In many of the blogs I’ve written thus far, I keep on coming back to the delicate balance between liquid water and solid ice. In this environment, where all precipitation falls as snow, and the vast majority of water is in solid form, a small change in temperature can have major consequences. For a small change of temperature in the tropics, liquid water remains liquid water. But here in the polar regions, a small change in temperature results in one of the most incredible transformations: from solid, inaccessible and unmoving ice, to life-sustaining, flowing water.
As I’ve mentioned previously, an increase in liquid water may have large consequences for the Dry Valleys. These past few days, though, I’ve been thinking about this phase transformation a little more broadly. Yesterday, we went on a walk around Observation Hill, and it struck me how much of a change I’ve seen in the short three weeks I’ve been here. When I arrived, the sea ice around Ross Island was completely solid. It was hard to remember we were on an island at all. Now, there’s open water extending far off from McMurdo. Part of this is a natural progression of the summer season, and part is due to the Polar Star, the US Icebreaker that has arrived in McMurdo.
This isn’t just a visual change – there are other consequences as well. Liquid water brings life – and we’ve been seeing many adelie penguins and some minke whales from the helicopter and right out our lab window!
Our helicopter flights are longer now, since we have to remain over solid ground at all times (not a problem, when our flights are so spectacular!). And for the first time, I really get the sense that I’m on an island, that the Southern Ocean is right there.
Today, I had a small-scale experience with the delicate water-ice balance. This morning, we headed out for a full day of fieldwork at Lake Bonney, arriving at our site at around 10:00am. You might think that with 24 hours of sunlight, there are no daily cycles here in Antarctica. But in fact, the daily cycle is strong enough to tip that balance between water and ice back and forth. This morning, the small stream near our experimental plots was frozen over, with liquid water flowing underneath.
When we left, at around 4pm, the ice was completely gone. Tonight, as I write, the water is turning solid again. While there’s nothing terribly significant about this small stream freezing and thawing (although it was incredibly beautiful), it reinforced for me the importance of this most critical phase change.
The phase change between liquid water and solid ice isn’t only important in Antarctica. Can you think of ways it impacts the ecosystem where you live, in Vermont? How would our landscape, ecosystem, and culture be different without the transition between water and ice?