(Practice Question: What do you understand by ‘permafrost’? Account for the effect of melting of permafrost on the climate.)
What is ‘permafrost’?
Permafrost is a combination of ice, soil, plants, and other materials that has remained frozen for years or centuries under topsoil. It contains carbon-rich organic material, such as leaves, that froze without decaying. It can be compared to a ‘sponge’ that soaks up carbon and nutrients.
How does the melting of ‘permafrost’ affect the climate?
Permafrost occurs mostly in high latitudes. It comprises 24% of the land in the Northern Hemisphere, and stores massive amounts of carbon. As a result of climate change, permafrost is at risk of melting (also called ‘thawing of permafrost’), releasing the stored carbon in the form of carbon dioxide and methane, which are powerful heat-trapping gases. In addition, permafrost is structurally important, and its melting has been known to cause erosion, disappearance of lakes, landslides, and ground subsidence. It will also cause changes in plant species composition at high latitudes.
Flooding: The most obvious challenge of melting permafrost is flooding, which poses a threat to sea levels as well as facilities in the Arctic circle like the doomsday vault, which stores seeds for every known crop on the planet. Melted ice water recently flooded the vault, but ultimately the water was kept away from the seeds.
Release of carbon dioxide and methane: Arctic permafrost contains 1.8 trillion tons of carbon, more than twice as much as is currently suspended in the Earth’s atmosphere. As the permafrost in the Arctic melts, it could release that carbon dioxide, along with methane, an even more potent gas that traps in 30 times as much heat as carbon dioxide. Such a release could influence the global climate.
Return of deadly diseases like smallpox: As has been warned by the experts, deadly diseases such as smallpox could return as the frozen tundra of Siberia melts and releases the virus from the corpses of people who died in a major epidemic about 120 years ago.