Sea Level Change and Greehouse: Implications for Wetlands

In 1985, the Conference on Greenhouse Warming held at Villach, Austria, predicted a rise in sea level by 2030 AD of between 0.2 and 1.4m caused by melting of ice-caps (including mountain glaciers) and thermal expansion of the oceans (World Meteorological Organisation 1986). Recent research, however, suggests that thermal expansion of water in the upper 100-200m of the oceans is the most likely major cause of future sea level rise. Predictions about the extent of this rise have been revised downward because it is now realized that warming of air around the Antarctic ice-cap will lead to increased snowfall, thus counteracting the effect of thermal expansion. What has not been widely recognized is the fact that sea level behavior from year to year and over the long term, especially in Australia, is climactically controlled, with complex feedback mechanisms operating on regional scales (Bryant 1988a, Bryant et al. 1988). The short term variability in sea level behavior may be 1-2 orders of magnitude greater than the average trends defined from many sea level records. In this paper the nature and variability of sea level changes within Australia will be discussed first. Secondly, the impact of this variability upon Greenhouse predictions of sea level rise and some more current predictions for sea level elevations in the next 40 years will be presented. Finally, planning options necessary to minimize the effect of rising sea level upon wetlands will be reviewed.