Interesting article

http://www.newyorker.com/fact/content/?050425fa_fact3


Any piece of ground that has remained frozen for at least two years is,
by definition, permafrost. In some places, like eastern Siberia,
permafrost
runs nearly a mile deep; in Alaska, it varies from a couple of hundred
feet
to a couple of thousand feet deep.

Fairbanks, which is just below the Arctic Circle
, is situated in a region of discontinuous permafrost, meaning that the
city is freckled
with regions of frozen ground. One of the first stops on Romanovsky's
tour was a
hole that had opened up in a patch of permafrost not far from his
house.
It was about
six feet wide and five feet deep. Nearby were the outlines of other,
even bigger holes,
which, Romanovsky told me, had been filled with gravel by the local
public-works department.

The holes, known as thermokarsts, had appeared suddenly when the
permafrost gave way,
like a rotting floorboard. (The technical term for thawed permafrost is
talik, from
a Russian word meaning "not frozen.")
Across the road, Romanovsky pointed out a long
trench running into the woods. The trench, he explained, had been
formed when a wedge
of underground ice had melted. The spruce trees that had been growing
next to it,
or perhaps on top of it, were now listing at odd angles, as if in a
gale. Locally,
such trees are called "drunken." A few of the spruces had fallen
over. "These are very drunk,"
Romanovsky said.

In Alaska, the ground is riddled with ice wedges that were created
during the last glaciation,
when the cold earth cracked and the cracks filled with water. The
wedges, which can be dozens
or even hundreds of feet deep, tended to form in networks, so that
when they melt they leave
behind connecting diamond- or hexagonal-shaped depressions.

A few blocks beyond the drunken forest,
we came to a house where the front yard showed clear signs of
ice-wedge melt-off. The owner,
trying to make the best of things, had turned the yard into a
miniature-golf course.

Around the corner, Romanovsky pointed out a house-no longer
occupied-that had basically
split in two; the main part was leaning to the right and the garage
toward the left.
The house had been built in the sixties or early seventies; it had
survived until almost
a decade ago, when the permafrost under it started to degrade.
Romanovsky's mother-in-law
used to own two houses on the same block. He had urged her to sell them
both. He pointed out
one, now under new ownership; its roof had developed an ominous-looking
ripple.
(When Romanovsky went to buy his own house, he looked only in
permafrost-free areas.)

"Ten years ago, nobody cared about permafrost," he told me. "Now
everybody wants to know."
Measurements that Romanovsky and his colleagues at the University of
Alaska have made around Fairbanks
show that the temperature of the permafrost has risen to the point
where,
in many places, it is now less than one degree below freezing. In
places
where permafrost has been disturbed, by roads or houses or lawns, much
of it is already thawing.

Romanovsky has also been monitoring the permafrost on the North Slope
and has found that there,
too, are regions where the permafrost is very nearly thirty-two
degrees Fahrenheit. While the age
of permafrost is difficult to determine, Romanovsky estimates that most
of it in Alaska probably
dates back to the beginning of the last glacial cycle.
This means that if it thaws it will be doing
so for the first time in more than a hundred and twenty thousand years.


"It's really a very interesting time,
" he said.


One of the risks of rising temperatures is that this storage process
can start to run in reverse. Under the right conditions, organic
material
that has been frozen for millennia will break down, giving off carbon
dioxide
or methane, which is an even more powerful greenhouse gas. In parts of
the Arctic,
this is already happening. Researchers in Sweden, for example, have
been measuring
the methane output of a bog known as the Stordalen mire, near the town
of Abisko, for
almost thirty-five years. As the permafrost in the area has warmed,
methane releases have
increased, in some spots by up to sixty per cent. Thawing permafrost
could make the active
layer more hospitable to plants, which are a sink for carbon. Even
this, though, probably
wouldn't offset the release of greenhouse gases. No one knows exactly
how much carbon
is stored in the world's permafrost, but estimates run as high as
four hundred and fifty
billion metric tons.

Dooo tell! Tain't no permafost around here.
cuhulin