What’s a Few Days’ Delay When Preparing to Visit a 33 Million-Year-Old Ice Sheet?
By Julian Spergel
The Rosetta team has been delayed in Christchurch, NZ since October 20th, and we are all hoping very hard that today (the 24th) will be the day–that the weather will cooperate and the plane will have no issues so that we can get to McMurdo Station and start preparing to work. Morale is still high, we have enjoyed exploring the local sights in Christchurch in the spare time we suddenly have. But it would be a huge inconvenience if we stay here too long.
The dangers of Antarctic air travel cannot be emphasized enough. The weather is notoriously temperamental: winds as fast as 199 mph (327km/h) have been recorded at Dumont D’Urville station. Wind gets funneled down mountains and through fjord valleys, picking up speed. Blowing snow can limit visibility in a matter of seconds. Even crossing the Antarctic Circle is dangerous. Because there are no large landmasses to break the 40th line of latitude, ocean and wind currents can spin unimpeded around the continent. This is called the Antarctic Circumpolar Current. Sailors called the latitudes between New Zealand and Antarctica, in order of southernness, the Roaring Forties, the Furious Fifties, and the Shrieking Sixties.
Yet this inaccessibility is two-sided. The spinning wall of wind and water acts as a thermal insulator and keeps Antarctica chilly. The extreme environment, the massive ice sheet, and the unique ecosystems that attract the scientific community are all due to this forbidding climate system.
Was Antarctica always so inhospitably cold? Surprisingly, no. The development of the Antarctic ice sheets are relatively recent compared to the 4.5 billion-year-old history of the Earth. The precise mechanism that triggered Antarctic glaciation is still debated, but there is significant evidence that continental scale glaciation began around 33 million years ago, at the boundary of the Eocene and Oligocene. A combination of lowering CO2 levels and the formation of the Circumpolar Current when South America and Antarctica detached led the mountain glaciers in the Trans-Antarctic mountains to expand until the continent was covered. Prior to this point, Antarctica is believed to have been forested, and dinosaur and early mammal fossils have been found around the continent.
The glacial and geological history of the Ross Embayment, the bay in which the Ross Ice Shelf sits, is one of Rosetta-Ice’s leading research questions. By making measurements of the seafloor, we hope to improve our understanding of the timing and distribution of sea-floor extension in the geological past. The tectonics of the region are still not well understood. We theorize that the crustal depression that has become the embayment developed during the break-up of Gondwana, the Mesozoic supercontinent composed of modern-day South America, Africa, Australia, Antarctica, India, and Arabia around 200 million years ago. As it pulled apart over millions of years, it stretched the crust in the region of the Ross Sea, thinning and depressing it. Over the past 33 million years, glacial ice has carved out landforms that now lie under the ice. During our work, we will use our instruments to look through the ice shelf and map those present day landforms. We would like to improve our knowledge of the history of the region, both of the geology and of the ice shelf. Why is this important? In addition to increasing our knowledge of the world’s geological history, the past of the Ross Sea can give us clues to its future. If we see evidence that the Ross Ice Shelf has broken up or disappeared in the past, we can say that the present-day ice shelf has the capacity to disappear in the future.
Stay tuned for updates on our Antarctic arrival and our scientific work. We’re standing by in Christchurch, parkas on, bags in hand, excited and ready to start another season of Antarctic science.
Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Professor Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery. He graduated with a B.S. in Geophysical Sciences from the University of Chicago in 2016. He has been involved with a number of diverse projects and has been interested in polar studies since early in his career. His fieldwork has brought him north to the Svalbard Archipelago and south to McMurdo Station, Antarctica.
Learn more about previous years’ research, here.
For more on this project, please visit the project website: http://www.ldeo.columbia.edu/rosetta