Eideard

Posts Tagged ‘Eric Rignot

The first map that tracks the motion of Antarctica’s glaciers

leave a comment »


Click to enlarge

Scientists have produced what they say is the first complete map of how the ice moves across Antarctica.
Built from images acquired by radar satellites, the visualisation details all the great glaciers and the smaller ice streams that feed them…

It should aid the understanding of how the White Continent might evolve in the warmer world being forecast by climatologists.

This is like seeing a map of all the oceans’ currents for the first time. It’s a game changer for glaciology,” said lead author Dr Eric Rignot. “We are seeing amazing flows from the heart of the continent that had never been described before”…

The map incorporates billions of radar data points collected between 1996 and 2009 by satellites belonging to Europe, Canada and Japan.

Ice drains from the interior via huge glaciers that calve icebergs into the sea…Ice velocities on the new map range from just few cm/year near places where the ice divides into different paths, to km/year on fast-moving glaciers and the ice shelves that float out from the edges of the continent.

RTFA for history and details. Interesting stuff.

About these ads

Written by Ed Campbell

August 21, 2011 at 2:00 am

Melting ice sheets now largest contributor to a rising sea level

leave a comment »

The Greenland and Antarctic ice sheets are losing mass at an accelerating pace, according to a new study. The findings of the study – the longest to date of changes in polar ice sheet mass – suggest these ice sheets are overtaking ice loss from Earth’s mountain glaciers and ice caps to become the dominant contributor to global sea level rise, much sooner than model forecasts have predicted…

The nearly 20-year study reveals that in 2006, a year in which comparable results for mass loss in mountain glaciers and ice caps are available from a separate study conducted using other methods, the Greenland and Antarctic ice sheets lost a combined mass of 475 gigatonnes a year on average. That’s enough to raise global sea level by an average of 1.3 millimeters (.05 inches) a year. (A gigatonne is one billion metric tons, or more than 2.2 trillion pounds.) Ice sheets are defined as being larger than 50,000 square kilometers, or 20,000 square miles, and only exist in Greenland and Antarctica while ice caps are areas smaller than 50,000 square km.

The pace at which the polar ice sheets are losing mass was found to be accelerating rapidly. Each year over the course of the study, the two ice sheets lost a combined average of 36.3 gigatonnes more than they did the year before. In comparison, the 2006 study of mountain glaciers and ice caps estimated their loss at 402 gigatonnes a year on average, with a year-over-year acceleration rate three times smaller than that of the ice sheets.

That ice sheets will dominate future sea level rise is not surprising — they hold a lot more ice mass than mountain glaciers,” said lead author Eric Rignot, of NASA’s Jet Propulsion Laboratory, Pasadena, California, and the University of California, Irvine. “What is surprising is this increased contribution by the ice sheets is already happening. If present trends continue, sea level is likely to be significantly higher than levels projected by the United Nations Intergovernmental Panel on Climate Change in 2007. Our study helps reduce uncertainties in near-term projections of sea level rise.”

Rignot’s team combined nearly two decades (1992-2009) of monthly satellite measurements with advanced regional atmospheric climate model data to examine changes in ice sheet mass and trends in acceleration of ice loss…

The team found that for each year over the 18-year study, the Greenland ice sheet lost mass faster than it did the year before, by an average of 21.9 gigatonnes a year. In Antarctica, the year-over-year speedup in ice mass lost averaged 14.5 gigatonnes…

While this provides one indication of the potential contribution ice sheets could make to sea level in the coming century, the authors caution that considerable uncertainties remain in estimating future ice loss acceleration.

The inherent conservatism of bona fide scientists once again accounts for the element of a “surprising” rate of melting. Not that it means much to pundits or politicians committed to fossil fuel funding. Or, sadly, a populace in general that’s hardly past WW2 in terms of general understanding of science.

The flywheel effect is so strong that even when people are pushed far enough, no longer being able to ignore reality – it will take generations to begin to halt and then reverse the effects of global warming.

Written by Ed Campbell

March 9, 2011 at 6:00 am

Follow

Get every new post delivered to your Inbox.

Join 1,801 other followers