Sea-level rise projections can improve with state-of-the-art model
New ice-sheet 'emulator' focuses on Antarctica

Date:
October 7, 2020
Source:
Rutgers University
Summary:
Projections of potentially dramatic sea-level rise from ice-sheet
melting in Antarctica have been wide-ranging, but a Rutgers-led
team has created a model that enables improved projections and
could help better address climate change threats.



FULL STORY ========================================================================== Projections of potentially dramatic sea-level rise from ice-sheet melting
in Antarctica have been wide-ranging, but a Rutgers-led team has created
a model that enables improved projections and could help better address
climate change threats.


==========================================================================
A major source of sea-level rise could come from melting of large swaths
of the vast Antarctic ice sheet. Fossil coral reefs jutting above
the ocean's surface show evidence that sea levels were more than 20
feet higher about 125,000 years ago during the warm Last Interglacial
(Eemian) period.

"Evidence of sea-level rise in warm climates long ago can tell us a
lot about how sea levels could rise in the future," said lead author
Daniel M. Gilford, a post-doctoral associate in the lab of co-author
Robert E. Kopp, a professor in the Department of Earth and Planetary
Sciences within the School of Arts and Sciences at Rutgers University-New Brunswick. "This evidence suggests that as climate change drives warming
in the atmosphere and oceans, future global sea- level rise could
reach considerable heights." The study, published in the journal JGR:
Earth Surface, delves into how paleoclimate evidence from about 125,000
years ago can be used to improve computer model projections of Antarctic ice-sheet collapse and sea-level rise.

Such evidence is increasingly effective for improving projections,
providing valuable insights into ice sheet vulnerability through at
least 2150.

The study takes advantage of the similarities between past and potential
future sea levels to train a statistical ice-sheet model, using artificial intelligence. The fast, simple, less expensive "emulator" -- a form of
machine learning software -- is taught to mimic the behavior of a complex
model that focuses on ice-sheet physics, enabling many more simulations
than could be explored with the complex model alone. This avoids the
costly run times of the complex ice-sheet model, which considers such
phenomena as ice-sheet fractures due to surface melting and the collapse
of tall seaside ice cliffs.

What may happen to the Antarctic ice sheet as the climate warms is the
biggest uncertainty when it comes to global sea-level rise this century,
the study notes. When combined with evidence of past sea levels, the
new model can boost confidence in sea-level rise projections through at
least 2150.

"If big swaths of the Antarctic ice sheet melted and collapsed about
125,000 years ago, when the polar regions were warmer than today, parts
of the ice sheet may be similarly prone to collapse in the future as
the climate warms, affecting our expectations of sea-level rise and
coastline flooding over the next 130 years," Gilford said.

New estimates of sea levels about 125,000 years ago could be used to
indicate whether, 75 years from now, Hurricane Sandy-like flooding
(about 9 feet above ground level in New York City) is likely
to occur once a century or annually along parts of the Northeast
U.S. coastline. Improved projections could also be included in reports
such as the Intergovernmental Panel on Climate Change's upcoming Sixth Assessment Report, likely helping officials and others decide how to
address climate change threats.

Co-authors include Erica L. Ashe, a post-doctoral scientist in Kopp's
lab, along with scientists at the University of Massachusetts Amherst, Pennsylvania State University and the University of Bremen.


========================================================================== Story Source: Materials provided by Rutgers_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Daniel M. Gilford, Erica L. Ashe, Robert M. DeConto, Robert E. Kopp,
David Pollard, Alessio Rovere. Could the Last Interglacial Constrain
Projections of Future Antarctic Ice Mass Loss and Sea‐level
Rise? Journal of Geophysical Research: Earth Surface, 2020; DOI:
10.1029/ 2019JF005418 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201007085611.htm

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