A new study has revealed significant changes in the strength and position of the Southern Hemisphere westerly winds over the past 11,000 years.
Researchers, including those from British Antarctic Survey (BAS), found that these winds were stronger and more mobile in the past than they are today, which could have major implications for ice shelves, ocean circulation, and global carbon dioxide levels in the future. The study is published in the journal Communications Earth and Environment.
Using sediment samples from a remote lake perched on a promontory at Cape Horn-the southernmost lake in the Americas-scientists reconstructed past changes in salt spray, a key indicator of wind activity. Their analysis shows that up until 10,000 years ago, the westerly winds were positioned closer to Antarctica. However, between 10,000 and 7,500 years ago, these winds shifted northward and intensified directly over Cape Horn, reaching their strongest recorded levels before gradually weakening northward to their present position.
Future climate models suggest that with continued global warming, these winds will likely shift further south. However, the extent of this movement remains uncertain. The findings from Cape Horn provide new evidence that the 'wind belt' has been highly dynamic in the past, with potentially significant consequences for climate and sea levels worldwide.
Lead author of the study, paleo-climate scientist, Dr Bianca Perren from BAS, emphasized the importance of these findings:
"There's been so much debate about what the Southern Hemisphere westerlies have been doing over the last 10,000+ years, especially in South America. Here we show that winds that disappeared from the mid-latitudes in the early Holocene (about 11,000 years ago) were actually sitting down at and below the southern tip of Cape Horn. The migration of the winds in the last several decades has already begun to change the Southern Ocean and ice dynamics around Antarctica. But what we see today isn't even close to what happened 10,000 years ago, this record from Cape Horn gives us a glimpse into what the future could look like."
The study underscores the importance of understanding past climate patterns to predict future changes. As the westerly winds play a crucial role in ocean circulation and ice shelf stability, their continued shift due to climate change could have profound implications for global sea levels and how the oceans are able to store carbon dioxide from the atmosphere.
With climate models already predicting major shifts in atmospheric circulation, studies like this provide critical insights into the long-term impacts of climate change, and a stark warning of what may lie ahead.
