The Geography of Antarctica
The continent of Antarctica makes up most of the Antarctic region. The Antarctic is a cold, remote area in the Southern Hemisphere encompassed by the Antarctic Convergence, an uneven line of latitude where cold, northward-flowing Antarctic waters meet the warmer waters of the world’s oceans. The whole Antarctic region covers approximately 20 percent of the Southern Hemisphere. Antarctica is the fifth-largest continent in terms of total area, larger than both Oceania and Europe. It is unique in that it does not have a native population. There are no countries in Antarctica, although seven nations claim different parts of it: New Zealand, Australia, France, Norway, the United Kingdom, Chile, and Argentina.
The Antarctic Ice Sheet dominates the region. It is the single piece of ice on Earth covering the greatest area. This ice sheet even extends beyond the continent when snow and ice are at their most extreme. The ice surface dramatically expands from about 3 million square kilometers (1.2 million square miles) at the end of summer to about 19 million square kilometers (7.3 million square miles) by winter. Ice sheet growth mainly occurs at the coastal ice shelves, primarily the Ross Ice Shelf and the Ronne Ice Shelf. Ice shelves are floating sheets of ice that are connected to the continent. Glacial ice moves from the continent’s interior to these lower-elevation ice shelves at rates of 10 to 1,000 meters (33-32,808 feet) per year.
Antarctica has numerous mountain summits, including the Transantarctic Mountains, which divide the continent into eastern and western regions. A few of these summits reach altitudes of more than 4,500 meters (14,764 feet). The elevation of the Antarctic Ice Sheet itself is about 2,000 meters (6,562 feet) and reaches 4,000 meters (13,123 feet) above sea level near the center of the continent.
Without any ice, the continent would emerge as two distinct areas: a giant peninsula and archipelago of mountainous islands, known as Lesser Antarctica, and a single large landmass about the size of Australia, known as Greater Antarctica. These regions have different geologies; Greater Antarctica, or East Antarctica, is composed of older, igneous rocks whereas Lesser Antarctica, or West Antarctica, is made up of younger, volcanic rock. Lesser Antarctica, in fact, is part of the “Ring of Fire,” a tectonically active area around the Pacific Ocean. Tectonic activity is the interaction of plates on Earth’s crust, often resulting in earthquakes and volcanoes. Mount Erebus, located on Antarctica’s Ross Island, is the southernmost active volcano on Earth.
Antarctica has an extremely cold, dry climate. Winter temperatures along Antarctica’s coast generally range from -10° Celsius to -30° Celsius (14° Fahrenheit to -22° Fahrenheit). During the summer, coastal areas hover around 0°C (32°F) but can reach temperatures as high as 9°C (48°F). In the mountainous, interior regions, temperatures are much colder, dropping below -60°C (-76°F) in winter and -20°C (-4°F) in summer. In 1983, Russia’s Vostok Research Station measured the coldest temperature ever recorded on Earth: -89.2°C (- 128.6°F). An even lower temperature was measured using satellite data taken in 2010: – 93.2°C (-135.8°F)
Precipitation in the Antarctic is hard to measure. It always falls as snow. Antarctica’s interior is believed to receive only 50 to 100 millimeters (2-4 inches) of water (in the form of snow) every year. The Antarctic desert is one of the driest deserts in the world. The oceans surrounding Antarctica provide an important physical component of the Antarctic region. The waters surrounding Antarctica are relatively deep, reaching 4,000 to 5,000 meters (13,123 to 16,404 feet) in depth.
The Antarctic region has an important role in global climate processes. It is an integral part of the Earth’s heat balance. This balance, also called the energy balance, is the relationship between the amount of solar heat absorbed by Earth’s atmosphere and the amount deflected back into space. Antarctica has a larger role than most continents in maintaining Earth’s heat balance and ice is more reflective than land or water surfaces. As a result, the massive Antarctic Ice Sheet reflects a large amount of solar radiation away from Earth’s surface. As global ice cover (ice sheets and glaciers) decreases, the reflectivity of Earth’s surface also diminishes. This allows more incoming solar radiation to be absorbed by the Earth’s surface, causing an unequal heat balance linked to global warming, the current period of climate change.
Interestingly, NASA scientists have found that climate change has caused more ice to form in some parts of Antarctica. They say this is happening because of new climate patterns caused by this change, which in turn create a strong wind pattern called the ‘polar vortex.’ These kinds of polar winds lower temperatures in the Antarctic and have been building in strength in recent decades—as much as 15 percent since 1980. This effect is not seen throughout the Antarctic, however, and some parts are experiencing ice melt.
Answer the questions below. Choose NO MORE THAN TWO WORDS from the passage for each answer.
Write your answers in boxes 14-17 on your answer sheet.
- Antarctica’s location far from other continents means that it is very 14. ……………
- Antarctica is alone among the continents in having no 15. ……………
- The Antarctic ice sheet holds the record as the largest 16. …………… ice sheet on Earth.
- 17. …………… are blocks of ice connected to the Antarctic ice sheet.
Do the following statements agree with the information given in the passage on the previous page?
In boxes 18–21 on your answer sheet, write :
TRUE if the statement agrees with the claims of the writer
FALSE if the statement contradicts the claims of the writer
NOT GIVEN if it is impossible to say what the writer thinks about this
18. …………… Some of Antarctica’s mountains are popular with climbers.
19. …………… The temperature in Antarctica never rises above 0°C.
20. …………… Antarctica constitutes around one-fifth of the southern half of the world.
21. …………… Rain in Antarctica is rare but falls occasionally.
Complete the summary using the list of words, A-G, below.
Write the correct letter, A-G, in boxes 22-26 on your answer sheet.
A. reflectivity; B. ice melt; C. solar radiation; D. Palar vortex winds; E. heat balance; F. water surfaces; G. global warming
ANTARCTICA AND THE CHANGING CLIMATE
Antarctica plays an important role in regulating the Earth’s climate through the process of 22 …………… . 23 …………… is diverted away from the Earth by the huge Antarctic ice sheet. As the size and 24 …………… of the ice sheet have decreased, 25 …………… has caused melting in some parts of the continent. However, other areas of Antarctica have experienced falling temperatures in recent years, due to , climate patterns leading to reduced temperatures.
14. Answer: remote
- Key words: location, far, other continents
- We can find information about Antarctica’s location in the first paragraph. The continent is described as “remote”, indicating that it is situated far from, or distant from others. The correct answer is “remote”.
- far from = remote
- The answer is remote.
15. Answer: native population
- Key words: alone, continents, having no
- Still in the first paragraph, Antarctica is said to be: “…unique in that it does not have a native population”.
- The word “unique” here means the only one (among the continents), so it is the same as “alone”.
- Therefore, we can say that Antarctica is alone among the continents in that it does not have a native population. The answer is “native population”.
- alone = unique
- The answer is native population.
16. Answer: single
- Key words: ice sheet, record, largest, Earth
- Paragraph 2 begins:
- “The Antarctic ice sheet dominates the region. It is the single piece of ice on Earth covering the greatest area”.
- Clearly, the “greatest area” means “largest”, so it means that Antarctica is the largest single piece of ice on Earth. The word to fill in the blank is “single”.
- largest ~ greatest area
- The answer is single.
17. Answer: ice shelves
- Key words: blocks, ice, connected, ice sheet
- In paragraph 2, we also learn that:
- “Ice shelves are floating sheets of ice that are connected to the continent”.
- Obviously, “blocks of ice” and “sheets of ice” are similar, and the “continent” here refers to Antarctica. Hence, ice shelves are blocks of ice that are connected to Antarctica.
- The answer is ice shelves.
18. Answer: NOT GIVEN
- Key words: mountains, popular, climbers
- The third paragraph contains information about Antarctica’s mountains, but there is no mention about their popularity. The information given about the mountains describes only their location and height. Thus, the statement is Not Given.
- The answer is NOT GIVEN.
19. Answer: FALSE
- Key words: temperature, never, above, 0°C
- We refer to paragraph 5, as this is the only one about the temperatures in Antarctica.
- Read closely and you will see that in the summer:
- “…coastal areas hover around 0°C (32°F) but can reach temperatures as high as 9°C (48°F)”.
- 9°C is obviously above 0°C, so the statement saying the temperature there never rises above 0°C is undoubtedly wrong.
- The answer is FALSE.
20. Answer: TRUE
- Key words: one-fifth, southern, half, world
- The author mentions in the first paragraph that:
- “The whole Antarctic region covers approximately 20 percent of the Southern Hemisphere”.
- The word “hemisphere” means half of the sphere, or half of the world, so southern hemisphere is the same as “southern half of the world”. Also, “approximately 20%” is paraphrased as “around one-fifth”. Thus, another way to say this is: the Antarctic region covers around one-fifth of the southern half of the world. The statement is therefore True.
- around = approximately
- one-fifth ~ 20 percent
- half of the world ~ hemisphere
- The answer is TRUE.
21. Answer: FALSE
- Key words: rain, rare, occasionally
- Paragraph 6 contains details about “rain”, but it is referred to as “precipitation”:
- “Precipitation in the Antarctic is hard to measure. It always falls as snow”.
- In other words, the only kind of precipitation in Antarctica is snow, which means there is no rain. The answer is False.
- rain = precipitation
- The answer is FALSE.
22. Answer: E. heat balance
- Key words: regulating, Earth’s climate, process
- The information concerning Antarctica’s important role in the Earth’s climate can be found in the two first sentences of paragraph 7:
- “The Antarctic region has an important role in global climate processes. It is an integral part of the Earth’s heat balance”.
- The word “integral” means “fundamental, important”, so by saying Antarctica is an integral part of the Earth’s heat balance, it means that it “plays an important role” in the process of heat balance. Thus, E is the correct answer.
- important = integral
- Earth ~ global
- The answer is E.
23. Answer: C. solar radiation
- Key words: diverted, , Earth, ice sheet
- This information can also be found in paragraph 7:
- “…the massive Antarctic ice sheet reflects a large amount of solar radiation away from Earth’s surface”.
- The word “divert” means “cause (someone or something) to change course, or turn from one direction to another”, so in this context it is similar to “reflect”.
- What is reflected/diverted away from the surface of the earth is ‘a large amount of solar radiation’. The answer is ‘solar radiation’.
- divert ~ reflect
- huge = massive
- The answer is C.
24. Answer: A. reflectivity
- Key words: size, ice sheet, decreased, caused, melting, parts, continent
- The information for question 24 is given in paragraph 7:
- “As global ice cover (ice sheets and glaciers) decreases, the reflectivity of Earth’s surface also diminishes”.
- Thus, as the size of the area covered by the ice sheets decreases, less solar radiation is reflected from the surface of the Earth. The reason is given earlier in paragraph 7: “…ice is more reflective than land or water surfaces”.
- Therefore, the word that we need is ‘reflectivity’.
- A is correct for question 24.
25. Answer: G. global warming
- we need to know what caused melting in some parts of Antarctica among the four remaining answers, namely B, D, F and G.
- Answer B is incorrect because ice melt and melting are the same; it is simply not logical to put “ice melt” in the blank. D is also incorrect because polar vortex winds are said by NASA to reduce temperatures, thus causing MORE ice to form. Finally, F is irrelevant.
- We can tell G is the correct answer because global warming causes ice to melt, and it is linked to the decrease of ice sheets and reflectivity mentioned previously. As the Earth’s surface becomes less reflective with the reduction in size of the ice sheets, so more heat radiation from the sun is absorbed. As a result, this causes:
- “…an unequal heat balance linked to global warming”.
- So, in some parts of the Antarctic – we are told in paragraph 8 – more ice is forming, while in other parts the ice is melting due to global warming.
- decrease = diminish