Shamrock Glacier, Neacola Mountains, Alaska

August 7th, 2019

While in the Neacola Mountains of Alaska last month, we flew over Shamrock Glacier. This first image is from the head of the glacier, where crevasses have been filled in with snow during the accumulation season.

Farther down the north-flowing glacier, we see the merging of the east and west branches and a fine example of a medial moraine.  However, also note on the far lower-right the recently exposed rock. This part of the glacier is shrinking in size, becoming a narrower ice stream.

The toe of Shamrock Glacier is just plain beautiful, ending at a small lake that is dammed from two larger lakes by a ring of moraines. Estimates in a blog post by Mauri Pelto are that the glacier extended all the way out to that moraine as recently as 1950.

In fact, back in 2015, Mauri showed a Landsat satellite image showing the retreat of Shamrock Glacier away from its moraine from 1987 to 2014.  Updating this with the most recent July 2019 imagery, you can see the continued retreat of Shamrock Glacier just in the past four years.  A big section on the left has calved off, and the glacier has slipped off a rise on the right.

Finally, taking a view from the ground, we can better see how the glacier has not only retreated back, but also thinned and narrowed over the past few years. (The 2015 line is based on a photo from Jerry Pillarelli It’s still a pretty glacier, and the sound of calving icebergs while eating lunch  is always welcome.  However, it won’t be long before it retreats upslope sufficiently to no longer calve off into the lake.

Columbia Bay’s Emerging Landscape

July 5th, 2019

I had the distinct pleasure of working in Columbia Bay, Alaska for ten days along with researchers Drs. Tim Barrows from the University of Wollongong – Australia, Peter Almond of Lincoln University, New Zealand, and Wooster’s own, Nick Wiesenberg.

Tim with the retreating West Branch glaciers in the background.

Peter with the spectacular backdrop of the calving glaciers in the West Branch.

Nick reclining in the old growth mountain hemlock forest overlooking Lake Terentiev – sure to be a classic tree-ring record of past climate.

Logistic centered on travel in an aluminum skiff. Captain Peter took the helm and Nick kept us off the ice, which on some days was easier than others (see below).

One of the primary objectives was to sample boulders on moraines and bedrock surfaces to determine the timing of glacial changes in Columbia Bay. Tim and Nick sampling for cosmogenic dating on a surface outside of the Little Ice Age limit.

Sampling a boulder that is well vegetated. Note the bug nets – we did notice the bugs.

Peter is a soil scientist and he dug pits on most surfaces we studied; here a well-developed spodosol is revealed. It had been years since we have dug soil pits and I was amazed. Future trips will include soils work and a stout spade.

The geomorphology was interesting at all turns – here is a beach berm that likely formed when the glacier, now 25 km away, was nears its maximum during the early decades of the 20th century. Note the trees growing on the surface; a nice project for dendrogeomorphology.

In 1909 Tarr and Martin observed the then expanded and soon to be advancing Columbia Glacier – the top panel is their photograph taken in 1909 with the Columbia Glacier looming over a remanent forest. The lower panel is a photo from the same location in June of 2019.

We were also fortunate to work on Heather Island (great thanks to the Tatitlek Corporation for permission to visit the Island). The upper panel is the Tarr and Martin 1909 photograph from near the summit of Heather Island and the lower photograph was taken in June of 2019.

The photo above was taken in June of 2014 – note the location of the calving glacier in the background relative to the photo below taken in June of 2019.

The active ice in the west arm of Columbia Bay is now 4 tributary glaciers – a dramatic change in less than five years.

New publication on an Alaskan glacier – coauthored by a Wooster student, staff and faculty member

June 11th, 2019

Dr. Ben Gaglioti (Lamont-Doherty Tree Ring Lab and University of Alaska – Fairbanks) just published an article entitled: Timing and Potential Causes of 19th-Century Glacier Advances in Coastal Alaska Based on Tree-Ring Dating and Historical Accounts. Three of the coauthors include Wooster Earth Scientists and Tree Ring Lab workers, Josh Charlton (’19), Nick Wiesenberg (Department technician) and Dr. Wiles (Earth Sciences faculty). This contribution describes the Little Ice Glacier History of LaPerouse Glacier on the outer coast of Glacier Bay National Park and Preserve.

Dr Gaglioti did a great job putting together the glacial chronology for the site, and then coming up with some new ideas explaining why this glacier advanced to its Holocene maximum between CE 1850 and 1890. This was a time when it was not as cold as some other times within this broad interval (~ CE 1250-1850) we call the Little Ice Age. Dr. Gaglioti draws on some new and not-so-new proxy records that show a strengthening of the Aleutian Low over the past several 100 years and he suggests that the cooler summer temperatures aided by increased winter snowfall forced this glacier to its maximum extent. His methods and presentation in this paper are new and provide some excellent possibilities for future work by Wooster students. We look forward to continuing our collaboration with Dr. Gaglioti.

The photos below are from Dr. Gaglioti and show (top) the location of the glacier, (middle) the setting of the buried forest he discovered, and (bottom) what the amazing pristine trees look like as the ice retreats. Within this buried forest is also the first Alaskan Cedar paleo-forest that has been discovered. Here is a link to a National Geographic sponsored blog describing some of the field work. Special thanks to Lauren Oakes for her excellent blog. The project was partially supported by the National Geographic Society, the Lamont-Doherty Earth Observatory and the National Science Foundation.

 

 

Concluding 2018 summer research in the Tree Ring Lab

July 27th, 2018

Summer 2018 research in the Tree Ring Lab has come to a close. The group of five students worked on a variety of projects, learning about the climate and history of Ohio and Alaska, and the application of different dendrochronological techniques and statistical analyses. They also gained experience effectively conveying their research to others and writing official reports of their findings.

The summer research team on their last day working together (Left to right: Greg Wiles, Nick Wiesenberg, Victoria Race ’19, Juwan Shabazz ’19, Kendra Devereux ’21, Josh Charlton ’19, and Alexis Lanier ’20).

AMRE students with a sampled oak tree at Brown’s Lake Bog in Wooster, Ohio (Alexis Lanier ’20, Juwan Shabazz ’19, and Kendra Devereux ’21).

The AMRE team accomplished a lot during the eight weeks they were here on campus. Their research started with the principles of dendrochronology, when they learned how to count individual tree rings and measure their widths under the microscopes. From here, the team learned how to run this data in different programs like COFECHA and ARSTAN. This process allowed them to date many historical structures across Northeast Ohio such as Gingery Barn and Miller House and Barn. You can find a full list on the TRL’s reports page.

AMRE students with Nick Wiesenberg collecting samples from historical structures at Sonnenberg Village in Kidron, Ohio.

Alexis and Kendra visiting one of the historical structures at Sonnenberg Village.

The AMRE students also learned how to take these chronologies and make hypotheses regarding past climate by uploading the data to Climate Explorer and running various correlations with other datasets.

We were fortunate enough to go out in the field and personally collect most of the data that we worked with this summer. These eventful trips included a lot of tree coring and required lots of bug spray. Some of the AMRE group’s favorites trips included Stebbin’s Gulch and Brown’s Lake Bog.

Stebbin’s Gulch at the Holden Arboretum (Left to right: Josh Charlton ’19, Juwan Shabazz ’19, Alexis Lanier ’20, Kendra Devereux ’21, and Dr. Wiles).

Juwan with the machete, ready to clear a path for the rest of the team at Brown’s Lake Bog.

Lining up to cross the moat at Brown’s Lake Bog after a weekend of strong thunderstorms.

Kendra Devereux ’21 with the sample bag at Barnes Preserve in Wayne County.

Josh Charlton ’19 coring a tree at Stebbin’s Gulch in the Holden Arboretum.

The other two summer researchers working in the Tree Ring Lab this summer, seniors Victoria Race and Josh Charlton, have been working with tree ring data collected from Alaska. Their work focuses on the modeling of Columbia Glacier located in Prince William Sound, Alaska. They are currently working on an abstract to submit to the upcoming GSA conference this fall. Stay tuned for more information regarding their project!

AMRE students with Victoria Race ’19 and Arrow at Brown’s Lake Bog.

Special thanks to the National Science Foundation, the Sherman Fairchild Foundation and the AMRE program for helping to make this research possible. Enjoy the rest of your summer!

Summer Research at Wooster: Rain-on-Snow in Alaska

July 13th, 2018

The following post is courtesy of Anna Cooke (’20), who worked with Dr. Alex Crawford through Wooster’s Sophomore Research Program this summer

In the heat of Ohio’s summer, it’s been a small bit of relief to turn my attention to Alaska; or more specifically, to rain on snow events in Alaska. A rain on snow event is pretty much exactly what it sounds like. It occurs when rain falls on a preexisting snowpack. For this to happen, the temperature must rise above freezing during a precipitation event. If the temperature then falls below freezing following the event, the result is a layer of ice on the surface of, in, or underneath the snowpack.

But why should those of us who live in the continental interior care?

Rain on snow, hereby referred to as ROS, has some interesting and possibly devastating effects. One such effect is on caribou populations. The diet of Alaskan caribou varies, but something that most caribou have in common is the dependence on ground foliage, such as lichens, as a winter food source (Joly et al., 2015). ROS is dangerous for caribou because of the possibility that the resulting ice layers will block this food source. Nutritional stress caused by ROS can lead to declining birth rates and calf weights. At the most extreme, mass die-offs can result from starvation (Mallory and Boyce, 2018). The resulting population decline or emigration of caribou impacts the hunters who rely on the caribou as a food source.

Fig 1: Caribou photo courtesy of Dr. Karen Alley.

Other impacts of ROS include the shutdown of airports and loss of revenue from tourism, and permafrost degradation. If enough rain infiltrates through the snowpack to its base, when it refreezes, the latent heat that is released will maintain a soil temperature of 0 degrees Celsius when it should be much colder. The resulting warming of subsurface temperatures could destabilize permafrost systems, causing slope instability and avalanches (Rennert et al., 2009).

Identifying ROS Events

If we want to mitigate the effects of ROS events, it is important that we understand where, when, and how often they occur. To do this, ROS can be identified and analyzed using climate models, satellite data, and observational data from weather stations. One difficulty in identifying ROS events is that no one agrees on just what a ROS event is. Some people define it as 3 mm of rain falling on 5 mm of snow water equivalent, or SWE, which is the amount of water present if the snowpack were to be melted. Others use different thresholds than 3 and 5 mm. Some use measures such as over 12 continuous hours of precipitation visually classified as drizzle and greater than 0.0 mm.

Despite this variation all identification strategies share one limitation: none keep track of refreezing after the precipitation event. This is an issue because ROS without refreezing does not have the same impacts as ROS followed by freezing, and if we are interested in the events most likely to have strong effects, refreezing is imperative.

I experimented with different identification strategies and thresholds trying to find a method that was restrictive enough that I wasn’t overcounting the number of events, but not so stringent that I was undercounting. The graphs below show the average number of events per year divided by season at five different weather stations in Alaska when counting events as 0.1 inches of precipitation on 0.1 inches of SWE, or 1 inch of snow depth for stations where SWE is not available. The first graph shows the total number of ROS events counted. The second graph shows the number of ROS events followed by refreezing. In all cases, fewer events are counted when refreezing is accounted for, and in several cases no more than half of ROS events are followed by refreezing. Thus, it’s likely that many studies are overestimating the number of impactful ROS events.

Results

Fig 2: Number of rain on snow (ROS) events per year by season for (top) all events and (bottom) events followed by refreezing.

As you can see from the graph above, most ROS events seem to occur in the spring, which is defined as March, April, and May. ROS functions a bit differently depending on the season. In the fall, the temperatures are often warm enough for rain to occur, but there may not be a snowpack for the rain to fall on. In the winter, the limiting factor is not snowpack, but rain, since the precipitation that falls is more likely to be snow. In the spring, the presence of a snowpack and the increase of the temperature to allow for rain are likely. However, a refreezing event is less likely. Moreover, even if there is refreezing afterwards, the number of days that the temperature remains below freezing is likely to be lower than the number of days for a winter event.

As such, events in each season pose different threats to caribou herds. In the fall, healthy caribou which have spent the summer with plentiful food access are more likely to be weakened than killed off. However, major winter events in which the snowpack is frozen over for weeks afterwards are more likely to decimate populations. Events in the spring are also dangerous because, even though the ice is not likely to inhibit foliage access for more than one or two weeks at a time, caribou may already be weakened from harsh winters.

Since there are so many factors to take into account in the study of ROS events, more research is necessary, especially since the frequency with which events occur is likely to increase with global warming. There are ways that we can mitigate the effects of ROS on wildlife and human populations, but only if we can understand its causes and effects. The research done this summer is piece of a larger story, and it was a pleasure to add this piece to the puzzle.

Fig 3: Caribou photo courtesy of Dr. Karen Alley

Works Cited:

  • Joly, Kyle, Samuel K. Wasser, and Rebecca Booth. 2015. Non-Invasive Assessment of the Interrelationships of Diet, Pregnancy Rate, Group Composition, and Physiological and Nutritional Stress of Barren-Ground Caribou in Late Winter. PLoS One, 10 (6): 1-13 (DOI: 10.1371/journal.pone.0127586).
  • Mallory, Conor D. and Mark S. Boyce. 2018. Observed and predicted effects of climate change on Arctic caribou and reindeer. Environmental Reviews, 26 (1): 13-25.
  • Putkonen, J., T.C. Grenfell, K. Rennert, C. Bitz, P. Jacobson, and D. Russell. 2009. Rain on Snow: Little Understood Killer in the North.EOS,90 (26): 221-222.
  • Rennert, Kevin J., Gerard Roe, Jaako Putkonen, and Cecilia M. Bitz, 2009. Soil Thermal and Ecological Impacts of Rain on Snow Events in the Circumpolar Arctic. Journal of Climate,22: 2302- 2314 (DOI: 10.1175/2008JCLI2117.1).

The Northern Pacific Coastal Temperate Rainforest (PCTR)

July 4th, 2017

The high rainfall and high coastal ranges nourish the icefields of southern Alaska along and with the extensive carbon-rich forests and ecosystems of the Northern Pacific Coastal Temperate Rainforest (PCTR).

Chris surveys the North Pacific noting the extensive moisture source and ocean pasture that is just offshore of the terrestrial ecosystems we are studying.

Malisse sits atop a shore pine, another slow growing coastal species that is experiencing potential decline.

Kerensa sites atop an obducted ophiolite – we were 71% sure that there were pillows in the basalt.

Josh cores another Alaska Yellow cedar – we were able to sample three sites in the Juneau area. These cedars are in decline due to warming and loss of snowpack, which makes their fine roots vulnerable to frost. Our objective is to work up the tree-ring record of the sites to contribute to our understanding of the decline.

Alora takes a break from taking notes and GPS coordinates for each tree.

Ice caves fund to explore and act as a conduit to meltwater and warm air accelerating the melt.

Blue the dog – takes a break from pursuing porcupines in the muskeg.

Nick of the Ophiolite.

Kerensa wades through the deep texture of coastal carbon.

Buried forests emerge from the wasting margin of the Mendenhall Glacier.

Nugget Falls – this is a classic hanging valley that has been revealed by the Mendenhall Glacier over the past 80 years.

A granite erratic just offshore.

A marmot sites on a stone in front of the emerging shoreline and new stands of Sitka Spruce.

A recently stripped cedar. The Tlingit strip the trees for a variety of reasons, primarily to procure the inner bark for weaving.

The field group taking a rest on the way back from Cedar Lake. The group is now working intensively on the Yellow Cedar cores to develop the tree ring record.

Thank you Jesse Wiles for your excellent photography and logistical support.

Team Alaska’s Last Day

July 3rd, 2017

To wrap up an incredible journey, Team Alaska scrambled over glacially-scoured rock faces and occasionally bush-whacked through thick shrubbery to Mendenhall Glacier. Small glimpses of the glacier that were periodically revealed through high points or gaps in the forest

Approaching Mendenhall Glacier…can you spot the people for scale?

Subglacial hydrology, captured within an ice cave #NoFilter

Malisse, Chris and Kerensa explore the Ice Caves beneath the Mendenhall Glacier.

Jesse treks out onto the vast, icy terrain

Team Alaska plays follow the leader to get off the glacier safely

Alora coring subfossil snag trees from the Little Ice Age.

Taking in the immensity of the glacier

Day 4 – Keck Gateway – Alaska

June 27th, 2017

Day 3 consisted of Team Alaska exploring Juneau the way a tourist might. The group roamed around the downtown area stopping at quaint book stores, trading posts, and the Alaska State Museum. This allowed the team to relax their aching feet and gain a new perspective of the city and borough of Juneau. After visiting the museum, the team gained a deeper appreciation for Alaska’s native cultures and complex history.

On day 4, Team Alaska conquered Bridget Cove, led by local forest ecologist and conservationist John Krapek. In order to get to the site, the team hiked over a mile of steep terrain covered by a large and spinous plant called Devil’s club. The team was able to collect a plethora of samples including that of yellow-cedar and western hemlock. After collecting the samples, the team took a lunch break and enjoyed a nearby muskeg. Finally, Team Alaska descended the slippery and densely vegetated trail, which was marked only by their previous footsteps. We wish Team Utah the best of luck braving triple digit weather, excited to meet back in Ohio in the coming days!

The group smiles upwards as Jesse snaps a quick picture.

A quick look at one of the group’s field notebooks.

John shows us how the ecologists do it!

Malisse of the pines.

Kerensa cranks out another core.

Alora peers into the canopy.

A wild Dr. Wiles is spotted from a far.

Josh gets his arm workout for the day.

Chris and Jesse take a break and find a tree to climb. No trees were harmed in the making of this picture.

Team Alaska Day Two

June 26th, 2017

Team Alaska hikes through the woods on a cloudy day to Cedar Lake. At this site they retrieved over 50 increment cores from 25 trees, which will be compared with tree-ring data from Cedar Lake collected in previous years. Lunch included an astounding view of the Pacific Ocean, the misty Chilkat Mountain Range, and some seals! The day ended with another home-cooked meal, followed by some well-earned rest.

Malisse is always ready for the camera.

Nick, Wooster’s geology department technician, relaxes on a rocky outcrop for lunch. Nine miles behind him can be seen the expansive Chilkat Mountain Range.

The group finds a rope swing above a creek beside a public-use cabin. Be careful, Chris!

Alora hikes through the temperate rain forest in search of more cedars to core!

Kerensa wades through skunk cabbage to find the rest of the trail.

Team Alaska poses before Cedar Lake; behind them you can see the yellow-cedars waiting to be cored.

Josh cores high on the tree to avoid sampling a rotted section. Good workout!

Jesse, Team Alaska’s exceptional photographer, takes his turn coring some trees.

Nick and Dr. Wiles compare fresh cores while Alora records data.

Team Alaska Day One

June 25th, 2017

Day one involved team Alaska hiking the East Glacier Trail led by Brian Buma, a forest ecologist from the University of Alaska Southeast. Their goal was to sample yellow-cedar trees at high elevation sites and understand how the dynamics of the forest relate to climate change. The trip was off the beaten path after 2 miles and continued for another 6 miles through a steep, muddy, dense understory. The group only stopped to eat lunch, but it was a sublime day with amazing company. Upwards of 50 samples were collected from a boggy environment, known as a “muskeg”. After a very long but exciting day the group headed down the trail for home-cooked fish tacos. Yum!

Brian Buma, forest ecologist, gives the group information regarding adolescent cedar trees.

The group treks through the unknown terrain, they may be lost.

After realizing they were not actually lost Team Alaska catches their breath and admires the views atop the mountain.

Chris measures the DBH, diameter at breast height, to assist Brian Bumas’ study of these economically, culturally, and ecologically important trees.

Alora stands in the foreground to upstage the natural beauty of the mountain, it is possible to look good in a bug net!

Team Alaska poses for a quick photo-op before starting their fieldwork.

Josh, member of Team Alaska, reads his field notes and records data.

Kerensa labels a straw, containing a yellow-cedar tree core for future analysis.

Malisse, renowned multi-tasker, records field notes, holds cedar cores and protects herself from the hordes of insects trying to sample her blood. Thanks to Jesse Wiles for the photographs.

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