Sea Level at Port Arthur, Tasmania

The authors write as background for their study that "on 1 July 1841, a sea level benchmark was struck on a small cliff on the Isle of the Dead, near the penal settlement of Port Arthur, Tasmania ... by T.J. Lempriere, an amateur scientist and storekeeper at Port Arthur, and Captain James Clark Ross, who was visiting Tasmania during his explorations of 1839-43." Thereafter, they compared Lempriere's measurements of 1841-1842 with observations made at Port Arthur in 1875-1905, 1972 and 1999-2002. So what did Hunter et al. learn?

The full set of data indicated an average rate of sea level rise, relative to the land, of 0.8 ± 0.2 mm/year over the period 1841 to 2002, which yields, in their words, "an estimate of average sea level rise due to an increase in the volume of the oceans of 1.0 ± 0.3 mm/year, over the same period."

In considering these findings, the three researchers say their results may be compared with recent estimates for the two longest (continuous) Australian records of Fremantle and Fort Denison of 1.6 and 1.2 mm/year, respectively, after glacial isostatic adjustment, citing Lambeck (2002). Noting that "historic and modern records from Port Arthur, Tasmania, cover the longest time span of any sea level observations in the Southern Hemisphere and are related to a single benchmark," they say "they provide a significant contribution to our knowledge of past sea level rise in this data-sparse region." And part of that significance must reside in their noting that their sea level rate-of-change results "are at the lower end of the recent estimate by the Intergovernmental Panel on Climate Change on global average rise for the 20th century."

Additional Reference
Lambeck, K. 2002. Sea level change from Mid Holocene to recent time: An Australian example with global implications. In: Ice Sheets, Sea Level and the Dynamic Earth. American Geophysical Union, Washington DC, Geodynamics Series 29: 33-50.