In West Antarcticain a region of the Ross platform called “Crary Ice Rise”the third drilling campaign of the SWAIS2C project (Sensitivity of the West Antarctic Ice Sheet to two degrees of warming). The project involves researchers from 10 countries, including Italy, with the INGV (National Institute of Geophysics and Volcanology), the University of Siena, the University of Trieste and the OGS (National Institute of Oceanography and Experimental Geophysics). Its goal is to sample beneath the ice sheet sediment cores which contain information relating to the climate of the last hundreds of thousands of years. Of particular interest are those concerning the periods in which the planet’s temperatures were similar to today’s. Knowing how the ice of West Antarctica – particularly vulnerable to rising temperatures – behaved on these occasions will allow us to develop more accurate forecasts on the future consequences of ongoing climate change.
How sediment cores are extracted and analyzed in Antarctica
With an area of 473,000 km², the Ross platformwhere the drilling takes place, is the largest floating ice shelf on the planet. To reach the investigation site, the equipment must be transported hundreds of kilometers across the ice in tracked vehicles. Here the entire thickness of the platform, approximately 500 m, is drilled before encountering a layer of ocean water and finally reaching the seabed. From the sediments that constitute the latter it is planned to extract cores up to 200 m longwhich will then be sent to New Zealand, where researchers will analyze them to identify microfossils of marine algae: organisms that require light to survive. Their presence in a layer corresponding to a certain time interval suggests that, at the time, no ice was present in that area and that, as a consequence, temperatures were higher. Carrots will therefore allow you to reconstruct ocean temperatures and the extent of sea ice in the past. Of particular interest is the behavior of the ice shelves and the Antarctic ice sheet in periods in which, due to factors of natural origin, the global temperature was similar to or higher than the current one. For example, it is estimated that around 125,000 years ago temperatures were 1 – 1.5 °C higher than in the pre-industrial period and that the sea level was more than 6 m higher due to the melting of the caps.
The risks associated with melting ice in West Antarctica
The function of the Ross shelf is very important because it protects the ice that extends onto the mainland of Western Antarctica by acting as a buttress and slowing its slide into the sea. However, today it is increasingly vulnerable due to hot water flows and deep of the circumpolar current which also threaten the other Antarctic platforms. These waters have a decisive role in the processes of melting of the ice at the base of the platformwhich can weaken it to the point of fragmentation, thus favoring the flow of land ice towards the sea. We currently do not know precisely what increase in global temperature could cause the platform to collapse. The SWAIS2C project is aimed at determining to what extent the Ross Shelf and the West Antarctic Ice Sheet will melt in the presence of a increase in temperatures equal to +2 °C compared to those of the pre-industrial period. As a result, it will be possible to develop more accurate predictions also regarding the extent of future sea level rise.
