Hotter tropical pool ‘temporarily’ slows Antarctic ice loss, study claims

Antarctica

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How temporary was this? The article below says: ‘Further observations and simulations showed that similar sustained tropical warm-pool warming events occur approximately once every decade.’ The really massive snow dump is described as ‘brief’. It smacks of an attempt to play down a significant event, even if the current trend for snow cover in the region is tending downwards. Simulations can’t be any guarantee of future weather or climate, so don’t ‘show’ anything. If the warm pool is getting warmer, might that mean more and/or larger events like this? Nobody knows.
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A warming pool of tropical ocean acted like a “regulator,” dialing up snowstorms over East Antarctica and contributing to a brief net ice-sheet mass gain of 695 billion tons, according to a new study published in Nature on August 19.

The study revealed that sustained warming of the tropical warm pool during 2021–23 triggered a Rossby wave train propagating toward Antarctica, formed a north–south dipole circulation over East Antarctica, reorganized moisture transport, and enhanced regional snowfall, thereby temporarily slowing Antarctic ice-sheet mass loss, says EurekAlert.

The Antarctic Ice Sheet is one of the major sources of uncertainty in future global sea-level rise.

Over the past two decades, it has experienced sustained mass loss at a rate of approximately 140.5 billion tons per year. However, its mass increased by about 695 billion tons during 2021–23, marking the largest mass-gain event recorded by the GRACE satellites.

To identify the cause, a research team led by the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) combined gravity-satellite observations, ice-core snow-accumulation records, and atmospheric circulation model simulations to investigate the atmospheric circulation mechanisms and moisture sources underlying this mass-gain event.

The results showed that, during 2021–23, sustained warming occurred in the tropical warm pool located in the region where the tropical western Pacific and eastern Indian Ocean meet. This warming triggered a Rossby wave train toward high southern latitudes.

Eddy-mean flow feedbacks amplified and sustained the resulting circulation, establishing a north–south dipole with low- and high-pressure anomalies south of Australia and along the East Antarctic coast, respectively. The dipole redirected moisture and enhanced atmospheric-river transport from the midlatitude Indian Ocean to East Antarctica.
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Further observations and simulations showed that similar sustained tropical warm-pool warming events occur approximately once every decade. The tropical warm pool therefore acts like a remote “regulator,” influencing multiyear variations in snowfall and ice mass over East Antarctica.

Full article here.