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|WHERE I WENT
Some Antarctic Geography and Icy-ness
(Or, trying to make sense of what I saw)
It also shows the location of several glaciers along the
Beagle Channel which are pictured in Gallery 5. The map
is from the Wikimedia Commons and is distributed under
the GNU Free Documentation License. Go to those links
for more information, but it pretty much allows free
distribution of the image.
The Beagle Channel is not named after someone's dog, it
is named after a ship of the same name. This ship
carried Charles Darwin around the world in the 1830's on
the trip where he collected the samples, evidence, and
experiences that he eventually turned into his theory of
evolution by natural selection. When the ship named the
"Beagle" visited this region with Darwin aboard, the
channel had already been named after it, since this was
the ship's second visit to the area.
I wonder if I will get a second visit.
PICTURE AT THE TOP OF THE PAGE: The map of Antarctica in this and the other pictures on this page
is a public domain image from the Global Warming Art Site based on NASA images. I have superimposed
details of what I want to talk about (OK, write about) on the images of Antarctica. For example, up there
at the top, you can see that our cruise just touched the tip of the Antarctic Peninsula, that strip of land
toward the upper left. Which way is north in that picture? Well, every direction that points away from the
south pole is north. Geographic poles are funny that way, If you go away from the pole and up the
Peninsula, you will come to South America.
In particular, there are the places at the tip of the Peninsula where
my cruise went. Although north is any direction away from the
pole, this picture shows the most relevant north for present
Those two ice shelves, the Larsen and the Wilkins, have been in the
news a lot lately because they have been breaking into pieces. We
didn't actually go to them, though. Who wants to run into that
many chunks of broken ice?
Whuts a ice shelf??? See below.
This Antarctic map seems to have been based on pictures taken
before the breakups.
The Larsen Ice Shelf is (or was) divided into A, B, and C sections, and
I have seen a reference to a D section on the south end. The A and B
sections don't exist any more. Although there has been a more or less
continuous loss of ice from them, the big breakup early in 2002 of the
remnant of the B section probably got the most press.
Look just below. There is my attempt to make sense of ice shelves,
glaciers, calving, icebergs, and some ice of a different origin called
"sea ice". Actually, sea ice (also called pack ice) is just frozen sea
water. That happens every winter. But icebergs are chunks of ice
from glaciers, which form on land. Icebergs are much taller, but sea
ice can cover more of the surface of the sea.
On this trip, I saw plenty of glaciers and icebergs, and I have many pictures in the other galleries. I didn't
get to see any calving here, but I did see it in Margerie Glacier and Northwestern Glacier in Alaska in June,
2007. We couldn't get to any ice sheves -- too much sea ice in the way. I did, however, see many big,
flat icebergs called tabular icebergs, which come from ice shelves. See Gallery 7. I also have many other
iceberg pictures in Gallery 6 and Gallery 8 (not finished yet). Antarctic glaciers are too numerous to name or
even to count. But there are numerous glacier pictures in Galleries 2, 3 and 4 and some South Ameican
glaciers in Gallery 5.
It is not good for a ship to encounter an iceberg especially at or
below the waterline. The ship tends to come off second best.
However, ships cannot move in sea ice either if it is very thick.
.In 2007, a cruise ship named the Explorer sank due to ice not
far from the path we later sailed. The best known story of a
ship stranded in sea ice is probably the saga of the Shackleton
expedition of 1914 - 1916 in the well-named ship the Endurance.
It became stuck in sea ice on Jan 18, 1915 and remained so until
Nov 21, 1915. It did not get loose though, it was crushed and
sank. Shackleton and the crew eventually came through, but with
extreme difficulty. Photography and the story of the expedition.
So a cruise like this one avoids the sea ice. Here, to the right,
are satellite maps of the sea ice during the month of our trip, Jan
of 2009. These pictures are from the National Snow and Ice Data
Center (NSIDC). You can find the sea ice extent on many other
dates at THIS LINK to their web site.
If you look at that sea ice picture, you will notice that there was plenty of sea ice along the upper coast of
the Antarctic Peninsula. That is the eastern side of it, by the way. And this is the minimum sea ice
extent, too. January in Antarctica is the middle of summer. Just about every other map on this page
points out that the Larsen Ice Shelf is down that eastern side of the Peninsula. Well, what is left of the
Larsen is there, anyway. So there was too much sea ice to get through to get there without pulling an
"Endurance". Another ice shelf, the Ronne-Filchner, which has not disintegrated, is much farther down the
coast and is even less accessible.
But the tip of the Peninsula was ice free. That is where we went.
On the lower side (the western side), there is virtually no sea ice. As it happens, that is the warmest part
of Antarctica, and if you check that NSIDC SITE mentioned above, you will see that sea ice has trouble
forming there even in the winter. At least, now it does. If you check back to 1979-1980, there was a lot
of it there in the winter (June), even though the total area covered was about the same.
In spite of the near lack of sea ice, the Wilkins ice shelf, which is on that side of the Peninsula, was too far
to reach, and besides the area around it is covered with fragments broken off of it. Those fragments are
icebergs, not sea ice although the NSIDC picture above does show some sea ice there too.
We certainly did see icebergs, especially in the Antarctic
Sound area. That was the place where we saw the big
tabular bergs (Gallery 7). Where did they come from?
Well, they came from either the Larsen Ice Shelf or the
Ronne-Filchner Ice Shelf, but it is impossible to say which.
The drift direction of bergs from these shelves is pretty
well known to be in the direction of the Antarctic Sound as
I have tried to show in the picture to the right. Most of
the bergs probably bypass the Sound, but quite a few
should still drift that way. HERE is a study by the NSIDC
called the Ice Trek in which several bergs in this area
were followed. Don't be put off by that word "study".
They have a fascinating log of events with lots of pictures
and iceberg tracks. So HERE it is again. The drift of
icebergs in this area seems pretty regular with little
change as the year goes by, and the Shackleton ship, the
Endurance, functioned as another drift observation. Its
approximate path while drifting is in the picture to the
right as well. HERE IS a detailed map from a history site.
A group of German researchers has charted the drift of
sea ice and buoys over a period of several years, and it
is fun to look at their pictures. There is a sample to
the right with arrows showing the direction of drift and
the colors indicating the speed. The purple is
essentially no motion, the blue is about a quarter of a
mile per hour. It increases up to around a half of a
mile per hour for the yellow. This stuff isn't fast.
The drift tends to change as the months go by. This
picture is a composite for Sept, Oct, and Nov.
According to the study's web site, the use of this
picture is free, and the credit goes to this group from
the University of Karlsruhe, in Germany:
C. Schmitt, Ch. Kottmeier, S. Wassermann, M. Drinkwater:
Atlas of Antarctic Sea Ice Drift, 2004.
The point here is that this drift is pretty consistent for that east side of the Peninsula, where the
Larsen and Ronne-Filchner ice shelves are. The arrows don't change much from month to month. These
bergs can be counted on to drift toward the Antarctic Sound where we saw so many of the tabular
icebergs. On the other hand, there is not much drift at all away from the Wilkins Ice shelf on the west
side. And as the months go by, the direction of drift from that area keeps changing. Although we
visited some places on the west side and saw many icebergs there,we didn't see any of the tabular bergs
from an ice shelf. But, then, I guess we shouldn't have. THIS SITE from NSIDC discusses the Wilkins
Ice shelf breakup, which has been going on since 1998, and it points out that the fragments had barely
moved at least through 2008. The Wilkins discussion is a little over half way down the page. HERE IS
an image from Dec, 2008, only a month before my trip, showing many fragments still hanging around the
Wilkins Ice Shelf.
|This image is from the Wikimedia
Commons and is licensed under the
Creative Commons Attribution ShareAlike
3.0 License. This allows sharing and
derivative works of the file under the
conditions that you appropriately
attribute it, and that you distribute it
only under a license identical to this one.
At the outer edge of the drift map above, the water tends to
circulate around the continent. Although some of this circulation is
out of the mapped area, it actually exists all around Antarctica,
and it includes both air and water currents. This is allowed by
the lack of land masses to restrict motion of wind and water, and
the wind can make the trip from South America to Antarctica
quite stormy. The stretch of water in this area, called the
Drake Passage, is famous for its wind and waves. However, it
was calm and foggy for us going south, because these winds tend
to let up in the summer (which includes January). We did enjoy
some 50 knot winds going north a few days later.
All of this circulation tends to keep the world's weather and
climate variations out of Antarctica and make it a world apart --
not really a separate planet but as close as you can get without
leaving this one. Any air and water moving south will just get
caught in the circulation, although there is exchange of water at
deep levels. The boundary thus created between air and sea
conditions in the rest of the world and in Antarctica is called the
"Antarctic Convergence". It is shown as the wavy green line
around the continent on the map to the right. You don't notice
anything sailing through it, but instruments show a decrease of
several degrees in temperature over about a two hour period on
the way south. Since the ocean around Antarctica is so different
from the ocean to the north, it has come to be known by a
separate name, the "Southern Ocean", which you can add as a full
fledged member to the list of the worlds oceans.
This climate isolation, along with the continent's polar
position, the low angle of the sun, the complete 24-hour
darkness in the winter, the high altitude caused by the
2-mile thick ice sheet, and the refrigerating effect of the
ice itself, keeps this continent in a perpetual ice age. At
least that is true so far. But notice (on the drift map)
that the circulation does run into the Antarctic Peninsula,
which is by far the warmest place in the continent. That
place and some other coastal areas are the only places in
Antarctica that ever get above freezing, global warming or
not, and then only in the summer.
Researchers have not settled on all of the climate dynamics driving the conditions on this peninsula, which
include the pullback of glaciers and ice -- sometimes leaving bare rock on the coast. The conditions also
include the breakup of the ice shelves and a general warming of the peninsula region greater than the
warming in most of the world. At the US Palmer Research Station on Anvers Island (map below right), the
midwinter temperature has increased by 6 degrees Celsius - almost 11 degrees Fahrenheit - since 1950.
That is the world's highest and 5 times the global average according to THIS PAPER, which is also quoted in
Gallery 4 and Gallery 9. The annual temperature has increased 3.4 degrees Celsius (6 degrees Fahrenheit)
in a century.
However, the intrusion of warmer temperatures from the north - through some combination of air currents,
shallow water currents, and deep water currents - is pretty surely involved in all these indicators of warming.
As a consequence, I was surprised at the temperatures we encountered on the ship sailing off the coast of
the Peninsula. Those temperatures were in the mid to upper 30's (Fahrenheit), and they kept me peeling off
the layers of clothing that I thought I needed to wear. Well, some of them. Judging from the look of the
land, the above-freezing temperatures, which allow coastal melting, probably did not extend very far inland.
On another topic, the isolation of most of Antarctica has produced the atmospheric conditions that have
allowed the so-called ozone hole to form in the Antarctic winter. Due to chemical processes on small ice
crystals that hang in the air in the winter, this region has been an engine that destroys stratospheric ozone,
which shields us from ultraviolet light from the sun. That ultraviolet light causes sunburn, among other
effects. As summer progresses, that winter ozone hole tends to spread out affecting the areas we visited.
I don't know if that was the main cause, but I did get a bit of a sunburn on the one day that I forgot my
sunscreen. That was the first day in the Antarctic Sound, and it happened even though the sun is very low
on the horizon all day. One such data point is not a controlled experiment, but it might be that I was a
fairly efficient human ozone detector.
For reference purposes, here is some more detail on the places we visited on each of our three days in the
Antarctic. The left hand picture shows the Antarctic Sound and some islands in it that we saw on the first
day, Jan 14, 2009, my sunburn day. The other picture shows where we played around during the other
two days, Jan 15 and Jan 16.
Finally, just below, I can't resist including one region outside Antarctica. Since I am talking about ice,
snow, and glaciers, here is another place where we saw glaciers. This map shows extreme southen South
America including Cape Horn and the Beagle Channel, which we visited after Antarctica.
So now you know why I took this trip in January. January is mid-summer down in Antarctica and, in fact,
in the whole southern hemisphere. Summer is when the wind and waves die down in the Drake Passage so a
greenhorn tourist can make the trip without bouncing off of too many walls. And summer is when the sea
ice melts at least enough to keep from gluing the ship in place somewhere. Holland-America, I was told,
only makes the trip between Christmas and early February although a few other cruise ships expand that a
little. Not much, though.
That picture just above and to the right is a pretty good representation of what I saw in Antarctica. An ice
age. This picture is of a spot between Anvers Island and the Lemaire Channel (see map below or near the
top). But click the picture for an enlarged version and take a close look at the coast. There is a strip of
rock visible there. It is an ice age with some cracks in it, some of which are larger than this one appears
to be. So are these cracks caused by the warming observed in global climate change? Probably. At least
some of them.
I know pictures can lie, especially if you have a photo
editor. But there on the left is me on the morning of Day
1, (Antarctic Sound) before my sunburn. And on the right,
there I am on the morning of Day 2 (Gerlache Strait)
afterwards. I promise that I didn't touch either picture
except for cropping. That is fog behind me on Day 1. Day
2 was mostly clear of fog. In both pictures, I am
illuminated by the flash while the background is natural
light. Without the flash, I would have been a dark shadow.
Anyway, I got burned on Day 1. So there.
I am wearing a sweatshirt and light coat in both pictures.
That is a hood on the white sweatshirt on Day 2. Both
times, I got hot later and peeled off the sweatshirt.