Archives par mot-clé : Southern Ocean

Study finds Southern Ocean’s surface is becoming saltier and losing sea ice, not experiencing an ‘ocean current reversal’

by ScienceFeedback, July, 2025


KEY TAKEAWAY

Recent articles and social media posts inaccurately summarized findings from a June 2025 PNAS paper by claiming that a ‘major current in the Southern Ocean has reversed’. In reality, the PNAS paper does not mention any ‘ocean current reversal’. Instead, the paper mentions a ‘reversal’ of a decades-long trend: the Southern Ocean’s surface is now becoming saltier, instead of ‘fresher’. A saltier ocean surface can speed up the melting of Antarctic sea ice – floating ice which surrounds Antarctica – by drawing heat in the ocean upward toward the ice. This trend surprised scientists in the study, given that prior observations show the Southern Ocean’s surface becoming fresher (less salty) since the 1980s.

Figure 1 – Plot showing that sea ice began retreating around 2015 when the Southern Ocean’s surface became saltier, as shown by the red line representing sea surface salinity (SSS) anomalies obtained via satellite. Source: Silvano et al. (2025)[1]

Ocean “Reversal” Hysteria: Facts Not Included

by W. Eschenbach, July 6, 2025 in WUWT


ery so often, the climate media machine spits out a headline so breathless you’d think the laws of physics had just been accidentally repealed by a badly-worded executive order. Case in point: bne IntelliNews in Germany recently told us that a “major ocean current in the Southern Hemisphere has reversed direction for the first time in recorded history,” and that climatologists are calling it a“catastrophic” tipping point. It also quotes a climatologist as saying “The stunning reversal of ocean circulation in the Southern Hemisphere confirms the global climate system has entered a catastrophic phase.”

And the headline for that hysteria?

Southern Ocean current reverses for first time, signalling risk of climate system collapse

The implication: pack your bags, the climate apocalypse is here, and don’t forget your floaties.

But as is so often the case, the devil isn’t just in the details—it’s in the words they didn’t mention. The article, like a magician with something up both sleeves, never links to the actual scientific study.

So, after a bit of digital spelunking, I dug up the source. It’s an article in PNAS, the Proceedings of the National Academy of Sciences, yclept “Rising surface salinity and declining sea ice: A new Southern Ocean state revealed by satellites.”

And when I got to the study, what do you know? The study doesn’t mention “tipping point,” “collapse,” “current reversal,” “Southern Ocean current” or even “overturning circulation.” The only “reversal” in the paper refers to satellites detecting a reversal in surface salinity trends from decreasing to increasing, not a reversal in the the direction of the Southern ocean’s most complex circulation shown above.

So what did the study actually say? Here’s the paper’s abstract:

“For decades, the surface of the polar Southern Ocean (south of 50°S) has been freshening—an expected response to a warming climate. This freshening enhanced upper-ocean stratification, reducing the upward transport of subsurface heat and possibly contributing to sea ice expansion. It also limited the formation of open-ocean polynyas. Using satellite observations, we reveal a marked increase in surface salinity across the circumpolar Southern Ocean since 2015. This shift has weakened upper-ocean stratification, coinciding with a dramatic decline in Antarctic sea ice coverage. Additionally, rising salinity facilitated the reemergence of the Maud Rise polynya in the Weddell Sea, a phenomenon last observed in the mid-1970s. Crucially, we demonstrate that satellites can now monitor these changes in real time, providing essential evidence of the Southern Ocean’s potential transition toward persistently reduced sea ice coverage.”

‘A Significant And Robust Cooling Trend’ In The Southern Ocean From 1982–2020 Defies Climate Models

by K. Richard, June 27, 2022 in NoTricksZone


A new study reports there has been a -0.3°C cooling in the Southern Ocean since 1982 per multiple observational data sets. The authors detail the “failure of CMIP5 models in simulating the observed SST cooling in the Southern Ocean.”

The Southern Ocean is today about 1-2°C colder than it has been for nearly all of the last 10,000 years (Shuttleworth et al., 2021, Civel-Mazens et al., 2021, Ghadi et al., 2020).

Image Source: Shuttleworth et al., 2021