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TitleTundra ponds as initiators of peat plateau thaw, northern Hudson Bay Lowland, Manitoba
AuthorDyke, L D; Sladen, W E
SourceArctic vol. 75, no. 3, 2022 p. 364-377, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20210411
PublisherArctic Institute of North America
Mediapaper; digital; on-line
File formatpdf
NTS42P; 43; 53I; 53J; 53O; 53P; 54
AreaChurchill; Hudson Bay; James Bay; Nelson River
Lat/Long WENS -96.0000 -80.0000 59.0000 51.0000
Subjectsenvironmental geology; Nature and Environment; peat; permafrost; climate; modelling; Hudson Bay Lowlands
Illustrationsphotographs; location maps; graphs; schematic cross-sections; tables
ProgramClimate Change Geoscience Permafrost
Released2022 09 12
AbstractFrozen peat in permafrost regions poses a potential source of increased greenhouse gas production should these deposits thaw. Ponds on frozen peat plateaus in northern Manitoba are numerically modelled as heat sources to determine their potential to promote thaw. Modelling indicates that anticipated climate warming of approximately 2?C between 2020 and 2050 will produce taliks up to a few metres thick beneath ponds a few tens of metres across. However, active-layer thickness in the subaerial parts of peat plateaus will not increase beyond the peat thickness. These findings assume 1) a climate warming rate under a moderately effective intervention in greenhouse gas production, 2) pond freezing regimes that represent both rapid ice formation and ice formation delayed by rapid snow accumulation, and 3) snow thermal conductivities that anticipate snow conductivity increase during the freeze interval. These conditions and properties may turn out to be less conducive to talik expansion than the values that will actually occur. Despite these uncertainties, peat plateau pond sizes and plateau margin positions can be monitored to ascertain the onset of accelerated thawing.
Summary(Plain Language Summary, not published)
Frozen peat plateaus in northern Manitoba are maintaining their frozen state under the present climate. This paper examines the sensitivity of these frozen peat plateau surfaces to climate warming. To do this we analyze ponds on frozen peat plateaus as heat sources to determine their potential to degrade permafrost. Air and ground temperature records for the area, as well as projected air temperature increases based on the climate models, are incorporated into a numerical heat flow model. Our results suggest that by 2050, thawing of a few metres will take place beneath shallow ponds on peat plateaus if climate warming continues at the same rate as the last few decades. However, thawing will not progress beyond the peat thickness in the adjacent peat plateaus. If climate warming continues for two to three decades, pond expansion and peat plateau thaw will likely accelerate.

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