GEOGRAPHY STAGE 6
ECOSYSTEMS AT RISK
ANTARCTICA
TABLE OF CONTENTS
SPATIAL PATTERNS AND DIMENSIONS………………………………………………………..3
MAP………………………………………………………………………...... 4
BIOPHYSICAL INTERACTIONS…………………………………………………………………….5
Weather/Climate
Hydrologic Processes
Bioregional Processes ………………………………………………………………………...6
Adjustments in Response to Natural Stress
NATURE AND RATE OF CHANGE………………………………………………………………….7
HUMAN IMPACTS
Negative ………………………………………………………………………...... 8
Positive………………………………………………………………………...... 9
TRADITIONAL AND CONTEMPORARY MANAGEMENT STRATEGIES...... 10
BIBLIOGRAPHY…………………………………………………………………...... 13
SPATIAL PATTERNS AND DIMENSIONS
Antarctica, the world’s second largest continent, was only categorized as such in 1840, replacing the prior title of a group of isolated islands. Active territorial claims exist upon Antarctica, as stated by twenty-eight countries including Argentina, Australia, Chile, France, New Zealand, Norway and the United Kingdom(See Figure 1.1).However, disputes have arisen between nations regarding mutual recognition and agreement of claims and are as such in dispute status.
Thus Antarctica has no official language, currency or capital city. The population of Antarctica is also recorded as officially none, however governmental research stations and tourist populations occupy the continent year round. This will be discussed in detail in Human Impacts.
Glaciers, barren expanses of rock and exposed soils, ice-covered basin lakes, and glacial melt water streams, dominate the Antarctic landscape. The composition of Antarctica is approximately 90% solid ice, with only 0.01% exposed rock. Geologically, Antarctica is divided into two major ice sheets: East Antarctica (south of Australia) and West Antarctica (south of South America)by the Transantarctic Mountains (TAM). This mountain range extends 3,500km and runs approximately along the 0-180 degree meridian.
Topographically, the highest summits reachmore than 4,500 metres above sea level. The summits and dry valleys of the TAM include Antarctica’s exclusive areas not engulfed in ice.
Antarctica is located within the Southern Ocean, at latitude of 90* South and longitude of 0* East. The continent currently covers an area of approximately 13, 200, 000 km2, and accounts for 8.9% of Earths landmass. The nature of Antarctica’s landmass (ice) is subject to variation via ice-shelf movement and melting. If the entirety of Antarctica’s ice were to melt, the world’s sea level would rise by an estimated 65-70m. Antarctica’s coastline extends approximately 17,970km. Antarctica’s average altitude of 2500m qualifies it as the earth’s highest continent. Vinson Massif is the continents highest point at a recorded 4897m, and Bentley Subglacial Trench is the lowest point at -2555m.
Following, figure 1.1 demonstrates the shape and context of Antarctica’s position, as well as nation-specific land claims.
MAP
BIOPHYSICAL INTERACTIONS
WEATHER/CLIMATE
Antarctica is classified as a polar region. The definition of a polar region is given as the part of the earth's surface forming a cap over a pole; characterized by frigid climate.
Antarctica holds the lowest recorded temperatures on earth. The lowest record-holding temperature is -89*C at the Russian Station Vostok in 1863. Antarctica’s severe low temperatures vary with latitude, elevation and distance from the ocean. The average annual temperatures at American McMurdo, Amundsen-Scottand Russian Vostok Stations respectively are -16.9*C, -49.4*C and -55.1*C. The distribution of these stations is in order of coastal location to inland location (Vostok is located inland on the highest Antarctic plateau), therefore evidencing that average temperature increases with proximity to the sea, subsequent increase in latitude and decrease in elevation. Higher temperatures occur along the coast in the month of January, only averaging minimal below freezing.
Wind is a dominant climatic feature of the Antarctic landscape, with common wind speeds of 60km per hour. The highest wind speed of 327km per hour was recorded at Dumont d’Urville, of French Antarctica along the southeastcoast (See Figure 1.1).
The polar nature of the continent inhibits evaporation, therefore stabilising precipitation cycles. As a result,
Antarctica has a very low average annual precipitation, just over 50mm precipitation as snow per year. Liquid precipitation (rain) is very rare in the Antarctic climate. This contributes to Antarctica’s status as one of the driest continent on earth.Antarctica is in fact classed as a desert on the basis of its mean annual precipitation.Comparatively, along the coast, precipitation as snow is higher annually. This is a result of the slightly higher average temperature, particularly in January.
Climatic natural hazards include ocean-formed cyclonic storms with trajectories clockwise along the coast, coastward gravity-driven winds from the elevated interior topography and frequent formation of blizzards near plateau bases.
HYDROLOGICAL PROCESSES
Antarctica’s hydrologic processes proceed at a slow rate. As stated above in Weather/Climate, Antarctica’s precipitation cycle is very stable, a result of the continents very low evaporation rate. The stability of the cycle contributes to its massive water storage capacity.
Weathering and erosion is limited; transport of materials (predominantly ice particles) is by wind. Regardless of the high wind speeds, minimal to no weathering of rock occurs due to the lack of exposed rock surface.
Antarctica’s ice deposition fluctuates with the factors of sea ice, fast ice and pack ice. Sea ice is formed from seawater in proximity to major landmasses. Fast ice is ice mass that has formed and fastened to the land. When sea ice breaks up and away from the major landmass, it is called pack ice.
Antarctica’s circumscription by the Southern Ocean influences the shape of its coast. Wave action, especially in storms, has an erosive effect on the coastal physicality. Additionally, the action of the waves contributes to the exchange of gases and rise in oxygen within the marine environment, leading to a marine life increase. The decomposition of marine life also contributes to nutrient-rich debris, which accumulates in convergence zones along the coast.
BIOREGIONAL PROCESSES
Due to the features of the Antarctic ecosystem discussed thus far in the report (including Weather/Climate, Spatial Patterns and Distribution and Hydrological Processes), the continent has limited animal and plant life. The few successful organisms that inhabit the continent have undergone significant evolutionary processes and possess singular biological attributes.
The Antarctic soil is inhabited by microscopic nematodes, rotifers and tardigrades and extensive bacteria colonies of algae exist in some streams and lakes. The resilience of these organisms is high, as they require very nominal nutrients for survival.
The most successful plant organisms of the region are algae, lichen and mosses. Plants rely on reproduction via spores, transported by the wind, rather than seeds, which rely in part on digestion and deposition by animals. Due to their isolation, uniquely adapted vegetation exists on Antarctica’s islands.
Mainland Antarctica is inhospitable to mammals, and consequently all fauna are invertebrates. The largest known terrestrial animal is the wingless midge, measuring approximately 5mm long. Along the coastal rim of the continent, however, is a significant increase in marine and bird life. The marine ecosystem is supported by keystone species of phytoplankton and krill, and fluctuates dramatically in summer. Upwards of 12 million birds are attracted to the rich natural source of protein present in the Southern Ocean around Antarctica.
ADJUSTMENTS IN RESPONSE TO NATURAL STRESS
Antarctica’s adjustments in response to natural stress are gradual: Antarctica’s environment is not dynamic, and therefore allows the processes of adaptation in specific species to occur.
For example: The Antarctic species, Emperor penguin has a layer of sub-dermal fat up to 3cm thickand the highest feather density of any bird species. An extra layer of insulation is formed by separate shafts of downy filaments between feathers and skin. Feathers provide 80 – 90% of the Emperor penguins insulation. The species will produce fewer but larger eggs and huddle to keep warm. When temperatures rise in summer, the penguins malt to maintain an ideal body temperature.
An established behavioral response to resource stress is migration, a method of birds, whales and seals.
Plant species, such as lichens and mosses, have a low resilience and benefit from the lack of interference and species interactionin Antarctica.
NATURE AND RATE OF CHANGE
Annual rates of change are evident through the abundance of vegetation on the Antarctic Peninsula. An increase in distribution and abundance of species vegetation is the result of a 2.5*C rise in temperature on the Peninsula in the last forty years. Consequently summer has been extended from 60 days to 90 days, benefitting short summer incubation plants and the 12 million birds attracted to the ecosystem annually. Penguin populations are an effective indictor of the krill population, and usually, the phytoplankton and krill populations increase dynamically in spring and summer. If this occurs, penguin populations flourish. Interruptions in krill populations from harvesting for global commercial industry can affect the marine ecosystem dramatically by competing with native wildlife (penguins) for resources. The impacts and extent of Antarctic fishing are regulated under a series of laws and international agreements however, intended to promote the sustainable use of resources (See Contemporary Management Strategies).
Annual snow deposition archives the atmospheric conditions of consecutive periods of time. Using modern scientific technology, it is possible to identify temperature, precipitation, wind erosion, incidences of volcanic eruption and atmospheric levels of carbon dioxide and methane gas of a specific year. To access this preserved information, scientists use drill sampling equipment to remove large cylindrical sections of ice. These ice cores represent many thousands of years of snow accumulation, which over time and under compression have become glacier ice.
Ice cores drilled from Law Dome in Antarctica have been used to produce a record of lead concentrations and isotope compositions for the last 2000 years. Such a record demonstrates the level of pollution in the Southern Hemisphere by modern industrial activities (such as petrol emissions, mining and smelting) and assists our understanding of natural climate conditions and the intercontinental transport of aerosols.
The pollution of the atmosphere and its eventual deposition can lead to bioaccumulation in marine organisms. Bioaccumulation is the successive increasing accumulation of heavy metals (lead) upwards through the food chain. In the 20th century, levels of lead production are reflected in ice sample atmospheric conditions data, and the influence of lead derived from leaded petrol is observed from 1960 to the present. These variations in the concentration and origin of lead pollution in Antarctica are significant in that they provide information on the historical development and level of influence of pollution on the environment, confirm historical records and further our understanding of natural fluxes of lead in the atmosphere.
Stable isotoperatios of the oxygen and hydrogen making up layers of ice are used to reconstruct the air temperature at the time that the snow fell. Discovered from cylindrical ice samples, collected data indicates Antarctica’s annual temperature has increased 3°C over the past 50 years. Data used to calculate this figure extends back to 1945 at the Russian Vernadsky station.
This recorded increase in temperature is causing the disintegration of Peninsula ice shelves. In 2007 the Intergovernmental Panel on Climate Change concluded that over the period from 1993-2003 melt from Antarctica contributed about 0.2mm per year to sea-level rise.
Antarctica undergoes a large adjustment climatically and bioregionally from winter to summer, and accordingly, there is slowness in the continents rate of change.
HUMAN IMPACTS
NEGATIVE
Globally, Antarctica is appreciated for its heritage and intrinsic value; as a rare expanse of beautiful land relatively untouched by human interaction. Ironically, this stimulates a high tourist trade (utility value). Because of the pristine nature of Antarctica, noted human impacts are generally regarded as negative, and currently outweigh the positive impacts of human activity on the continent.
The development of research facilities and human structures creates competition for exclusive rock landforms of Antarctica with native wildlife. Development can also directly harm native populations and destroy established habitats. For example: in 1983, France built an airstrip on Antarctica, during the construction of which it dynamited Emperor Penguin colonies and destroyed a group of small islands. France admitted that it violated the Antarctic Treaty System's environmental protection mandate, but no other nation ever made a formal complaint for fear of antagonizing the French. The irresponsibility of human development significantly impacted local geography and penguin populations in this scenario and is still at risk.
The environmental implications of tourism on as fragile ecosystems as Antarctica are great. As tourism population increases, so too does the potential for environmental damage and accidents. Since 1985, the number of tourists doubled and currently reaches upwards of 10,000 a year. The Greenpeace association claim that tourists litter beaches, stress animals and destroy delicate mosses and lichens that will take centuries to re-establish. Antarctica’s flora and fauna are highly susceptible to mild disruptions that potentially inhibit an organisms slim opportunities to feed grow and reproduce. An example that demonstrates this is of a photographer approaching a sea birds nest. The bird, frightened, alights from the nest leaving it’s chicks exposed to the elements and predators. This direct interference decreases the chances of survival for that species population. Additionally, the presence of humans may bring in contagion.
In 1989, a devastating accident did occur that had long-term negative impacts on the Antarctic ecosystem. The Bahia Paraiso, an Argentinian ship with supply cargo and tourists, leaked several thousand gallons of fuel into the Southern Ocean and capsized when it ran aground on off Anvers Island. The oil had decimated penguin and seabird populations within weeks and continued to do so for months afterwards. Rehabilitation and containment programs were limited due to lack of facilities; the January oil spill was Antarctica’s first. Chemically, oil spills deteriorate into their harmless components at a slower rate in cold climates. The human impact of spilling oil or chemicals, burning rubbish and/or noise disturbance has disastrous impacts on local ecosystems.
Resource exploitation is a result of the global fishing industry and a pre-existing concern for Antarctica’s future. Potentially, the intricate food webs of the Southern Ocean could be disrupted, traumatising Japan, Poland, South Korea and the Soviet unions major industry. These nations utilise deep-sea vessels to harvest krill off the northern Antarctic Peninsula. Fishing can adversely affect unconnected organisms such as albatross and petrels, which are often snared by long line hooks. Fishing is governed by numerous sets of regulations, which establish limits on the amount of fish that can be harvested. This is explored further in Contemporary Management Strategies.
Early explorers and pioneers of Antarctic discovery exploited native wildlife (whales, seals, penguins) due to abundance and a lack of knowledge in sustainable practices. Today, Antarctica is still under risk of resourceexploitation, however the focus has shifted to minerals. International demand for rapidly depleting fossil fuels has spurred intense interest in mining expansion. Antarctica is viewed as a potentially fuel-rich site. Regulations and law currently stands to prohibit such land-use. This is explored later in the report, under Contemporary Management Strategies.
The largest human settlement in Antarctica exists at McMurdo Station, with a summer population of approximately 1000 people. Regulation and removal of waste is crucial to limiting human impact, however, efficient and environmentally responsible waste discharge has not been practiced since site construction four decades ago. The ramifications are an intense contamination concentration of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in Winter Quarters Bay, adjacent to the station. These toxic chemicals combine with sediments and enter the digestion of marine life, leading to bioaccumulation. Other research stations dispose of raw seweragein vast garbage dumps, pumps and dumping ofurine-filled gallon drums into the ocean.
Over the last century, earth’s dependence on fossil fuels (oil, coal and gas) has lead to unprecedented amounts of harmful emissions that result from fuel burning. Major emission contributors are electricity, industrial manufacture and vehicles. The toxic emissions are released and trapped within the earth’s atmosphere, promoting what is known as the greenhouse gas effect. This process is responsible a steady increase in global temperatures. Solar radiation penetrates earth’s ozone layer, is partly absorbed and reflected off the worlds water bodies to be trapped under the thickened atmospheric layer. Increase in temperatures at Antarctica could potentially melt a portion of the continents ice-mass, causing a rise in sea level, and the inundation of coastal communities.
POSITIVE
The positive impacts of human activity on continental Antarctica are predominantly academic. The research volume conducted on site rivals any other natural scientific enquiry on earth. Projects carried out in Antarctica have provided models for ecosystem research in all parts of the world. Successful research projects of Antarctica include: the discovery of fossils and thus clues on evolution and its process. The discovery of intact meteorites, contributing to our knowledge of the solar system.Investigation into the interaction between Earth’s magnetic field and the magnetic field of interplanetary space. The study of physiology and psychology; human behavior in an isolated environment. All contribute to humankind’s understanding of our environment, origins and ourselves.
Antarctica is a sensitive indicator of global change. This is evidenced through glaciology, the study of ice core samples and the information they contain of past atmospheric conditions. The continued monitoring of climate change is paramount, with calculations onthe stability of the ice sheet being especially important, considering sea level rise, and its implications on global population. Antarctica provides nations of the world with an unprecedented opportunity for liaison in the peaceful pursuit of knowledge.