Sea level changes in the Pacific region and impacts of the 2009 El Niño in Fiji waters [assessment from 18 years land-based data]

Abstract

The sea level rise issue is one of the major topics that has gained increasing global attention. In particular, its impacts on many Pacific island countries and other low lying countries have been more prevalent over the last two decades. Sea level data from the AusAID funded South Pacific Sea Level and Climate Monitoring Project will be focused in this study despite the fact that the length of data is not sufficiently long. The project was set up in response to concerns raised by Pacific island countries over the potential impacts of an enhanced greenhouse effect on climate and sea levels in the South Pacific initially for 20 years and probably more. Based upon 18 years of sea level data from the project, the range of sea level rise rate in the Pacific region is between 3.1 mm y–1 (Kiribati) and 8.4 mm y–1 (Tonga) as of June 2011. This is 3–4 times higher than the global average of 1–2 mm y–1. Although the data length is for the last 18 years, the sea level trend values do not fluctuate significantly since 2002. It simply indicates that the rate of sea level rise in the Pacific region is not accelerating as anticipated by the local community. Interestingly, the profound effects of El Niño on sea level changes are quite unpredictable even during the 2009 mild El Niño. In two particular spots in the Pacific and their vicinities (at latitude 12°S & longitude 180°E and latitude 14°S & longitude 157°E) sea level drop in these areas is ~40 cm during March 2010. Although the present effect of El Niño on sea level changes is isolated and not Pacific wide like in 1997–98 El Niño, it simply indicates the complexity of sea level issue and danger of projecting future sea level trends at a particular area.