We have estimated the erosion of sediment and organic carbon input from the Kara Sea coast based on extensive mapping, geologic and cryolithologic investigations of coastal zone and seafloor sediments, and revision of previously published data. The amount of coastal sediment eroded into the Kara Sea was determined to be approximately 35 million tons. Twenty-seven million tons are attributed to solid material, 7.6 million to thawed ground ice, 0.4 million to organic carbon, and 0.3 million to soluble salts. The estimate of organic carbon input presented herein is 2.5-fold less than previously published elsewhere. The majority of organic carbon in marine clayey deposits was found to be present in an adsorbed form. Its quantity corresponds to the content of clay particles in Pleistocene sediments. Organic carbon content in clay marine sediments remains unchanged during freeze-thaw processes, indicating that this form of carbon is stable unless thermoerosion is taking place.