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Research Highlights

Role of Ground Ice Dynamics and Ecological Feedbacks in Recent Ice-wedge Degradation and Stabilization

Ice wedge Fish Creek Yuri Torre

Yuri Shur and Torre Jorgenson stand in front of a large ice wedge, which is protected by only a thin layer of soil that thaws during the summer.

Ground ice is abundant in the upper permafrost throughout the Arctic and fundamentally affects terrain responses to climate warming. Ice wedges, which form near the surface and are the dominant type of massive ice in the Arctic, are particularly vulnerable to warming. Yet, processes controlling ice-wedge degradation and stabilization are poorly understood. In a recent paper published in the Journal of Geophysical Research: Earth Surface, Torre Jorgenson and colleagues from the University of Alaska Fairbanks and the U.S Geological Survey quantified ice-wedge volume and degradation rates, compared thermal regimes and ground-ice characteristics across a sequence of degradation and stabilization stages, and evaluated biophysical feedbacks controlling permafrost stability near Prudhoe Bay, Alaska. By measuring thermokarst pits on imagery from 1949 to 2012, they showed ice-wedge degradation abruptly increased in the 1990s and covered 9% of the area by 2012 (below).

PBU Time-Series 1968-2012 Five Yrs Half-page

In early stages, thaw settlement caused water to impound in thermokarst troughs, creating positive feedbacks that increased net radiation, soil heat flux, and soil temperatures. The disturbance stimulated plant growth and organic-matter accumulation, providing negative feedbacks that allowed ice to aggrade and heave the surface, thus reducing surface water and soil temperatures in later stages. Due to these ecological feedbacks, mean annual soil temperatures varied by 9 °C, nearly twice as large as projected regional climate warming by century’s end. This greatly complicates efforts to model and project permafrost response to climate change.

Prudhoe thermokarst pit measuring temperatures

Measuring permafrost temperatures below in a recently collapsed thermokarst pit.

Jorgenson, M. T., M. Z. Kanevksiy, Y. Shur, K. Wickland, D. R. Nossov, N. G. Moskalenko, J. Koch, R. Striegl. 2015. Role of ground-ice dynamics and ecological feedbacks in recent ice-wedge degradation and stabilization. Journal of Geophysical Research – Earth Surface 120:2280-2297.

In the news

6 May 2017. M. Torre Jorgenson was awarded the Honorary Degree of Doctor of Science from the University of Alaska Fairbanks on May 6, 2017 for his outstanding contribution to the fields of permafrost science, thereby greatly enhancing understanding of the Northern environment. From UAF News release: “Jorgenson has an international reputation as a permafrost scientist who has studied linkages in geomorphology, ecology, hydrology and soil science. His business, Alaska Ecoscience, is dedicated to studying the impacts of climate change on Alaska’s landscapes. Jorgenson’s contributions to UAF began as a camp manager at Toolik Field Station in 1977, which led him to earn a master’s degree in land resources management from UAF in 1986. His has contributed to oilfield impact assessments, land rehabilitation techniques, ecosystem and permafrost mapping, and coastal dynamics research. He has worked with many UAF graduate students and holds affiliate faculty positions with UAF’s Institute of Northern Engineering and Institute of Arctic Biology.”
article

 

30 June 2016. Torre Jorgenson received the Wiley-Black Permafrost and Periglacial Permafrost Journal award for excellence in permafrost research at the International Conference on Permafrost (ICOP) at Postdam, Germany on 20 June 2016. The award was given in recognition of his major influence in bridging geocryology, thermokarst research and ecology, and stimulating research in permafrost as a unifying discipline for northern scholarship. He recently coauthored with Steve Kokelj a recent synthesis on thermokarst, which was the top-cited paper in the 2014 Impact Factor Period for PPP. In accepting the award he gave a keynote address at ICOP on permafrost-ecological interactions. A video of his acceptance speech for the award is posted at Youtube,
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8 Dec. 2015. Up to a quarter of the permafrost that lies just under the ground surface in Alaska could thaw by the end of the century, releasing long-trapped carbon that could make its way into the atmosphere and exacerbate global warming, according to a new study by Neal Pastick, as reported by Climate Central of Scienctific American. The paper, co-authored by
Torre Jorgenson and others, was published in the journal Remote Sensing of Environment. article

1 Dec. 2015. Dana Brown recently published a paper investigating how the warming climate reduces permafrost’s ability to recover following wildfires in Alaskan lowland forests. Her study, as part of her PhD research with Torre Jorgenson, was highlighted in Eos Earth & Space Science News. article

26 Nov. 2015. Alaska Daily News has an interview with Misha Kanevskiy, permafrost scientist at UAF, about his recent paper, co-authored with Torre Jorgenson in Geomorphology, on river erosion of extremely ice-rich Pleistocene permafrost (yedoma) in Northern Alaska. article

Nov. 12 2014. Alaska scientists used satellite images to look through clouds during storms and for the first time could see how far tidal flooding on the Yukon-Kuskokwim Delta extended inland. It was much farther than they imagined. In a radio new program by Daysha Eaton on APRN, Jorgenson said “It’s really extensive, it can go just about 20 miles inland during these really large storm events. So it covers a very large portion of the outer Delta”.
For APRN radio podcast podcast

For journal article in Arctic article