by Judith Curry
The latest analysis of sea ice extent by the NSIDC shows that early June sea ice extent is lower than corresponding 2007 value. A recent article at Yale360 discusses how as Arctic sea ice retreats, storms take toll on the land.
For background info on Arctic sea ice, see this previous thread pondering the Arctic Ocean.
For background on storm surges on the Arctic coast, see this previous paper by Lynch et al. that I coauthored entitled “Towards an integrated assessment of the impacts of extreme wind events on Barrow, Alaska”.
Some excerpts from the Yale360 article:
A recent study conducted by Benjamin Jones of the U.S. Geological Survey found that a 40-mile stretch of Alaska coastline along the Beaufort Sea
One stretch of Alaska coastline lost 28 feet of land per year between 2002 and 2007.
retreated an average of 6.8 meters (22 feet) per year between 1955 and 1979; over the next 23 years, that rate increased by another six feet per year. The low-lying coastline then lost 28 feet of land per year between 2002 and 2007, and 45 feet between 2008 and 2009. These extreme losses are due not only to greater exposure of the land to storms from an increasingly ice-free Arctic, but also to melting permafrost that hastens crumbling of the coastline.
A study published last month showed another insidious impact of the growing number of Arctic storm surges. Canadian scientists researched the effects of a massive surge of seawater from the Beaufort Sea that in 1999 pushed 12 miles inland along the Mackenzie River delta in Canada’s western Arctic, flooding lakes, streams, and hundreds of square kilometers of tundra vegetation. The effect of that influx of seawater into the delta transformed the affected areas, killing nearly 90 percent of the alders, which shriveled in the now-salty soil. In addition, scientists documented a dramatic increase in a salt-loving algae — Navicula salinarum — in one inland lake, suggesting that the freshwater system affected by the flooding was being transformed into a new, more saline ecosystem.
To date, the surges have been most intensely felt in northwestern Canada and northeast Alaska, where winds blowing over ice-free water in the summer can create large storm surges. These surges are particularly bad in the Beaufort and Chukchi seas and parts of the Bering Sea because of the shallow water there. The water being pushed towards shore has to go somewhere. If it is deep, the water can simply descend to greater depths when it nears the coast. If it is shallow, however, the water is forced up onto the land.
The impact of this relatively warm, salty water coming onto shore is exacerbated by the fact that 50 to 70 percent of the soil consists of frozen water — a “dirty iceberg,” as geomorphologist Robert Anderson of the University of Colorado at Boulder describes it. Once it comes into contact with the warmer water, it falls apart and slips into the sea.
Anderson and other researchers believe that as the Arctic Ocean becomes increasingly ice-free, storm surges will affect ever-larger areas of shoreline in the Arctic basin, including Russia’s immense Arctic coastline, which stretches many thousands of miles. “No other coastal landscape in the world is as vulnerable,” says Anderson, who has a research camp on the north coast of Alaska between Barrow and Prudhoe bays. “From the western Arctic of Canada to the north slope of Alaska and Siberia, the landscape is very flat. When you fly over this territory, you can see how even the smallest surges can have an impact when there is little or no sea ice.”
In addition to the ecosystem issues documented by the Yale360 paper, the Lynch et al. paper documents two case study storms in 1963 and 2000, and the impacts to the coast, buildings, utilities infrastructure, and transportation.
Community vulnerability has increased over the decades with community modernization, which includes increased structures, electricity and telephone lines above ground, the underground water and sewage utilidor, and natural gas pipelines. In addition, the diversity of storms and their impacts on Barrow in the past implies that policies to reduce community vulnerabilities cannot anticipate in suffi- cient detail major storms of the future. Hence, resil- ience is necessary to expedite recovery from impacts of a severe storm, and flexibility is necessary to accom- modate what is learned from each storm to reduce vulnerabilities over the long term.
JC comments: Whereas storm surge risk is generally associated with tropical storms, arguably the greatest risk storm surge risk is on the Arctic Ocean coast. Open water in autumn associated with reduced sea ice extent provides fertile ground for the development of polar low storms in the Arctic Ocean, which can have very high wind speeds and result in substantial storm surges. Storm surges along the Arctic coast cause substantial erosion of the ground which is characterized by permafrost. Apart from the loss of land, the erosion of permafrost puts methane into the atmosphere, a greenhouse gas.
The Arctic Ocean coast is home to numerous villages, predominantly inhabited by Inuit (this one is for Martha). The villages are located on the coast to provide proximity to marine resources. One coastal village, Shishmaref, is trying to obtain funds to move the entire village.
In addition to the vulnerable coastal villages, offshore resource extraction activities and coastal refining activities are vulnerable to winds, high seas and storm surge particularly in autumn, a time that historically has had landfast ice protecting the coast.
As discussed on the previous Arctic sea ice thread, the attribution of the decline in Arctic sea ice extent is not straightforward, it is some combination of natural climate variability and greenhouse warming.