Publication Date:
2024-04-22
Description:
Permafrost is perennially frozen ground, such as soil, rock, and ice. In permafrost regions, plant and microbial
life persists primarily in the near-surface soil that thaws every summer, called the ‘active layer’ (Figure 20). The
cold and wet conditions in many permafrost regions limit decomposition of organic matter. In combination with
soil mixing processes caused by repeated freezing and thawing, this has led to the accumulation of large stocks
of soil organic carbon in the permafrost zone over multi-millennial timescales. As the climate warms, permafrost
carbon could be highly vulnerable to climatic warming.
Permafrost occurs primarily in high latitudes (e.g. Arctic and Antarctic) and at high elevation (e.g. Tibetan
Plateau, Figure 21). The thickness of permafrost varies from less than 1 m (in boreal peatlands) to more than
1 500 m (in Yakutia). The coldest permafrost is found in the Transantarctic Mountains in Antarctica (−36°C)
and in northern Canada for the Northern Hemisphere (-15°C; Obu et al., 2019, 2020). In contrast, some of
the warmest permafrost occurs in peatlands in areas with mean air temperatures above 0°C. Here permafrost
exists because thick peat layers insulate the ground during the summer. Most of the permafrost existing today
formed during cold glacials (e.g. before 12 000 years ago) and has persisted through warmer interglacials. Some
shallow permafrost (max 30–70m depth) formed during the Holocene (past 5000 years) and some even during
the Little Ice Age from 400–150 years ago.
There are few extensive regions suitable for row crop agriculture in the permafrost zone. Additionally, in areas
where large-scale agriculture has been conducted, ground destabilization has been common. Surface
disturbance such as plowing or trampling of vegetation can alter the thermal regime of the soil, potentially
triggering surface subsidence or abrupt collapse. This may influence soil hydrology, nutrient cycling, and
organic matter storage. These changes often have acute and negative consequences for continued agricultural
use of such landscapes. Thus, row-crop agriculture could have a negative impact on permafrost (e.g. Grünzweig
et al., 2014). Conversely, animal husbandry is widespread in the permafrost zone, including horses, cattle, and
reindeer.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Inbook
,
peerRev
,
info:eu-repo/semantics/other
Format:
application/pdf
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