On the fifth day of our expedition, we are getting deeper into the Antarctic Peninsula region. There are islands all around us, both large and small. Snow, rock and ice blends together. It is often difficult to tell things apart. It’s a land of black, white and grey, and lots of shades of blue. Our expedition leaders have said we have been very lucky with bright sun, blue skies and relatively balmy weather for most of our trip – making touring conditions quite pleasant. But the weather can get very nasty here, very quickly. Imagine those early explorers who may have been stranded here if their ships were wrecked or stuck frozen into the pack ice. The chances for survival must have looked bleak.
During the day we visited four key sites: Port Lockroy, Lemaire Channel, Pleneau Island and an Ice Field.
Port Lockroy is the first permanent base in Antarctica set up by the British after many decades of exploration and scientific research expeditions by well-known adventurers such as Robert Falcon Scott and Ernest Shackleton. Established in 1944 during World War II, the original purpose of the base was to spy on German shipping movements. The site is now a museum, tour shop and post office – all managed by the British government! There are also several penguin colonies around the two buildings there and these little guys seem quite used to the human presence as they walked within feet of me several times. Port Lockroy is one of the most visited places in Antarctica. (Congratulations to Terry for winning the contest – your postcard from Port Lockroy, complete with an Antarctica postmark, is on its way!)
In the afternoon, our ship navigated the Lemaire Channel, a narrow stretch of water flanked by mountains on both sides. The most remarkable thing about the passage was the proximity of the boat to the sides of the channel, which allowed me to have a closer view of a cross-section of the glaciers. Glaciers are formed through the accumulation of snow over millions of years. As the snow accumulates, the snow on the bottom becomes more and more compacted, and eventually turns to ice, as I described in my blog post from a couple of days ago. When ice has accumulated to a sufficient mass and volume, the glacier begins to move, over and around mountains (photo 1). When it reaches the sea, pieces begin to break off into the ocean and you can see the layers of ice and snow that have accumulated over time (photo 2). The pieces that break off are called icebergs. (photo 3).
After the Lemaire Channel, our ship anchored near Pleneau Island. Below are four photographs I have stitched together in an attempt at making my own panoramic shot (I will see if I can find some software to improve it once our trip has concluded). From my vista about halfway up the mountain, I was able to see for miles. It was simply spectacular. The fifth photo (which you can click on and enlarge) provides some perspective – our ship is in the centre of the photo. The black squiggly line starting from just below our ship and running down and off to the right is a crack in the ice and approximately delineates where land ends and the sea begins, of which a large section is covered in sea ice. In the foreground you can see a Gentoo penguin colony. For about 45 minutes, I sat on those rocks and watched the penguins interact.
Then, in the evening, we navigated an incredible field of icebergs, floes of pack ice and glaciers which stretched to the horizon in every direction. The purpose of the visit was to take advantage of the sunny conditions and see an amazing sunset over this seascape (see photo below). We also had an opportunity to see killer whales hunting seals. As summer rolls in, the sea ice is slowly breaking up into pieces as the temperature warms to a balmy 32 deg F, 0 deg C or higher during the day (saltwater freezes at a slightly lower temperature). This creates ideal conditions for killer whales to hunt seals by “wave-washing” them from their perch on an ice floe into the water where they are quickly gobbled up. (Watch this video on YouTube.) During this time of year, the sun “sets” at about 11pm at night and rises again at 2:30am. But it never really goes away and darkness never really sets in – instead you’ll have a glow of pink and orange light cast over magnificent seascapes.
There are two main “types” of ice in Antarctica. The first is glacial ice, which I described briefly above. The second is pack ice or sea ice, which forms when sea water freezes together. There are several steps to the freezing process – the process is analogy to a “reverse snowfall”. First, as seawater cools down to its freezing temperature, crystals form in the water and rise to the surface. As they collect, this layer is called “grease ice”. It looks like an oil slick, and it tends to bump up against each other. As it starts to stick together, it is called “pancake ice”. At this point it begins to look like a slurry, or soup-like (thick and bumpy, and opaque in colour). You wouldn’t be able to walk on it, but soon it will begin to solidify. During this entire time, crystals are continuing to rise beneath the surface. Over time it gets thicker and thicker. Depending on how cold the weather is year round, pack ice can build up over a period of years and become very thick and difficult for ships to break.
In the first and second photo below, you can see the difference between glacial ice (the large, tall pieces which break off of glaciers and are also known as tabular ice) and the pack ice which forms when seawater freezes and which breaks up in springtime. Often times, the largest part of an iceberg is underneath the water. This is the type of ice that can easily sink ships (and has!) . Note the difference in the colours of photos 2 and 3. They were both taken around the same time of day but I was playing with the white balance setting on the photo to add warm or cold colours as I wanted.
Here are some other commonly-cited fast and fun facts about ice:
- More than 99.4% of the Antarctic continent is covered by ice
- Antarctica’s ice cap contains more than 70% of the world’s fresh water, and comprises 90% of the world’s ice, in some places it is 2-3 miles thick
- If the Antarctic ice cap melted, it is estimated that the world sea level could rise by an average of 180 feet (55 metres) – that is almost as high as a 20 story building!
If you have any questions about what you read here, please feel free to leave a comment on this blog post! Later today, I am going to post a link to some slides from a presentation given by Jason Kelley, a geologist on board the National Geographic Explorer, who discussed with us the different types of ice. Thanks also go to Jason for a lot of what I learned and have summarised here. Please check back if you are interested in getting access to his slides later on.