Discussion on the preceding papers

Abstract

J . E. Smith. May I ask, at the outset of our discussion of this morning’s papers, whether there is any evidence of long- or short-term secular changes of climate in the Signy Island area? G. de Q. Robin. J. A. Heap, in preparing an ice atlas of the Antarctic seas, drew upon the long period of meteorological records from the Argentine station ‘Orcadas’ on Laurie Island, South Orkney Island, and from the British station at Grytviken, South Georgia. He was able to show that in the late 1920s there were several years with mean annual temperatures 1 or 2 degC below average, while in the 1950-60 period moderate fluctuations in climate could be associated with fluctuations in the pack ice. M. W. Holdgate. Because of the lack of suitable ‘indicator species’ in the land flora, pollen analysis from the Antarctic zone is not likely to help in this problem. However, some evidence of climatic change may be derived from the fluctuating fortunes of the small elephant seal population at Signy Island. When first studied by R. M. Laws in 1948 this was producing 80 to 100 pups annually: latterly numbers have fallen off dramatically and in some seasons only four or five have been born. This is a marginal population of a species not penetrating deeply within the ice zone, and hence will probably be a good indicator of changing climate and ice conditions.