MOSCOW. (Dmitry Zamolodchikov for RIA Novosti) - The level of the world's oceans continues to rise at a rate of 3 mm per year; and the speed of the process is increasing.
Climate Change 2007, the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPPC), said the level of the world's oceans would rise by at least 60 cm by 2100. Last century, a 17 cm increase in water levels, an all-time high in the past 2,000 years, was registered.
Coastal erosion, a major negative consequence of global warming, is caused by rising seawater and the melting of land-based ice sheets of Greenland and other Arctic regions. The onslaught of ocean waters annually erodes the global coastline by 60 centimeters.
It is interesting to note that the 50,000-km northern Russian coastline is retreating faster because up to 56% of the landmass, including permafrost and thermal-karst lakes, is washed by the Arctic Ocean.
Rising ocean levels, waves and tides are not the only factor contributing to the erosion. Melting permafrost, which is also covered in ice veins and lens ice (up to 70% of the area), causes landslides on varying scales. Geologists call this process thermal abrasion.
Scientists from the Earth Cryosphere Institute in Tyumen, West Siberia, and the Permafrost Institute of the Siberian Division of the Russian Academy of Sciences in Yakutsk, North-East Siberia, have studied many aspects of Arctic coast erosion and have found that 20% of the Kara Sea coast is affected by thermal abrasion. Coastal areas of the Yugra Peninsula and the western sector of the Yamal Peninsula in North-West Siberia are being eroded at a rate of two meters per year, while the sea annually creeps up 50 cm in the mouth of the Ob River, West Siberia, and the Yenisei Bay in North-East Siberia.
About 33% of Russia's eastern Arctic coast also suffers from thermal abrasion. The Laptev, East Siberia and Chukchi Seas advance at 3.8, 3.4 and 2 m per year, respectively. In some places, the coast annually retreats 15 m inland.
Summer temperatures and the force of wave impact are the main factors influencing long-term regional coastal-erosion dynamics. Rising summer temperatures and more powerful storms caused by global warming will lead to even greater erosion.
A forecast model for the next 50 years implies that the sea will advance 2-5 times faster, and that maximum erosion of the East Arctic coast (5 to 15 m per year) will probably take place in 2040-2045.
The sea began to advance at the end of the last Ice Age, rather than throughout the 20th century. Hence the following conclusion: global warming caused by humans does erode the Arctic coast, but it is not the main cause of this process.
In real life, the perennial laws of nature, as well as the planet's natural history, lead to coastal erosion. A concept suggested by researchers from Moscow State University's Geography Department claims that the shoreline of the Russian Arctic's east sector has retreated 300 km in the vicinity of the Laptev Sea and by 800 km near the East Siberia Sea over the last 15,000 years.
The encroaching sea destroyed lake and thermal-karst lowlands and turned the more resistant permafrost structures into islands, some of which succumbed to thermal abrasion. Such islands as the Andreyev Land, Vasilyevsky, Semyonovsky and others have vanished completely in the last 200 years. The Shelonskiye, Mostakh and Makar islands will be eroded in the near future.
Rising sea levels will affect the 150 million people living in coastal areas all over the world. National governments will have to spend a great deal of money in order to relocate the populations of inundated areas and to build protective dams.
Although the sparsely populated Russian Arctic will suffer less than other regions, local ethnic groups usually live on the coast. Coastal erosion and inundation are already causing major problems on the Chukchee Peninsula.
Experts must do their best in order to reliably assess coastal dynamics and work out timely recommendations and measures that would help coastal territories to adapt to new realities. This is becoming a top priority at a time when some Arctic areas, including the Kara Sea shelf, appear to contain huge hydrocarbon deposits.
Dmitry Zamolodchikov is a professor at Moscow State University.
The opinions expressed in this article are the author's and do not necessarily represent those of RIA Novosti.
