IELTS Academic Reading Practice Test 446

Before the middle of the nineteenth century, shopping in a European city was a specialised business. A customer who wanted cloth, ribbons, buttons and shoes might have to visit three separate shops, each no bigger than a large room, and would often have to ask an assistant for every item, since most goods were kept in drawers behind the counter. Prices were rarely marked, bargaining was normal, and anyone who had paid too much had little hope of exchanging the goods. Fixed prices, free entry and the freedom to walk among goods without buying anything were all unfamiliar ideas. The grandest shopping streets already had glass-roofed arcades, but these were rows of separate shops rather than single enterprises.

The business that did most to change this stood on the rue de Sèvres in Paris. In 1852 Aristide Boucicaut became a partner in the small drapery concern, and within a few years he and his wife Marguerite had taken control and begun to expand. Boucicaut's method was to mark every article with a fixed price, keep the profit on each one low and rely on selling a very large volume of goods. He allowed customers to exchange what they had bought and to wander through the building without any obligation to buy. Profits were ploughed back into enlarging the premises and hiring more staff. Displays that changed with the seasons drew customers from the whole city. By the end of the century the store occupied most of a city block, and part of its iron and glass structure had been engineered by Gustave Eiffel.

Across the Atlantic the same formula appeared in a more monumental form. In 1846 the merchant Alexander Turney Stewart opened a dry-goods store on Broadway in New York in a building faced in white marble, and in 1862 he added a far larger store whose slender iron columns allowed uninterrupted floors of selling space. Stewart's was widely described as the largest retail building in the world. Stewart bought his stock directly from manufacturers rather than through wholesalers. Rowland Macy, who had opened a small shop in 1858, moved uptown in 1902 to a store at Herald Square, and Marshall Field's built a similar palace in Chicago.

London was slower to respond. William Whiteley opened a shop in Bayswater in 1863 that grew into a vast emporium, and Harrods in Knightsbridge developed from a grocer's into a store of many departments. The most famous arrival, however, was Selfridges, which opened on Oxford Street in 1909. Its founder, Gordon Selfridge, an American who had learned his trade at Marshall Field's in Chicago, brought with him a genius for publicity. The new building contained a restaurant, a library, a roof garden and a room set aside for silence, where customers could sit undisturbed. Harrods, meanwhile, had already installed its first moving staircase in 1898, and nervous customers were offered a glass of brandy at the top.

The new stores invested heavily in the techniques of display. Plate glass allowed goods to be seen from the street, and merchandise was laid out on open counters and tables rather than kept in drawers. Electric lighting, still a novelty in the 1880s, made the interior bright on winter afternoons and allowed trading to continue after dark. Wanamaker's in Philadelphia was among the earliest stores to install electric light. Passenger lifts made the upper floors as easy to reach as the ground floor, and a visit to the store became an outing for the whole family.

The workforce behind the counters was large, and much of it was young and female. By the 1880s Le Bon Marché employed more than 1,700 people, and comparable stores in other cities ran into the thousands. Many assistants lived in dormitories inside the building, under rules that governed their hours, their meals and their conduct, and they were fined for lateness or for mistakes at the till. Pay was low, but for a young woman from the countryside the store offered a wage, a room and a degree of independence that few other occupations could match.

Not everyone welcomed the change. Shopkeepers in the surrounding streets found that they could not compete on price, and some blamed the department stores for their failure. Religious commentators worried that the buildings encouraged vanity and debt, and the stores answered partly by presenting themselves as respectable places where a woman might spend an afternoon without damage to her reputation. Some of these anxieties proved short-lived; others have never quite gone away.

The stores also altered how people thought about buying. Émile Zola gathered material in Le Bon Marché for his novel Au Bonheur des Dames, published in 1883, which describes a vast store crushing its small neighbours. The book did much to fix the image of the department store as both thrilling and ruthless. Seasonal sales, catalogues sent by post and elaborate Christmas displays turned shopping into an event, and the store became a place to meet, eat and be seen.

Many of the practices that the first department stores established — fixed prices, refunds, the open display of goods, the restaurant on the top floor — are now so ordinary that their origin is forgotten. The buildings have proved more fragile, and a number of famous names have disappeared or been absorbed into larger groups, but the idea itself has spread to almost every city in the world. The shopping centres that followed inherited much from them: the covered street, the mixture of shops and restaurants, and shopping as a day out.

In the grasslands of Africa and northern Australia, termites of the genus Macrotermes build mounds that may stand three metres high, and occasionally twice that. A single colony can contain more than a million insects. What makes these structures remarkable is not their size but the fact that they are, in effect, life-support systems. Inside them the termites cultivate a fungus that digests the grass they collect, and the fungus is far more demanding than the insects themselves. It grows best at around 30 degrees Celsius and in air that is distinctly humid, yet the outside temperature may fall close to freezing at night and climb above 40 degrees in the afternoon.

The mound is built from grains of soil cemented with the termites' saliva and with their own droppings. At its centre runs a vertical chimney, a wide passage that in a large mound may be a metre across, and from this a maze of smaller tunnels leads outward. The outer surface is not smooth. It is broken by narrow ridges that run up the sides like the fluting of a column. At the foot of the mound these ridges widen into thick buttresses that support the weight above. The wall between the outside world and the interior is thin and porous, riddled with pores far too small to see, through which gases can pass. Near ground level there are openings that connect the internal passages to the open air.

The fungus is grown on combs — spongy masses of partly digested plant material stacked in chambers scattered through the upper part of the mound. The termites cannot digest grass themselves; the fungus breaks down the cellulose for them, and the combs are also the colony's food store. They are its furnace as well. As the fungus grows it releases heat, and this metabolic heat, together with the warmth of the insects' bodies, is the main reason the interior stays warm. A working colony therefore faces a problem of plumbing. Fresh air must reach the combs, and the carbon dioxide they produce must be removed, without letting the heat escape or the outside air flood in.

For several decades the standard explanation was elegant and simple. In the early 1960s a Swiss entomologist, Martin Lüscher, proposed that the mound worked like a thermosiphon. Warm air, heated by the fungus and the termites, rose up the chimney and escaped through the porous walls near the top. Cooler, fresher air was drawn in through the openings at the base. The circulation would continue as long as the colony produced heat, so the mound appeared to be a self-regulating air-conditioning machine. The idea passed into textbooks, and into the plans of architects.

Direct measurement has since complicated this picture. From the 1990s onwards, the American physiologist J. Scott Turner and his colleagues studied mounds of Macrotermes michaelseni in Namibia by releasing traces of gas and following their movement. They found that air inside the mound was not moving steadily upward. It oscillated, and it seemed to be driven by the wind. As gusts passed over the ridges and buttresses, the pressure on different faces of the mound rose and fell, pushing air in at one opening and out at another. In this account the mound behaves less like a chimney than like a lung, breathing in and out with the weather. Turner also recorded carbon dioxide concentrations well below those the thermosiphon model had predicted, and internal temperatures that followed the outside air more closely than expected.

Not all of this is settled. A mound is difficult to study without disturbing it: any hole a researcher drills alters the pattern of airflow, and the termites rapidly repair the breach. Instruments must therefore be sealed in place and left for months. A mound is also a structure that is continually being extended and rebuilt, so its shape is never final. It further remains unclear how much of the structure is deliberate climate control and how much is a by-product of building and of the need to exchange gases. Several species build mounds of quite different shapes, and generalisations from one are risky. Some researchers doubt that a colony regulates its temperature as precisely as the textbook account suggests. Others reply that a mound's sheer mass of soil must smooth out short-term swings, even if the airflow is erratic.

One striking variation has attracted attention for over a century. In the Northern Territory of Australia, the species Amitermes meridionalis builds flat, blade-like mounds aligned almost exactly north–south. The broad faces receive the morning and afternoon sun, while the thin edge faces the midday heat. Some biologists explain the orientation as a way of avoiding overheating at the hottest hour; others argue that it helps the mound dry out after rain. The debate is a reminder that a single feature may serve several purposes at once.

Engineers have borrowed the idea, sometimes loosely. The Eastgate Centre, an office and shopping complex completed in Harare, Zimbabwe, in 1996, was designed by the architect Mick Pearce with a central atrium and a system of fans. The fans draw cool night air through the building and release warm air at the top. It is said to use considerably less energy than a conventionally air-conditioned building of similar size, and Pearce has acknowledged that the termite mound was one inspiration among several. Materials scientists, meanwhile, study the way the mound's cemented soil resists rain and heat, in the hope of learning how to build cheaply with local earth.

Air travel is cheap. A seat on a flight from London to Barcelona can cost less than the taxi to the airport. The fuel that carries the aircraft is among the few forms of energy that are not taxed at all. It dates from the 1944 convention that established the rules of international civil aviation, and from the bilateral treaties that followed, which generally forbid the taxation of fuel carried on board an international flight. Supporters argue that the arrangement stopped countries from taxing each other's airlines and kept a fragile industry alive. Its critics reply that it gives aviation an advantage over every other form of transport.

The environmental case is straightforward. Aviation is responsible for somewhere between two and three per cent of global carbon dioxide emissions, and rather more when the warming effects of contrails and other pollutants released at altitude are counted. Most economists who work on climate policy take the view that emissions should carry a price, and that the price should be as uniform as possible across countries and industries. A tax, unlike an offsetting scheme, also raises money that can be spent on the alternatives the industry needs.

Airlines and their trade associations oppose the idea. Their argument is not that aviation should pay nothing but that a tax is a blunt instrument. Margins are thin, so a levy would be passed on to passengers in higher fares, cutting demand and the revenue carriers need to buy new aircraft. They point out that a tax imposed in one region only would push long-haul traffic through hubs elsewhere — carbon leakage, in the jargon. The money, they add, would disappear into national budgets rather than into decarbonisation. Their preferred instrument is CORSIA, a global offsetting scheme run through the International Civil Aviation Organization, which they describe as the only measure that applies to international flights everywhere.

Experience so far illustrates the difficulty. The European Union brought aviation into its emissions trading system in 2012, but only for flights within Europe. A plan to cover flights entering or leaving European airports was abandoned after protests from other governments, which argued that it breached their sovereignty. Governments have instead taxed passengers rather than fuel. The United Kingdom introduced a passenger duty in 1994, Germany a similar tax in 2011 and France a levy on departing flights in 2006. These charges differ widely in size and design, and because they fall on passengers rather than on fuel they do little to reward an airline for burning less.

The design of any levy raises harder questions than its principle: should the charge fall on fuel, on tickets or on permits, and who should receive the proceeds? Economists tend to favour a straightforward fuel charge, because it is simple to administer. Campaigners often prefer a levy that rises with the number of flights a person takes, on the grounds that a small minority of the world's population is responsible for most flying. A flat charge, they say, would be felt hardest by those who fly once a year to visit relatives. Airlines object that such schemes would be intrusive and difficult to police.

Fairness between countries is delicate. In much of Africa, the Caribbean and the Pacific, tourism depends on long-haul flights. A levy that raised the cost of reaching those destinations would fall on economies that have contributed little to the problem. The principle of common but differentiated responsibilities, accepted in the climate negotiations, suggests that richer countries should bear more of the burden. One answer is to return part of the revenue to poorer countries, or to exempt their carriers, though exemptions create exactly the distortions that a uniform tax is meant to avoid.

Nor should a tax be expected to do more than it can. The price of a flight would have to rise substantially before it changed behaviour, and demand for leisure travel is growing fast in middle-income countries. Sustainable aviation fuel, made from waste, currently supplies well under one per cent of the world's jet fuel and costs several times more than kerosene. A levy that funded its production might speed the transition; a levy that simply raised the price of flying would not, by itself, produce a single extra litre of the stuff. Battery-powered aircraft remain too heavy for anything but the shortest flights, and hydrogen is at an early stage of testing.

The non-carbon effects of aviation, such as the contrails that form at high altitude, are poorly understood and hard to price. No one can say with confidence how much a given levy would reduce emissions, since the answer depends on how airlines respond and on what happens to the revenue. And international agreement is slow: the aviation body works by consensus, which gives any large country an effective veto.

My own view is that the exemption can no longer be defended. A levy on aviation fuel, agreed by as many countries as possible and introduced gradually, with a share of the proceeds directed to poorer nations, would be a modest but honest step. Part of the money should also fund research on cleaner fuels. A levy would not solve the problem of aviation and climate change on its own, and it should be combined with efficiency standards and support for alternatives. But a global industry that pays no tax on its fuel while households pay tax on the electricity they use is difficult to justify to anyone.