Submitted by Greg Nilson on Mon, 11/21/2011 - 11:45
Earth may be in for some serious climate change. A lot of it will have to do with permafrost.
What is Permafrost and why is the Earth at risk?
On the globe’s most northern lands, there is a thin and active layer of soil, rock and vegetation right at the surface which freezes and thaws each year with the seasons. There's even more in the northern regions, like Alaska and Siberia; just beneath this active layer, is a second layer of rock and soil which remains frozen year round. This is what is known as the permafrost layer.
Just as our topsoil contains liquid water, the permafrost layer also contains water – in the form of ice. Depending upon region, the permafrost layer can be as little as inches to as many as thousands of feet deep.
Since the 1930s, permafrost temperatures at various depths have been recorded, and after more than seventy years of gathering data, it is clear that the permafrost is heating up, which just might spell trouble.
Prior to 1970 there were year-to-year fluctuations, but for the most part since then, the permafrost stayed well below freezing. Something unexplainable changed around the 1980s. The more superficial ground temperatures have been rising and over the past 20 or so years have stayed fairly consistently above freezing.
What does this mean? Although deeper layers of permafrost remain frozen, the majority of ground ice in that more superficial layer is melting. This is not isolated to a particular region, but has been consistently captured by independent scientists in the US, Russia, Canada, Norway, China, Kazakstan and Mongolia.
Why does melting permafrost matter?
There is a sequence of pretty straightforward consequences of this progressing thaw that we can see with our own eyes. First, as permafrost melts, ice turns to water which saturates the soil, creating cold wetlands. With the loss of the ice, which was once part of the soil structure, the terrain begins to shift and becomes unstable. Because the water is now liquid, as soil shifts the water drains from the land.
Here’s just a taste of what we are beginning to understand about how the process above ripples out in its effect. Boreal forests (forests specifically adapted to live on permafrost soils) are being destroyed when the frozen water melts and over-saturates the soil. Unstable soil has not only shown its destructive power over any infrastructure built upon or within it (think airports and oil lines), it has also changed the paths of rivers.
Ecoystems, food chain at risk
We have only begun looking at what this means for aquatic ecosystems and the rest of the food chain that relies on the stability of Arctic and subarctic waters. But for a taste of the potential harm, a prime case study is the north-western Alaskan river of Selawik. In that region, melting permafrost caused the ground to become unstable and spontaneously dammed up the river and disrupted the migration of fish. Whether the local villages - whose livelihood depends on the health of local fish populations - will survive this disaster is yet to be seen.
The destruction goes even further. Satellite images of Siberia from the 1970s to present show the initial swelling, then gradual loss of large Arctic lakes that have drained but never refilled and are considered to be permanently dried out. This is in spite of increased rainfall and again points back to the loss of permafrost soil structure allowing melting, then drainage of these waters.
The loss of soil water in these areas raises concerns about increasing risk for uncontrolled fires (lightening strikes these areas frequently but under normal permafrost conditions rarely starts fires). It also raises questions about what massive freshwater input into our oceans might mean.
There is another bigger concern that we can’t see with our own eyes, but we can measure. In the permafrost, temperatures are low enough that for thousands of years, dead animals and vegetation have been decomposing very slowly. Consequently, the permafrost region is the largest deposit of carbon on earth. More carbon exists within the permafrost than in all living things on earth combined.
Dead animals and vegetation, long frozen, now face decomposition as the northern lands "rot" away
When permafrost thaws and the ice within it - melts, the habitat that was previously hostile to decomposing bacteria suddenly becomes a welcoming home and decomposition goes into overtime. This is a serious matter because the by-product of all this decomposition is carbon dioxide, a greenhouse gas that is a key element of global warming.
As more permafrost becomes an active layer that even risks melt in winter, we will see a sharp uptick in the amount of carbon dioxide it pours out. Another carbon based by-product we should expect to see coming out of our melting permafrost: Methane, with about twenty-five times the warming potential of carbon dioxide. And remember, this is the largest carbon sink in the world.
It's very possible that once a warming "switch" has been thrown, there will be no turning back the global climate change we will all face, short of the very hand of God.
You're right. We're looking
You're right. We're looking at some serious danger to the Earth here. The melting of the permafrost goes hand in hand with the melting of glaciers and the dissipating of the oceans. The Earth is heating up and that means major changes headed our way. It's something that scientist have been worried studying for, as you said, decades. In the past couple of decades it's become more and more worrisome.
It's only within the past decade or so that it's grown to status of worldwide alarm. The permafrost melting is an even newer alarming calculation. Once the permafrost hits a certain point in its melting then, also as you said, decomposing bacteria will be released. Once that happens, there's really no telling what will occur next. All we can be certain of is that it won't be good, it won't be stopped.