NASA Research Leads to First Complete Map of Antarctic Ice Flows
First complete map of the speed and direction of ice flow in Antarctica, derived from radar interferometric data from the Japan Aerospace Exploration Agency's ALOS PALSAR, the European Space Agency's Envisat ASAR and ERS-1/2, and the Canadian Space Agency's RADARSAT-2 spacecraft. The color-coded satellite data are overlaid on a mosaic of Antarctica created with data from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra spacecraft. Pixel spacing is 984 feet (300 meters). The thick black lines delineate major ice divides. Subglacial lakes in Antarctica's interior are also outlined in black. Thick black lines along the coast indicate ice sheet grounding lines.
"The map points out something fundamentally new: that ice moves by slipping along the ground it rests on," said Thomas Wagner, NASA's cryospheric program scientist in Washington. "That's critical knowledge for predicting future sea level rise. It means that if we lose ice at the coasts from the warming ocean, we open the tap to massive amounts of ice in the interior."
I asked about the bold text above and was told: "Wagner is referring to deformation, like a tank tread. In fact, the bed is considered frozen in most of Antarctica, so it is a bit surprising." Alan Buis JPL.
Water, it seems, is even stranger than I was taught with many more phases than I knew about until now.
The rest of it merely confirms what I've been saying for the past several years...that warming is a positive feedback process which accelerates each season.
The rates of movement of the ice shelves in Western Antarctica (magenta & blue) indicate that it will not be long before the ice on land is free to move and accelerate.
That ice will cause sea level rise--eventually around 5-10 meters.
There will also be a rebound of the currently depressed land, pushed down by the weight of the ice. How rapidly the land will rebound is unknown, but even a few cm per year will increase the sea level and the rate of ice flow in Eastern Antarctica--the largest block of ice on the planet.
http://www.jpl.nasa.gov/news/news.cfm?release=2011-256&cid=release_2011-256
The new data does not change my pessimistic estimate of 5-20m sea level rise by 2027. Nor does it alter the projection that the rise will be non-linear with acceleration (each year it will rise more than it did the year before.)
Note that the rate of visible rise may stay the same or even drop depending upon the slopes of the areas flooded. Steep coasts will show a greater increase than gentle slopes.
To see this effect, fill a glass of water 1/4 full. Note where the surface is on the glass. Now tip the glass over slowly and watch the level rise, stopping when the surface is 3/4 up the glass.
See how much less water it takes to flood a shallow slope. The trade-off is height for horizontal distance.
A rise of 1m at the Gibraltar cliffs will flood well inland on the Nile and other river deltas....
