October 26, 2007

Settling on an unstable Alaskan shore: A warning unheeded

Filed under: Arctic, Polar

An intense storm struck the northwestern tip of Alaska during the fall of 1963. This storm caused over 3 million dollars in damage, primarily to the U.S. Government research camp that was located at Barrow, AK, as 55mph winds (gusting to 75mph) and waves topping 10 feet pushed a storm surge over the 10 foot high protective beach. The storm hit during an unusual ice-free period in early October—the primary reason why the seas grew to such damaging heights. During most months there, near shore sea ice coverage is sufficient to dampen (or prevent entirely) the build up of significant wave heights. James Hume and Marshall Schalk, described the damage from the 1963 storm in an article written for the journal Arctic in 1967 and based upon historical weather records and the recollection of Inuit elders, reckoned that the storm was about a “200 year” storm.

This storm, and others like it, should have served as ample warming against settling on the unstable coastline of much of Alaska. Instead, today we here repeated reports of recently-established native Alaskan villages having to be moved inland because of an encroaching ocean—and the culprit is always anthropogenic global warming, never lack of foresight.

The wind and waves from the great 1963 storm took a tool on the Barrow shoreline. Hume and Schalk estimated the erosional damage from the 1963 storm to be equivalent to about 20 years work of “normal” erosive processes. And the “normal” erosive processes themselves were known to be quite high along much of Alaska’s coast, which is made up of loose sediments held together by ice. Erosion rates were measured to range from a few feet to a few tens of feet per year along much of Alaska’s western and northern shorelines (MacCarthy, 1953; Hume et al., 1972; Hartwell, 1973; Lewellen, 1977; Harper, 1978).

Hartwell, described the processes acting on the northern Alaska coast like this in his 1973 paper:

Most of this coastline is marked by an abrupt break in slope between the relatively horizontal terrain of the mainland and the gently-sloping sea floor. In bedrock areas this break is generally a steep sea cliff with loose talus material at its base. In areas of perennially frozen sediment which are exposed to direct wave attack along the coast, the relief is often sheer and is formed by slumping of large blocks of frozen sedimentary material. This is a result of both thermal and mechanical erosion along the base of the sea cliff and inland along the banks of estuaries and rivers where undercutting of the frozen sediments forms a “thermo-erosional niche.” Such niches which are unique to this environment can form rapidly and may extend several metres under the bank, making the overhanging bank unstable and susceptible to collapse especially where ice wedges are intersected. Thawing along the ice wedges which underlie the troughs of polygonal ground frequently causes the cliff to slump as large tundra blocks. At many locations the micro-relief along polygon margins is accentuated by erosion in the polygonal troughs at the edge of the main sea cliffs. Vegetation frequently hangs as a thin mat draped over the edge of the cliff.

Along the coastal plain the shoreline is retreating rapidly, even where sheltered from direct wave action; but actual coastal relief remains about the same because the surface of the mainland is nearly level. The net effect of continual cliff retreat is to form generally smooth coastlines with nearshore marine deposits such as beaches, spits, and barrier islands, like the coast near Barrow. Temporary protection from coastal retreat is provided by material which accumulates at the base of the main coastal slope. In the summer, slumped soil and tundra vegetation material protect the slope from direct wave attack. In the winter the seasonal cover of wind-blown snow dramatically alters the surficial geometry of the coastal features and masks the coastal relief by forming a gently sloping ramp from the tundra edge down onto the frozen sea surface. Such wedges of snow and ice tend to insulate the slope from thawing well into the summer melt season. Larger ramps usually develop along higher sea cliffs, affording somewhat greater protection from coastal retreat than in areas of low cliffs.

And acting on top of these erosive processes are the extremely strong late summer/early fall storms, such as the October storm of 1963. After comparing the high rates of event-based erosion (such as the 1963 storm) to the ongoing long-term erosion rates, the Hume and Schalk ended with an eerie (considering that it was written in June of 1967) warning about the future:

A practical consideration also arises from this study. If, as has been suggested, the climate is becoming warmer as a result of the addition of carbon dioxide to the atmosphere (Plass 1956; Callender 1958; Kaplan 1960; Mitchell 1965), the likelihood of an open ocean and strong winds coinciding to produce such a storm in the future is constantly increasing. Another such storm can be expected, and care should be exercised in the selection of building sites and construction methods. The best sites would be at least 30 feet above sea level and either inland or along a coast which is not eroding. If a site which is low and near the ocean must be used, then a protected position leeward of a point or island would be best. The buildings should be built on the highest points available, away from areas of rapid erosion, and should be erected on piles to put them above the reach of the water. Finally, borrowing from the beaches should be kept to a minimum. The best protection that such an installation can have is a naturally high, coarse beach. Building of groins, breakwaters, and other structures will never be an economical substitute where strong ice action is found. In northern Alaska, the coast is one of transgression, with the recent dominant action being coastal submergence. The gravel along the beaches is a concentration of the coarse sediment from a large mass of material over a long period of time. It cannot be replaced by natural processes without a large amount of erosion. It should, as much as possible, be left in place as protection. Where need and economics dictate that borrowing must be done. It should be recognized that the protective nature of the beach is being reduced.

Apparently, much of this advice went unheeded. Nowadays, we hear story after story describing the plight of the native Alaskans as their villages, which were constructed on the unstable bluffs along the Alaskan coast, are being undermined by the retreating shoreline (see this New York Times article, for example). Understandably, as the native Alaskans began a transition from their traditional nomadic lifestyles to more permanent villages, replacing snowhouses with tin and plywood buildings, dogsleds with snowmobiles, and seal oil lamps with electric lights, many of these settlements were located very near (the already-receding) shoreline to provide ready access to the oceans, a primary source of the coastal Inuit’s sustenance. But as the processes leading to shoreline erosion have continued and perhaps even intensified, the ocean has begun encroaching on the Inuit settlements—a situation which today has become a rallying cry for global warming alarmists, but a situation which was by and large avoidable had the advice given by Hume and Schalk, some 40 years ago, been followed.

In earlier times, when the Inuit were more nomadic, they simply would have broken camp and moved to a more suitable location. In fact, the historical scientific literature contains references to abandoned Inuit camps located on the precipices of an eroding coast. For instance, Gerald MacCarthy, in an article published in Arctic in 1953 entitled “Recent Change in the Shoreline Near Point Barrow, Alaska” wrote:

At ‘Nuwuk’ [Point Barrow] the evidence of rapid retreat is especially striking. The abandoned native village of the same name, which formerly occupied most of the area immediately surrounding the station site, is being rapidly eaten away by the retreat of the bluff and in October 1949 the remains of four old pit dwellings, then partially collapsed and filled with solid ice, were exposed in cross section in the face of the bluff. In 1951 these four dwellings had been completely eroded away and several more exposed.

But, to a large degree, these earlier times are now gone and the native Alaskan’s are transitioning to a more modern lifestyle. But the transition has not come smoothly, which is often the case as a culture is faced with an uncertain, and oftentimes unwanted, upheaval. Establishing “permanent” settlements in a less than ideal setting is just one of the bumps along the road, but hardly a new mistake. For instance, consider the first English settlements at Roanoke Island, North Carolina or Jamestown, Virginia, or for that matter, look no further than establishment of the village of Barrow, Alaska back in the 1960s. Hume et al. (1972) include this photograph (Figure 1) with the caption: “Aerial view of the bluffs near the village recently settled. One building collapsed and one has been moved from the bluffs as a result of the 1968 storm. The beach formerly was 30 m. in width at this point. Photo taken in August 1969.” The authors go on to add “The village will probably have to be moved sometime in the future; when depends chiefly on the weather…”


Figure 1. Photo from 1969 of the (then) recently established village of Barrow, Alaska showing the encroaching ocean (from Hume et al. (1972)).

Clearly, erosion has been gnawing away at the Alaska coast for many, many decades and this fact has been known for equally as long. Wind and waves acting on soil held together by ice acts through a positive feedback to expose more frozen soil to the above-freezing temperatures of summer and the warm rays of sunshine, softening it for the next round of waves and wind. And so the process continues. A decline in near-shore ice cover helps to exacerbate the process. Ignoring these well-known environmental conditions has led to the unfortunate situation today where Inuit villages are facing an imminent pressure to relocate. This situation has less to do with anthropogenic climate change than it does to poor planning in the light of well-established environmental threats—threats that have existed for at least the better part of the 20th century.

References:

Harper, J.R., 1978. Coastal erosion rates along the Chukchi Sea coast near Barrow, Alaska. Arctic, 31(4), 428-433.

Hartwell, A.D., 1973. Classification and relief characteristics of northern Alaska’s coastal zone. Arctic, 26(3), 244-252.

Hume, J.D., and M. Schalk, 1967. Shoreline processes near Barrow Alaska: a comparison of the normal and the catastrophic. Arctic, 20(2), 86-103.

Hume, J.D., et al., 1972. Short-term climate changes and coastal erosion, Barrow Alaska. Arctic, 25(4), 272-278.

Lewellen, R., 1977. A study of Beaufort Sea coastal erosion, northern Alaska. Environmental Assessment of the Alaskan Continental Shelf, Annual Reports of the Principal Investigators, Vol. XV (Transport). National Oceanic and Atmospheric Administration, pp. 491-527.

MacCarthy, G.R., 1953. Recent changes in the shoreline near Point Barrow, Alaska. Arctic, 6(1), 44-51.




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