Global warming impact on sea levels studied

Press, 28 January 1988, Page 15

Global warming impact on sea levels studied

PA Wellington The Conservation Department has initiated a study of tide gauge records to see whether global warming has had an impact on sea levels. The head of the department’s coastal and marine resources directorate, Dr Jeremy Gibb, said scientists were predicting sea levels would rise Im to 2m over the next 100 years as a result of global warming — the “greenhouse effect.” This was already occurring because of a build-up of pollution in the atmosphere. If the theory was correct a 0.15 m rise in sea level world wide, which had been observed since the beginning of the cen-

tury, was the first sign of a global warming, Dr Gibb said. As there was no information on how New Zealand was being affected, the department contracted the Department of Survey and Land Information to analyse tide gauge records from Auckland, Wellington, Lyttelton and Dunedin harbours for sea level trends. Some records went back to the 1890 s. As well as providing information on historical trends, the survey would help predict future rises. It was hoped the survey would lead to the establishment of a full network of tide gauges to monitor sea levels over the next century.

Crude analysis of Auckland and Wellington records showed they were consistent with the recorded world rise. The chief geodesist with the Department of Survey and Land Information, Dr John Hannah, said the model used to analyse the data would make sure the rises were “real” by taking into account the effect of atmospheric conditions and any movement of the tide gauges due to land subsidence. Analysis was expected to be completed by the end of April. Preliminary results should be ready for presentation at a workshop on the “greenhouse effect” in Wellington in March.