As we sail southwest in the Scotia Sea from South Georgia to
Antarctica, the air is developing that tingling cold you associate with polar
regions. The cold sea gently rolled today in the aftermath of the storm we
experienced yesterday.
The water we sailed over today was deep and deep water is
relatively unproductive because of low nutrient levels at the surface where the
light is. The seabirds told us these waters were unproductive by their relative
absence. We had a few of the ever-present Cape Petrels with us all day and the
odd Giant Petrel and Black-brown Albatross- nothing like the abundance of
seabirds we had yesterday off South Georgia.
And now to the main topic of the blog- icebergs. They are an
iconic symbol of polar regions and we saw our first good-sized ones today. In
Antarctica, they come in several types- the one we saw today was tabular which
means “like a table”.
Tabular icebergs originate from ice shelves. Ice shelves
are portions of the Antarctic ice cap that flow down and over embayments. The
ice is supported by the water and the adjoining land, and remains intact. However, pieces often break off due to tidal action, which moves the shelf up and down.
Contrast this with icebergs that calf from a glacial front- they break off erratically
and produce almost randomly-shaped chunks of ice.
There is a lot of interest in climate change in the
Antarctic, which shows itself most obviously in the breakup of large parts of
ice shelves, which float out to sea and form often huge ice islands. This is
happening on the Antarctic Peninsula where warming is taking place at a higher
rate than anywhere else in the world. Off the peninsula on the main part of
continental Antarctica, the climate is actually cooling a little.
So, we continue out voyage to Antarctica and have one more
sea-day before we arrive at the “Last Continent”.
