Permafrost: History and Periglacial Environments

• Permafrost is related to the periglacial environment

History of Permafrost Studies

• 1822: First depiction of permafrost by Soviets in Kotzebue, Alaska. The Russian American expedition was led by Otto von Kotzebue
• Early 1900s: The term "periglacial" was introduced by Polish geologist Walery von Lozinski to describe the physical weathering of sandstone
• 1906: Swedish geologist Anderson described quartzite blockfields, attributing their formation to a cold climate. Lozinski described the same landscape as a "periglacial facies" and today blockfields are called felsenmeer or kurums
• WWII: The first systematic study in English appeared during WWII, when the Alaska Highway was built. S.W. Müller coined "permafrost" for permanent frost
• 1950-1970: Periglacial geomorphology rapidly developed, and in large part due to IGY in 1957-58. Permafrost studies have weaknesses like, physical weathering definition issues, climate understanding and the lithology influence on landforms
• The 1882-83 First IPY included 12 expeditions to the Arctic and 3 to Antarctica to study meteorology, geomagnetism, auroral phenomena, ocean currents, tides, structure/motion of ice, and atmospheric electricity
• 1932-33 Second IPY: 44 nations participated and created a world data center now called the IMO
• The 1957-58 IGY: 70 nations participated, paving the way for the space age and the Antarctic Treaty in 1961
• The 2007-09 Third IPY: Involved thousands of scientists from 60+ nations with 200+ projects. For the first time, included the human dimension

Periglacial Definition Note

• Periglacial conditions, including freeze-thaw of the ground and permafrost presence, are commonly found in forested zones south of the treeline
• The term "periglacial" refers to cold, non-glacial processes dominated by frost-action in the near-surface (active layer) and permafrost presence

Geomorphology vs Geocryology

• Initially regarded as an unimportant section of geomorphology
• Critical diagnostic criteria to study periglacial geomorphology cannot just be limited to permafrost alone
• Permafrost involves thermal concepts while geomorphology focuses on effects on the surface, and surface temperature
• Initially isolated studies were performed in Russia, China, and North America
• Russia and China adopted a holistic approach to geocryology and North America separates science from engineering when it comes to permafrost study
• Geography traditionally taught periglacial geomorphology, while engineering/geology/earth sciences taught geocryology, however, ground ice existence is shared across both studies
• Over the geocryology has developed into a branch of Quaternary studies

Permafrost Definition

• Ground that remains at or below 0°C for two or more years, representing the ground's thermal state. Includes bedrock, sediments, soils and the material. The contents does not have to contain free water
• The definition of ground that remains frozen for two or more years, relates to the physical state of water. The ground must then contain water
• Permafrost terrain consists of an active layer that annual freezes and thaws, it lies above perennially cryotic (or frozen) ground

Permafrost Zones

• Permafrost regions are divided into zones with varying spatial extent
• Continuous permafrost: >90% of the ground is underlain by permafrost, usually absent under rivers/lakes that don't freeze to the bottom. At a continental scale, the limiting annual mean air isotherm is about -8°C
• Discontinuous permafrost: Variations due to microclimatic effects lead to widespread permafrost, where 50-90% of the ground is underlain by permafrost
• Sporadic discontinuous permafrost: 10-50% of ground is underlain by permafrost, which is mainly relict/local vegetation effects

Permafrost Distribution

• Distribution and thickness are controlled by factors influencing a heat balance and heat flow
• Modification of temperature between the atmosphere and permafrost may occur due to vegetation, energy exchanges at the snow-ground surface, heat transfer through the active layer, local geological/hydrological conditions
• Permafrost thickness is largely influenced by MAGST (or TTOP) and geothermal heat flow and bedrock stratigraphy
• Geothermal heat is conducted through the permafrost, where the pore space is usually filled with ice and the temperature gradient varies with thermal conductivity of the bedrock

Permafrost in Alpine Regions

• Controlled by topography: aspect, lapse-rate , winter inversion
• Continuous, discontinuous and sporadic zones depend on location in the alpine region

Permafrost and Planets

• The thermal state of Planets with permafrost is a common phenomenon in our solar system, seven of nine planets and their moons, asteroids and comets are cyrogenic
• Earth has 100s m in polar regions decreasing to m in southerly regions
• 2009 LCROSS discovered ice near the south pole of the moon and is only found in permanently shadowed regions
• Mars has KM thick permafrost in polar regions to 100s of m near Equator
• Phobos and Deimos also have permafrost with Water > 20m depth near their poles, and >200m depth near their equators

Periglacial Engineering

• Nearly 10 million people live in periglacial regions
• Infrastructures and exploitation of natural resources can alter ground's thermal regime
• Impacts are largely dependent on sensitivity of terrain (ground ice content)