Leaving behind days (weeks) of rain, members of Cohort 4 and friends head to the Air National Guard Base for another deployment to Greenland. See you in August!
(Left to right) Alden Adolph (C4), Kristin Schild (C4), Ben Kopec (C2), Gifford Wong (C1), Leehi Yona, Julia Bradley-Cook (C1), Ross Virginia, and Mary Albert (in front). Thanks to expert packing by Gifford, the cargo all fit too!
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During my time in Greenland this summer, I was able to meet and talk with several people from Polar Field Services (who do a lot of the logistics work for supporting scientists working in Greenland). They were very excited about the groups I am involved in (IGERT and iisPACS) and wanted me to write a blog about my journeys to Greenland and share some pictures, as a way to get more people interested in science by seeing the type of work that is out there. The link to the blog is below:
Thanks for your interest!
Russel Glacier to the east of Kangerlussuaq
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On Tuesday, August 12th, there was a fairly large ice dam break on a lake along the edge of the ice sheet. Annie and I were out sampling lakes near the margin when we saw the remnants of what appeared to be a much larger lake. The first sign was a group of large blocks of ice sitting on the slope about 20 meters above the height of the current water level. When we started looking around, we noticed the high water line all around the valley and even on the ice. It also appears that there are many past fluctuations in the water height in this lake as well, as there is a lack of vegetation up to a certain height on the slope all around the area (much higher than the recent lake level). When we returned to KISS later that evening, our suspicions were confirmed by a group of students researching the meltwater hydrology. There was a water rise in the river in Kangerlussuaq but nowhere near as extreme as the flooding that destroyed the bridge.
Lake after ice dam break. Large ice blocks left on the slope at previous water level.
- Large ice blocks left after drainage event. You can see the old water line on the ice across the lake.
This shows the potential lake height from past events
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Greetings from Kangerlussuaq! Annie Putman and myself have finally arrived in Greenland after our constantly changing field plans and a chaotic couple of weeks of planning and packing. We are traveling as a part of the iisPACS group (Isotopic Investigation of Sea-ice on Precipitation in the Arctic Climate System), led by Xiahong Feng and Eric Posmentier of Dartmouth College, and John Burkhart of the Norwegian Institute for Air Research. We showed up to some rainy weather but did have a few breaks in the clouds to see the beautiful landscape, which was great for Annie’s first time to Greenland!
Break of sunshine through the clouds looking east from Kangerlussuaq
- Hanging out by the LC-130 in Happy Valley (Goose Bay, Canada) during a mid flight fuel stop (and ice cream break!)
During the trip we will be based out in Kangerlussuaq for the first week and then travel to the town of Qaanaaq in Northwest Greenland for the second half. In Kangerlussuaq, I will be continuing the lake research I started during last year’s IGERT Greenland Field Seminar. We will be resamping the same lakes from last year (and the lakes sampled by Xiahong in 2009) and measuring the water’s isotopic composition. By looking at the interannual variability of the lake water composition along with weather observations for the region, we can gain a greater understanding of the local hydrologic cycle, especially the processes of evaporation and transpiration.
Lake near the ice sheet sampled in 2011
For the second half of the trip, we will travel north to the town of Qaanaaq for the iisPACS project. In Qaanaaq, we are very excited to meet and work with school teacher, Dan Daorana Normann, and his students. Qaanaaq is a very important site for us since it has a high storm frequency and is at a very high latitude. We will be setting up a weather station at their school for continuous weather information and setting up a precipitation collector where rain and snow events will be collected by Dan and his students to be sent to Dartmouth College to measure the isotopic composition. We look forward to sharing our knowledge of meteorology and climate dynamics along with learning from their vast knowledge base to gain a better understanding of the region. This site will help us greatly towards our goal of understanding the link of sea ice extent and precipitation in the Arctic and the potential effects of climate change.
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This past week six Dartmouth IGERT Fellows presented their work at the 2012 International Polar Year Conference in Montreal. The five students who gave poster presentations spent time in front of their posters chatting with fellow researchers, educators, media and policy makers about their work and findings.
Check out the videos below to see Lauren Culler, Laura Levy and Ben Kopec giving a shortened version of their poster talk for the camera!
Laura Levy and her poster “Holocene glacier fluctuations, Scoresby Sund, eastern Greenland”
Ben Kopec and his poster “Lake water balance near Kangerlussuaq, Greenland and their interannual variability”
Lauren Culler and her poster “Temperature alters interactions between Arctic mosquitoes and their predators in snowmelt ponds in West Greenland”
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The 2011 IGERT cohort spent one week camping outside of Kangerlussuaq in the same site the 2010 cohort chose last year. The first things we noticed upon arriving at our campsite were the incredible views of the Russell glacier, the Little Ice Age moraine, and the glacial meltwater lakes.
Google map of the area between the IGERT camp near the Russell glacier and the Kangerlussuaq fjord. Air temperatures drop as you drive up the road from Kangerlussuaq to the IGERT camp and the glacier, perhaps offering a gradient useful for studying climate change and insect outbreaks.
But as a close second we noticed that the woody shrubs at the site were all leafless and brown, and that there were many large Lepidoptera larvae (caterpillars) roaming in search of food. This place had experienced a recent caterpillar outbreak. The larvae that were left had no more food to eat, and they crawled up our tents and boots or into any warm microclimate. Northern wheatears and snow buntings came in to camp to eat this easy prey off the tents. Adult moths also flew around in large numbers and we picked them out of our hair and our coffee. We identified this Lepidoptera species as Eurois occulta, the Great Gray Dart moth known to defoliate the dwarf birch and grayleaf willow common in Greenland.
Caterpillars ate all of the birch and willow leaves around camp, leaving a brown world.
Eurois occulta larva
Eurois occulta adult
However, the entire landscape was not brown. Many hillsides with similar aspect and distance from the glacier experienced only moderate levels of herbivory and remained green. Farther from the glacier, back toward Kangerlussuaq and the fjord, the brown outbreak patches disappeared. Acting on a hot tip from Mike Avery, a PhD student in Eric Post’s lab at Penn State University, we searched for evidence that caterpillars were attacked by a pathogen – desiccated caterpillar corpses draped in the willow leaves. We found many of these corpses in non-outbreak areas farther from the glacier but did not see any close to the glacier where air temperatures are much cooler.
Some nearby hillsides, however, suffered only slight defoliation.
Closeup of moderate levels of herbivory.
Carcass of a larva infected by a pathogen.
Why are some hillsides completely brown while others remain green? This is a big question in ecology, and one possible answer is that caterpillars in defoliated areas lack “top-down” controls by predators such as birds, other arthropods, and pathogens. The caterpillar immune system can fight off infection by pathogens (fungal or viral) but this defense requires a high protein diet. In plants much of this protein is RuBisCO, a nitrogen-rich enzyme essential for photosynthesis, and the protein content of leaves is expected to decrease as air temperatures get warmer and the growing season gets longer. Perhaps caterpillars farther from the glacier had less resistance to pathogens because of lower protein content of leaves, or perhaps there are more natural enemies such as birds or arthropods in warmer areas. The birch/willow shrub tundra of West Greenland is a great ecosystem to test competing explanations for why insect herbivores sometimes outbreak and how climate change may alter the frequency and intensity of these outbreaks.
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With the greatest effects of climate change expected to be seen in the Arctic, we will likely see major changes in the hydrologic cycle. The lakes in the Kangerlussuaq region of Greenland have unique ecosystems and, because of their great number, play an important role in the surface albedo and local climate of the region. These lakes are already changing in size and future expansion or contraction of the lake area may result in significant changes in the local water balance, surface albedo, and ecological processes. In order to predict the future changes of these lakes, such as changes in volume, chemical compositions, or ecological processes, we first need to understand the water balance of these lakes and the hydrologic cycle of this region.
There are two main types of lakes around Kangerlussuaq which have different hydrologic regimes. Most of the lakes receive water from precipitation only and because they are in closed basins, lose water primarily through evaporation. The other type of lake is located near the ice sheet and differs from the others by receiving the primary input of water from melting ice, with precipitation playing a lesser role. These inputs and outputs of water are going to be changing as climate change progresses so it is important to understand the current hydrologic cycle before these major shifts occur.
Ben and Sam overlooking meltwater lake
Precipitation fed lakes in Vulgaris Valley
In order to quantify these components of the hydrologic cycle, our group conducted a series of studies on a number of lakes in the Kangerlussuaq region. One of the primary efforts was to collect water samples to be measured for their isotopic composition as the isotopes of water are powerful tools that are used as tracers to understand hydrologic cycle dynamics. In addition, samples were taken to measure the water chemistry, determined the depth of lakes from our boat, identified if lakes were stratified or not, and we used a YSI multiprobe to measure various properties of the water that included temperature, pH, and conductivity. From these measurements, a series of mass balance relationships will be used to best determine the rates of inputs and outputs to these lakes to define a starting point in order to predict future changes.
Sam sampling on dried up lake near camp
- The team sampling from boat near the ice sheet
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