East Siberia’s permafrost contains about 500 Gigatons (1100 trillion pounds) of frozen carbon deposits that are highly susceptible to disturbances as the climate warms. Once started, irreversible thawing could release 4.4-6.2 trillion pounds of carbon per year into the atmosphere between the years 2300 and 2400, transforming 74 percent of the initial carbon stock into carbon dioxide and methane.