The Pine Island Glacier is a massive flowing river of ice on the western Antarctic ice shelf. And by massive, I mean massive: it's 250 km (150+ miles) long, and has an area of 175,000 square kilometers -- that's bigger than the state of Iowa! Every year, a staggering 79 cubic kilometers (19 cubic miles) of ice drains from this glacier in the ocean, flowing via a tongue of ice floating in the water off the main land.
Flying over the glacier on October 14, scientists aboard a NASA DC-8 airplane as part of the IceBridge mission were startled to see a huge crack across the glacier. Flying back over it on October 26, they were able to photograph and measure this huge rift, and found it will almost certainly soon give birth to a huge iceberg. Check out this lovely picture of the ice crack:
[Click to enfloenate - and you really want to; it's amazingly beautiful.]
Brrrr. The scale of this crack is much larger than you might think: it's 80 meters wide on average, and about 150 meters wide in the photo above, the size of a football stadium! It runs for 29 km (18 miles), and it's pretty deep; a topographic map (shown here) indicated it's 50-60 meters in depth.
Remember, Antarctica is a continent, a land mass, but this part of the glacier is flowing out over the ocean, and is floating. The ice at this point in the glacier is about 500 meters thick -- more than a quarter mile! -- but cracks like these grow with time. Eventually, it'll snap, and the seaward part of the ice will float free, a newly-born iceberg that will be something like 800 square kilometers (300+ square miles) in area. Such cracks have been seen before, but never mapped in such detail using airborne observations.
NASA put together a video about the flight over Pine Island:
This is wonderful science, studying how our dynamic planet changes over time. And to get to see such an amazing event as it's just getting started is very exciting! You can see other pictures from this flight on the NASA Ice Flickr page, and I suggest you do: the images are really cool (har har) and the science they're doing is important -- as the Earth warms (and it is) our ice is disappearing. Missions like IceBridge will help us understand how that is happening and what the effects are.
Credit: Digital Mapping System team and Michael Studinger; NASA/Goddard Space Flight Center/Scientific Visualization Studio