IELTS Academic Reading Practice Test 464

The Arabian oryx is a pale antelope, roughly a metre high at the shoulder, whose creamy white coat is broken by black markings on the face, the legs and the tail. Both sexes carry long, nearly straight horns that may reach 70 centimetres, and both will use them in defence against a predator. Against gravel plains and pale sand the animal is almost invisible at midday, when it rests in whatever shade it can find. Its broad, splayed hooves spread its weight on soft ground, and its legs darken towards the feet.

Survival in one of the driest environments on earth depends on a series of physiological adjustments. Rather than sweating heavily to keep cool, an oryx allows its body temperature to climb during the day, sometimes beyond 40 degrees Celsius, and then releases the stored heat during the cold night. This conserves water that would otherwise be lost through the skin. Its kidneys produce highly concentrated urine, and much of the water it needs comes from the plants it eats and from dew. The animals can go for weeks without drinking, and they travel long distances to reach the fresh growth that follows a rainstorm.

Historically the species ranged across most of the Arabian Peninsula and beyond it: northwards through what is now Jordan and Syria, and westwards into the Sinai. Nineteenth-century travellers described herds of up to a hundred animals moving across the plains, and the oryx appears repeatedly in Arabian poetry, where its endurance and the elegance of its horns are celebrated. A side view, in which the two horns overlap and appear as one, has often been suggested as a source of the unicorn, though the connection can never be proved. Rock drawings of single-horned animals in the region are sometimes interpreted in the same way.

The collapse came quickly. For centuries the oryx had been hunted on foot or from the back of a camel, and its speed and endurance gave it a reasonable chance of escape. In the twentieth century rifles and motor vehicles tipped the balance decisively in favour of the hunter. Roads built for the oil industry carried prospectors into areas that had previously been visited only by nomadic herders, and four-wheel-drive vehicles made it possible to follow an exhausted animal until it could run no further. Capture for zoos and private collections did further damage. By the 1950s only a few scattered groups survived, and the last known wild individuals were in the desert of Oman.

Operation Oryx, launched in 1962, was an attempt to save the species by bringing its remaining members into captivity. The Fauna Preservation Society, as Fauna and Flora International was then called, organised the work with support from the World Wildlife Fund and the government of Oman, and a small team travelled to the Jiddat al-Harasis in search of animals. The party succeeded in bringing back a small number of oryx. These were combined with others already held in the collections of the ruler of Kuwait and of London Zoo, and the resulting herd was established at Phoenix Zoo in Arizona, where it became known as the World Herd.

The first release into the wild came twenty years later, in 1982, when animals from the captive herd were set free in the Jiddat al-Harasis, the same stony desert where the last wild oryx had been seen. Protected by law and watched over by rangers, the herd grew steadily, and by the mid-1990s it numbered several hundred animals. For a time the project was held up as a model of what captive breeding could achieve.

The success did not last. From the late 1990s poaching removed animals faster than they could breed, and the trade in live oryx across the border proved difficult to control. Drought years reduced the grazing, and herds of domestic camels and goats competed with the oryx for what remained. By the early 2000s the wild population in Oman had fallen to a few dozen, and the surviving animals were taken back into enclosures. The lesson was uncomfortable: a species could be bred in captivity and returned to the desert, but only constant protection would keep it there.

Elsewhere the work continued. Saudi Arabia created a reserve at Uruq Bani Ma'arid, where releases began in the 1990s. Jordan returned oryx to the desert around Wadi Rum, and Israel established a small population in the Negev. The United Arab Emirates built up a large herd on Sir Bani Yas, an island in the Gulf, before releasing animals on the mainland, and several Gulf states now run breeding centres. Because these populations are separated by hundreds of kilometres of desert, exchange between them is negligible, and each depends on continued management.

In 2011 the species was moved from Endangered to Vulnerable on the IUCN Red List, a change that conservation organisations described as the first improvement in the status of an animal brought about by reintroduction. The oryx is not safe. Drought, overgrazing by livestock, road building and illegal hunting all remain threats, and several populations are small enough to be lost to a single outbreak of disease. What the story demonstrates is narrower than a simple triumph. Extinction in the wild need not be permanent, provided that someone is willing to pay for the fences, the fuel and the rangers for decades.

Ask almost anyone whether the weather affects their mood and the answer will usually be yes. A grey, wet afternoon is said to lower the spirits; the first warm day of the year is said to lift them. Yet when researchers have tried to measure the effect, it has proved surprisingly small, inconsistent between studies and difficult to pin down. The explanation is not that people are imagining things. It is that weather acts on mood through several routes at once, some of them indirect, and that individuals differ a great deal in how strongly they respond.

The clearest exception is seasonal affective disorder, the pattern of low mood and lethargy that returns each autumn and lifts each spring. In the mid-1980s a team at the US National Institute of Mental Health, led by Norman Rosenthal, described patients who became depressed in winter and recovered in summer, and proposed bright light as a treatment. Estimates of how common the condition is vary widely and rise with distance from the equator, which supports the idea that light is involved. Trials of light therapy suggest that it helps some patients, though not all, and that the benefit is moderate rather than dramatic.

Light does more than allow us to see. In the early 2000s researchers identified a small class of cells in the retina, the layer at the back of the eye, that respond to brightness rather than to images. They contain a pigment called melanopsin, and they remain active in some people who are registered blind. Their signals travel to a tiny cluster of neurons in the hypothalamus known as the suprachiasmatic nucleus, which acts as the body's master clock. That clock, in turn, controls the pineal gland, which produces melatonin, a hormone that makes us sleepy and whose level is suppressed by light.

In winter, with short days and long nights, melatonin is produced for a longer stretch, so people feel sleepy earlier in the evening and sluggish in the morning. The clock may also drift out of step with local time, and many people find that their sleep and appetite shift in the darker months. This pathway is well understood, and it is the strongest evidence that the seasonal pattern of daylight has a genuine effect on how people feel.

When researchers look for the effect of day-to-day weather, the findings are much more modest. An analysis of hundreds of millions of public messages posted on a social media service by users in more than eighty countries found that the length of the day was associated with larger shifts in the language people used than changes in temperature or rainfall. In other words, the season mattered more than the weather within it, which is not what most of us would predict from our own experience.

Temperature is the most studied variable. In laboratory experiments, uncomfortably warm rooms make people more irritable, less willing to help and more likely to read a neutral remark as hostile. Analyses of crime records report more violent incidents in hot weather. Yet the effect on mood is not a simple line: mild warmth tends to raise spirits, while extreme heat lowers them, and much of the aggression may come from discomfort, from alcohol and from the fact that hot evenings bring people together outdoors.

Wind has a folklore of its own. In the Alps, the warm dry foehn is blamed for headaches, irritability and accidents, and similar claims are made about certain winds elsewhere. Careful studies have generally failed to find a consistent effect, and the claims made for 'positive' and 'negative' ions in the air have not been supported by controlled measurement. People who believe that wind affects them tend to notice the days when they feel unwell and to forget the days when they do not.

Individual differences are large. Some people describe themselves as weather-sensitive, and questionnaires suggest that this group reports more headaches, fatigue and changes of mood than others do. Much of the evidence, however, comes from questionnaires in which people describe their own feelings. Part of the effect may lie in expectation: a person who expects a change in the weather to make them tired may interpret a normal afternoon slump in that light. Sleep, illness, personality and the amount of time spent outdoors all intervene, and few studies have been large enough to separate them.

A further difficulty is that weather changes behaviour, and behaviour changes mood. Fine weekends bring people outside, where they meet friends and take exercise; rain keeps them at home. A study that compares moods on sunny and rainy days is therefore not comparing like with like. Some researchers argue that much of the apparent influence of weather on mood is really an influence of what the weather allows people to do, and that the direct effect is smaller still.

None of this means that weather is irrelevant to how we feel. It means that the link is real but modest for most people, stronger for a minority, and best documented for light. Small studies that find nothing are less likely to be published, which can make a weak effect look more solid than it is. The subject also attracts confident claims from people selling lamps, holidays and apps. Anyone who has felt their spirits rise on the first warm day of spring will recognise the experience; describing it accurately turns out to be much harder.

Late in May 2019, a photograph taken from the summit ridge of Everest showed a line of climbers standing almost motionless in the snow, roped together and waiting. The queue had formed during a brief spell of calm weather, when teams that had been waiting at camps higher up the mountain all set out for the top at the same time. Eleven people died on the mountain that spring, and although no single cause explains every death, several climbers were reported to have run out of bottled oxygen while they waited. The image was widely used to argue that Everest had become too crowded.

Everest is 8,849 metres high and lies on the border between Nepal and China. Almost all commercial expeditions approach from the south, through Nepal, and the government charges foreign climbers $15,000 for a permit in the spring season, having raised the fee from $11,000 in 2025. In the 2020s it has issued several hundred permits each spring. The direct revenue is modest by the standards of a national budget, but the expedition industry as a whole is not: every permit-holder pays a guide, and the teams employ cooks, porters and high-altitude workers, buy food and fuel and hire helicopters. For many families in the Khumbu region, the climbing season is the best-paid work of the year.

The route from the south begins with the Khumbu Icefall, a shifting mass of broken ice that must be crossed by ladder before dawn, before the sun loosens the blocks of ice above. It is the guides, most of them Sherpas from the valleys below the mountain, who carry the ropes, the ladders and the oxygen and who break the trail through deep snow. They also take the greatest risk. On 18 April 2014 an avalanche in the icefall killed sixteen Nepali workers, and a year later an earthquake triggered an avalanche that buried part of Base Camp and killed at least eighteen people.

Queues are not really a product of the total number of climbers on the mountain. They are a product of timing. The summit can be reached only in a narrow band of acceptable weather, when the jet stream has moved away and the wind has dropped, and such windows may occur only a handful of times in a season. Everyone then moves at once. Above the South Col the route narrows, and on the ridge itself climbers must pass along a single fixed rope. The supply of bottled oxygen, and the amount a climber can carry, limits how long anyone can afford to stand still.

For those who want a limit, the case begins with safety. A climber who waits for hours on the ridge uses oxygen that was calculated to last for a faster ascent, and then descends in the dark and the cold; the consequences can be fatal not only for that climber but for the guides who try to help. These are serious concerns, and they are not answered by pointing out that climbers choose the risk. Rescue capacity is finite: helicopters can reach the lower camps but not the summit ridge, and a rescue may occupy several guides for a whole day. Camp Two has limited space and water, and rubbish and human waste accumulate in the ice.

The objections are weaker than they first appear. A cap, it is said, is a blunt instrument that would treat a problem of a few days as though it were a problem of the whole season. That is true as far as it goes, but scheduling is itself a form of limit, and somebody has to set it: the number of climbers matters less than the way their ascents are scheduled. The second objection is that expeditions would move to the north side, which China administers under its own rules and fees, and that any restriction in Nepal would redirect them there. Some would go, but the northern route has never attracted numbers on the same scale, and it suits only experienced climbers.

The two sides of Everest are administered under different rules and different fees, and no joint authority has the power to decide how many people may stand on the summit in a season. Conservation bodies have called for coordinated management, but the mountain is a national symbol in both countries, and any such arrangement is politically difficult. A limit agreed on one side would not bind the other.

Several operators have proposed that departure times from the highest camp should be staggered, so that teams reach the ridge at different hours, and that permits for each short period should depend on the forecast and on the number of guides available. Nepal has announced that applicants will in future need a medical certificate and evidence of having climbed a Nepali peak of at least 7,000 metres. A certificate, however, tells a permit officer very little about how a climber will behave at altitude, and paperwork of this kind has a poor record.

My own view is that a limit on numbers is justified. The mountain is a finite resource, the season is short, and the people most likely to be hurt when it is overcrowded are the guides, who have far less choice about being there than their clients do. But a figure pulled out of the air, fixed for every year and every season, would achieve little. The number should be tied to what the route can safely carry in a given window, and the revenue should pay for the rangers, the waste removal and the rescue teams. The question is not how many climbers Everest can hold, but how many it can hold on the same day.