The tale of an Antarctic octopus and the vulnerable West Antarctic Ice Sheet

Recent genetic analyses of an Antarctic octopus have shed light on the collapse of the West Antarctic Ice Sheet (WAIS) during the Last Interglacial period, approximately 129,000 to 116,000 years ago.

Despite a mere 1 degree Celsius increase in temperatures from preindustrial levels, the WAIS collapsed, emphasizing the vulnerability of this ice sheet to even minimal temperature rises.

These findings have significant implications for our understanding of future climate change and its impact on the cryosphere, particularly the potential irreversible collapse of the WAIS.

Vulnerability of the West Antarctic Ice Sheet

The West Antarctic Ice Sheet is known to be particularly susceptible to warming temperatures, and it could reach a critical tipping point within the current global climate targets of 1.5 to 2 °C.

The consequences of a total collapse of the WAIS would be severe, leading to an estimated global sea-level rise of 3 to 5 meters.

Given that global sea levels during the Last Interglacial period were 5 to 10 meters higher than preindustrial levels and temperatures were approximately 0.5 to 1.5 °C warmer, understanding how the WAIS responded to such conditions in the past is crucial for predicting its fate in our rapidly warming future.

Despite growing evidence suggesting the potential collapse of the WAIS during the Last Interglacial period, current oceanographic and modeling studies have produced conflicting and inconclusive results.

To address these uncertainties, Sally Lau and her colleagues took a unique approach by examining the genetic history of Turquet’s octopus (Pareledone turqueti). This species is found in the Weddell, Amundsen, and Ross Seas, geographically isolated and separated by the WAIS.

The octopus and the WAIS collapse

Lau et al. conducted genetic analyses, sequencing genome-wide single nucleotide polymorphisms in 96 octopuses collected from the Southern Ocean.

They discovered distinct genetic populations of the octopus but observed signs of admixture between the Ross Sea and the Weddell Sea.

This indicates a historical gene flow between these regions during the Last Interglacial period. The persistence and historic signals of gene flow suggest that the two seas were connected by an interior open waterway, where the WAIS now occupies.

This supports the hypothesis of complete WAIS collapse during the Last Interglacial. Andrea Dutton and Rob DeConto, in a related Perspective, highlight the significance of these findings.

They wrote, “Whether or not this analysis withstands further scrutiny and the test of time, the implications of this result pose some intriguing questions, including whether this history will be repeated, given Earth’s current temperature trajectory.”

Learning from the past to understand the future

This research underscores the importance of understanding past climate events and the potential for similar outcomes in the future.

The genetic analyses of Turquet’s octopus provide valuable insights into the collapse of the West Antarctic Ice Sheet during the Last Interglacial period.

This research highlights the vulnerability of the WAIS to even minimal temperature rises and emphasizes the need to comprehend its response to warming climates. As global temperatures continue to rise, understanding the consequences of potential WAIS collapse becomes increasingly critical.

In summary, by studying the past, we can shape a better understanding of our rapidly changing future and develop effective strategies to mitigate the impact of climate change on our planet.

The full study was published in the journal Science.

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