Mendenhall Glacier is a glacier about 13.6 miles
long located in Mendenhall Valley , about 12 miles
(19 km) from downtown Juneau in the southeast
area of the U.S. state of Alaska . [2] The glacier
and surrounding landscape is protected as the
5,815-acre Mendenhall Glacier Recreation Area, a
federally designated unit of the Tongass National
Forest . [3]
long located in Mendenhall Valley , about 12 miles
(19 km) from downtown Juneau in the southeast
area of the U.S. state of Alaska . [2] The glacier
and surrounding landscape is protected as the
5,815-acre Mendenhall Glacier Recreation Area, a
federally designated unit of the Tongass National
Forest . [3]
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Originally known as Sitaantaagu ("the Glacier
Behind the Town") or Aak'wtaaksit ("the Glacier
Behind the Little Lake") by the Tlingits, the
glacier was named Auke (Auk) Glacier by
naturalist John Muir for the Tlingit Auk Kwaan
(or Aak'w Kwaan) band in 1888. In 1891 it was
renamed in honor of Thomas Corwin Mendenhall.
It extends from the Juneau Icefield , its source,
to Mendenhall Lake and ultimately the
Mendenhall River.
The Juneau Icefield Research Program has
monitored the outlet glaciers of the Juneau
Icefield since 1942, including Mendenhall Glacier.
The glacier has also retreated 1.75 miles
(2.82 km) since 1958, when Mendenhall Lake
was created, and over 2.5 miles (4.0 km) since
1500. The end of the glacier currently has a
negative glacier mass balance and will continue
to retreat in the foreseeable future. [4]
Given that average yearly temperatures are
currently increasing, and the outlook is for this
trend to continue, it is actually possible that the
glacier might experience a period of stabilization
or slight advance during its retreating march.
This is because increasing amounts of warm,
moist air will be carried up to the head of the
icefield, where colder ambient temperatures will
cause it to precipitate as snow. The increased
amount of snow will feed the icefield, possibly
enough to offset the continually increasing
melting experienced at the glacier's terminus .
However, this interesting phenomenon will fade
away if temperatures continue to climb, since
the head of the glacier will no longer have cold
enough ambient temperatures to cause snow to
precipitate.
The glacier's retreat
Climate change
The US Forest Service, which manages the
Mendenhall Glacier, says "because glaciers are a
product of climate, they respond to climate
change ." [5] The Mendenhall glacier has been in
retreat since the end of the Little Ice Age in the
1700's. [6] In a joint article for the Juneau Empire
Geologist Cathy Connor and Geophysicist Roman
Motyka, both professors of the University of
Alaska said "climatic warming coupled with ice
loss through iceberg calving are the reasons the
Mendenhall Glacier is retreating and
shrinking." [7]
Main article: Global warming
Negative consequences
The retreat of the Mendenhall Glacier and other
glaciers in the area is believed by some to be a
result of broader retreat and breakup of the
Juneau Icefield. The Juneau Icefield is the fifth
largest icefield in North America. [8] For many
populations near glacial areas these glaciers are
a source of fresh drinking water. Once these
glaciers are gone the people relying on this fresh
water will be out of their familiar fresh water
source. For example, Anchorage is one of the
most populated cities in Alaska and many people
in this city rely on the Eklutna glacier for their
freshwater. If the recession of this glacier
continues they will be out of their main source of
water. [9][10] However Alaska has been receiving
record snowfall in the last decade. Snow is the
main factor that causes glaciers to advance. [11]
Benefits
Although there are many negative effects of the
recession of the Mendenhall Glacier and glaciers
in general, there are also a few positive
outcomes from it as well. With the retreat of the
Mendenhall Glacier, the Mendenhall Lake has
formed. The lake is a result of the run-off from
the glacier and is increasing in size as the
glacier continues to retreat. The lake began
formation in 1931 and has continued to grow
since then. [12] The lake has its own unique
ecosystem and is a popular location for sport
fishing ; fishers can find salmon and trout in the
lake. [13]
Ancient forest uncovered
As of recently a new discovery has been made
regarding the Mendenhall Glacier and its retreat.
Within the past year, tree stumps and logs with
roots and bark still attached have been appearing
from under the glacier as it has been retreating.
They are being found in their original growth
position, preserved by what was believed to be a
protective gravel casing covering them. By
uncovering these tree stumps and logs,
scientists are able to uncover information on the
ecosystem's past, from a pre-glacial time.
Scientists observing the area are able to
determine how old the trees were when they died
by looking at their preserved remains.
Originally known as Sitaantaagu ("the Glacier
Behind the Town") or Aak'wtaaksit ("the Glacier
Behind the Little Lake") by the Tlingits, the
glacier was named Auke (Auk) Glacier by
naturalist John Muir for the Tlingit Auk Kwaan
(or Aak'w Kwaan) band in 1888. In 1891 it was
renamed in honor of Thomas Corwin Mendenhall.
It extends from the Juneau Icefield , its source,
to Mendenhall Lake and ultimately the
Mendenhall River.
The Juneau Icefield Research Program has
monitored the outlet glaciers of the Juneau
Icefield since 1942, including Mendenhall Glacier.
The glacier has also retreated 1.75 miles
(2.82 km) since 1958, when Mendenhall Lake
was created, and over 2.5 miles (4.0 km) since
1500. The end of the glacier currently has a
negative glacier mass balance and will continue
to retreat in the foreseeable future. [4]
Given that average yearly temperatures are
currently increasing, and the outlook is for this
trend to continue, it is actually possible that the
glacier might experience a period of stabilization
or slight advance during its retreating march.
This is because increasing amounts of warm,
moist air will be carried up to the head of the
icefield, where colder ambient temperatures will
cause it to precipitate as snow. The increased
amount of snow will feed the icefield, possibly
enough to offset the continually increasing
melting experienced at the glacier's terminus .
However, this interesting phenomenon will fade
away if temperatures continue to climb, since
the head of the glacier will no longer have cold
enough ambient temperatures to cause snow to
precipitate.
The glacier's retreat
Climate change
The US Forest Service, which manages the
Mendenhall Glacier, says "because glaciers are a
product of climate, they respond to climate
change ." [5] The Mendenhall glacier has been in
retreat since the end of the Little Ice Age in the
1700's. [6] In a joint article for the Juneau Empire
Geologist Cathy Connor and Geophysicist Roman
Motyka, both professors of the University of
Alaska said "climatic warming coupled with ice
loss through iceberg calving are the reasons the
Mendenhall Glacier is retreating and
shrinking." [7]
Main article: Global warming
Negative consequences
The retreat of the Mendenhall Glacier and other
glaciers in the area is believed by some to be a
result of broader retreat and breakup of the
Juneau Icefield. The Juneau Icefield is the fifth
largest icefield in North America. [8] For many
populations near glacial areas these glaciers are
a source of fresh drinking water. Once these
glaciers are gone the people relying on this fresh
water will be out of their familiar fresh water
source. For example, Anchorage is one of the
most populated cities in Alaska and many people
in this city rely on the Eklutna glacier for their
freshwater. If the recession of this glacier
continues they will be out of their main source of
water. [9][10] However Alaska has been receiving
record snowfall in the last decade. Snow is the
main factor that causes glaciers to advance. [11]
Benefits
Although there are many negative effects of the
recession of the Mendenhall Glacier and glaciers
in general, there are also a few positive
outcomes from it as well. With the retreat of the
Mendenhall Glacier, the Mendenhall Lake has
formed. The lake is a result of the run-off from
the glacier and is increasing in size as the
glacier continues to retreat. The lake began
formation in 1931 and has continued to grow
since then. [12] The lake has its own unique
ecosystem and is a popular location for sport
fishing ; fishers can find salmon and trout in the
lake. [13]
Ancient forest uncovered
As of recently a new discovery has been made
regarding the Mendenhall Glacier and its retreat.
Within the past year, tree stumps and logs with
roots and bark still attached have been appearing
from under the glacier as it has been retreating.
They are being found in their original growth
position, preserved by what was believed to be a
protective gravel casing covering them. By
uncovering these tree stumps and logs,
scientists are able to uncover information on the
ecosystem's past, from a pre-glacial time.
Scientists observing the area are able to
determine how old the trees were when they died
by looking at their preserved remains.
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