4. Permafrost#

Frozen ground vs permafrost#

  • Seasonally frozen ground: freezes more than 15 days per year (The Ice Bowl)

  • Permafrost (permanently frozen ground): <= 0°C for at least 2 years (not necessary having water or ice!)

Permafrost zones#

../_images/permafrost_map.png

Fig. 6 Permafrost zones and locations for CO2 and methane flux measurements collected with eddy covariance (yellow) and chambers (blue). Source: EOS#

Permafrost formation#

../_images/permafrost_formation_tmp1.jpeg

Fig. 7 This diagram explains the formation of open-system and closed-system pingos. — Credit: Encyclopædia Britannica. Source: NSIDC#

Factors affect permafrost#

  • Diurnal cycle

  • Seasonal cycle

  • Geographic location

  • Elevation

  • Landscape: snow (insulator), soil type, peat, plants (evergreen trees)

  • Slope

  • Lakes and rivers: heat source, talik

  • Radiation

Thawing permafrost and climate change#

  • Satellite observations (e.g., GRACE and ICESat)

  • Air temperature

  • Moisture

  • Active layer

  • Lakes

  • Ecosystem

  • Sea level

Biological and human activities and permafrost#

../_images/pipline_permafrost_tmp1.jpeg

Fig. 8 NSIDC researcher Tim Schaefer stands behind an exposed ice layer at a subsidence feature, called a thermokarst, on August 19, 2012, near Toolik Lake, Alaska. Note the Alaskan pipeline in the distance. — Credit: K. Schaefer, NSIDC.#

Permafrost and carbon cycle#

  • Carbon dioxide

  • Methane

Literature review#

Sources#