One of the unique characteristics of Antarctica is that it's size changes during the seasons through the growth and melting of sea ice. Sea ice is really just want it sounds like - ice that forms on the sea. When the temperatures drop below freezing and stay that way for some time, the sea water actually freezes. In fact, the temperature must be a few degrees below freezing before the sea water begins to freeze. As anyone who have ever taken a gulp of water in at the beach knows, the ocean contains salt. For the same reason why people put salt down on sidewalks to prevent ice forming during winter, the same chemistry happens in the ocean water. As the ocean water freezes, the salt and other dissolved chemicals are left behind. This is one of the reasons why the polar ocean areas in the Arctic and Antarctic are important for the global ocean circulation. The cold, saltier water left behind from the formation of sea ice is more dense than warmer or just less saltier water and this cold, dense water sinks very deep down into the ocean. This movement of water is sometimes called the Ocean Conveyor Belt System. Everything in nature obeys the conservation of mass and energy and so more water must come to replace the water that has just been displaced. Without the formation of sea ice each winter, the global ocean circulation would slow down and this would have rather large impacts on the global climate system. This is one of the reasons why climate scientists are concerned about the demise of sea ice in the Arctic.
It is getting near the end of summer here in the Antarctic and there is still much sea ice around the continent. This sea ice is favored by seals as a nice resting location and currently the sea ice around McMurdo Station is dotted with hundreds of seals. I've only seen one lone penguin so far. Penguins need open ocean to hunt for food and usually only come around McMurdo when the sea ice has melted. This year the sea ice is still pretty solid so there has not been a whole lot of penguin activity. In fact, in order to allow the resupply vessel to reach the dock, an icebreaker ship had to lead the way to break up the sea ice. Residents said that a few days after the ice breaker cleared the way, there was quite a bit of marine activity including killer whales (orkas) and several penguins.
In the picture, you'll see a seal making their way up onto the sea ice for nice nap (or whatever seals prefer to do). In the front of the picture, toward the bottom, you'll also notice what looks likes mounds of sea ice. This feature is called a pressure ridge and is formed from the sea ice being forced up against the shoreline (or grounded land). This force causes the ice to fracture and be pushed up on itself. It's quite a beautiful feature.
It is getting near the end of summer here in the Antarctic and there is still much sea ice around the continent. This sea ice is favored by seals as a nice resting location and currently the sea ice around McMurdo Station is dotted with hundreds of seals. I've only seen one lone penguin so far. Penguins need open ocean to hunt for food and usually only come around McMurdo when the sea ice has melted. This year the sea ice is still pretty solid so there has not been a whole lot of penguin activity. In fact, in order to allow the resupply vessel to reach the dock, an icebreaker ship had to lead the way to break up the sea ice. Residents said that a few days after the ice breaker cleared the way, there was quite a bit of marine activity including killer whales (orkas) and several penguins.
In the picture, you'll see a seal making their way up onto the sea ice for nice nap (or whatever seals prefer to do). In the front of the picture, toward the bottom, you'll also notice what looks likes mounds of sea ice. This feature is called a pressure ridge and is formed from the sea ice being forced up against the shoreline (or grounded land). This force causes the ice to fracture and be pushed up on itself. It's quite a beautiful feature.