Headline Jan 21, 2018/ ''' ALASKA'S WARMING *ALAS! '''

''' ALASKA'S WARMING *ALAS! '''

HOW GLOBAL WARMING EFFECTS PERMAFROST -there is plenty of debate among scientists about when and how much of  Alaska's permafrost will thaw.

And there is no doubt that thawing of the full depth of permafrost would take millenniums.

IN ALASKA - a factory of warming the rise in emissions has been so significant that Alaska may be shifting from a storehouse of carbon to net source. 

Near-surface changes have been even greater. At one northern site he said, permafrost temperatures  at shallow depths have climbed from minus 8 degrees Celsius to minus 3.

''Minus 3 is not that far from zero,'' Dr. Romanovsky said. If emissions and warming continue at the same rate, he said near-surface temperatures will rise above freezing around the middle of the century.

Dr. Romanovsky said that his and other's work showed that permafrost ''is not as stable as people thought.''

In addition to greenhouse gas emissions, thawing wrecks havoc on infrastructure, causing slumping of land when ice loses volume as it turns to water.

The main road in Bethel where average temperatures have risen about 4 degrees Fahrenheit since the  mid-20th century is more of a washboard than a thoroughfare because of shifting ground.

Building foundations in Bethel move and crack as well.

Some roads, airport runways and parking areas have to be reinforced with liquid-filled pipes that transfer heat out of the permafrost to keep the ground from slumping.

THE THAWING of a permafrost is a gradual process.

Ground is fully frozen in winter, and begins to thaw from the top down as air temperatures rise in spring.

As average temperatures increase over years, this thawed, or active, layer can increase in depth.

At the field station, the researchers are especially interested in how wildfires affect the permafrost. Because burning removes some of the vegetation that acts as insulation, the theory is that burning should cause permafrost to thaw more.

Parts of the tundra here burned in the 1970s and in the summer of 2015, so the researchers took cores from both burned and unburned areas. Scientists wrestled with the bulky power auger as its stainless steel tube worked its way into the hard permafrost.

Cores, often containing thin layers solid ice -were labeled, packed in a cooler and sent by helicopter to a freezer in Bethel.

Thawing permafrost underneath or at the edge of a lake can cause it to drain like a leaky bathtub.

Thawing elsewhere can bring about small elevation changes that can in turn lead to changes in water flow through the landscape, drying out some parts of the tundra and turning others into bogs.

Beyond the local effects on plant and animal life, the landscape changes can have an important climate change impact, by altering the mix of carbon dioxide and methane that is emitted.

Although methane does not persist in the atmosphere for as long as carbon dioxide, it has a far greater heat-trapping ability and can contribute to more rapid warming.

SO the researchers devote much of their time to studying the flow of water and the carbon and nutrients it contains.

''It's one of the big questions to tackle -what's wet and dry now, and what will be wet and dry in the future,'' Dr. Natali said.

If the decomposing permafrost is wet, there will be less oxygen available to the microbes, so they will produce methane. If the permafrost is dry. the decomposition will lead to more carbon dioxide.

Estimates vary on how much carbon is currently released from thawing permafrost worldwide, but by one calculation emissions over the rest of the century could average about 1.5 billion tons a year, or about the same as current annual emissions from fossil-fuel burning in the United States.

Already, thawing permafrost and warmer temperatures are being blamed for rising carbon emissions  in the Alaska tundra, both here and farther north.

In a study earlier this year, researchers found that bacterial decomposition of thawed permafrost, as well as carbon dioxide produced by living vegetation, continues later into the fall because freezing of the surface is delayed.

The rise in emissions has been so significant, the researchers found, that Alaska may be shifting from a sink, or storehouse of carbon, to a net source.

Dr. Holmes said that the shift was not surprising given the climate trend, and he would expect that  sub-Arctic parts of Siberia, Canada and other areas with permafrost may be undergoing similar changes.

''THERE'S a massive amount of  carbon that's in the ground, and that's built up slowly over   thousands and thousands of years,'' he said.

''It's been in a Freezer, and that freezer is now turning into into a refrigerator.''

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''' Global Warming & Permafrost '''

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