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 A once-stable glacier in Greenland is now rapidly disappearing 
 Study finds warming Atlantic waters threaten previously stable glaciers


  Date:
      April 19, 2023
  Source:
      Ohio State University
  Summary:
      As climate change causes ocean temperatures to rise, one of
      Greenland's previously most stable glaciers is now retreating at
      an unprecedented rate, according to a new study.


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FULL STORY
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As climate change causes ocean temperatures to rise, one of Greenland's
previously most stable glaciers is now retreating at an unprecedented
rate, according to a new study.


==========================================================================
Led by researchers at The Ohio State University, a team found that between
2018 and 2021, Steenstrup Glacier in Greenland has retreated about 5
miles, thinned about 20%, doubled in the amount of ice it discharges
into the ocean, and quadrupled in velocity. According to the study,
such a rapid change is so extraordinary among Greenland ice formations
that it now places Steenstrup in the top 10% of glaciers that contribute
to the entire region's total ice discharge.

The study was published today in Nature Communications.

The Steenstrup Glacier is part of The Greenland Ice Sheet, a body of ice
that covers nearly 80% of the world's largest island, which is also the
single largest contributor to global sea rise from the cryosphere, the
portion of Earth's ecosystem that includes all of its frozen water. While
the region plays a crucial part in balancing the global climate system,
the area is steadily shrinking as it sheds hundreds of billions of tons
of ice each year because of global warming.

Over the past few decades, much of this loss has been attributed to
accelerated ice discharge from tidewater glaciers, glaciers that make
contact with the ocean. Many glaciologists believe that this recent
uptick in ice discharge can be explained by the intrusion of warming
waters that are being swept from the Atlantic into Greenlandic fjords --
critical oceanic gateways that can impact the stability of local glaciers
and the health of polar ecosystems.

The research team aimed to test that theory by examining a glacier in the
southeastern region of Greenland called K.I.V Steenstrups Nordre Brae,
an entity more colloquially known as the Steenstrup Glacier.

"Up until 2016, there was nothing to suggest Steenstrup was in any
way interesting," said Thomas Chudley, lead author of the study, who
completed this work as a research associate at the Byrd Polar and Climate
Research Center.

Chudley is now a Leverhulme research fellow at Durham University in
the UK.

"There were plenty of other glaciers in Greenland that had retreated
dramatically since the 1990s and increased their contribution to sea
level rise, but this really wasn't one of them."  As far as scientists
knew, Steenstrup had not only been stable for decades but was generally
insensitive to the rising temperatures that had destabilized so many
other regional glaciers, likely because of its isolated position in
shallow waters.

It wasn't until Chudley and his colleagues compiled observational and
modeling data from previous remote sensing analyses on the glacier
that the team realized Steenstrup was likely experiencing melt due to
anomalies in deeper Atlantic water.

"Our current working hypothesis is that ocean temperatures have forced
this retreat," Chudley said. "The fact that the glacier's velocity has
quadrupled in just a few years opens up new questions about how fast
large ice masses can really respond to climate change."  In recent
years, glaciologists have been able to use satellite data to estimate
the potential volume of glacial ice stored at the poles and how it might
affect current sea levels. For instance, if the Greenland Ice Sheet were
to melt, Earth's sea levels could rise by nearly 25 feet. In contrast,
if the ice sheet in Antarctica were to fall apart, it's possible that
oceans would rise by nearly 200 feet, Chudley said.

While Greenland and Antarctica would take centuries to collapse
completely, the global cryosphere has the potential to cause sea levels
to rise about six feet this century if the West Antarctic Ice Sheet
undergoes collapse.

As around 10% of the planet's population lives in low-lying coastal zones,
Chudley said that any significant rise in sea level can cause increased
risk to low-lying islands and coastal communities from storm surges and
tropical cyclones.

In the United States, sea level rise poses a particular risk to coastal
cities in places like Florida or Louisiana, Chudley said. But that doesn't
necessarily mean it's too late to stop such a future from happening. If
climate policies evolve rapidly, humans might have a chance at halting
the worst of sea level rise, Chudley said.

Overall, Steenstrup's unique behavior reveals that even long-term stable
glaciers are susceptible to sudden and rapid retreat as warmer waters
begin to intrude and influence new environments.

While the research says continued scientific observation of the Steenstrup
Glacier should be a priority, it concludes other similar glaciers also
deserve attention because of their potential to retreat due to warming
waters.

Understanding more about these interactions could provide key insight
into how glaciers thrive in other locations around the world and even
become an indicator of how these environments might change in the future.

"What's happening in Greenland right now is kind of the canary in the
coal mine of what might happen in West Antarctica over the next few
centuries," Chudley said. "So it would be great to be able to get into
the fjord with real on-the- ground observations and see how and why
Steenstrup has changed."  This work was supported by NASA. Other Ohio
State co-authors were Ian M. Howat and Adelaide Negrete of the Byrd
Polar and Climate Research Center. Michalea D.

King of the University of Washington was also a co-author.

    * RELATED_TOPICS
          o Earth_&_Climate
                # Global_Warming # Climate # Ice_Ages #
                Snow_and_Avalanches
          o Fossils_&_Ruins
                # Early_Climate # Ancient_DNA # Evolution # Origin_of_Life
    * RELATED_TERMS
          o Ice_sheet o Greenland_ice_sheet o Paleoclimatology
          o Global_warming_controversy o Global_climate_model o
          Climate_change_mitigation o Climate_engineering o Global_warming

==========================================================================
Story Source: Materials provided by Ohio_State_University. Original
written by Tatyana Woodall. Note: Content may be edited for style
and length.


==========================================================================
Journal Reference:
   1. T. R. Chudley, I. M. Howat, M. D. King, A. Negrete. Atlantic water
      intrusion triggers rapid retreat and regime change at previously
      stable Greenland glacier. Nature Communications, 2023; 14 (1) DOI:
      10.1038/ s41467-023-37764-7
==========================================================================

Link to news story:
https://www.sciencedaily.com/releases/2023/04/230419125120.htm

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