IELTS Academic Reading Practice Test 3

A. As the global population surges toward an estimated 9.7 billion by 2050, the challenge of feeding humanity sustainably has never been more pressing. Traditional agriculture already occupies roughly 40 percent of Earth's ice-free land surface, and expanding farmland further means destroying forests and wild habitats. Vertical farming, the practice of growing crops in vertically stacked layers within controlled indoor environments, has emerged as a potential solution to this dilemma, promising to produce food locally, year-round, with dramatically reduced environmental impact.

B. The concept is not entirely new. In 1999, professor Dickson Despommier at Columbia University began developing the theoretical framework for "skyscraper farms" capable of feeding thousands of city residents. His vision involved multi-storey buildings in which every floor functioned as a sophisticated greenhouse. Though initially dismissed as science fiction, the idea gained traction as LED lighting costs plummeted by 95 percent between 2010 and 2020, and hydroponic and aeroponic growing technologies matured.

C. Modern vertical farms operate using several soilless cultivation techniques. Hydroponics, the most established method, grows plants with their roots suspended in nutrient-rich water solutions. Aeroponics, used by companies like AeroFarms, takes this further by misting plant roots with a fine nutrient spray, using up to 95 percent less water than field farming. Both techniques are housed within sealed, climate-controlled environments where temperature, humidity, CO2 levels, and light spectra are precisely managed using computer algorithms that optimise growth conditions for each crop variety.

D. The environmental advantages are substantial. Vertical farms typically use 90-95 percent less water than conventional agriculture through closed-loop recirculation systems. Because crops are grown indoors, they require no pesticides or herbicides, eliminating chemical runoff into waterways. The proximity of vertical farms to urban consumers slashes transportation distances, reducing the carbon footprint associated with the "food miles" of conventionally grown produce. Some operations have achieved yields 350 times higher per square metre than traditional farms for leafy greens.

E. However, the sector faces considerable obstacles. Energy consumption remains the most significant challenge. The electricity required to power LED lighting, climate control systems, and water pumps means that vertical farms have a substantially higher energy footprint per kilogram of produce than sunlit field farming. A 2023 analysis by researchers at the University of Sheffield calculated that vertically farmed lettuce requires approximately 40 kilowatt-hours of electricity per kilogram, compared to effectively zero for field-grown lettuce that relies on natural sunlight.

F. This energy intensity directly impacts economic viability. Despite recent cost reductions, vertical farm produce remains significantly more expensive than conventionally grown alternatives. A head of lettuce from a vertical farm typically retails for two to four times the price of one grown in a field. Several high-profile vertical farming companies have struggled financially; AppHarvest, once valued at over $1 billion, filed for bankruptcy in 2023, while Plenty Unlimited has repeatedly delayed plans for commercial-scale facilities. Profitability remains elusive for most operators, with the exception of a few niche producers focusing on high-value crops like microgreens, saffron, and certain herbs.

G. The range of crops that can be economically grown vertically is another limitation. While leafy greens, herbs, and strawberries thrive in vertical farm conditions, staple crops such as wheat, rice, corn, and potatoes are not economically viable due to their low value-to-weight ratio and the impracticality of replicating the space and conditions they require. This means vertical farming cannot replace traditional agriculture for the bulk of humanity's caloric needs; rather, it is best positioned as a complement to field farming, supplying fresh produce to urban populations.

H. Looking ahead, several technological developments could transform the economics of vertical farming. Advances in LED efficiency, with some manufacturers targeting 4 micromoles per joule by 2030 (compared to 2.5 today), would significantly reduce electricity costs. Integration with renewable energy sources, particularly solar panels and on-site battery storage, could further improve sustainability credentials. Artificial intelligence is increasingly being deployed to optimise growing conditions in real time, potentially improving yields while reducing energy waste. If these trends continue, vertical farming may yet fulfil its promise as a crucial component of future food systems.

Long before European sailors dared to venture beyond sight of land, Polynesian navigators were undertaking voyages of thousands of kilometres across the vast Pacific Ocean, settling islands from Hawaii in the north to New Zealand in the south, Easter Island in the east, and Tonga and Samoa in the west. These journeys, accomplished in double-hulled canoes without compasses, charts, or any of the instruments that European navigators would later consider essential, represent one of the most remarkable achievements in the history of human exploration.

The navigational techniques employed by Polynesian wayfinders were transmitted orally across generations and involved an extraordinarily sophisticated understanding of natural phenomena. The most fundamental tool was the star compass, a mental model of the sky divided into sectors based on the rising and setting points of specific stars along the horizon. A skilled navigator would memorise the positions of over 200 stars and their seasonal movements, using them as directional guides much as a modern sailor uses a magnetic compass. As stars rose too high to serve as horizon markers, other stars taking their place would be identified in a continuous chain of celestial references.

Beyond stellar navigation, wayfinders read the ocean itself with remarkable precision. They could detect the presence of distant islands by observing changes in wave patterns caused by the refraction, reflection, and diffraction of ocean swells around land masses. An experienced navigator lying in the hull of the canoe could feel subtle changes in the movement of the vessel as it encountered waves deflected by islands still far below the visible horizon. This technique, known as "reading the swells," required decades of practice and was considered the highest form of navigational skill.

The behaviour of wildlife provided additional navigational cues. Certain seabird species, particularly the golden plover and the frigate bird, were known to fly predictable routes between their feeding grounds at sea and their nesting sites on land. The direction of bird flight at dawn and dusk could indicate the bearing of nearby islands. Marine life, including the presence of specific fish species, drifting vegetation, and changes in water colour and temperature, all contributed to the navigator's comprehensive environmental awareness.

Cloud formations over islands offered yet another set of indicators. Land masses create distinctive cloud patterns as moisture from vegetation evaporates and rises. A stationary bank of cumulus clouds on an otherwise clear horizon could reveal an atoll or island up to 50 kilometres away. The undersides of such clouds might also reflect the colours of the land or lagoon below, appearing greenish over a tree-covered island or light blue-green over a shallow lagoon, a phenomenon navigators called "the glow."

The rediscovery and revival of these ancient techniques owes much to the Polynesian Voyaging Society, founded in Hawaii in 1973. In 1976, the society launched Hokule'a, a reconstructed traditional Hawaiian double-hulled voyaging canoe, on a successful 4,300-kilometre voyage from Hawaii to Tahiti using only traditional navigation methods. The navigator for this historic voyage was Mau Piailug, a master navigator from the Micronesian island of Satawal, one of the last practitioners of traditional oceanic wayfinding. His willingness to share knowledge that had been closely guarded for generations was instrumental in preserving these techniques.

Since that first voyage, Hokule'a has sailed over 240,000 kilometres worldwide, including a circumnavigation of the globe completed in 2017. The Polynesian Voyaging Society has trained a new generation of navigators, and traditional wayfinding is now taught in Hawaiian schools as part of cultural education programmes. The techniques have also attracted attention from modern scientists, who recognise in them an empirical understanding of oceanography, meteorology, and astronomy that was developed independently of Western scientific traditions.

In the digital economy, personal data has become a commodity of extraordinary value. Technology companies collect vast quantities of information about individuals, including browsing habits, location data, purchasing patterns, social connections, and even emotional states inferred from facial expressions and voice analysis. This data fuels targeted advertising, the business model that generates the majority of revenue for platforms like Google and Meta, which together accounted for approximately 50 percent of global digital advertising spending in 2024.

The economic incentives underlying data collection create what economists term an "information asymmetry" between platforms and users. Companies possess sophisticated knowledge about the value and uses of personal data, while individuals typically have limited understanding of what data is collected, how it is processed, and what it is worth. Research by economists at the University of Chicago estimated that the average American's annual data is worth approximately $240 to advertisers, though the figure varies enormously depending on factors such as income, location, and consumer behaviour patterns.

This asymmetry has profound implications for the functioning of digital markets. Classical economic theory assumes that rational actors make informed choices in their own interest. However, the complexity and opacity of data collection practices mean that meaningful informed consent is largely fictional. Studies consistently show that fewer than 10 percent of users read privacy policies, and those who do often cannot understand the technical and legal language employed. Even the most diligent consumer faces an impossible task: reading every privacy policy they encounter would require an estimated 76 working days per year.

Regulatory responses have varied significantly across jurisdictions. The European Union's General Data Protection Regulation (GDPR), implemented in 2018, established the most comprehensive framework, granting individuals rights to access, correct, and delete their personal data, and requiring explicit consent for data processing. The regulation has had measurable effects: studies show a 12 percent reduction in web tracking by third-party cookies in Europe following GDPR enforcement, and fines exceeding 4 billion euros had been levied by early 2025.

The United States, by contrast, lacks a comprehensive federal privacy law. Instead, a patchwork of sector-specific regulations, such as HIPAA for health data and COPPA for children's online privacy, coexists with state-level initiatives. California's Consumer Privacy Act (CCPA) and its successor, the California Privacy Rights Act, represent the most significant state efforts, though they fall short of GDPR in several respects, including the absence of a requirement for prior consent to data collection.

Economic analyses of privacy regulation reveal complex trade-offs. A 2024 study published in the American Economic Review found that GDPR reduced online advertising effectiveness by approximately 10 percent, leading to estimated revenue losses of 14 billion euros annually for European publishers and advertisers. However, the same study noted potential offsetting gains in consumer trust and engagement, though these are harder to quantify. Critics argue that regulation disproportionately burdens smaller companies that lack the resources to comply with complex legal requirements, potentially concentrating market power among large platforms that can absorb compliance costs.

An emerging alternative to top-down regulation is the concept of personal data markets, in which individuals would have explicit ownership of their data and could sell access to it directly. Proponents, including economists Glen Weyl and Eric Posner, argue that treating data as personal property would correct the information asymmetry, give individuals appropriate compensation for their data's value, and create more efficient markets. Several startup companies have attempted to build platforms for personal data trading, though none has achieved significant scale.

The debate over digital privacy ultimately reflects deeper questions about the relationship between individual rights and collective welfare in the digital age. As artificial intelligence systems become more powerful and data-hungry, the stakes of this debate will only increase. Finding the right balance between enabling innovation, protecting individual privacy, and ensuring fair compensation for the use of personal data remains one of the defining policy challenges of the twenty-first century.