HUBBARD GLACIER
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DIFFERENT BEHAVIOR

Hubbard Glacier is advancing in a world (and a
region) where most are retreating.  There is is,
the front of it anyway, the white streak just above
the water between the two land masses, in the
picture to the right.

To locate its position in Alaska,
look at this map,
which is in a US Geological Survey (USGS) web
site.  I took the picture from Disenchantment Bay,
somewhere in the the word "Disenchantment" on the
map.  Russell Fjord (see map) is out of sight
behind the land mass on the right.  The two
smaller glaciers coming down on the left are out of
sight behind the land mass on the left.  You will
see Valerie Glacier on a couple of the pictues below.
You can click in each picture to get a larger version.  Use the "back" button to return from
the larger version.  If the picture snaps down to fit your screen, put the mouse pointer in it,
wait for an icon to appear in the lower right, and click the icon to see the large version.
Hubbard Glacier has retreated since the
year 1130, as shown on the map, but has
been moving ahead recently, as indicated
by the arrow on
the map.
That is a cruise ship called the "Summit" that
belongs to the
Celebrity Cruise Line up there.  It
is still about six miles from the glacier, about at
the last "t" in the word "Disenchantment" on the
map.  Later, my ship, the "
Volendam" of the
Holland America Line, got up there that close.

On the extreme left, there is Turner Glacier, the
larger of the two small glaciers to the left of
Hubbard.  It is now peeking around the land mass
on the left.
Refering to that USGS Map one more time, notice how close the front of the glacier is to cutting off
Russell Fjord.  In fact, it did cut it off twice -- once in 1986, between May and October, and once
in 2002.  Then the water running into Russell Fjord through various streams could not go anywhere.   
In 1986 the dam it formed backed up the water in Russell Fjord to a height of about 80 feet above
sea level before the dam broke.  Then the excess water emptied into the ocean a single day, the
largest such outburst in North America in the last 10,000 years.  You probably didn't read about it
in the disaster news, because the only thing to be flooded was the ocean itself.  In fact, there was
more of a flood threat before the dam broke as the Russell Fjord lake threatened adjacent areas.

The 2002 event was not quite as large, but the same process did repeat itself.  It will probably
happen again, too.  
Click here for more information and some great photos of the 2002 dam and
outburst.  Here is a some
information about the problems another closing of the Fjord might cause.
A GIANT FLOOD
Here is a closer look at the left side of Hubbard
Glacier.  Turner Glacier is out of sight to the
left in this picture.   Valerie Glacier is above
Hubbard here, but there is a better picture of
it to the right.
There is the front of Hubbard and Valerie
Glacier coming down the mountain above it.
Valerie Glacier has been known to "
surge", or
gallop ahead up to 100 times faster than
normal,  which
might be contributing to the
advance of Hubbard.  But that is not the
whole story.
A close look at the front of Hubbard Glacier,
which is a tidewater glacer, in fact the
largest tidewater glacier in North America.  
It is called that because it ends in an arm of
the ocean, where there are tides.  There is
part of Valerie Glacier above it, too.

Did you notice all the floating ice in the water
in these pictures?  These tidewater glaciers
tend to loose mass by calving, a word which
refers to chunks of ice falling off of a
glacier.  I didn't get to see this one calve,
though.  See my sections on Northwestern
Glacier and Margerie Glacier for some
pictures of calving.
Actually, I think that most of this floating ice
came from Turner Glacier, the one to the left
of Hubbard.  That's it in this picture.  The
ship couldn't get as close as usual because of
all that floating ice.

Another small glacier, Haenke Glacier, the
other small one next to Turner, does not reach
the water and so is not visible here.  Go
here
and scroll for a picture of this.

Notice the ice at the right side of this glacier
is very dirty.  I was told that much of the
front of it was that dirty not too long before
my visit.  But the dirty ice broke off and filled
the water.  Look just below for a couple of
pictures of that dirty, floating ice.
So what is going on with this glacier, anyway?  Why would it be advancing when most others are
retreating. (Only around 10 or so of Alaska's thousands of glaciers are advancing, and they tend to
be the tidewater glaciers on or near Alaska's southern coast.)

In general, many (but not all) tidewater glaciers that lose mass by calving are known to defy climate.
 
Here is a paper that discusses the matter while describing the 2002 closing of Russell Fjord.

Among other things, it says that such glaciers "have unusually small ablation areas compared to their
accumulation areas".  Just to interpret this, an "ablation area" is where the glacier is losing mass,
and an "accumulation area" is where the snow is falling on the glacier to make new glacier ice.  That
would allow it to make a lot of ice compared to what it loses.

In the case of Hubbard, 95% of the area is accumulation area.

Such glaciers also calve into unusually shallow water, which seems to make a difference.  The shallow
water is often caused by the glacier's terminal moraine -- the sediment and junk dropped by the
glacier as it loses its ice.   In general, the condition of the bottom of the fjord can govern how
rapidly the glacier does or doesn't grow.

This link takes you to the abstract of a similar paper.

More discussion at
this USGS site.