to 1.1 m of sea level rise by the end of the century - equating to over 600 million people living below the projected high tide line.”

Adele uses computer modelling to study the ocean currents around Antarctica, allowing her to understand the impact of very small and difficult to measure processes.

“I predict the future melt rates using the fastest supercomputer in Australia. I simulate how the ocean currents will change and the consequences for melting the Antarctic ice sheet. Although the sense of discovery is exciting, it’s also a scary future if we cannot curb the progression of climate change.”

With 40% of the global population and 85% of the Australian population currently living within coastal regions, sea level rise from the melting of Antarctica’s ice sheets is of major concern. Under a business-as-usual scenario, there could be more than 1 m of sea level rise by 2100, and more than 5 m by 2300. However, these projections depend heavily on the future path of carbon emissions.

“We can choose a future with less sea level rise. By limiting global warming to below 2°C, we can limit sea level rise to only around 40cm by 2100. But we need to act fast.”

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