Tuesday, 18 December 2012

7 - The uncertainties of planning scientific expeditions in Antarctica

When we set out on this expedition we had a clear route plan. We were to go from Punta Arenas direct to E9 (see map), then on to Kemp and Adventure craters and then finish at E2 before steaming back to Montevideo. The best laid plans...

Not long after leaving Punta Arenas we started checking the daily ice maps for Antarctica (www.polarview.aq). They showed that ice was still present as far north as 59°S and along the 30°W longitude. As E9 and the Kemp and Adventure craters are at approx. 60°S and 30°W, we could not get to them in the RRS James Cook as it is not an ice-strengthened ship. So we changed direction and went to our last station E2, where we spent a productive week examining the biology and chemistry of the vents there and making detailed maps of the vent environment.
Map showing JC080 cruise proposed destinations
Each day, even before breakfast, we logged on to the Polarview website to check the ice conditions. Over the last week the satellite images of the ice show a very slow retreat close to our southern stations. This may be the effect of the South Orkney Ridge and the southern end of the South Sandwich Island chain being relatively shallow and as a result the ice has frozen deeper relative to the water-column depth. In the open sea at the same latitudes the ice appears to be breaking up nicely. We are also in the austral spring after one of the most extensive freezes for many decades in Antarctica and ice melting is taking much longer.

So we have decided to move south and use our CTD to check for chemical evidence of vents in each of the segments of the East Scotia Ridge. Today we are at E5 and then we go on to E6 and E7 (see map), which may be close to the ice edge, although we hope that by the time we get there, it will have receded southwards. We have been lucky in all other respects, in that the seas are lovely and calm and the sun is shining.

All this shows is that even the best laid plans can be thwarted by nature. We have back-up plans and will use them until, we hope, our southern stations are free of ice.

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