Permafrost _ Weather Underground

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Permafrost

Figure 1.Idealized permafrost cross section.

Permafrost is permanently frozen soil, and occurs mostly in high latitudes. Permafrost comprises 24% of the land

in the Northern Hemisphere, and stores massive amounts of carbon. As a result of climate change, permafrost is

at risk of melting, releasing the stored carbon in the form of carbon dioxide and methane, which are powerful heat-

trapping gases. In addition, permafrost is structurally important, and its melting has been known to cause erosion,

disappearance of lakes, landslides, and ground subsidence. It will also cause changes in plant species

composition at high latitudes.

What is permafrost?

The Effect of Climate Change on Permafrost

Melting Permafrost Causes Greenhouse Gas Emissions

Carbon Exchange

Methane

Other Impacts of Melting Permafrost

Conclusion

Related Blogs

References

Further Information

What is permafrost?

ermafrost is permanently frozen soil, sediment, or rock. Its

assification is solely based on temperature, not moisture or groundover. The ground must remain at or below 0C for at least two

ears in order to be considered permafrost. Although new

ermafrost is forming, it can be over thousands of years old. For

xample, some of the permafrost in western Canada's boreal

eatlands has been there since the Little Ice Age of the 1600's

Turetsky et al., 2007).

ermafrosthas layers, of which frozen ground is just one portion

Figure 1). The active layeris ground that is seasonally frozen,

pically lying above the perennially frozen permafrost layer. Talikis

nfrozen ground that lies below the permafrost and between the

ctive layer and permafrost.

Where is permafrost found?

ost frequently, permafrost is found in high latitudes near the north

nd south poles. However, it can also be found at high altitudes inher locations around the world. Roughly 37% of the Northern

emispherepermafrost occurs in western North America, mainly in

aska and northern Canada, but also further south in the Rocky

ountains. The majority of permafrost in the Northern Hemisphere

ccurs in the Eastern Hemisphere, in Siberia and the Far East of

ussia, as well as northern Mongolia, northeastern China and the

betan Qinghai-Xizang Plateau (Zhang et al., 1999).

the Southern Hemisphere, permafrost is found in Antarctica, the Antarctic islands, and the Andes Mountains. In

reas where the conditions are such that the ground is cold enough year-round, continuous permafrost forms.

scontinuous and sporadic permafrost occurs in locations where temperatures only get cold enough in certain areas,

uch as in the shade, or on the northern side of a hill or mountain. Seasonal permafrost occurs during colder seasons

nd thaws or disappears during warmer times of the year.

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Global (ocean,

atmosphere, ice) heat

accumulation data from

Nuccitelli et al (2012).

Skeptical Science is aweb site devoted tocommunicating the

science behind climate

change, while debunkingthe pervasive myths that

confuse the issue.

Want a SkepticalScience widget on

Our climate has accumulated

Hiroshima nuclear bombsof energy since 2005

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Figure 2. Permafrost distribution in the Arctic. Image

credit: Philippe Rekacewicz, 2005, UNEP/GRID-Arendal

Maps and Graphics Librarybased on International

Permafrost Association (1998) Circumpolar Active-

Layer Permafrost System (CAPS), version 1.0.

he Effect of Climate Change on Permafrost

imate change will significantly affect the complex interactions between above- and below-ground climate regimes.

owever, even changes in temperature at the surface take time to impact permafrost at depth; According to the

eological Survey of Canada (GSC), "for thick permafrost this lag may be on the order of hundreds to thousands of

ears, for thin permafrost, years to decades" (GSC, 2007).

a recent study using freezing/thawing index, trend analysis of spatial data since 1970 indicates that in recent

ecades, there has been a decrease in freezing during the cold season throughout North America's permafrost

gions. Additionally, coastal areas and eastern Canada have started to see "significant" increases in warm season

awing of permafrost (Frauenfeld et al., 2007). Overall, this means there has been a decrease in freeze depths and in

e amount of permanent permafrost. Conversely, there has been an increase in seasonal permafrost. This increase in

easonal permafrost is not due to increases in acres frozen, but to the decrease in permanent permafrost which is not

maining frozen all year anymore. Since it is no longer perennially frozen, it loses its distinction as 'permanent' andecomes 'seasonal'.

Decreasing freeze depths have also been recorded in a

separate study of deep boreholes in mountain permafrost

in Svalbard and Scandinavia. Results from the study show

that the permafrost has "warmed considerably" at the study

sites and that "significant warming is detectable down to at

least 60m depth, and present decadal warming rates at

the permafrost surface are on the order of 0.04.0.07C

[per year], with greatest warming in Svalbard and in

northern Scandinavia. The present regional trend shows

accelerated warming during the last decade" (Isaksen et

al., 2007).

Although many studies, programs, and research, including

the Global Terrestrial Network for Permafrost (GTNP),

indicate a warming trend throughout the permafrost zone,

some have found no significant changes have occurred in

permanent Russian permafrost regions. According to the

authors of the study mentioned earlier, spatial trend

analysis shows that while permanent permafrost areas in

Russia have remained largely within the same freezing

regime, seasonally frozen ground areas are experiencing

"significant warming trends" (Frauenfeld et al., 2007).

All of these changes in permafrost areas are attributed to

increases in air temperature and changes in snow cover,

specifically in Canada and Alaska. This echoes the

conclusions of numerous other reports, such as those from

e Geological Survey of Canada and the Arctic Climate Impact Assessment, which attribute the northern polar region's

ermafrost thaw to dramatic warming over the past half-century. In regions of discontinuous and seasonal permafrost,

round temperatures are generally right around freezing. With even 1-2 degrees increase in temperature, these areas

permafrost will "likely ultimately disappear as a result of ground thermal changes associated with global climatearming" (GSC, 2007). Based on trends and forecasts predicted by climate models, however, we could be facing a

uch steeper increase in air temperature, leading to more significant effects on permafrost regions across the globe.

s Charles Harris, one of the authors of the Svalbard study, a geologist at the University of Cardiff, UK, and a

oordinator of Permafrost and Climate in Europe (PACE), said in a 2004 interview, "Boreholes in Svalbard, Norway, for

xample, indicate that ground temperatures rose 0.4C over the past decade, four times faster than they did in the

revious century. What took a century to be achieved in the 20th Century will be achieved in 25 years in the 21st

entury, if this trend continues" (Bently, 2004).

dditionally, thawing and warming permafrost areas do not seem to be reversing the trend from year to year. Instead,

ey keep warming. Researchers of Canada's peatland permafrost regions mentioned "The permafrost underlying

anada's peatlands show no sign of regeneration" (Turetsky et al., 2007). According to the IPCC, by the mid-21st

entury, the area of permafrost in the northern hemisphere is expected to decline by around 20 per cent to 35 per cent.

he depth of thawing is likely to increase by 30 percent to half its current depth by 2080 (UNEP, 2007). The end result

ould look something like the scenario depicted in the figure "Map of Permafrost in the Future".

mpacts of Melting Permafrost: Physical and Ecologic al

hawing permafrost has significant effects on surface and subsurface regimes, including those governing hydrology

nd energy and moisture balance. Ecosystem diversity, composition, and productivity are not only impacted by

creasing air temperatures, but by the associated effects of increasing ground temperatures as well. Because of this,

awing permafrost has significant impacts on infrastructure and ecosystems. Where ground ice contents are

omparatively high, permafrost degradation can have significant impacts, some of which may take not be as readily

pparent as others.

tructural Importance

he Geological Survey of Canada states "Of greatest concern are soils with the potential for instability upon thaw

haw settlement, creep or slope failure). Such instabilities may have implications for the landscape, ecosystems, and

frastructure" (GSC, 2007). Erosion, landslides, and subsidence can all result from permafrost degradation.
http://www.sciencedirect.com/science/article/pii/S0375960112010389http://www.skepticalscience.com/http://sks.to/heathttp://sks.to/heathttp://sks.to/heathttp://maps.grida.no/go/graphic/permafrost-distribution-in-the-arctichttp://maps.grida.no/go/graphic/permafrost-distribution-in-the-arctichttp://maps.grida.no/go/graphic/permafrost-distribution-in-the-arctichttp://maps.grida.no/go/graphic/permafrost-distribution-in-the-arctichttp://maps.grida.no/go/graphic/permafrost-distribution-in-the-arctichttp://icons.wxug.com/metgraphics/climate/permafrost_distribution_in_the_arctic_large.pnghttp://sks.to/heathttp://www.skepticalscience.com/http://www.sciencedirect.com/science/article/pii/S0375960112010389


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Figure 7. Permafrost distribution in the Arctic. Image credit: Philippe

Rekacewicz, 2005, UNEP/GRID-Arendal Maps and Graphics Library

based on International Permafrost Association (1998) Circumpolar Active-

Layer Permafrost System (CAPS), version 1.0.

gure 6. Sishmaref photo series: Only two hours separate the first photo from the second. For reference, red arrows

ark the barrel. By the time the second photograph was taken, the coastline in the foreground had retreated past the

arrel. Although coastal erosion was significant, this was not a particularly strong storm. Image courtesy of Tony

Weyiouanna Sr. Image credit: NSIDC.

Erosion

rosion is especially evident and worrisome in coastal areas, may of which are also being ravaged by winter storm

urge as the protective barrier of sea ice appears later and later (if at all) during the year. Intact permafrost is

xtremely resilient. However, when it becomes compromised, it and the ground above and below it become much more

ulnerable to the erosive forces of wind and water. On our Sea Icepage, you can see a picture of a house in

hismaref, Alaska that has had its foundation washed away by storm surge. These pictures to the right in Figure 4

ere also taken in Shishmaref, Alaska, during a storm in 2003.

some areas, erosion has been so much enhanced by exposed and degraded permafrost, the inhabitants might havebe evacuated. Costs to relocate are hefty . for towns such as Kivalina, Alaska, they have been estimated at

pwards of $400 million. Due to the heavy toll climate change is taking on Kivalina, the town recently sued two dozen

l, power, and coal companies for their contributions to global warming (CNN, 2008).

Landslides

s permafrost thaws, the friction needed between the frozen and thawing permafrost regions to maintain stability

sappears. On ice, you don't need a very sloped surface before you start to slip and slide . and that's exactly what

appens with the permafrost and overlying land, resulting in landslides. This happened in July of 1988 on the Fosheim

eninsula of Canada's Ellesmere Island after a few years of increasingly warmer temperatures during the summers.

undreds of landslides, some of which were the size of over three football fields, carried tons of soil into a number of

eek valleys.

ccording to the Permafrost and Climate in Europe (PACE) project, thawing permafrost is likely to have similar effects

n the slopes of Europe's Alps and Pyrenees as global temperatures continue to rise. Landslides, such as the Val Pola

ndslide of July 1987 in the Italian Alps are predicted to become more common as the permafrost underlying theopes of Europe's mountains degrades due to rising ground temperatures.

Subsidence

Ground subsidence can occur when

permafrost thaws and the soil

previously held up by the ice collapses.

The resulting landscape is characterized

by irregular surfaces of marshy hollows

and small hummocks called

thermokarst. Visitors and residents all

over permafrost regions have been

struck by the effects of this

phenomenon when they see a wooded

landscape affected by subsidence from

permafrost thaw. They call these areas"drunken forests" because of the way

that the trees lean, as shown in Figure

5.

However, subsidence can have other

effects on vegetation. A group of

scientists studying the effect of

permafrost thawing on vegetation in

Alaska noted, "This effect of warming

acts on vegetation indirectly by creating

localized variability in moisture

conditions as lower karst areas

ccumulate moisture and may have the water table near the soil surface, while nearby higher areas become drier"

Schuur et al., 2007). In some of these areas, these changing conditions allow new plant species to grow. In other

ockets, water collects and they become thermokarst lakes or ponds. Once the underlying permafrost has thawed
http://maps.grida.no/go/graphic/permafrost-distribution-in-the-arctichttp://www.nsidc.org/http://www.wunderground.com/climate/SeaIce.asphttp://www.wunderground.com/climate/SeaIce.asphttp://www.wunderground.com/climate/SeaIce.asphttp://www.nsidc.org/http://maps.grida.no/go/graphic/permafrost-distribution-in-the-arctic


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Changes in plant species composition

Figure 9. Disappearing arctic lakes in Siberia. Image

credit: Smith, 2005, NASA Earth Observatory.

ompletely away, however, this water sinks back in to the empty space and disappears. According to a 2005 article in

cience, this is what has been happening in Western Siberia, where thawing permafrost is the likely cause behind of

e disappearance of Siberian Arctic lakes during the past three decades over an area of 500,000 square km (see

gure 6).

addition to its ecological effects, subsidence caused by thawing can significantly compromise infrastructure built on

p of permafrost. Many permafrost areas are permanently inhabited by humans, and as such have roads, buildings,

nd other structures built on it. In places where these structures were not designed to withstand changes in

ermafrost, subsidence has created sinkholes that swallow up houses and small buildings, and has also caused

undations to shift and drop and roads and railroads to crack and heave (such as the building and railroad in Figure 7

right). In some permafrost areas, engineers are coming up with new ways to build on permafrost such that the

round is insulated from the heat created by whatever is on the ground above it. Additionally, these new engineering

chniques are making it possible for the infrastructure built upon it to weather changes in permafrost a little bit better.

he world's longest high-elevation railroad, the Qinghai-Tibet Railway or "Permafrost Express", in China and the 800-ile long Trans Alaska Pipeline in Alaska both involved engineering and design techniques sensitive to the permafrost

nvironment in which they were constructed.

gure 8. A railroad in Alaska (left) and building (right), both buckled due to thawing permafrost. Image credit: (left)

ASA and U.S. Geological Survey, (right) Vladimir Romanovsky, Geophysical Institute, University of Alaska Fairbanks.

cology

he changes brought about by thawing permafrost will also have significant impacts on the ecosystems of the Arctic.

addition to impacting migration routes and patterns in birds, reindeer, and caribou, it is expected that the effects of

awing permafrost will change the plant species composition of the area, as well as its productivity.

creasing temperatures are expected to have significant

mpacts on the species composition world wide. This is

so true of permafrost areas in northern latitude

cosystems, where plant species composition and

roductivity will change as increasing temperatures willlow new, warmer-climate species to grow. Tundra is

sually characterized by sedges and grasses. However,

th warming temperatures, these typical tundra species

re being overtaken by evergreen shrubs and trees. The

PCC projects that by 2100, between 10 and 50% of the

rctic tundra could be replaced by forests (UNEP, 2007).

Warming can affect plants directly, through its influences

ver plant growth, and indirectly, through changes in

utrient availability. In permafrost areas, where increasing

mperatures and subsequent thawing causes the

evelopment of thermokarst, warming can drastically

hange the hydrologic profile of an ecosystem.

esearchers working at permafrost sites across Alaska

nd at peatland sites overlaying permafrost across boreal

gions in Canada found changes in community

omposition, biomass, and productivity as a result of

armer air and soil temperatures as well as associated

hanges in the hydrologic structure of the soil (Schuur et

., 2007; Turetsky et al., 2007). Plant biomass shifted

way from traditional species to plants associated with

armer, wetter biotypes. Additionally, plant productivity increased due to improved availability of nitrogen and other

utrients from altered hydrological patterns caused by thawing permafrost.

s a warming climate allows snow and ice to thaw, and tundra species are replaced with evergreens, albedo changes.

stead of reflecting sunlight, the landscape begins to absorb more heat than it did previously, further increasing the

arming and thawing trends in the area.

onclusion
http://earthobservatory.nasa.gov/IOTD/view.php?id=5713http://earthobservatory.nasa.gov/IOTD/view.php?id=5713http://earthobservatory.nasa.gov/IOTD/view.php?id=5713


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ot all ecosystems in permafrost regions will respond the same way. Turetsky herself cautioned in an interview earlier

is year, "It will depend on the history of the permafrost and the nature of both vegetation and soils" (Physorg.com,

007). The quantity, distribution, and composition of the organic matter in permafrost areas are important in

etermining their effect on emissions. Some permafrost, such as yedoma permafrost found mostly in northern and

astern Siberia as well as in smaller amounts in Canada and Alaska, have more concentrated carbon and methane

ores than others.

dditionally, records and data for many regions are incomplete or of short-term duration, with the exception of Russia's

ng-term permafrost monitoring. There has been a push to extend current monitoring programs and enlarge their

cope. Programs such as the Global Terrestrial Network for Permafrost (GTNP) are working to organize data

ollection so that there is a global network for detecting and monitoring changes in permafrost regions, and predicting

mate change's impact on these affected areas. Advances in spatial analysis have contributed greatly, as evidenced

y the research conducted for the 2005 article on Siberian lake methane emissions. You can even monitor permafrost

aw with Google Earth!

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Adaptation to Climate Change Key Challenge for Arctic Peoples and Arctic Economy: Thawing Permafrost, Melting

ea Ice and Significant Changes in Natural Resources Demands Comprehensive Sustainable Development Plan."

nited Nations Environment Programme, April 10, 2007.

Climate change and permafrost thaw alter greenhouse gas emissions in northern wetlands."Physorg.com, August 9,

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Climate change threatens existence, Eskimo lawsuit says." CNN, February 27, 2008.

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Warm Arctic may enhance global warming."Environmental News Network, March 1, 1999.

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. J. Sutton, A. Bazzaz, and J. W. Munger. "Sensitivity of boreal forest carbon balance to soil thaw."Science279

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candinavia."Journal of Geophysical Research112 (2007): F02S04.

ohansson, Torbjoern, Nils Malmer, Patrick M Crill, Thomas Friborg, Jonas H Aakerman, Mikhail Mastepanov, and

orben R. Christensen. "Decadal vegetation changes in a northern peatland, greenhouse gas fluxes and net radiative

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chuur, Edward A. G., Kathryn G. Crummer, Jason G. Vogel and Michelle C. Mack. "Plant Species Composition and

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