Dr. John Jaeger's Abstracts
7:00 pm Thursday, April 15, 2010; Schaible Aud. in Bunnell Bld., UAF
Gulf of Alaska glacier melting events and the connection to oceanic and atmospheric circulation
In Alaska, changes in North Pacific and Arctic climate systems lead to decadal-long shifts in Arctic air temperature and precipitation, which in turn has led to pronounced changes in regional oceanography and quite noticeably in the accelerated melting of Alaskan glaciers. However, there are few annual records of meltwater discharge directly from large cliff-calving glaciers to test how glacier melt varies in response to high-frequency climate change over the last several decades. Marine sediments in the Gulf of Alaska region offer a potential means to create a decadal-long proxy record of the impact of the PDO and ENSO on glacial meltwater discharge and its impact on regional oceanography. This talk will review how the PDO and ENSO affect the meteorology and oceanography of the Gulf of Alaska region, which lead to changes to glacial mass balances and meltwater production, and how glacial-marine sediments can be used to document how the PDO and ENSO have potentially altered meltwater discharge.
1:00 pm Friday, April 16, 2010; 501 Akasofu (IARC), UAF
The Quaternary Marine Record of Bering Glacier Dynamics: Ice streams, Surges, and Outburst Floods
Bering Glacier, Alaska is the largest, but until recently, one of the more poorly studied dynamic glaciers in North America. It is largely known for its dramatic surging events, six of which have occurred in historic times. A primary mid-to-late Holocene history of the Bering has been established from on-shore studies of glacial termini position and evidence of glacial advances, but little is known of the late Quaternary history of the Bering. The recent collection of high-resolution bathymetric and seismic reflection data and a proxy sedimentary record of glacial dynamics provide new insights into the formation of the Bering and its late Quaternary evolution. Deep-penetrating (> 1 km) high-resolution seismic images acquired along the Bering Trough constrain Quaternary sedimentation and ice coverage on the continental shelf, revealing a transition in glacier morphology from smaller, more dispersed termini throughout the inner shelf in the Pilocene to the generation of a Pleistocene ice stream in the position of the modern Bering. The Last Glacial Maximum (LGM)-to-present dynamics of the Bering are revealed from a series of jumbo piston cores and high-resolution seismic reflection profile seaward of the Bering Glacier. The LGM terminus of the Bering was at the continental shelf edge, with glacial retreat from the shelf complete by the start of the Bølling-Allerød (14.6 kya). Increased sediment fluxes to the shelf at ~ 4 kya indicate renewed glacial advances likely attributed to the Holocene Neoglacial period. Just prior to the Little Ice Age, the Bering had likely reached a position similar to its modern extent. Mid-shelf deposits near the head of the Bering Trough reveal a significant change in sediment input and likely glacier dynamics during and after the Little Ice Age. During the LIA, sedimentary records indicate of more frequent (<10 yr recurrence) flooding events, which differs appreciably from the past century, where dramatic outburst floods occur on multi-decadal time scales. This suggests that the Bering Glacier's hydrology during the LIA was altered relative to the present conditions that result in quasi-periodic surges.
Dr. Julie Brigham-Grette's Abstracts
7:00 pm Thursday, March 18, 2010; Schaible Aud. in Bunnell Bld., UAF
Arctic Immersion with Undergraduates in Kongsfjord, Svalbard
Contemporary studies of tidewater glacier margins in Kongsfjord, Svalbard (79oN), provide an unparalleled opportunity for introducing motivated third year undergraduate students to the challenges and rewards of polar field research. Rates of rapid change in this high-latitude Arctic environment emphasizes the complexity of the Earth System at the interface of the ocean, atmosphere and cryosphere. Given background information in glaciology, glacial geology, hydrology, climatology and fjord oceanography not routinely offered in undergraduate curricula, students develop the science questions to be addressed and establish a field plan for instrumentation and sampling. Working together in small boats in one of the most challenging natural environments, the students expand their leadership skills, learn the value of teamwork and collaborative data sharing while maintaining a strong sense of ownership over their individual science projects. The rigors of studying an actively calving tidewater glacier also builds on their outdoor skills, especially when it is necessary to improvise and become resourceful due to instrumentation failures or weather-related delays. Self-confidence and problem solving skills emerge from both field and laboratory research operations when students draw upon and expand their base of practical knowledge via trial and error. The Kings Bay logistical facilities in Ny Ålesund offer an international experience with opportunities for dialog with scientists of a wide variety of disciplines working at research stations representing more than 12 different European and Asian countries. All students in the program complete yearlong senior theses or independent studies and make presentations at a professional meeting to complete the scientific process.
3:30 pm Friday, March 19, 2010; 201 Reichardt Bld., UAF
Successful recovery of 3.6 Myrs of Arctic History from Lake El'gygytgyn, Chukotka
Lake El’gygytgyn, 100 km north of the Arctic Circle (67°30' N, 172°05' E), was created 3.6 Ma by a meteorite impact. In Spring 2009, drilling operations recovered 512 m of lake sediment and impact breccia that will provide new insights into the climate evolution of the Arctic and late Cenozoic formation of the crater. The temporal length and geologic significance of the climate record is absolutely unprecedented in the Arctic region, and more than 30 times longer than temporal records from the Greenland Ice Sheet.
Nearly 355 m of sediment were cored with outstanding recovery from three adjacent holes, drilled side by side. Replicate cores to ~130 m below lake floor (mblf) from each site date back to ~2.6 Ma based on early paleomagnetic evidence. In addition, a single core extending to the time of impact at 3.6 Ma was collected to a depth of 315 mblf, albeit with lower recovery in places due to surprising sequences of coarse sand and gravel interbedded with lacustrine mud. These coarser units suggest unexpected glacial or hydrologic influences that imply different moisture sources and snowline depression for the earliest Northern Hemisphere glaciations. Roughly 185 m of the lower sediment sequence records the earliest history of the lake since the warm middle Pliocene. This interval is especially valuable as a possible analog for future climate due to CO2 forcing. This portion of the record will also contribute new information concerning the Late Cenozoic climate evolution of the Arctic for comparison with Arctic Ocean (ACEX) and subarctic marine records. Core opening was initiated in October, 2009 and is ongoing.
Field measurements were restricted to whole core magnetic susceptibility and a range of other properties using down-hole logging instruments. Yet warm/cold cycles, similar to those seen in pilot cores extending to 300 ka ago (16 mblf), are identified in the new cores extending to more than 130 mblf. This record suggests the cores will produce new information on the style and onset of Northern Hemisphere glacial cycles for the first time seen with such clarity in an arctic terrestrial setting.
Dr. John England's Abstracts
7:00 pm Thursday, February 11, 2010; UA Museum Auditorium, UAF
A tale of two Arctic ice shelves: lessons learned from ancient and modern examples
Two ice shelf stories are told. The first describes probably the world’s best geological record of an ancient glacier ice shelf - a vast apron of ice floating in the sea, fed from the grounded margin of the northwest Laurentide Ice Sheet. This ice shelf is noteworthy because it formed catastrophically (in less than a human lifetime), advancing 400 km and covering 100,000 sq. km of the marine channels of the western Canadian Arctic Archipelago. The ice shelf overrode the coasts of several islands, depositing distinctive sediments still visible on satellite images. I describe the evidence for the extent and age of the ice shelf, together with the factors that may have favoured its growth as well as its equally abrupt disappearance 400 years later. The ice shelf is not simply an event locked in the geological past but provides important insights into ice shelf dynamics that are relevant to many parts of the modern West Antarctic Ice Sheet and its adjoining ice shelves whose stability has long been questioned.
The second sea-ice ice shelf is entirely modern and forms a coastal apron attached to northern Ellesmere Island where it floats on the Arctic Ocean at the apex of North America. The Ellesmere Ice Shelf was originally described as a “rolling prairie of sea ice” used by both European (Aldrich) and American (Peary) explorers who sledged across it for hundreds of miles during the late 1800’s. Modern interest in the ice shelves returned when joint American and Canadian air force surveys discovered giant “ice islands” floating on the Arctic Ocean. Their surface of huge ridges and troughs gave the ice islands their distinctive ‘washboard’ appearance, and like pieces in a jig-saw puzzle they were eventually matched to the pattern of the Ellesmere Ice Shelf from which they had broken off. Long before ships could navigate the Arctic Ocean’s severe sea ice, these massive ice islands served for decades as the earliest research platforms. This talk describes the history of the Ellesmere Ice Shelf and how its previously unknown age of formation has been documented by radiocarbon-dating driftwood carried across the Arctic Ocean from Russia. The driftwood indicates that the Ellesmere Ice Shelf formed 5500 years ago and has persisted ever since, preventing further driftwood entry. However, since the 20th century, the Ellesmere Ice Shelf has been progressively down-sized and its breakup continues today. This history of ice shelf reduction during the past century is directly relevant to the history of Arctic Ocean pack ice whose similar reduction has been documented for only the past four decades of satellite surveillance. The Ellesmere Ice Shelf suggests that the pack ice also underwent an earlier (pre-1970) reduction previously undocumented. What is left of the Ellesmere Ice Shelf –the oldest sea ice in the Northern Hemisphere – is now precariously hanging on as four small remnants that offer insights about how significantly the Arctic is currently changing.
3:30 pm Friday, February 12, 2010; 201 Reichardt Bld., UAF
Ongoing revision of the NW Laurentide ice Sheet: implications for paleoclimate, the northeast extremity of Beringia, and Arctic Ocean sedimentation
For the past half-century, reconstructions of North American ice cover during the Last Glacial Maximum have shown ice-free land distal to the Laurentide Ice Sheet, primarily on Melville and Banks islands in the western Canadian Arctic Archipelago. Both islands reputedly preserve at the surface multiple Laurentide till sheets, together with associated marine and lacustrine deposits, recording as many as three pre-Late Wisconsinan glaciations. The view that the western Canadian Arctic Archipelago remained largely ice-free during the Late Wisconsinan is reinforced by a recent report of two woolly mammoth fragments collected on Banks and Melville islands, both dated to ~22 ka BP. These dates imply that these islands constitute the northeast extremity of Beringia.
However, a fundamental revision of this model is now warranted based on widespread fieldwork across the adjacent coastlines of Banks and Melville islands, including new dating of glacial and marine landforms and sediments. Late Wisconsinan ice advanced northwestward over Banks and Melville islands, grounding in the 500 m deep strait separating them. Shells of Mid-Wisconsinan age have been dated from the most extensive Laurentide till. Deglaciation is recorded by widespread meltwater channels that show both the initial separation of Laurentide and local Melville ice, as well as the successive retreat of Laurentide ice to the south. Forty dates on shells collected from associated glaciomarine rhythmites record near synchronous ice retreat from M’Clure Strait and Dundas Peninsula to north-central Victoria Island ca.11.5 ka BP. Along the adjacent coast of Banks Island, deglacial shorelines of similar age also record the retreat of Laurentide ice both eastward through M’Clure Strait and southward into the island’s interior.
The last retreat of ice from northern Banks Island, previously assigned to northward retreat into M’Clure Strait during the Early Wisconsinan, is contradicted by geomorphic evidence for southward retreat into the island’s interior during the Late Wisconsinan. This revision of the pattern and age of ice retreat across northern Banks Island results in a significant simplification of the previous Quaternary model that reported the preservation of surficial deposits from multiple glaciations. New observations now support the amalgamation of these multiple till sheets – previously assigned to at least three pre-Late Wisconsinan glaciations – into the Late Wisconsinan. This revision also removes their formally named marine transgressions and proglacial lakes for which evidence is lacking. An extensive Late Wisconsinan Laurentide Ice Sheet across the western Canadian Arctic is compatible with similar evidence for extensive Laurentide ice entering the Richardson Mountains (Yukon) farther south and with the Innuitian Ice Sheet to the north. Widespread Late Wisconsinan ice, in a region previously thought to be too arid to sustain it, has important implications for paleoclimate, ice sheet modelling, Arctic Ocean ice and sediment delivery, and clarifying the northeast limit of Beringia.
Dr. Tom McGovern's Abstracts
7pm Thursday February 26th, 2009; University of Alaska Museum Arnold Espe Auditorium
Extinction, Survival, and Sustainability- thresholds and conjunctures in the Viking North Atlantic
The North Atlantic has seen dramatic interplay of humans, island ecosystems, and changing climate over the past thousand years. The Viking age expansion of people, economies, and social systems out of mainland Scandinavia into the northern British Isles, Faroes, Iceland, Greenland and (briefly) Vinland/ North America set up a common culture across a very diverse set of island ecosystems, which would be affected in very different ways by later climate change and accumulated human environmental impacts. The different island communities experienced radically different fates by 1500 AD- the Faroese had established a generally successful sustainable adaptation that produced little environmental change, the Icelanders conserved many resources but ultimately lost their battle against soil erosion on a large scale, and the Greenlandic colony became entirely extinct. The circumpolar north has become increasingly recognized as a sort of "global mine canary" for rapid environmental change and it is clear that present changes cannot be understood without a long term record of human / environmental interaction- a historical ecology of human ecodynamics. An international research cooperative (North Atlantic Biocultural Organization- NABO [www.nabohome.org]) has been working with support from the international polar year initiative to combine archaeology, history, environmental science, and climatology to provide a better understanding of the dramatic stories of human/ environment interaction in the N Atlantic and this talk will present some of the most recent results of this coordinated research effort.
3:30 pm Friday February 27th, 2009; 304 Eielson Bld., UAF
Human Ecodynamics in the North Atlantic- recent IPY results
As part of the International Polar Year collaborative effort the North Atlantic Biocultural Organization (NABO) was funded by the US NSF, Canadian, Danish, and Icelandic funding sources beginning in 2007 to carry out interdisciplinary work in archaeology/ environmental science/ education/ public outreach in the Shetlands, Faroes, Iceland, and Greenland (www.nabohome.org). Our mandate has been to combine interdisciplinary long term human ecodynamics research in this historically and environmentally key portion of the circumpolar north with a program of education aimed at doctoral students through K-12 and the engagement of local museums, schools, and communities in the region. While the program is ongoing, we do have some exciting new results on human/climate/ landscape dynamics in the Norse N Atlantic to report and some approaches to delivering our results and engaging our public to share with Alaskan colleagues long engaged in similar research, education, and outreach efforts. We have some new perspectives on Norse adaptations in the N Atlantic, and a very different understanding of the interaction of Viking age and medieval settlers with a changing environment- the story told to Jared Diamond in "Collapse" needs major updating. This talk will present some highlights of project results and a discussion of where we hope to go with our coordinated multi-island effort through 2010.
Dr. Mary Edward's Abstracts
3:30 pm Thursday, April 23, 2009; 401 IARC
Climate change and wildfire: a long-term perspective
3:30 pm Friday, April 24, 2009; Elvey Auditorium
A novel approach to the description of past and present arctic plant communities using DNA barcoding techniques
The potential of ancient DNA (aDNA) to inform palaeo studies has recently been investigated in a number of contexts. I will discuss a novel approach that uses short-sequence barcoding and high-throughput sequencing to characterize aDNA present in modern and ancient sediments—specifically arctic soils and Quaternary sediments in permafrost terrain. The work builds upon pioneering work by Willerslev and Taberlet on aDNA extraction and barcoding and is part of an ongoing EU project ‘Ecochange’. Over 800 species of arctic vascular plant have been catalogued and a barcode taxonomy has been developed. Last year we retrieved recent and sub-recent DNA from soils underlying tundra vegetation in Norway, and compared the DNA assemblages with modern vegetation cover. The results are promising and the method performs as well as pollen analysis. Future developments promise to increase taxonomic resolution and expand the technique to other groups of organisms. Rapidly advancing sequencing technology will make such an approach cost-effective as a rapid survey tool and a new palaeoecological technique, although some sediment archives impose temporal limitations on palaeo-reconstructions.