“Sea-Level Projections Too High” from Global Warming

(p. A10) In the summer of 2015, two New York Times journalists joined a team of researchers in Greenland that was conducting a unique experiment: directly measuring a river of meltwater runoff on the top of the ice.
Now, the scientists have published the results of that work. A key finding — that not as much meltwater flows immediately through the ice sheet and drains to the ocean as previously estimated — may have implications for sea-level rise, one of the major effects of climate change.
The scientists say it appears that some of the meltwater is retained in porous ice instead of flowing to the bottom of the ice sheet and out to sea.
“It’s always treated as a parking lot, water runs straight off,” said Laurence C. Smith, a geographer at the University of California, Los Angeles who led the field work in 2015. “What we found is that it appears there is water retention.”
“It’s plausible that this is quite an important process, which could render sea-level projections too high,” he added.
There’s still much that remains unknown about the ice sheet, which at roughly 650,000 square miles is more than twice the size of Texas.
. . .
When he first sent the results to modelers, Dr. Smith said, “they couldn’t believe it.” After months of back-and-forth, Dr. Smith and his colleagues concluded that the model estimates were accurate, but there was something else going on with some of the meltwater. “What is missing,” he said, “is a physical process that is not currently considered by the models — water retention in ice.”
. . .
“If there’s a mismatch between observation and model,” Dr. Tedesco said, “that means the model is moving the mass in one way or another and not respecting the way things happen in the real world.”

For the full story, see:
HENRY FOUNTAIN AND DEREK WATKINS . “As Greenland Melts, Where’s the Water Going?” The New York Times (Mon., DEC. 13, 2017): A10.
(Note: ellipses added.)
(Note: the online version of the story has the date DEC. 5 [sic], 2017.)

The published article presenting the results briefly mentioned above, is:
Smith, Laurence C., Kang Yang, Lincoln H. Pitcher, Brandon T. Overstreet, Vena W. Chu, Åsa K. Rennermalm, Jonathan C. Ryan, Matthew G. Cooper, Colin J. Gleason, Marco Tedesco, Jeyavinoth Jeyaratnam, Dirk van As, Michiel R. van den Broeke, Willem Jan van de Berg, Brice Noel, Peter L. Langen, Richard I. Cullather, Bin Zhao, Michael J. Willis, Alun Hubbard, Jason E. Box, Brittany A. Jenner, and Alberto E. Behar. “Direct Measurements of Meltwater Runoff on the Greenland Ice Sheet Surface.” Proceedings of the National Academy of Sciences of the United States of America 114, no. 50 (2017): E10622-E31.

Leave a Reply

Your email address will not be published. Required fields are marked *