One hundred thirty miles north of Nome, a small coastal village on Sarichef Island is feeling the effects of climate change. Shishmaref, Alaska, is falling into the sea. Rising temperatures are melting the permafrost, the layer of frozen ground beneath the surface. Without this firm base, waves have eroded the land on which Shishmaref's villagers make their home. They must relocate their houses inland or start all over somewhere else.
Nowhere is global warming having as obvious an impact as in the Arctic, and people living in Alaska, northern Canada, northern Scandinavia and Siberia have front-row seats. Some experts say that temperatures in these regions have risen by 3˚ to 5˚F over the past 30 years. And the temperature in the Arctic has warmed at twice the global average rate in the past century, according to the 2007 Intergovernmental Panel on Climate Change (IPCC) report. Permafrost is ground that maintains a temperature below freezing for at least two years. In some areas, that frozen layer is thawing, causing roads to collapse, runways to crack, and homes to sink, split apart, or even fall into the sea. But inside that icy ground is a threat more dangerous than crumbling infrastructure: massive amounts of greenhouse gases that, if released into the atmosphere, have the potential to quickly intensify climate change.
Understanding the Thaw
The soil, rock and sediment that make up permafrost are divided into two layers. The top, known as the active layer, runs slightly less than one foot to several feet deep and thaws every summer. The bottom layer remains solid year-round. Thickening of an area's active layer indicates that the frozen ground beneath it is melting.
Continuous permafrost dominates the northern stretches of the Arctic, where temperatures are coldest. South of this area, permafrost breaks up into patches that make up the discontinuous zone. Places with even less permafrost comprise two more zones, called sporadic and isolated. Far north, where the permafrost is continuous, the lower layer is stable, extending hundreds and even thousands of feet down—2,400 feet in some parts of northern Alaska and as much as 5,000 feet in northern Siberia. But in the more southern, discontinuous reaches of the permafrost zone, the frozen layer is only a foot to several feet thick, making it susceptible to warming temperatures.
Permafrost contains carbon, accumulated from the decomposition of plants and animals over tens of thousands of years. Last September, researchers at the University of Florida estimated that more than 1,800 billion tons of carbon are stored in northern permafrost—twice the amount in the atmosphere today. In its frozen state, organic matter decays very slowly. But as the temperature rises and permafrost melts, the material breaks down rapidly, releasing carbon into the atmosphere.
When organic matter degrades in dry air, carbon dioxide is emitted. And in wet soil or underwater, where there is little or no molecular oxygen, anaerobic bacteria break down the organic materials and give off methane. Both CO2 and methane are greenhouse gases. As they are released into the atmosphere from permafrost, scientists predict that a disastrous cycle will emerge: The gases will trap hot air, raising the air temperature and melting the permafrost, releasing more carbon and further heating the planet.
According to a measure used by the IPCC called Global Warming Potential, methane will be responsible for producing 25 times as much heat as CO2 over the course of this century. But "there is going to be a significant impact whether carbon is released as CO2 or as methane," says Edward Schuur, an ecosystem ecologist and lead author of the University of Florida study. Although methane's molecular structure allows it to trap heat better than CO2, it is released more slowly into the atmosphere and dissipates at a faster rate.
Based on their current computer climate models, scientists can't yet pinpoint just how much carbon will be added to the atmosphere as a result of thawing permafrost. That depends on complex factors like the degree and speed of the thaw and changes that could offset permafrost emissions, such as an increase in CO2 absorption from new vegetation.
The Heat Is On
Just how much warmer will it get? Computer climate models project that temperatures in the Arctic will increase by 3.6˚to 16˚ by the year 2100, according to the IPCC report. But for now, the consequences of global warming are most obvious in the discontinuous zone. Here, where frozen ground is thinnest, annual average temperatures approach 32˚.
Consider, for example, the changes taking place in Fairbanks, Alaska, a city with a population of around 34,500 just south of the Arctic Circle. The average annual temperature range is typically between 23˚ and 28˚ here but will probably increase by as much as 4˚ by 2050, according to a World Wildlife Federation report from last April. Depending on how climate-change scenarios play out by the end of the century, Fairbanks, which is already feeling the effects of the permafrost thaw, could see a 12˚ increase in temperature.
In Manitoba, Canada, temperatures have risen by 2.3˚ since 1970. In some areas, the southern limit of the permafrost zone is retreating north at a startling rate of one foot per year. Phil Camill, an ecologist at Carleton College, who is monitoring the effects of the thaw in Manitoba, estimates that if warming continues at present rates, all the permafrost in the five sites he studies will melt by 2100. The amount of carbon that will be released into the atmosphere remains to be seen.
Melting Permafrost, Shifting Landscape
Warmer climates with less frozen ground are changing Earth's northern landscape. The shape of these changes depends on the physical makeup of the region. Some peatlands and low-lying tundra can turn swampy, whereas upland tundra areas and forests with good drainage often dry up after a melt. Exceptions certainly exist, and more observational studies are necessary to predict how permafrost thaw will affect the saturation of different areas.
Important data come from the sub-Arctic peatlands of northern Sweden, where permafrost measurements and aerial photographs have recorded ground thaw and resulting vegetation changes since 1970 at the Stordalen mires, a boggy area more than 800 miles north of Stockholm. Melting permafrost has resulted in much wetter conditions, and some water-loving plants are replacing those that thrive in a dryer environment.
Different plants take in and release varied amounts of gases over their life cycle. Although the vegetation that has appeared in Stordalen has increased carbon absorption there by 13 percent since 1970, methane emissions from decomposing plants, which have been exposed by melting permafrost, still outpace that carbon uptake, according to work by Torben R. Christensen, a biogeochemist at Lund University in Sweden. His calculations show that methane output at the Stordalen mires rose by 22 percent over the past 30 years. Studies suggest that Stordalen's plight is similar to warming trends throughout northern Sweden and parts of Alaska and Canada.
In some areas of the Arctic tundra—which is typically barren or sparsely covered with low-lying vegetation like moss and lichens—trees and especially shrubs, which spread quickly, have begun to invade as the ground softens. This so-called shrubification is changing the landscape, with unknown consequences. These plants will take in CO2 from the atmosphere, but they'll also release it as they die and decay.
In areas once covered by snow and ice, which reflect heat from sunlight, encroaching plant life has altered the albedo, or reflectiveness, of the region. Plants absorb sunlight for photosynthesis. This traps heat close to the ground, which further increases air temperature and melts permafrost, in turn releasing carbon into the atmosphere.
An Uncertain Future
How much permafrost will thaw between now and 2100, and what will be the result? Using the IPCC climate forecasts, David Lawrence of the National Center for Atmospheric Research in Colorado predicts that between 60 percent and 90 percent of the top 10 feet of Arctic permafrost could completely thaw in the next 100 years. But different modeling systems produce different results, and Lawrence's figures are at the high end of the range.
The Arctic landscape—with its varieties of vegetation and topography—is notoriously hard to model. Unknown factors, such as future temperature and snowfall trends, increase the margin of error. Higher temperatures can increase precipitation in the form of snow. Ironically, extra snow cover may insulate permafrost from cold air in the winter, contributing to the thaw. Conversely, new moss growth in warmer, wetter areas could protect permafrost layers from melting under the sun's rays in the summer, but it's unclear whether or not this will be enough to counteract continued global warming. "In particular, methane emissions from permafrost regions remain a wild card in the global climate system," Christensen says. "We urgently need more studies to reduce the uncertainties."
A report published last September offers hope that the melt may not be as drastic as some suggest. While working in Canada's central Yukon Territory, Duane Froese, an earth- and atmospheric-sciences professor at the University of Alberta, found 740,000-year-old volcanic ash on top of a formation called an ice wedge in a layer of permafrost [see , next page"Underground Icicles,"]. The ice must be older than the ash above it, meaning it predates Earth's last major warming period—the interglacial era that occurred 120,000 years ago—by hundreds of thousands of years. The implication: Even severe global warming may not melt every frozen region on Earth.
With such preliminary and sometimes contradictory information, it's hard to predict the rate of permafrost thaw. "The challenge is to incorporate the key processes into our ecosystem and carbon-climate models," Lawrence says. Better modeling systems are in the works in several research centers around the world, and the results should appear in the next IPCC report in 2013 or 2014. In the meantime, residents of towns like Shishmaref will have to seek firmer ground.
In Canada, scientists recently found an ice wedge that survived Earth's last major warming cycle 120,000 years ago, suggesting that even extreme climate change may not wipe out all of the planet's frozen matter. But what exactly is an ice wedge?
During the long Arctic winter, frozen soil on the tundra can crack from the extreme cold. In the spring, water from melting snow fills the cracks and then freezes again because of the surrounding permafrost. The ice narrows and tapers to a point, forming the appearance of an underground icicle, or ice wedge.
Each year, this cycle repeats and the ice wedges get bigger. If one is exposed to the air in warm months, it can melt. The melting causes thaw lakes, which release methane into the atmosphere. As Arctic temperatures rise, thaw lakes get bigger and emit more methane.
If all of these "positive feedback loops" such as permafrost melting exist in our ecosystem, how has our planet continued to remain in equilibrium for such a long time. I can only conclude that their must be some sort of negative feedback that kicks in once climate reaches a drastic state. The only question is how severe is the negative feedback and what consequence will it have on humanity.
I've Been Told By My Daddy Since I Was A Kid That Weather Is A Random Natural Event.
Hopefully and with a little luck, these predictions will be underestimating the emmisions just like the last predictions were. This way by the time I retire I won't have to move to Florida to enjoy the beach.
Actually I'm pretty sure that 650 climatologists (many current and former UN IPCC scientists) recently called Global Warming(tm) bogus and that the earth is coming out of a long heating phase and is entering a 100,000 year ice age. The past ten years has seen temperatures decline to early 1980s levels. Maybe in 100 years the Appalachian Trail will be overtaken by the popular New York-London transatlantic trail. But that won't stop failed politicians (who are not real scientists, like Al Gore) from convincing many governments to waste many millions of dollars in attempting to prevent climate change.
Global warming or not, I think the only thing mankind should do is to ... pollute less! After all, we have only one planet.
I just hope that, if one day a bunch of scientists says that global warming is a completely natural phenomenon, we will feel free to pollute because "it's not our fault if the oceans are rising".
Also 31,000 scientist signed this against manmade global warming.
Less polution is a great thing, but calling CO2 a pollutant is incorrect. CO2 follows temperature rise. Humans only churn out about 5% of the CO2 that is out there. The rest is done naturally by the planet.
I think that global future humanity is in doubt, and that we need to make changes to preserve what we can in this changing world.
I'm not certain that we can prevent what's happening to climate, nor that, in the end, it'll be worthwhile to try. I only hope that my daughter has a chance to grow old, and see her grandchildren survive into a peaceful, global, life which is worth living.
These thoughts apply to my, and my offspring's future; but they should also apply to families currently living in sub-saharan Africa, the mid-East, and parts of Asia NOW....and they don't......so lets worry less about what you think may not happen, and try to deal with what IS HAPPENING !
By the time one finishes reading the article with all of its uncertainties the headline for this article should read: "The Big Thaw???".
A very interesting article. It brings up more questions/comments that are enjoyable to ponder:
- Of the carbon content in the perma frost, how much becomes carbon dioxide, how much becomes methane and how much stays as peat and eventually coal/oil/natural gas?
- This seems to be an explanation for why atmospheric CO2 content trails temperature change historically (pre industrial). What caused the trend to reverse in the past (more CO2 absorbed than exhausted)?
- As a structural engineer, I question the wisdom of placing a house so close to the shoreline knowing that beach erosion in the area has been severe for several hundred years and then claiming it is due to permafrost thawing (it is but it thawed because of beach erosion)
- What is the actual impact of doubling the CO2 content in the atmosphere? (how can estimates vary from 1 to 5 degrees celsius?)
stoatsngroats - What IS HAPPENING? Given the choice for your grandkids, would you focus on their economic opportunities or (mutually exclusive) potential environmental health? Given that the increase in fossil fuel use was drastically reduced during the Great Depression would that be a good solution?
The thawing of permafrost is actually a boon to much of life. Yes there are tree species that depend on it for support, but not many HAVE to have it. There are a few animals that need the snowpack permafrost allows, but there are not many that HAVE to have it. Even so, biodiversity decreases at the poles where climatic shift is most noticable.
Retreating permafrost, as seen in the speculatice picture, however, opens up a breadbasket of ariable land for both Asia and N America. So long as steps are taken to reduce desertification at the equator, this trend would be benifical to man. It seem ridiculous to worry about a few dozen species that global warming would destroy given the millions spared by moving more development away from the tropics.
My very limited understanding of what's happening, is drought, famine, starvation, war, and selfish gain to the detriment of others, assisted by political inaction at a global level.
In MOST industrialised nations there is, it seems, no 'pro bono' ethic towards our fellow man. I'm hijacking this comment thread, so I'll stop there, but thanks for the chance to comment!
All these "scientists" with their computer models, degrees and whatnot, can't seem to accuratly forcast tomorrow's weather. Now they expect us to take them seriously when they predict the weather a century from now.
I personally just find it ironic that the author in this article uses photos from 2006 and quotes the 2007 IPCC report, while on the day the article was published, the high temperature was -17F in Nome, AK...And, there was exactly TWO days during the whole month of January where the high temps went above freezing while at no time did the lows go above freezing.
Hey, but what can I say, I like to see the irony in things like this!
I still think that James Lovelock's GAIA HYPOTHESIS is on target: his and LynnMargulis' view of the Earth and its biosphere as a living organism capable of self-regulation.
The basics here: http://en.wikipedia.org/wiki/Gaia_hypothesis
Additional information on GOOGLE Search page: http://www.google.com/search?source=ig&hl=en&rlz=&q=James+Lovelock+the+Gaia+Hypothesis&btnG=Google+Search&aq=o
Don't close doors before opening them. Too much GROUP THINK within the scientific community has abandoned ideas like this for all the wrong reasons.
Heck, in today's morning newspaper there is an AP photo of ice divers in Maine, where the ice is 16 inches thick and the air temp is minus 20.
I once taught in a little village schools system (the Bering Strait School District.) I don't remember if I visited Shishmaref or not, but most villages right next to the ocean are built on sand dunes and gravel, not tundra proper. Eskimos always used to think convenience, not long-term, so it is not like these were planned to be permanent villages. The villages just grew up where it was convenient for fishing in the summer and the arrival of the supply barges. Barrels of fuel oil would be rolled off the barges and into the villages, and boxes of stuff unloaded on the beach where they would remain until needed.
idratherbegolfing_413 asked if the planet has a mechanism that kicks in once the planet reaches a drastic state. I believe the answer is yes, but it is possible we are destroying it.
The theory behind global warming is that increased CO2 emissions will increase temperature. An increase in temperature will change the plant life that can survive. We would likely move to more tropical plants, ferns etc. There would likely be an overall increase in plant life as the colder areas become more hospitable. The result would be that these plants would begin to extract CO2 at a higher rate. This would reduce CO2 and balance out the temperature.
Now assuming that any of this is true, deforestation will destroy the Earths ability to heal itself. So the problem for us may not be increased emissions but rather decreased plant life.
To Eggman002's point about the decreased plant life...
Did you know that the total biomass on Earth has increased by 16% for the last 20 years due to ... increased CO2 content. Here is the link to Nature's website (http://blogs.nature.com/news/thegreatbeyond/2008/06/biomass_boosting.html)
1) Biomass increase is not the same as increase in plant life. Certainly a portion of that biomass (probably a large portion) is plant life but it could also include animal life (or non-photosynthetic plant life). The type of biomass is as important (or more important) than the volume.
2) A 16% increase in biomass may not be enough to offset the increase in CO2. If it wasn't for deforestation, perhaps this increase would be 25%.
3) When I mentioned a decrease in plant life I was referring specifically to deforestation (which is a fact, not a theory). I was not referring to ocean algae or other types of plant life.
I am not an advocate of the idea of Global Warming. I think there is too much we don't understand to conclusively confirm or deny the idea. But deforestation is a fact. It is happening, it is a problem, and if Global Warming is in fact caused by CO2 in the atmosphere, deforestation is certainly a large contributor and will damage the Earth's natural defense against CO2.
From what I've seen this “global warming” threat is real, however its not caused by man. If one were to look at the history of the Earth one would see that there has been natural warming and cooling in global climate, sometimes it is more drastic but the point is that is is natural. Bud the Chud said that humanity is only responsible for about 5% of the Co2 in our atmosphere, the rest in natural. The answer to our problems is easy; nothing, that is nothing we can do to stop it however we can prepare. Humanity is very adept, we will have to make changes and thats what ever one is “afraid” of, change is hard but necessary. To quote stoatsngroats “drought, famine, starvation, war, and selfish gain to the detriment of others, assisted by political inaction at a global level” must be stopped for the greater good (how though is a different story) to survive.
After watch several The Learning Channel about the permafrost melting, how the Eskimo are not able to store food in the permafrost freezers, that have been used for generations, because ground has thawed. Walking upon the ground that used to be permafrost is dangerous, suddenly giving way. So if the Eskimo believe in Global Warming, so do I.