Assessing the Resilience and Vulnerability of Permafrost Landscapes to Environmental Change

1. Assessing the Resilience and Vulnerability of Permafrost Landscapes to Environmental Change Torre Jorgenson, Yuri Shur, Mikhail Kanevskiy, Matt Dillon, and Eva Stephani

2. Approach to Assessing Permafrost Stability • Define permafrost in relation to climate and ecosystems • Determine ground ice characteristics in relationships to terrain units • Assess magnitude of positive and negative feedbacks related to vegetation and water • Compare permafrost stability in relation to terrain

3. Redefined Permafrost in Terms of Climate-Ecosystem Relationships Shur, Y. L. and Jorgenson, M. T. 2007. Patterns of permafrost formation and degradation in relation to climate and ecosystems. Permafrost and Periglacial Processes 18: 7-19.

4. Ecologically mediated ice aggradation increases vulnerability to degradation Climate-driven, Ecosystem-modified Permafrost Vegetation-soil processes in the thinning active layer allow accumulation of 2-3 m of excess ice during floodplain evolution. Buildup of excess ice in upper permafrost form conditions for development of thaw lakes, even under cold climates Floodplain evolution Thermokarst lake development at MAATs of -12 C

5. Ecosystem-Driven Permafrost Ground ice aggradation in relation to Sphagnum growth Soil drainage after permafrost degradation

6. Ecosystem-Protected Permafrost Fish Creek MAAT -11.5 C Naknek Lake MAAT +1.5 C Layered ice in epigenetic permafrost formed in “warm” climates Ataxitic ice in syngenetic permafrost formed in cold climates

7. A New Permafrost Map for Alaska Map based on terrain units and climate From Jorgenson et al. 2008. Permafrost Characteristics of Alaska. NICOP Proceedings

8. Relating Ground Ice to Terrain Units Glaciomarine Kanevskiy et al. submitted Loess Kanevskiy et al. submitted Colluvium From Jorgenson et al. 2008. Permafrost Characteristics of Alaska. NICOP Proceedings

9. Ice Volume in Relation to Terrain Units Lacustrine Organic Silt Eolian Sand

10. Buried Glacier Ice Barter Island Abundant in Wisconsin and Little Ice Age Moraines Toolik Lake, NE14 Basal Ice Barter Island Basal Ice Matanuska Glacier Kanevskiy, M., T. Jorgenson, Y. Shur, and M. Dillon (2008), Buried glacial basal ice along the Beaufort Sea Coast, Alaska, Eos Trans. 89, 53, C11D-0531.

11. Generalized ice profiles for common types of permafrost Resilience and vulnerability of permafrost depends on type and amount of ground ice Conceptual model by M. Kanevskiy Jorgenson, M. T., Romanovsky, V., Harden, J., Shur, Y., O’Donnell, J., Schuur, E. A. G. and Kanevskiy, M. 2010. Resilience and Vulnerability of Permafrost to Climate Change. Canadian J. Forest Research.

12. Feedbacks Strongly Affect Permafrost Stability Permafrost can degrade at MAATs of -20 C due to surface water Permafrost can persist at MAATs of +2 C due to protection by vegetation and organic soil Jorgenson, M. T., Romanovsky, V., Harden, J., Shur, Y., O’Donnell, J., Schuur, E. A. G. and Kanevskiy, M. 2010. Resilience and Vulnerability of Permafrost to Climate Change. Canadian J. Forest Research.

13. Effects of Vegetation-Soil and Water on Ground Temperatures Positive Feedback from Water Negative Feedback from Vegetation-Soils • Vegetation and soil reduce permafrost temperatures by 7 deg. C. • Water can raise ground temperatures by 12 deg. C. • Positive and negative feedback effects are larger than predicted climate warming Thermal modeling by V. Romanovskiy in: Jorgenson, M. T., Romanovsky, V., Harden, J., Shur, Y., O’Donnell, J., Schuur, E. A. G. and Kanevskiy, M. 2010. Resilience and Vulnerability of Permafrost to Climate Change. Canadian J. Forest Research.

14. Alpine Rocky Dry Dwarf Scrub Upland Moist Tall Scrub Upland Moist Broadleaf Forest Upland Wet Needleleaf Forest Upland Moist Needleleaf Forest Bedrock Lowland Bog Meadow Lowland Wet Forest Lowland Broadleaf Forest Permafrost Loess Lowland Wet Low Scrub Lowland Fen Meadow Lowland Tussock Bog Riverine Barrens Retransported Silt Lake Thick Peat Gravel Riverbed PF Stratified Silt and Sand Landform–Soil–Vegetation-Permafrost Relationships

15. Upland Lowland Loamy Rocky

16. Resilience of Silty Uplands • Slopes shed water, reduce positive feedback • High ice content and latent heat slow thawing • Vegetation recovery after fire, allow negative feedbacks to stabilize permafrost. Ice-poor silt freezes back.

17. High Vulnerability of Silty Lowlands Innoko Flats Flat terrain allows water to impound, creating positive feedback to ground temperatures

18. Gravelly Lowlands with Thaw Lake Sinks Yukon Flats Lake drainage after losing permafrost curtain?

19. CONCLUSIONS • Large climate gradient across Alaska creates range of permafrost temperatures and ground ice conditions • Ground ice develops in response to temperature, soil texture, and ecology • Permafrost can be highly resilient due to vegetation-soil development, yet highly vulnerable due to water • Permafrost degradation sensitive to many interacting factors but can be broadly grouped by topography and soils.