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Rough Science 3 New Zealand: Ellen McCallie's diary: Ice ice baby

Updated Tuesday, 27th February 2007

The Rough Science team are in New Zealand, and have the challenge of determining whether a glacier is advancing or retreating.

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the team at the foot of the glacier Copyrighted  image Icon Copyright: Production team

Day 18, 19 & 20 – rest days

So how did I end up in Wanaka? I was supposed to go on the Milford Sound trip, but the drive times we were being quoted just got longer and longer. On a four-day break, I didn’t want to drive for two days, especially when all the driving has to be done during the day and very defensively. So, the night before we left I had changed my mind. I figured I bounce around the extended Franz Josef area and use public transportation. I had packed my bag for a day hike to Robert’s Point when I saw evidence that the Wanaka group was just preparing to leave. “Easy ride to Wanaka, four hours away. Then I’d work myself back.” Kathy, Derek, John and Pippa welcomed me and said I could stay the whole time. I didn’t want to barge in on their trip, even though most people had grouped up based on interest in going to a locale. In any case, Derek said if I stayed his total share of the living accommodations would be less, so I should stay. That was all the convincing I needed. Fabulous trip!

In any case, we belly-laughed for four days. Thank goodness we split up during the day, usually Kathy and Pippa on ski slopes, Derek and John in the beginning ski area and I was off somewhere on foot.

I hiked up Mount Roy one day. The birding was great. The third day I had planned to fly to Milford Sound, but it was cloudy, so Pippa and I walked along the lake for an hour or so.

Thanks to careful driving by John and Pippa, we are back safely and have met the others in Franz Josef. It is raining and raining and raining. My laundry, which was standing on its own yesterday, is now on its way to being clean and dry. We have today off, but what to do in the rain but type into a computer or perhaps read a book?

Incredible four days off – many thanks to Derek, John, Kathy and Pippa for allowing me to join their adventure! Couldn’t have laughed more! (Even the wait-staff at restaurants said they’d never seen a group that laughed so much and seemed so happy. Good, clean fun!)

Day 21 – rest day

It goes from absolute downpours to pouring down rain to constant rain to heavier than a sprinkle to rain, rain, rain, rain. We are all well aware that this is likely to go on for three to five days.

You know how it is said that Intuits have 60 different words for snow? Based on my desire to describe the endless rain and the types of rain here, I wonder their 60 words for snow are like saying “downpour”, “drizzle”, “sprinkle”, etc. If I lived here, I would probably come up with nice collection of words to describe the spectrum of rain quantity and quality that falls here.

Whilst here I have also needed to change my concept of driving and road transportation. The roads here are blacktopped and look very nice. The big thing about the roads, however, is that because they are two-laned with no shoulders and because the terrain is rather rough, the roads are winding, sometime steep and sometimes full of hairpin turns. Even the areas that are relatively rolling are tough, however, as they are well shaded and black ice is not uncommon. As a total group, we have totaled one car and slid numerous times in others – all during the day: 10 am, 2pm, 4 pm. It doesn’t matter if it has been sunny all day. There can be ice. This may also be why driving times people give us seem to vary so much. The same place can have a five-hour difference in quoted driving times: 8-13 hours.

Five of us drove to Wanaka in one of the white vans, which feel like tin cans set up on wheels. As the scientists do not have driving privileges, the crew members of our group drove. They were very diligent in their driving, especially as we had just heard that one of our vehicles had rolled – thankfully no one was hurt – though the car has been totaled.

Day 22 – speed and melt of the glacier

 

Some folks get to spend the night on a glacier during this program. Unfortunately, I’m not one of them. Any chance I could get some plants to grow up there by tomorrow?

So, what’s the challenge this time? Mike B and I are responsible for determining if the glacier is advancing or retreating over the next couple of days. We are also supposed to make portable warming devices.

In order to see results, we set up the glacier movement equipment today. We’ll work on concocting portable warmth tomorrow.

So, how do you measure if a glacier is advancing or retreating?

Background: A glacier is a “river” of ice that moves downhill because of gravity acting on the glacier’s great mass. So we know a glacier is always moving and it is moving downhill. Whether it is advancing or retreating is another story. This has to do with the amount of melting that occurs at the end of the glacier vs. the amount of ice that is pushed down each day. If more melting occurs than ice moving down to replace the melt, then the glacier “retreats”, actually it shrinks by melting. If more ice moves down the valley that is melted away at the end, then the end of the glacier is pushed farther down the valley, so the glacier is advancing.

In either case, the glacier ice is always moving downward. We are in the temperate zone and this glacier extends below the snowline, so glacial ice is always melting. (Snow and ice melts below the snowline.)

What is going on now? From walking up the glacial valley, we could see several indications that the glacier was once much longer that it is today. First, we saw striations in bedrock where large boulders, carried by the glacier, had scraped against bedrock, making deep grooves. Rock is hard stuff. Rivers carve out rock, they don’t make scrape-marks, so we can be certain that at some point in the past the glacier, carrying large boulders, scraped rock against rock. Second, as we looked around the valley, tall, mature forests were found up high, while younger forests were found lower down. The closer to the valley bottom, the younger the trees. This indicates that the glacier has recently covered the lower area and has only retreated recently, which allowed the trees to germinate and grow. The fact that the youngest trees are at the bottom and they get older as one looks higher on the cliff faces, says to me that the glacier once filled the valley to very high up and slowly melted. As the area became exposed, trees grew. The last area to be exposed from the ice is at the bottom.

So we know that compared to today the glacier was well advanced in the past, probably a couple hundred years ago. Maybe even up to 500 years, based on the age of the trees.

What are we measuring to get an idea of what is going on with the glacier now?

We are set up to take two different kinds of measurements. To measure how much (in distance) the glacier is advancing or retreating right now, we set up a “triangle-broomstick” contraption. Basically, we mounted the base triangle on bedrock (something that will not move) and then marked on the stick the distance to the current edge of the glacier. Because we are using a stationary base, bedrock, we will be able to tell if more ice is moving down the valley than is melting (advancing). Or, if ice is melting faster than ice is moving down from the glacier (retreating).

The second setup allows us to visualize the ice melting at the end of the glacier. No matter if the glacier is advancing or retreating, ice is always melting. We stuck several skewer sticks into the ice (with a drill). We put them 5 cm down into the ice and from 2 to 6 cm from the edge of the glacier. This will allow us to see how much of the ice at the current edge of the glacier melts, both from the edge and from above. I think this has the potential of being really cool as well as complementing our actual challenge.

I am getting sick fast. I’m dosing vitamin C and zinc.

Day 23 – speed and melt of the glacier

 

Up at 8 am. I felt pretty good but beating a bacterial infection without antibiotics is a long, painful road. I was at the doctor’s office by 8:45. My appointment wasn’t until 9:30 am, but I was hoping the doctor might take pity on me. He did, so I was able to meet the rest of the group and we headed up to the terminal face of the glacier to do our measurements.

It may seem silly, but I was so excited to actually see what happened with our two setups. These aren’t scientific experiments: no controls, treatments, etc. Instead, we are making observations and measuring what we see - very exciting all the same. I wanted to run to the terminal face and round the corner just to see if there were sticks on the ground, having melted out of the glacier. Logically, I knew that at least one stick, representing a two-centimeter melt, would be on the ground, but I’ve never seen direct evidence of a glacier moving, so I was excited to see it for myself.

Yes, I rounded the corner and saw two sticks on the ground and the third having fallen over. I said on camera that it was about 6 cm. Actually, it was more like 5 cm, as the third stick had not fallen through yet. I got a bit excited and exaggerated unintentionally. Not only did the ice melt 5 cm in length, it melted about 3 cm downwards.

How was I so sure there would be melt? Basically, the terminal face of this glacier is below snowline. The ground is not cold enough to keep things on it frozen, plus the sun is beating down from above. Thus, there is melting everyday. Mike B, Kate and I documented that in the last two days 5 cm of ice have melted off the terminal face.

Kate then asked if we now knew the glacier was retreating – nope, we didn’t until we looked at where the glacier was in relation to a fixed point, in this case, bedrock. If the glacier was moving downhill at a rate of 5 cm every two days, then the measurement Mike B set up would be exactly as it was two days prior. If the glacier was moving downhill faster than 5 cm every two days, then the broomstick and nail would not have been straight. If, as was the case, the glacial ice was melting faster than the glacier was moving downhill, then it would appear that the glacier backed up – it actually just melted more than it moved forwards. (Glaciers, like rivers, don’t flow upstream.) Cool, cool result.

In terms of the other team, it sounded like everyone had a fabulous time up on the glacier overnight. Their measurements were really good as well. It was fun to hear that a real glaciologist studying this glacier using satellite images got results nearly identical to ours.

 

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