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Antarctic Sea Ice: ‘The beginning of the end!’ – again

Dr David Whitehouse, Science editor

The great sleeping giant that is Antarctica that — apart from the Antarctic Peninsula — refuses to respond to global warming may just have begun to stir, and the implications are, well, apocalyptic.

According to CNN “Antarctic sea ice hits record lows again. Scientists wonder if it’s “the beginning of the end.” CNN also reports that, “90% of ice around Antarctica has disappeared in less than a decade.”

CNN are not the only media outlets to report on this years’ record low sea ice around Antarctica in apocalyptic terms, other media extremists are available. For Sky News it’s the accelerating melt of polar regions. For the BBC “There is now less sea-ice surrounding the Antarctic continent than at any time since we began using satellites to measure it in the late 1970s.” All this is technically true, but misleading. When it’s put into context one sees a different picture.

So let’s have a look at the actual satellite data of Antarctic sea ice collected monthly since 1979. The NSIDC gives two data sets for what it calls i) sea ice extent, and ii) sea ice area. So let’s examine both of them.

The first graphs is sea ice area, the second sea ice extent.

From the empirical data it is evident that there is hardly any change of sea ice over the 44-year time span. Since 2016 there is a dip with possibly more variability (of which more later), and the lowest month (February) does show a record low, but by hardly anything (and also look at the data for 1992). Does this actual data look like the beginning of the end to you? Where is CNN’s 90% loss or Sky News acceleration?

Millions of sq km; Source: National Snow & Ice Data Center
Millions of sq km; Source: National Snow & Ice Data Center

Antarctic sea ice evolution has no significant trends along the whole period, but a volume drop is observed since 2016. Some scientists say there was a rapid decline in 2015/16, and record minima because believing that this ice loss marks an abrupt transition from a high to a low ice state that cannot be explained by year-to-year variability. Such a change is possibly associated with a long-term variability arising from ice–ocean feedbacks. Some evidence for this is that the transition was preceded by an increasing upper Southern Ocean density stratification, and an accumulation of heat at the subsurface; suggesting a decoupling of the surface from the subsurface ocean. In 2015/16, the upper ocean density stratification in the ice-covered region suddenly weakened, leading to a release of heat from the subsurface, contributing to the sea ice decline during winter. Perhaps this is a significant change in the coupled circumpolar ice–ocean system. Time will tell.

One could say that this prime example of science miscommunication is the fault of the NSIDC scientists and their comments posted on their website which were taken by journalists, and repeated without analysis or true context. So much of science journalism these days consists of “turning around” a press release.