New Study: The 2016-2020 Antarctic Sea Ice Decline May Be Traced to Natural Processes

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Defying climate models, the sea ice surrounding Antarctica steadily increased during the 37 years from 1979-2015.

Even after many decades of studying climate processes and a supposed “consensus” that hemispheric-scale sea ice should decline in a rising CO2 concentration world, climate models cannot simulate the causative mechanisms for sea ice variability.

“Over recent decades Antarctic sea-ice extent has increased, alongside widespread ice shelf thinning and freshening of waters along the Antarctic margin. In contrast, Earth system models generally simulate a decrease in sea ice.”  – Ashley et al., 2021

“Antarctic sea ice extent (SIE) has slightly increased over the satellite observational period (1979 to the present) despite global warming. [F]ully coupled Earth system models run under historic and anthropogenic forcing generally fail to simulate positive SIE trends over this time period.”  – Blanchard-Wrigglesworth et al., 2021

Not just around Antarctica, but the sea ice in the entire Southern Hemisphere steadily increased from 1979-2015, in concert with the trends (cooling) in Southern Ocean sea surface temperature (Comiso et al., 2017).

Image Source: Comiso et al., 2017

New Study: Ice-Breaker Ship Saved By Cyclones

In contrast to the rising sea ice trends from 1979-2015, there were “record low” values of Antarctic sea ice recorded from 2016 to 2020. This short-term decline likely excited those who have a penchant for attributing any warming or decreasing sea ice trend to human activity (as they dismiss 37 years of cooling and sea ice increases).

But as a new study (Jena et al., 2022) once again shows, natural processes dominate as the causal mechanism driving sea ice variability in the Southern Hemisphere.

In April, 2019, a cargo ship was perilously stuck in sea ice in the Southern Ocean’s Lazarev Sea. The ice was so thick the ship’s ice-breakers could not forge a way out.

A causal mechanism analysis affirms that an anomalous series of “explosive polar cyclones” led to about a 10°C sea surface temperature increase (17-25 April) in the region, melting the ice surrounding the ship sufficiently enough to free it from the ice trap.

“We show that the anomalous sea ice variability was due to the occurrence of eastward-moving polar cyclones, including a quasistationary explosive development that impacted sea ice through extreme changes in ocean-atmospheric conditions. The cyclone-induced dynamic (poleward propagation of ocean waves and ice motion) and thermodynamic (heat and moisture plumes from midlatitudes, ocean mixed layer warming) processes coupled with high tides provided a conducive environment for an exceptional decline in sea ice over the region of ship movement.”

Nowhere in the paper do the authors mention anthropogenic CO2 emissions as a factor determining sea ice trends.

Image Source: Jena et al., 2022

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By Kenneth Richard on 30. May 2022