Thesis defence in the University of Oulu 13.3.2020

Friday, March 13, 2020

Doctoral Candidate

Master of Science Olli Karjalainen

Faculty and research unit

University of Oulu Graduate School, Faculty of Science, Geography Research Unit

Field of study

Geography

Date and time of the thesis defence

13.3.2020 12:00

Place of the thesis defence

University of Oulu, Linnanmaa, IT116

Topic of the dissertation

Statistical modelling of circumpolar permafrost: thermal and geomorphic sensitivities to climate change and societal implications

Opponent

Professor Martin Hoelzle, University of Fribourg, Switzerland

Custos

Professor Jan Hjort, University of Oulu

Thawing permafrost threatens Arctic natural and human environments

The thesis suggests that the thawing of permafrost due to warming climate presents threats for the natural and human systems in the Arctic. Permafrost is not permanent. As a consequence of the ongoing climate change its temperatures are rising and intensifying degradation of near-surface permafrost is observed across the Arctic. The presence of frozen ground governs hydrological and geological landscape properties and sustains unique ecosystems. Moreover, permafrost provides support for the settlement, transportation and industry infrastructure serving millions of people living in the area.

This thesis examined present-day near-surface permafrost and predicted its changes in a warming world. Statistical modelling allowed for the analysis of permafrost temperature, seasonal thawing depth and associated thaw-related hazards at higher spatial detail than before. In addition, suitable environmental conditions for the occurrence of permafrost landforms were modelled in recent and future climates for the first time across the whole Northern Hemisphere permafrost region.

According to the results, near-surface permafrost will thaw over extensive land areas. Resulting ground subsidence and loss of bearing capacity may damage infrastructure. Increasing damages and high maintenance costs of critical infrastructure hinder the sustainable development of Arctic communities and utilization of natural resources. By mid-century, around one-third of infrastructure may be affected by permafrost thaw-related hazards. Oil and gas extraction areas and large cities in northwest Siberia are among the potentially most threatened regions.

Adaptation to the societal implications of thawing permafrost requires modern infrastructure solutions and change monitoring. The geographical approach applied in this thesis produced new insights which could facilitate Arctic planning and decision-making. The results show that permafrost thaw and related consequences could be reduced by mitigating the ongoing climate change.

Dissertation

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Event location

Linnanmaa, sali IT116

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Last updated: 10.3.2020