Arctic sea ice variability and effects
ashore –geomorphological, hydrological and ecological within the Fyrsjöen catchment, west coast of Svalbard
Mohammad Hassan Khajeh Abdollahi
Thesis submitted to the International Institute for Geo-information Science and Earth Observation in partial fulfilment of the requirements for the degree of Master of Science in Geo-information Science and Earth Observation for Environmental Modelling and Management
International Institute for Geo-Information Science and Earth Observation
Enschede, The Netherlands
One of the daily news on medias is global warming. The impact of Global warming on Arctic area is more than the rest of the earth, because the rate of warming in Arctic area is about twice than the rest of the world. There is interaction between sea ice changes and climate temperature. More sea ice results in colder weather temperature because sea ice has a high Albedo and reflects the sunlight. Warmer temperature melts the sea ice so sun radiation is absorbed by water that results into warmer weather.
Sea ice declining has some impacts on Svalbard as an Arctic Island. The study area of this thesis is Fyrsjöen Lake research catchment on the west coast of the main Spitsbergen Island, on the West coast of Svalbard. In normal year sea ice formed during the winter on the west coast of Spitsbergen. Global changes and sea ice reduction created an ice free area on the west coast of this island during the winter. So there is a distance between sea ice and coast without sea ice. This distance is long enough to allow the sea waves to form when there is west-east storm. The sea waves carries the coarse sand and beach cobbles to the island ashore and makes ridges there. These ridges are also being built against outlet of the catchments, which drain to the Ocean. These ridges that contain a high amount of seaweeds (Kelp) freeze because of cold weather that is -4 to -12Co during the winter and become as strong as concrete. In the next summer, ice and snow in the catchment begins to melt and flow toward outlet, which was blocked by concrete storm ridge, so the water cannot flow out, accumulates behind the ridge. The accumulated water overflows on the catchment and flood the catchment. The flood damages the habitant and also makes the active layer deeper. In mid July the ridges break because of water pressure and it’s ice melting. A huge amount of water with discharge of 6 CMS flows out from the Fyrsjöen Lake research catchment, while its normal maximum discharge is about 0.3 CMS. This huge discharge causes a lot of erosion.
Storm ridge formation and active layer changes, where two factors which their relation with Arctic sea ice changes, West-East wind speed in that area and weather temperature both local and global were studied. The research was done according to some previously three decades recorded data by Åkerman (1980, 2008), national snow and ice data centre (NSIDC) data about sea Ice area and extent and metrology information that was provided by Norwegian metrology institute.
It was concluded that storm ridge occurrence is inversely correlated with Arctic sea ice extent and Arctic sea ice area. It means sea ice reduction increases the probability of storm ridge occurrence. There is a critical span in sea ice extent between 12 to 12.2 million km2. By decreasing sea ice extent from 12.2 to 12 million km2 the probability of storm ridge occurrence raises sharply.
Another reason that proves the importance of this span is global weather temperature. There is turning point also in relation between total Arctic sea ice extent and global weather temperature, increasing sea ice extent results in decreasing global weather temperature, but when sea ice extent reaches to 12.2 million km2, global weather increase by increase of sea ice extent.
Storm ridge occurrence is also highly correlated with global weather temperature. It was concluded that with such increasing rate of global warming, the probability of storm ridge occurrence is more than 90 percent. It is obvious that storm ridge is not a direct result of global warming, the global warming influences on other factors that result in storm ridge occurrence. Storm ridge occurrence is also correlated with the number of the west-east winds with the speed more than 7 m/s, during autumn and winter in that area.
Active layer is inversely correlated with sea ice extent, the more sea ice extent, the shorter the active layer. There is also a turning point around 12 million km2 where decreasing sea ice extent dos not increase active layer. Active layer is also correlated with sea ice distance from the catchment. The longer the distance from the catchment causes warmer temperature, which cases the deeper active layer. Active layer is highly correlated with total Degree day . It was also concluded that flood which is a result of storm ridge, makes that active layer deeper within the catchment. The threat of increasing active layer depth is increasing methane emitting to the atmosphere, which is one of the green house gases that causes global warming.
Flooding the catchment as a result of storm ridge has some impacts on bird breeding in the catchment. It reduces the number of birds because it damages their nests.