IELTS Academic Reading Practice Test 63

Rapa Nui, also called Easter Island, is a remote volcanic island in the south-eastern Pacific Ocean, more than 3,500 kilometres from the coast of Chile. The island is best known for the moai, hundreds of enormous stone statues carved by its Polynesian inhabitants between roughly the thirteenth and sixteenth centuries. These figures have fascinated outsiders for generations, and they raise obvious questions about how a society with no metal tools or wheeled vehicles could have created and moved them.

Almost all of the finished moai were produced at Rano Raraku, a volcanic crater in the east of the island whose slopes are made of a compressed volcanic ash called tuff. This stone is soft enough to be worked with basalt tools and hardens when exposed to air. Carvers generally worked on each statue while it lay on its back on a ledge within the quarry, and they finished the face and most of the body before freeing the figure from the surrounding rock. After the final connection to the cliff was cut, the moai was slid down the slope. Around 900 statues, many of them incomplete, have been recorded in the quarry and elsewhere, and the largest unfinished example is over 20 metres long.

The completed moai were transported, sometimes for several kilometres, to coastal platforms known as ahu, where they were erected in lines with their backs to the sea. The statues are stylised human figures with large heads and strong brows, and they are generally interpreted as representations of important ancestors. They were not simple portraits but idealised images that linked the living community with its past leaders, and they became the focus of ceremonies and offerings. Originally, many of the statues had eyes made from white coral and red scoria, which were placed in the sockets during ceremonies to bring the ancestors to life.

How the islanders moved the moai without wheels or draft animals has been debated for many years. Oral traditions describe the statues walking to their platforms, and some researchers have taken this idea seriously. In 1986 the Czech engineer Pavel Pavel and the Norwegian explorer Thor Heyerdahl showed that a five-tonne statue could be rocked forward and made to 'walk' upright using ropes. Other experiments have demonstrated that a wooden sledge or a system of rollers and ropes could also have worked, but none of these reconstructions proves which method, or combination of methods, was actually used.

The American archaeologist Jo Anne Van Tilburg has mapped and recorded the moai for decades, and she has argued that the transport required careful planning and a large coordinated labour force. Some researchers have proposed that trees were cut down to make wooden sledges or rollers, while others, including the anthropologist Terry Hunt and the archaeologist Carl Lipo, have supported the idea that the statues were moved upright by a controlled rocking motion. Their experiments demonstrated that small teams could move a moai along a prepared track, but the debate continues.

Whatever the method, the transport and erection of so many statues required considerable resources, particularly timber. Pollen evidence shows that Rapa Nui was once covered by a dense palm forest, but most of this forest had disappeared by the time Europeans arrived. The loss of trees may have reduced the supply of wood for fuel, building and transporting statues, and it probably led to serious soil erosion. Some archaeologists argue that environmental degradation was a major cause of social collapse on the island, while others point to later European diseases and slave raids as more important factors.

The first recorded European visit was made by the Dutch navigator Jacob Roggeveen, who arrived on Easter Sunday in 1722 and gave the island the name it is often known by today. Roggeveen observed the moai, many of them standing, and described the islanders as healthy and numerous. Over the following century, further European contact brought new diseases against which the islanders had no immunity. In the early 1860s, Peruvian slave raiders seized around 1,500 islanders, and by 1877 the population had fallen to only 111 people.

Rapa Nui is now a special territory of Chile, and the moai are protected as part of Rapa Nui National Park, a UNESCO World Heritage site. Archaeologists continue to study the statues and the platforms on which they stood, and several major restoration projects have re-erected fallen moai. Tourism has brought economic benefits but has also placed pressure on the island's fragile environment and on its limited water supplies.

The Rapa Nui people have experienced a cultural revival in recent decades, and the moai have become a powerful symbol of their identity. Descendants of the original carvers remain on the island, and they are closely involved in the protection and interpretation of the statues. For them, the moai are not simply archaeological puzzles but living links to their ancestors.

Hydrogen is the most abundant element in the universe, but on Earth it is almost always bound to other atoms, in water and in organic compounds. To be used as a fuel, it must first be separated, which requires energy. For this reason, hydrogen is best described not as an energy source but as an energy carrier: a way of storing and transporting energy that has been generated elsewhere. Advocates argue that hydrogen could replace fossil fuels in many hard-to-electrify sectors, but its production, storage and distribution present formidable challenges. These challenges are not new, but they have become more urgent as countries seek to decarbonise their economies.

Today, the vast majority of hydrogen is produced from natural gas through a process called steam methane reforming, in which methane reacts with high-temperature steam to yield hydrogen and carbon dioxide. Because this method releases significant amounts of CO2, the product is often called grey hydrogen. It is the cheapest way to make hydrogen, which is why it dominates the market, but every tonne of grey hydrogen is typically associated with around ten tonnes of carbon dioxide emissions, undermining its environmental benefits. Global demand is now roughly 95 million tonnes a year, most of which is used in oil refining and in the manufacture of ammonia for fertilisers.

One attempt to reduce these emissions is blue hydrogen, produced in the same way as grey hydrogen but with the addition of carbon capture and storage, or CCS. In theory, most of the CO2 is captured and injected underground, but in practice capture rates vary and the process adds cost and complexity. Some studies have suggested that blue hydrogen may still retain a significant carbon footprint because of methane leaks from natural gas supply chains, although the technology continues to improve. Several large CCS projects have been cancelled because of high costs, although a handful operate successfully.

In a fuel cell, hydrogen is combined with oxygen from the air to produce electricity, with water and heat as the only by-products. The most common type is the proton exchange membrane fuel cell, which operates at relatively low temperatures and is well suited to vehicles. Fuel cells are more efficient than internal combustion engines, but they require pure hydrogen and contain expensive catalysts such as platinum, which adds to their cost. Other types, such as solid oxide and alkaline fuel cells, operate at higher temperatures and are used mainly for stationary power generation.

Hydrogen fuel cells have been tested in passenger cars, buses, trucks, and even trains and ships. However, the number of hydrogen vehicles on the road remains tiny compared with battery-electric vehicles, largely because of the high cost of the vehicles themselves and the scarcity of refuelling stations. A few countries, including Japan and Germany, have invested in hydrogen refuelling networks, but these networks are still limited to a small number of locations. In several cities, hydrogen buses are already in regular service, and hydrogen-powered trains have been tested in Germany.

Storing and moving hydrogen is technically difficult because it is the lightest gas and has a very low energy density by volume. To store useful amounts, it must be compressed to high pressure or cooled to minus 253 degrees Celsius to become a liquid. An alternative is to convert hydrogen into ammonia, which is easier to transport and can be converted back to hydrogen at the destination, though this adds inefficiency. Pipelines can carry hydrogen, but the gas can embrittle some metals, requiring special materials. Metal hydrides, which absorb hydrogen and release it when heated, are being investigated for smaller applications.

Beyond cost and infrastructure, hydrogen poses safety concerns. It is highly flammable and burns with an almost invisible flame, and because it is the smallest molecule, it can leak through joints that would be gas-tight for larger molecules. However, proponents point out that hydrogen is lighter than air and disperses rapidly outdoors, unlike petrol fumes or propane, so the risk can be managed with proper design and ventilation. Building public confidence remains essential if hydrogen is to be widely used. Yet the gas has been handled safely in industry for many years, with established procedures and equipment.

The future of hydrogen depends heavily on the falling cost of renewable electricity. Green hydrogen, produced by electrolysis using power from wind or solar farms, has the potential to be a truly low-carbon fuel, but it is currently far more expensive than grey hydrogen. As electrolyser manufacturing scales up and renewable energy becomes cheaper, many analysts expect the gap to narrow significantly. Governments in Europe and Asia are now offering subsidies and setting targets to accelerate this transition. For example, the European Union has announced a target of installing 40 gigawatts of electrolyser capacity by 2030.

Across the developed world, populations are growing older. Life expectancy has increased by decades, while birth rates have fallen well below the level needed to maintain a stable population. According to the United Nations, by 2050 one in six people in the world will be over the age of 65, up from one in eleven in 2019. This demographic shift is the fundamental cause of the financial pressure now facing pension systems, and it is not a temporary problem. This shift is the result of a demographic transition in which improved health care and falling child mortality lead first to longer lives and then to fewer children.

Most state pension schemes are organised on a pay-as-you-go basis: the contributions of today's workers are used to pay the pensions of today's retirees. This system works reasonably well when the working-age population is large relative to the retired population, but the arithmetic of pay-as-you-go systems becomes increasingly difficult as the ratio of workers to pensioners falls. In many wealthy countries, that ratio has fallen from around five to one in the 1960s to roughly three to one today, and is projected to fall to two to one by 2050. International organisations have warned that, without reform, public pension spending could rise sharply as a share of national income.

The pay-as-you-go model was first introduced in Germany by Chancellor Otto von Bismarck in the late nineteenth century, and it has been adopted in various forms around the world ever since. Its strength is simplicity: contributions are collected from employers and employees, and pensions are paid out immediately. Its weakness is that it relies on a continuous supply of young workers. When that supply dwindles, the system comes under strain, and the longer governments wait to adjust it, the sharper the eventual corrections will have to be. Bismarck's system originally set the retirement age at 70, at a time when few workers survived that long.

Governments therefore face a difficult choice: they must raise taxes, reduce pension benefits, or require people to work longer. Each of these options is unpopular, and none is sufficient on its own. Raising the retirement age is the most commonly proposed reform, but it is often resisted by workers who have spent decades in physically demanding jobs and by those who simply look forward to retirement.

Raising the retirement age without other reforms may simply push older workers into poverty. In many countries, employers are reluctant to hire older workers, and health problems become more common with age. A rise in the pension age can therefore result in a period during which people are neither working nor receiving a pension. To be effective, any increase in the retirement age must be accompanied by measures to keep older people in employment, such as anti-discrimination laws, flexible working arrangements and retraining programmes.

Some countries have introduced automatic adjustment mechanisms that link the pension age or benefit levels to changes in life expectancy. Sweden, for example, has a notional defined-contribution system in which pension benefits are adjusted according to the growth of the economy and the average life expectancy of each generation. Such mechanisms reduce the need for repeated political battles, but they can be complex and may still require safeguards for those with shorter life expectancies, such as manual workers. Germany has introduced a sustainability factor that adjusts pensions as the ratio of contributors to pensioners changes.

Increasing contribution rates is another lever, but it reduces take-home pay and can discourage work at a time when labour is already scarce. Reducing benefits is politically dangerous and hits the poorest pensioners hardest. Encouraging private savings through tax incentives can help: private savings can supplement state pensions, but they cannot replace them, because many low-paid workers have little capacity to save.

Immigration can ease the pressure in the short term, but it cannot offset the ageing trend indefinitely. Immigrants also grow old, and their birth rates tend to converge with those of the host population. Moreover, large-scale immigration often faces political resistance, making it an unreliable basis for long-term planning.

In my view, the only realistic response is a comprehensive package of reforms. Higher productivity would increase the output of each worker, making it easier to support a larger retired population. Pension systems themselves need to become more flexible: partial retirement, phased withdrawal from the labour force and portable benefits between jobs would allow people to work longer without being forced to do so. Lifelong learning and better health care can also extend working lives in a way that is acceptable to individuals. Some countries have introduced partial retirement schemes that allow older workers to reduce their hours while drawing part of their pension.

Delaying reform will only make the necessary adjustments more abrupt and more painful. The demographic wave is already visible, and it will not be reversed by wishful thinking. Societies must adapt their pension systems to the new reality, or they will face a future of intergenerational conflict and fiscal crisis.