BEST IELTS Academic Reading Test 439

BEST IELTS Academic Reading Test 439

IELTS Academic Reading Test

The Slow Destruction of the Zachariae Isstrom Glacier

The Zachariae Isstrom glacier is the latest in a string of Greenland glaciers to undergo rapid change in the warming world. A new NASA study has found that Zachariae Isstrom has broken loose from a glaciologically stable position and entered a phase of accelerated retreat. It is expected that the consequences will be felt for decades to come. The reason for these long-term effects is the size of the Zachariae Isstrom glacier.

It drains ice from an area of 91,780 square kilometres, which is about 5 per cent of the Greenland Ice Sheet. All by itself, it holds enough water to raise global sea level by 46 centimetres if it were to melt completely. The Zachariae Isstrom glacier is currently crumbling, losing 5 billion tons of mass every year, which is disintegrating into the North Atlantic Ocean. Jeremy Close, one of the researchers on the NASA study, explains: “North Greenland glaciers are changing rapidly and especially the form and dynamics of Zachariae Isstrom have been transformed over the last few years. The melting glacier will now result in rising sea levels for decades to come.”

IELTS Academic Reading Test

The cause of the change in the Zachariae Isstrom glacier is solely due to warmer water temperatures. Greenland marine scientist Sophie Boldt explains the situation. “The warmer waters have caused the end of the glacier to float free from a ridge of bedrock below sea level on which it had rested until just recently. Without that natural brake, the glacier is now sliding more quickly and more icebergs are snapping off, adding a net five billion tonnes of ice a year to the oceans.”

The NASA team used data from aerial surveys conducted by NASA and satellite-based observations acquired by multiple international space agencies coordinated by the Polar Space Task Group. The various tools used, including a highly sensitive radar sounder, gravimeter and laser profiling systems, coupled with radar and optical photographs from satellites, monitored and recorded changes in the shape, size and position of glacial ice over long time periods. This provided precise data on the state of Earth’s polar regions.

IELTS Academic Reading Test

The scientists determined the bottom of Zachariae Isstrom is being rapidly eroded by warmer ocean water mixed with growing amounts of melt water from the ice sheet surface. “Ocean warming has played a sole role in triggering the glacier’s retreat,” said section leader Joanna Morgan, “but we need more oceanographic observations in this critical sector of Greenland to determine the glacier’s prognosis.”

Adjacent to Zachariae Isstrom is another large glacier that is also melting rapidly, but is receding at a slower rate because it is protected by an inland hill. The two glaciers make up twelve per cent of the Greenland ice sheet and would boost global sea levels by more than ninety-nine centimetres if they fully collapsed. The sector where these two glaciers reside is one of three major marine-based basins in Greenland, along with Jakobshavn Isbrae in central west Greenland and the Petermann-Humboldt sector in central north Greenland. Glaciologist, Tom Ellis, explains that potential danger is imminent within the latter two areas.

IELTS Academic Reading Test

“The Jakobshavn Isbrae and the Petermann-Humboldt basins hold enough water to raise global sea level by over half a metre each, and both are also undergoing significant changes related to warming at present. Even a small increase in sea levels can have devastating effects on shoreline habitats, and half a metre is not a small increase.” As rising seawater reaches farther inland, it can cause destructive erosion, flooding of wetlands, contamination of aquifers and agricultural soils, and lost habitat for fish, birds, and plants. In addition, hundreds of millions of people live in areas that will become increasingly vulnerable to flooding.

Higher sea levels would force them to abandon their homes and relocate. Low-lying islands could be submerged completely. One of the NASA study’s authors, Paulina Weiler, summarises the study’s conclusion. “It is likely that many of these Greenland glaciers will lose their ice shelves in coming years, further increasing Greenland’s future contributions to global sea level rise. It is unlikely that world governments will take the necessary decisions to stop the melting and it is actually moot whether any action taken now would create the required changes in time.”

IELTS Academic Reading Test

The actual process of polar glacier iceberg calving into the sea is similar in most situations of glaciers that are situated next to the sea. First of all, the glacier must, of course, extend into the sea. This part has usually become rather thin, due to relatively warm circumpolar water that flows in from the deep and causes melting to the underside of the glacier. This water is cooled and then moves away from the sub-ice cavity in shallower water.

The warm water continues to erode the underside of the glacier, particularly at the grounding line, which is where the glacier comes into contact with glaciomarine muds, on which it rests. The weight of the thinning glacier as it extends into the sea causes crevasses to form on the top side and these will in turn snap off and calve the icebergs of the future. Higher up in the glacier, ice thinning is present and these fractures will eventually become the crevasses lower down.

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IELTS Academic Reading Test

Look at the following statements (questions 14 – 19) and the list of people below. Match each statement with the correct person’s initials. Sets of initials may be used twice. Write the correct initials in boxes 14 – 19 on your answer sheet.

14. The Zachariae Isstrom glacier is creating more and more icebergs.

15. What is happening to the Zachariae Isstrom glacier could affect many of the world’s coastal ecosystems.

16. The shape of the Zachariae Isstrom glacier has changed a lot recently.

17. Political action on the environment might not even affect what is happening.

18. The loss of an attachment of the Zachariae Isstrom glacier to a physical underwater feature has led to movement forward of the glacier.

19. More research is required in order to evaluate the future of the Zachariae Isstrom glacier.

IELTS Academic Reading Test

JC. Jeremy Close

SB. Sophie Boldt

JM. Joanna Morgan

TE. Tom Ellis

PW. Paulina Weiler

IELTS Academic Reading Test

Do the following statements agree with the information given in the text? In boxes 20 – 23 on your answer sheet write:

TRUE – if the statement agrees with the information

FALSE – if the statement contradicts the information

NOT GIVEN – if there is no information on this

20. The melting of the Zachariae Isstrom glacier could raise sea levels by half a metre.

21. One tool used by the NASA research team was images taken from space.

22. The NASA research team is made up of scientists from all over the world.

23. The warming of the sea is the only reason that the Zachariae Isstrom glacier is melting

IELTS Academic Reading Test

Label the diagram below. Write NO MORE THAN THREE WORDS from the text for each answer.

IELTS Academic Reading Test

IELTS Academic Reading Test


BEST IELTS Academic Reading Test 439

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14. SB

15. TE

16. JC

17. PW

18. SB

19. JM


21. TRUE


23. TRUE




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