Tuesday, December 6, 2011

Antarctic Answers!

1. How has Antarctica changed over the years?
This is a great question, and one I’ll answer first.  To understand Antarctica, you have think very long term.  Continents are all found on massive plates that move over the mantle of the Earth.  The US and Europe are moving away from each other at about a ½ inch a year, as the mid-atlantic ridge grows.  On the other side, the Pacific is slowly subducting, and in a few million years, trips to Japan will be a little shorter than they are now. Antarctica used to be connected to other landmasses in a supercontinent called Gondwana.  About 50 million years ago, Australia and Antarctica split apart and Antarctica drifted south.  All plants and animals left on Antarctica eventually died, but we still find fossil records of plants that existed millions of years ago.
As Antarctica moved south, ice began to develop as ocean waters cooled, and the continent started to resemble what it is today. By 15 million years ago, Antarctica was covered in ice and snow.  So much in fact, that it weighs down and depresses the entire continent by as much as half a mile!

Much more recently, humans have had some small impacts on the area, the largest is McMurdo where I live.  There are roughly 1500 people on station in a recent season, but the military had as many as 4000-5000 here in the 1940’s and 1950s doing exercises and building the station originally. The impact from humans is small compared to the rest of the world, but still we do find evidence of pollution.  One notable problem – in the 1950s, they just pushed all their trash right on to the sea ice. When it melted in summer, the trash sunk to the bottom of the sound.  Obviously it wasn’t going anywhere, so that trash still sits there today and includes things like trucks, housing materials, food trash, sewage, and more.

2. What is the range of temperatures in Antarctica? How is the weather during the summer?
Because it is summer here right now in the southern hemisphere it is relatively warm for Antarctica.  I looked up the current temperature here and it is 30F with 6mph winds, so not worse than an average January day in NYC really. South Pole station, because it is much farther from the ocean, further south still, and at a much higher altitude, is much colder however. It is currently -17F, -27F with wind chill there, and that is almost as warm as it gets there. For the most part the summers are relatively mild on the coast where we are, much like a New England winter.  The interior of the continent is much colder in general.  And in the winter, when it’s dark 24 hours a day, everything is cold.  The coldest temperature ever recorded on earth was at Vostok Station (a Russian station) was −128.6 °F on July 21, 1983. Brrrrrrr. 

You can see average temperatures at a few Antarctic stations, as well as New York, 
London, and Sydney.  Notice how New York and London seasonal changes are 
reversed from Antarctica and Sydney.

3. Does the ice ever crack near you? And why does it crack?
Oh yes, all the time.  By ice though, I’m talking about sea ice.  There is, of course, many millions of kilometers of land ice out here, but that stuff is far more stable.  The sea ice, on the other hand, actually breaks, floats away, melts, and reforms in large sections every year. When we drive our vehicles over the ice, we have to always be on the lookout for ice cracks. Under snow, it can look very small, but a crack could be several feet wide at the base, and you don’t want to drive right into the water!  It is always a bit weird to remember that I’m not on land when we drive to our field sites, I’m over hundreds of feet or more of seawater.  The cracking occurs every year in the summer months due to a couple of factors. First and most importantly is temperature - as the ice warms it melts a little bit.  This causes a weak spot to form.  And because it is made from seawater, the ice isn’t as strong as land ice, due to the salt. Another factor is the influence of tidal shifts.  As the ocean underneath flows back and forth, it creates pressure against the ice.  If the ice has been weakened by melting, it may crack.  This crack may continue to grow, or if it gets colder “heal up” and reform with new ice. 

What you are seeing here is a pressure ridge, caused by the transition of sea ice to land ice right where the land meets the sound.  They are beautiful formations, but they can be very dangerous to try to cross with vehicles.

4. What types of animals have you seen up close?
I have gotten to see a lot of marine invertebrates – including the sea urchins we work on, and the super cool sea spiders! Also, I have gotten to hang out with some fish with antifreeze proteins in their blood.  They have this because they live in seawater that is below the freezing temp for fresh water, and if they didn’t have antifreeze, their blood could freeze inside them! And as for larger animals, I’ve seen a number of Weddell Seals near sea ice cracks, as well as in our research ice holes, and of course my favorite, Emperor Penguins!  They are really amazing animals!
Seal, hanging out by a sea ice crack

This penguin knows how good it looks.  Show off.

5. Do you hear the seals calling under the ice? How do the seals survive in that kind of weather?
Unfortunately, I haven’t had a chance to hear any of them, since I haven’t been out on the ice with recording equipment on a quiet day.  I know the scene from the movie you are referring to, and it is an amazing sound.  If I get a chance, I will ask one of the divers here if they’ve experienced the Weddell Seal sounds underwater, and get back to you. As for how they survive out here in this weather, that's a great question - in fact it's a question that scientists are currently studying right now! They are using infrared heat sensing cameras to understand how a seal maintains it's internal body temperature when the outside temperature is downright bitter cold. What we know is that they have a huge layer of blubber - fat - that helps insulate them in the very chilly water and sometimes even colder air. They have evolved to be as round as possible, because the less of their body that is exposed to the cold, the warmer their core can be. Also, they can keep blood from flowing to their extremities when they're diving, conserving as much heat as possible in their chest and body.

That is a fat and happy Weddell seal.  We named him Rusty.

6. Is Frosty Boy good?
I had Frosty Boy yesterday!  And yes, it’s delicious.  It is the best soft-serve ice cream I’ve had. I’ve tried vanilla, butterscotch, mocha, cinnamon, and mint tea.  I do NOT recommend mint tea – it tastes like a mouthful of frozen tooth paste.  However, the rest are all delicious, and they go great with the other wonderful deserts found here occasionally – like chocolate chip cookies or pumpkin pie.  Also, for the ladies, the South Pole Station has a machine they’ve called Frosty Girl. 

That’s it for now – Jan-Hendrik I’ll get to your questions soon, and more pictures on the way!

1 comment:

  1. This is wonderful!! I am sharing it with the class today and using it to talk about text features like pictures and graphs and how they help readers understand a text. Thanks again for taking the time to respond. Its super duper awesome. And if I'm accurately using some of today's youngin' vernacular correctly, I would say its pretty SWAG. : )