Investigation of Arctic Sea Level Rise

Sea level is a natural integral indicator of climate variability. It reflects changes in practically all dynamic and thermodynamic processes of terrestrial, oceanic, atmospheric, and cryospheric origin. The use of estimates of sea level rise as an indicator of climate change therefore incurs the difficulty that the inferred sea level change is the net result of many individual effects of environmental forcing. Since some of these effects may offset others, the cause of the sea level response to climate change remains somewhat uncertain. This project is focused on an attempt to provide first order answers to two questions, namely:

1) What is the rate of sea level change in the Arctic Ocean? and
2) What is the role of each of the individual contributing factors to observed Arctic Ocean sea level change?

Unlike most other manifestations of climate change, sea level rise is already a significant problem throughout the Arctic (ARCUS, 1997; Shaw et al., 1998; Brown and Solomon, 2000; Forman and Johnson, 1998; IASC, LOIRA, 2000; Smith and Johnson, 2000). Global warming and the anticipated sea level rise in the Arctic is expected to influence shoreline erosion, sediment transport, navigation conditions, oil and gas operations, hunting, and other human activities. In January 2000, the Alaska Science and Technology Foundation sponsored a workshop entitled "The Warming World: Effects on the Alaska Infrastructure" (University of Alaska Anchorage). Workshop participants concluded that sea levels will rise, storms will be stronger and more frequent, and coastal communities now struggling with erosion will see shoreline retreat accelerate (Smith and Johnson, 2000). The Intergovernmental Panel on Climate Change (IPCC, 2001) concluded that the rate of sea level rise in the 20th century was in the range 0.1-0.2 cm per year (http://www.ipcc.ch/).

But what is the current rate of sea level rise in the Arctic Ocean and what is its cause? The search for an answer to this question constitutes a complex scientific problem because observed sea level change, if we are able to observe it accurately, is the net result of a myriad of individual effects of dynamic and thermodynamic processes of terrestrial, oceanic, atmospheric, and cryospheric origin.

A fundamental problem in determining the rate of sea level change in the Arctic has been the lack of accurate data from sites along the Arctic Ocean coastline. With the recent (January 2003) release of the data for the Russian sector of the Arctic this circumstance has improved dramatically. Approximately 70 tide-gauge stations in the Barents Sea and Siberian Seas (Kara, Laptev, East Siberian, and Chukchi Seas) have recorded sea level changes from the 1950s through the 1990s. Preliminary analysis has shown that over this 50-year period, most of these stations have a positive trend in sea level (e.g. Proshutinsky et al., 2001). These sea level data were collected by the Arctic and Antarctic Research Institute (AARI), St. Petersburg, Russia. The data sets have been made available for analysis by the international community and the monthly mean relative sea level records for all gauges are now included in the Permanent Service for Mean Sea Level archive (http://www.pol.ac.uk/psmsl/pub/nucat.dat).


Contemporary erosion of the coast in the East Siberian Sea.

The existing sea level data sets in the Arctic are relatively short for the analysis of global sea level rise. Peltier and Tushingham (1989), and Douglas (1991, 1992, 1997) have stressed the importance of employing very long records for this purpose (more than 60 years). Following a detailed analysis of the sea level rise detection problem, Douglas (2000), in particularly, concluded: "What is needed for an understanding of global sea level and its relation to climate is an accurate budget of the contributors to sea level rise...". Indeed, a major goal of the present contribution is to begin this task by calculating and assessing an accurate budget of the various contributions to sea level rise in the Arctic.

The study of sea level variability in the Arctic Ocean is important in its own right, primarily, because of its practical importance for people living and working in Arctic coastal regions. For them the current rates of local sea level rise are already causing severe problems. In addition, the variability of sea level in the Arctic Ocean can be used as an indicator of changes in ocean circulation (Proshutinsky and Johnson, 1997), water, ice and sediment transport, coastal erosion, and many other processes.