Tuesday, 13 March 2018

Ice shelf Antarctica growing!

By Dr. Sebastian Lüning and Prof. Fritz Vahrenholt
(German text translated/edited by P. Gosselin)
Whenever a chunk of ice breaks off the Antarctic ice shelf, the guilty party is immediately found by the media: man. He did it with his SUVs, his planes, and his container ships.
But what makes everything all the more surprising is a recent press release from Scripps Institution of Oceanography from 8 January 2018. Weather phenomenon El Niño is causing the ice shelf in the Amundsen Sea to melt from underneath.
Additional snowfall is unable to compensate for the loss. During a La Niña phase, the opposite occurs: The ice sheet grows. It’s natural variability at work. Gradually we are beginning to understand how it works. The press release follows:
New Study Reveals Strong El Niño Events Cause Large Changes in Antarctic Ice Shelves
Oscillations of water temperature in the tropical Pacific Ocean can induce rapid melting of Antarctic ice shelves. A new study published Jan. 8 in the journal Nature Geoscience [Paolo et al. 2018] reveals that strong El Niño events can cause significant ice loss in some Antarctic ice shelves while the opposite may occur during strong La Niña events.
El Niño and La Niña are two distinct phases of the El Niño/Southern Oscillation (ENSO), a naturally occurring phenomenon characterized by how water temperatures in the tropical Pacific periodically oscillate between warmer than average during El Niños and cooler during La Niñas. The research, funded by NASA and the NASA Earth and Space Science Fellowship, provides new insights into how Antarctic ice shelves respond to variability in global ocean and atmospheric conditions.
The study was led by Fernando Paolo while a Ph.D. graduate student and postdoc at Scripps Institution of Oceanography at the University of California San Diego. Paolo is now a postdoctoral scholar at NASA’s Jet Propulsion Laboratory. Paolo and his colleagues, including Scripps glaciologist Helen Fricker, discovered that a strong El Niño event causes ice shelves in the Amundsen Sea sector of West Antarctica to gain mass at the surface and melt from below at the same time, losing up to five times more ice from basal melting than they gain from increased snowfall. The study used satellite observations of the height of the ice shelves from 1994 to 2017.(acknowledgements to Pierre Gosselin (www.notrickszone.com), also Principia Scientific International John O`Sullivan http://principia-scientific.org.)