NOTE: Just after finishing this and while brushing my teeth outside my tent, I almost ran into a couple of musk ox—or rather, they almost ran into me. I was watching another musk ox grazing across the river half a mile away when I heard something, looked down and saw two more walking towards me. I was on a rock just above them and as soon as they saw me they charged straight up the hill, almost right at me. I jumped up and ran backwards out of their way as they ran right past me and up the hill overlooking our camp. There, they stopped and looked back to figure out what I was.
I’d read that musk ox always like to get to higher ground when they feel threatened but I guess I’m still surprised at how serious they are about it. I ran to get the rest of the team and together we took some pictures of them running through our camp. What an exciting end to the day! It’s moments like these that make working in Greenland worth it.
My hope is that the stories in this post and the previous speak to a wider audience about climate change, glaciers, and field science. I realize that I could’ve done a better job with citations throughout this post but hopefully you’ll forgive me as I’m writing all this in a tent in Greenland and don’t have access to journal articles I would normally have if I had Internet. I’ve listed a few papers at the end of each that you can check out. For anyone who’s interested, I’d encourage you to look at the websites listed at the end of this post. I think the Wikipedia pages on global warming and climate change are great places learn the basics of climate change.
Thanks for reading! I'll be home in a month!
A Breakthrough: A Glacier Moves When Our Probe Says So
"What do you have on July 16?"
If this were a movie, the music would be tense and building; this was the moment of truth. It was late in the evening and Andrew Tedstone, a graduate student at Edinburgh University, and I were huddled over our laptops, the orange glow of the mess tent in the low sun were lighting our faces. Chocolate bars and mugs of steaming hot powdered milk were spread out on the big metal box that serves as our dining table.
Andrew’s lab group specializes in deploying extremely accurate global positioning systems (GPS) on glaciers and the Greenland Ice Sheet (see Bartholomew et al., 2010). Amazingly, the GPS stations can precisely measure hourly changes in glacial uplift, acceleration, and thinning. On Leverett Glacier, the stations have observed small daily surges in glacial uplift and acceleration as well as large glacial surges several times a summer.
How, why, when, and how much glaciers move are surprisingly complex questions and scientists have spent decades looking into these problems. We know that glaciers grow when there is more snowfall than melt and that they are pulled downhill by gravity. Anecdotal evidence, such as old photos and people’s memories, tell us that more of the world's glaciers are shrinking than growing and that most seem to be melting faster every year. Decades of data collected by satellites, GPS stations, and field scientists have confirmed these observations and on the whole ice caps in Greenland and Antarctica, as well as most alpine glaciers everywhere, are melting rather than growing.
Last season, I deployed a new type of water chemistry probe designed to measure the fraction of glacial meltwater that had been "delayed," or stored at the base of the ice sheet. This delayed water fraction is hypothesized to be responsible for daily cycles in glacial uplift and in seasonal surges in the movement of glaciers. It seems that, to understand how ice is transported from the high cold interiors of the Greenland Ice Sheet to its edges, one has to understand this delayed water. However, proving this has been difficult, as the delayed water fraction doesn’t seem to have a reliable chemical or physical signal to differentiate it from the rest of the meltwater. We hoped my new water probe would be able to detect this delayed water fraction like no other method could.
"Let me check. OK July 16, the GPS stations recorded a major glacial uplift followed by one of the biggest accelerations of the season."
"Wow you’re kidding! That was the biggest peak my water probe recorded too! OK let’s check June 15, what time of day was the glacier moving fastest?"
"On June 15? The glacier accelerated fastest at 2:15 p.m."
"That’s exactly what my water probe predicted!"
I couldn’t believe it, the water probe my lab had developed was telling us in real time when the glacier was physically moving. It was as if we’d stuck a magic wand into the river coming out from beneath the glacier, and it told us what time of day the glacier was moving and, in relative terms, by how much. What’s more, the chemical mixing model we’d built was predicting the volume of delayed water responsible for each daily uplift observed by the GPS stations. Everyday, the ice sheet was being lifted up, moved slightly forward, and set back down as this delayed flow water passed beneath it.
The problem with having a scientific breakthrough is that no awesome music starts up like in the movies. It’s just you and your friend, sitting in a tent late at night dunking chocolate bars in mugs of warm powdered milk.
For the four of us in camp, the rising river increases our chances of being marooned. Because two rivers and the Greenland Ice Sheet surround us, we are on a sort of island. During peak meltwater flow, herds of musk ox and caribou become stranded on the island with us. Leverett River, is currently huge and drains a large section of the Greenland Ice Sheet. Another river, the Russell, drains the next glacier to the north. Our boat crossing is on the Russell River and, although it is significantly smaller than the Leverett, the Russell is prone to large, unpredictable outbursts that cause the river to rise rapidly (over the course of several days) and stay high for weeks on end. Last season, I crossed without incident on July 4, but several days later,two members from our team made the crossing in the morning, spent the day in town and returned that evening to find the river doubled in size and full of icebergs. We shut down the river crossing and a helicopter had to fly several people in and out of camp. I wasn’t able to get out on those flights, so I stayed in camp a week longer than expected, waiting out the high water. The river was finally safe to cross again on August 10.
During the two seasons before last, the boat crossing was at a wider, slower section of the Russell that seemed to handle strong currents better. However, wider crossing was ripped out during a massive outburst event in August 2010. The river went back down a few weeks later and everyone stuck in camp were able to walk across the river in chest waders.
We had hoped to find another, more suitable location for our boat crossing this season, but found nothing even remotely better or safer than the 2011 location, so there it’s stayed. If the river becomes too large to cross again this year, those of us on the camp side will have to wait out the high water because we are out of funding for a helicopter resupply or evacuation. Fortunately, we seem to have plenty of expired canned hot dogs.
If we are again marooned in our camp, I’ll send a satellite phone call to get a note put up on this blog that our team is stuck on one side of the river and to check back later.
Bartholomew, I., Nienow, P., Mair, D., Hubbard, A., King, M.A., Sole, A., 2010. Seasonal evolution of subglacial drainage and acceleration in a Greenland outlet glacier. Nat Geosci 3, 408-411.
Woods Hole Oceanographic Institution’s website about the ocean and climate
Wikipedia page on global warming
All photos by Ben Linhoff, Woods Hole Oceanographic Institution
Previously in this series: