As Alaska Glaciers Melt the Land Rises
Published:
May 17, 2009
Morgan
DeBoer, a property owner, opened a nine-hole golf
course at the mouth of
“The
highest tides of the year would come into what is now my driving range area,”
Mr. DeBoer said.
Now,
with the high-tide line receding even farther, he is contemplating adding
another nine holes.
“It
just keeps rising,” he said.
The
geology is complex, but it boils down to this: Relieved of billions of tons of
glacial weight, the land has risen much as a cushion regains its shape after
someone gets up from a couch. The land is ascending so fast that the rising
seas — a ubiquitous byproduct of global warming — cannot keep pace. As a
result, the relative sea level is falling, at a rate “among the highest ever
recorded,” according to a 2007 report by a panel of experts convened by Mayor
Bruce Botelho of
As
a result, the region faces unusual environmental challenges. As the sea level
falls relative to the land, water tables fall, too, and streams and wetlands
dry out. Land is emerging from the water to replace the lost wetlands, shifting
property boundaries and causing people to argue about who owns the acreage and
how it should be used. And meltwater carries the
sediment scoured long ago by the glaciers to the coast, where it clouds the
water and silts up once-navigable channels.
A
few decades ago, large boats could sail regularly along Gastineau Channel
between Downtown Juneau and
Already,
people can wade across the channel at low tide — or race across it, as they do
in the Mendenhall Mud Run. At low tide, the navigation buoys rest on mud.
Eventually,
as the land rises and the channel silts up, Douglas Island will be linked to
the mainland by dry land, said Eran Hood, a
hydrologist at the University of Alaska Southeast and an author of the 2007
report, “Climate
Change: Predicted Impacts on Juneau.”
When
that happens, Dr. Hood said, the Mendenhall Wetlands State Game Refuge, 4,000
acres of boggy habitat, will be lost. “That wetland will have nowhere else to
go,” he said.
In
some places along the coast, the change has been so rapid that kayakers whose
charts are not up-to-the-minute can find themselves carrying their boats over
shoals that are now so high and dry they now support grass or even small trees.
In
and around
The
topographical changes have threatened crucial ecosystems and even locally vital
species like salmon.
“The
lifeblood of our region has been salmon species and their return — and what is
the impact when they return and the streams are dry?” said Mayor Botelho, who was born and raised in
He
said he did not think that any species were in imminent danger, but added,
“Anyone who is following climate change has to see that there are risks,
perhaps great ones.”
Dr.
Hood said many people in
Relative
to the sea, land here has risen as much as 10 feet in little more than 200
years, according to the 2007 report. As global warming accelerates, the land
will continue to rise, perhaps three more feet by 2100, scientists say.
The
rise is further fueled by the movement of the tectonic plates that form the
earth’s crust. As the Pacific plate pushes under the North American plate,
“When
you combine tectonics and glacial readjustment, you get rates that are
incomprehensible,” Dr. Molnia said.
In
Gustavus, where Mr. DeBoer’s
property is, the land is rising almost three inches a year, Dr. Molnia said, making it “the fastest-rising place in
In
addition to expanding the golf course, Mr. DeBoer is
negotiating with the Nature Conservancy to
preserve some of the newly emergent land. He can do both, he said, because the
high tide line has pushed almost a mile out to sea since his family first
homesteaded on the property.
Where
the shoreline is relatively flat, “it doesn’t take much uplift to make quite a
bit of difference,” Mr. DeBoer said.
Kristin
White, a 28-year-old schoolteacher who grew up in Haines, a town north of here,
is from another family in the area whose real estate grew as land rose. When
her father tried to sell some property in Haines, she said, “he
had to have it resurveyed.”
But
for Ms. White, who has vivid memories of visiting the Mendenhall glacier as a
child, the gain in acreage has been bittersweet. Seeing the glacier retreat,
she said, is “as if you lived in the