On Aug. 16, 1897, the Research Vessel Belgica set sail from Antwerp, Belgium. The ship's destination — via Rio de Janeiro, Montevideo and then Punta Arenas, Chile — was Antarctica, a continent that until that time remained completely unexplored by westerners.
But now, for large parts of the year, the once plentiful sea ice encountered by the ill-fated voyage seems to be disappearing. By submitting your information you agree to the Terms & Conditions and Privacy Policy and are aged 16 or over.Edward Doddridge: The RV Belgica's voyage to Antarctica departed in 1897 and was the first of what became known as the"heroic age" of Antarctic exploration. This was the very end of the 19th century and the beginning of the 20th. Antarctica was a completely unknown place that no one had been to.
ED: This is why I think that the RV Belgica's voyage is such an interesting one to look at now. The region of the Antarctic coastline they sailed to has been ice-free for the first time since satellite records began — it now doesn't have any ice for months and months of the year. That's pretty surprising in a 45-year record, but when you look back 125 years ago, and you see that they were trapped in ice that was 2 meters thick, that's a huge change.
ED: Almost disbelief. The measurements that we get for Antarctic sea ice are extremely well-calibrated, we know that the satellite is truthfully telling us how much ice there is. But looking at that graph, it was hard to comprehend that it could be so different from previous years. ED: The difference is that the Arctic is an ocean surrounded by continents, whereas the Antarctic is a continent surrounded by ocean. So in the Arctic, the amount of ice that you have in the winter is basically just the amount of ocean that you have, but you're never going to run out of ocean around Antarctica.
There's a layer at the top of the ocean called the mixed layer. It has the same properties at any given location — it doesn't really change in temperature or saltiness. Around Antarctica, that layer is mostly about 100 meters thick during winter. Below that is where warmth comes up from other parts of the ocean and mixes with the top layer where it can inhibit sea ice.