The environmental issues affecting the Alaskan North Slope coastal region are the decline in ice extent in the Beaufort and Chukchi Seas, gouging of shelves and coast by sea ice, rise in sea level, and storm hazards. Thawing of permafrost, decreasing sea ice extent and rising sea level contribute directly to increased harshness of meteorological events on coastal areas, including high winds, storm surges, sea ice compaction, flooding, and shoreline erosions.
Minimum ice extent in the northern autumn has declined by 3.6% per decade since 1961. During the period 1953-1998, 6 of the 10 years of minimum summer ice extent have occurred since 1990, and the past decade has been characterized by increased regional variability. Two key factors appear to be influencing these changes in ice distribution. The first factor is an intense warming of more than 0.5oC per decade that has occurred during the past thirty years over much of the northern land masses. The second factor is a major change in arctic air circulation patterns. Average sea level pressure has dropped over the central Arctic Ocean and there has been an increase in high latitude storms. As a result of these changes, relatively warm spring and summer air masses from much of the Arctic coast are able to penetrate far over the Arctic Ocean, melting some sea ice and driving much of the remainder away from the shore and towards the central ice pack. One of the major results of these changes has been a lengthening of the melt season. The melt season has varied between 55 and 75 days between 1979 and 1996, and has lengthened at a rate of 5.3 days (8%) per decade during that time.
Global sea level has undergone a rising trend for at least a century. Based upon careful analysis of observations and climate model simulations, the Intergovernmental Panel on Climate Change stated that a best estimate of global sea level rise in 2030 would be 18 cm, and 44 cm by 2070. Unfortunately, tide gauges are not routinely used to measure sea level in the Alaskan coastal region.
The low tundra coastline is heavily indented with shallow bays and lagoons, and the continental shelf is relatively narrow, extending 50 to 100 km off the coast between Barrow and Prudhoe. The coast is predominantly low lying wetland tundra, dotted by numerous thaw lakes. The coast has a gently sloping bathymetry with relatively flat terrain inland. Offshore islands and shoals moderate the influence of pack ice where they occur. Most of these islands are sand and gravel barrier islands, bounding shallow lagoons, while others are relics of earlier coastal retreat processes and lie farther offshore. These islands, and stretches unprotected mainland coast, are subject to considerable erosion by wave action. Aided by thermal erosion of the tundra, erosion rates average 1 to 3 m per year but in some locations may reach 38 m in a single severe storm.
Because of this geography, much of the Chukchi-Beaufort coast is vulnerable to storm surges. Fall storm season is the most dangerous time of the year, when high winds, wind driven high tides, and coastal flooding are common. The areas around and east of Barrow, and the east end of Kotzebue Sound are particularly susceptible. Barrow is exposed to a long stretch of open ocean in an arc of over 200o, allowing a long fetch where strong winds can generate maximum waves and swell before being broken up by land.
Increasing amounts of open water in the arctic seas combined with rising sea level and the coastal geography will contribute to increased harshness of meteorological events on coastal areas, often resulting in damages from high winds, storm surge, flooding, and shoreline erosions. Storm surges are greater when the air temperature is colder than the water and when the sea has little ice cover, due to increased fetch. Further, changes in the persistence of landfast ice along the coast is an important factor, since landfast ice provides coastlines with protection from erosion. These meteorological events can also spawn secondary threats such as hazardous materials spills, which are particularly damaging to coastal environment at high latitudes.
