Scientists at the British Antarctic Survey (BAS) discovered that record-low sea ice levels around Antarctica in 2023 were highly unlikely to occur without the influence of climate change. Without climate change, this low would have occurred once every 2000 years, but it would have been four times more common. The findings were published in the journal Geophysical Research Letters on May 20, with the heading “CMIP6 models rarely simulate Antarctic winter sea-ice anomalies as large as observed in 2023.”
Lead scientist Rachel Diamond said that, while climate change increased the likelihood of exceptionally low sea ice in 2023, the models still considered it exceedingly unusual.She says:”This is the first time a large number of climate models have been used to determine how unlikely 2023’s low sea ice was. We only have 45 years of satellite measurements of sea ice, making it extremely difficult to assess changes in sea ice extent. Climate models are particularly useful in this situation.
According to the simulations, without climate change, the record-breaking minimal sea ice extent would occur once every 2000 years. This indicates that the incident was exceedingly extreme; anything less than one-in-100 is regarded as extremely unusual.”
Caroline Holmes, co-author of the study, stated:
“Strong climate change — i.e. the temperature changes we’re already seeing, as well as those expected if emissions continue to rise rapidly — in the models makes such a significant decline in sea ice extent four times more likely.” This implies that climate change increased the likelihood of an extreme low in 2023.
The researchers also used the algorithms to predict how well sea ice will rebound. By examining similar instances in the models, the authors discovered that following such severe sea ice loss, not all of the sea ice around Antarctica returns—even after twenty years. This adds model evidence to current observational evidence that the recent low sea ice may indicate a long-term regime shift in the Southern Ocean.