High Quality Content by WIKIPEDIA articles! Yedoma is an organic-rich (about 2% carbon by mass) Pleistocene-age loess permafrost with ice content of 50–90% by volume. The amount of carbon trapped in this type of permafrost is much more prevalent than originally thought and may be about 500 Gt, that is almost 100 times the amount of carbon released into the air each year by the burning of fossil fuels . Melting yedoma is a significant source of atmospheric methane (about 4 Tg of CH4 per year).