Greifswald Mire Centre & Universität Greifswald

1. Peatland & Permafrost:
a cool relationship
Hans Joosten
joosten@uni-greifswald.de

2. https://www.bbc.com/news/science-
environment-48678196
If you do not yet believe in climate change, this graph will convince you….

3. The Arctic (60-90°N) is now warming twice as fast as global average
(SWIPA 2017)

4. The northern circumpolar region holds almost half of the world’s soil organic
carbon (Hugelius et al. 2013)…

5. …by frost related burial (cryoturbation)…

6. …but largely in the form of permanently frozen peat…

7. In the High Arctic
permafrost
formation
co-determines
peat
accumulation
In the Middle/Low Arctic facilitates
In the Subarctic requires
Peatlands and permafrost have a dialectic relationship:
Permafrost shapes peatland and peatland shapes permafrost…

8. In the dry High Arctic, peat formation only occurs where plant productivity is
boosted by fertilization (birds!). The peat is then directly conserved by permafrost

9. In the Middle/Low Arctic permafrost prevents meltwater loss in summer whereas
ice wedges obstruct surficial water flow. Both processes facilitate peat formation

10. In the Subarctic, permafrost only occurs under very special conditions, primarily in
peatlands (zone of discontinuous permafrost).
Non-permafrost Permafrost

11. Dry peat has a very low thermal conductivity (~0.1 Wm-1K-1), that of wet and frozen
peat is five and 25 times higher

12. Dry peat in summer acts as insulator obstructing summer heat flow, whereas
wet/frozen peat in winter allows winter cold to get in

13. This one-way cold pump ( ‘thermal diode’) creates/protects permafrost in places
where it otherwise could not exist (even at MAAT of + 2oC)

14. Permafrost is thus not only the result of cold air temperatures but depends on
various complex interacting landscape components…

15. As illustrated in this FRONTIERS 2018/19 graph:
Peatlands and permafrost: the role of peat, plants and water

16. Positive feedbacks in permafrost development: the battle between ice and water
 contrasting developments and rapid changes
drier vegetation
insulating better in
summer
colder ice core in
winter
more ice
remaining and
more
aggregation
higher, larger and
thus drier ice
mounds

17. Permafrost degradation is most evident in the peatland/carbon-rich discontinuous
permafrost zone

18. Changing patterns of permafrost (green), thermokarst ponds (blue) and fen
vegetation (white) between 1957 and 2003 (Quebec, Canada, Payette et al. 2004).

19. Round collapse scars in permafrost peat plateaus (Lakitusaki L., ON, Canada)

20. Thawing of permafrost peat plateau edge caused by flooding of the fen : “drunken
forest” (Peel R., NWT, Canada)

21. But also recent formation of new palsa permafrost mounds (red arrows) in
generally degrading permafrost peatland (Stordalen N-Sweden)

22. Human intervention in various landscape components may affect permafrost…

23. Climate change and sea level rise: to be combatted worldwide

24. Climate scenarios predict massive thawing of permafrost until 2099 (Slater &
Lawrence 2013). Present-day permafrost is shown by gray shading.

25. Vegetation removal: 4 yr after shrubs cutting, surface has collapsed with 3 dm!

26. Fire removes the insulating vegetation and soil layers…

27. Thermokarst starts by changing heat balance

28. Ice wedges melt, leaving bajcherakhi’s

29. Permafrost-based forest changes in a non-permafrost underlain lake

30. Water accumulates summer heat, acts as a heat source in winter and thereby
affects the local distribution of permafrost.

31. Infrastructure changes hydrology: Progression of thermokarst along the Prudhoe
Bay Spine Road (Alaska), which was constructed in 1969 (Walker et al. 2014).
1949 1972 1979 2010 2013

32. Knowledge gaps and research needs (SWIPA 2017) include:
• the amount of carbon in permafrost areas, its release potential, and its connection to the
global carbon cycle
• the multiple interrelated feedbacks that determine timing, magnitude, and risk of future
permafrost changes
• the amount of global warming that would trigger abrupt shifts in the permafrost system
• the strength of the positive feedback between thawing permafrost and warming climate
• the effect of permafrost degradation on coastal erosion, ecosystems, and infrastructure
• improvement of monitoring, satellite interpretation, process studies, modeling, and
coordination between these activities
• quantification of impacts in terms of economic and societal costs.

33. “The physical complexity of permafrost peatlands and the significant risks of their
degradation and disruption demand a holistic approach to land-use planning and
management, requiring integrated knowledge for planners and policymakers”