Clouds over the Southern Ocean hold the key to better climate change predictions, study says

  • Aug 08, 2020
  • Nelson Mail

To the untrained eye they are just fluffy, white shapes in the sky, but a team of New Zealand scientists say clouds could hold the key to more accurate climate change predictions.

A team from University of Canterbury (UC) assessed cloud formations in the Southern Ocean, near to Antarctica.

Despite the freezing temperatures and rough seas, they used hi-tech instruments to probe the atmosphere and collect highly detailed information about the structure and physics of clouds.

They discovered the current New Zealand Earth System Model - which is based on a British MetOffice climate model - simulates too few low-level clouds over the Southern Ocean, which could lead to errors.

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Their data will now be used by the United Nations Intergovernmental Panel on Climate Change (IPCC) and will provide greater accuracy, particularly when models are applied to the Southern Hemisphere.

Among the team was UC Research Associate Peter Kuma who said clouds are important because they regulate how much solar radiation reaches the planet’s surface, and they also absorb thermal radiation from Earth.

“Clouds are the biggest uncertainty for the models used when calculating climate change and the Southern Ocean is an area where they struggle the most,” he said.

“It’s one of the world’s most inaccessible places, so accurate measurements of clouds have been hard to get and are usually based on satellite information, which misses lower level cloud.

“It can’t be seen from space because it’s obscured by higher level cloud so having more accurate measurements from the ground is vital.”

To gather the data, Kuma spent time on the research vessel Tangaroa that visited the Campbell Plateau for two weeks in 2017 and six weeks in the Ross Sea in 2018 – but unlike many of his colleagues, he didn’t get seasick on the voyages.

“I just enjoy being outdoors so for me it felt natural,” he said.

“It’s an exciting place for climatologists to go because it’s a very under-studied place on the globe.

“Our results do not necessarily nullify previous research, but are an iterative improvement in our knowledge of the Southern Ocean clouds and identify an area where climate models are struggling currently.”

The project was led by Adrian McDonald, director of UC’s Gateway Antarctica, and is one of 44 initiatives organised as part of the Deep South National Science Challenge, which aims to better understand the role of the Antarctic and Southern Ocean in determining climate and the future environment.

The study was a collaboration between UC, National Institute of Water and Atmospheric Research (NIWA), the Australian Antarctic Division, University of Colorado and the New Zealand Defence Force.

The observations and data collected by the team during three-years of study have been analysed and will now help experts to accurately predict the impact of increasing greenhouse gases on the planet.

And the research findings appear in the international journal Atmospheric Chemistry of Physics.

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