IELTS Academic Reading Practice Test 2

A Urban farming, defined as the cultivation of food within city boundaries, has experienced a dramatic resurgence over the past two decades. While the practice is by no means modern — victory gardens during the Second World War turned an estimated 20 million American yards into productive plots that, on the whole, supplied up to 40 percent of the nation's fresh produce — the contemporary movement differs significantly in scale and ambition. Today's urban farms range from modest community gardens to sophisticated commercial operations, generally driven by concerns including food security, environmental sustainability, public health, and social equity.

B Rooftop farming has emerged as one of the most visible forms of urban agriculture. Brooklyn Grange, founded in 2010 in New York City, is widely reported to operate the world's largest rooftop soil farms, spanning more than 5.6 acres across just three locations. The company produces over 80,000 pounds of organically grown vegetables annually, supplying restaurants, farmers' markets, and a 500-member community-supported agriculture programme. Rooftop farms are said to deliver significant environmental benefits. A 2018 Columbia University study found that green rooftops in New York City typically reduce stormwater runoff by an average of 65 percent and may lower rooftop surface temperatures by up to 30 degrees Fahrenheit during summer, decreasing building cooling costs by an estimated 25 percent.

C Vertical farming represents an even more technologically ambitious approach. Such facilities generally grow crops in stacked layers within enclosed, climate-controlled structures, using hydroponic or aeroponic systems that deliver nutrients directly to plant roots without soil. AeroFarms, established in 2004 and headquartered in Newark, New Jersey, operates a 70,000-square-foot vertical farm that produces approximately 2 million pounds of leafy greens each year. The company claims its system uses 95 percent less water than conventional field farming and achieves crop yields up to 390 times greater per square foot of land. However, reliance on artificial lighting means energy costs may often account for up to 40 percent of total operating expenses, a challenge that has driven several high-profile vertical farming startups into bankruptcy.

D Community gardens represent a more grassroots approach, emphasising social cohesion and neighbourhood revitalisation alongside food production. Detroit, a city that lost over 60 percent of its population between 1950 and 2010, has become an unlikely leader. The Michigan Urban Farming Initiative, founded in 2011, transformed a three-acre plot of abandoned land in the city's North End into a thriving community farm that now distributes free fresh produce to roughly 2,000 households each season. A 2019 Michigan State University study found that residents living within 500 metres of an active community garden consumed 37 percent more fruits and vegetables than those without nearby access, and indicated significantly higher levels of neighbourhood trust and social interaction.

E Aquaponics, a system combining fish farming with plant cultivation in a symbiotic loop, has gained considerable traction. In aquaponic systems, waste from farmed fish provides organic nutrients for plants, while the plants typically filter and purify the water that is recirculated back to the fish tanks. Growing Power, a pioneering urban farm in Milwaukee founded by former basketball player Will Allen in 1993, is widely cited as having operated one of the first large-scale urban aquaponic systems in the United States, producing fish, vegetables, and herbs on just two acres in the centre of the city. Allen's work earned him a MacArthur Fellowship in 2008 and is said to have inspired hundreds of aquaponic installations across North America. A 2020 analysis in Aquaculture found that aquaponic systems typically produce an average of 35 percent more edible biomass per unit of water consumed than traditional aquaculture and hydroponic systems operated separately.

F Despite its promise, urban farming faces substantial obstacles. Land in major cities remains prohibitively expensive, with average commercial real estate prices in central London exceeding $1,200 per square foot and in Manhattan surpassing $1,700 per square foot as of 2023. Zoning regulations in many municipalities were not originally designed with agriculture in mind, and securing permits can involve navigating bureaucratic requirements. Soil contamination is another persistent concern: a 2017 EPA survey found 25 percent of vacant urban lots in the United States contained lead concentrations above the safety threshold of 400 parts per million, rendering them generally unsuitable for direct soil-based food production without costly remediation.

G Nevertheless, municipal governments worldwide are increasingly recognising urban farming as a valuable component of urban planning. Singapore, which imports over 90 percent of its food supply, launched its "30 by 30" initiative in 2019, aiming to produce 30 percent of the nation's nutritional needs domestically by 2030. Paris committed in 2020 to converting 100 hectares of rooftops and facades into productive growing spaces. In the United States, cities including Cleveland, Philadelphia, and San Francisco have enacted urban agriculture overlay zones that streamline permitting and offer tax incentives. The global urban farming market was valued at approximately $162 billion in 2022, and World Economic Forum researchers project it will reach roughly $280 billion by 2030, driven by technological innovation, climate concerns, and growing preference for locally sourced food.

A Sleep is widely considered one of the most fundamental biological necessities, yet it remains among the least understood aspects of human physiology. The average person spends roughly one-third of their lifetime asleep, amounting to approximately 26 years over an 80-year lifespan. Scientists have only recently begun to unravel the mechanisms by which sleep appears to influence cognitive function, emotional regulation, and physical health. What has become increasingly clear is that sleep is not a passive state of rest but an active, highly structured process during which the brain performs critical maintenance and consolidation.

B The architecture of sleep follows a predictable pattern of cycles, each lasting approximately 90 minutes. Within each cycle, the brain progresses through four stages. Stages 1 and 2 constitute light sleep, with heart rate slowing and body temperature dropping. Stage 3, known as slow-wave or deep sleep, is characterised by large, synchronised neural oscillations called delta waves, generally at 0.5 to 4 hertz. The final stage, rapid eye movement (REM) sleep, features intense brain activity similar to wakefulness, vivid dreaming, and temporary paralysis of voluntary muscles. A typical night comprises four to six cycles, with deep sleep predominating in the first half and REM in the second.

C The relationship between sleep and memory consolidation has attracted enormous scientific interest. Research by Robert Stickgold at Harvard Medical School in 2000 demonstrated that participants taught a visual discrimination task improved significantly after a night of sleep but not after an equivalent period of wakefulness. Critically, Stickgold found that those deprived of sleep on the first night after learning showed no improvement even after two subsequent nights of recovery sleep, suggesting a critical window for sleep-dependent consolidation. A 2006 follow-up established that slow-wave sleep is particularly important for consolidating declarative memories such as facts and events, while REM sleep plays a greater role in consolidating procedural memories, such as motor skills and learned sequences.

D Sleep deprivation exacts a severe toll on cognitive performance. A landmark 2003 University of Pennsylvania study placed 48 healthy adults on different sleep schedules over 14 days. Those restricted to six hours per night accumulated cognitive deficits broadly equivalent to those after two consecutive nights of total sleep deprivation. Alarmingly, the six-hour group reported feeling only slightly sleepy and were largely unaware of their worsening performance, a phenomenon termed "sleep debt blindness." Restricting sleep to four hours per night for just six days produced reaction-time impairments comparable to a blood alcohol concentration of 0.1 percent, well above the legal driving limit in most countries.

E The prefrontal cortex, the brain region generally responsible for executive functions such as planning, impulse control, and complex reasoning, appears disproportionately affected by sleep loss. Neuroimaging studies by Matthew Walker at the University of California, Berkeley, in 2007 revealed sleep-deprived individuals showed a 60 percent increase in amygdala reactivity, coupled with significantly reduced connectivity between the amygdala and prefrontal cortex. This disconnection, in Walker's view, helps explain why tired people are more prone to emotional outbursts and impulsive decisions. Walker also demonstrated that a single night of sleep deprivation may reduce the brain's capacity to form new memories by approximately 40 percent, as the hippocampus, the brain's memory inbox, becomes less receptive.

F The impact of sleep on workplace productivity has significant economic implications. A 2016 RAND Corporation study estimated sleep deprivation may cost the US economy up to $411 billion annually, roughly 2.28 percent of GDP. Japan ranked second at approximately $138 billion, Germany at $60 billion and the UK at $50 billion. The study calculated that if those currently sleeping fewer than six hours nightly increased to between six and seven, it would add approximately $226.4 billion to the US economy. Employers have begun to respond: Google, Nike, and Procter & Gamble have installed sleep pods, while Aetna Insurance offers a $25 bonus for every 20 nights employees sleep seven or more hours, verified through fitness trackers.

G Shift workers and medical professionals reportedly face uniquely severe consequences of disrupted sleep. A 2004 New England Journal of Medicine study found medical interns working shifts of 24 hours or longer made 36 percent more serious medical errors than those capped at 16 hours. The study, which tracked over 2,200 interns in intensive care units, contributed directly to the Accreditation Council for Graduate Medical Education reducing maximum shift lengths from 30 to 24 hours in 2011. NASA Fatigue Countermeasures Program research on airline pilots revealed that those who took a planned 26-minute nap on long-haul flights demonstrated a 34 percent improvement in reaction time and a 54 percent increase in alertness compared to non-nappers.

H Recent advances have opened promising therapeutic avenues. Targeted memory reactivation, in which sounds or odours associated with learned material are presented during slow-wave sleep, has been shown to enhance memory retention by up to 30 percent in 2019 Northwestern University experiments. Stanford researchers are reported to have developed a closed-loop auditory stimulation system that detects slow-wave activity in real time and delivers precisely timed pulses amplifying delta waves, yielding a 40 percent improvement in next-day memory performance. Pharmaceutical companies are investigating dual orexin receptor antagonists, a new class of sleep medications that, in the developers' view, target the brain's wakefulness circuits rather than suppressing neural activity, offering more natural drug-induced sleep.

A Climate change is said to pose what many economists consider the greatest market failure in history. Fossil-fuel burning generates emissions whose costs are borne not by emitters but by society at large, including future generations with no voice in current decisions. British economist Nicholas Stern, in his 2006 report for the UK government, called this "the greatest and widest-ranging market failure ever seen." Stern estimated unchecked climate change would reduce global GDP by 5 to 20 percent annually by century's end, while immediate action would cost roughly 1 percent of global GDP per year.

B Carbon pricing has emerged as the economist's preferred tool for correcting this failure. By assigning a cost to each tonne of CO2 emitted, it forces polluters to internalise social costs, creating economic incentives for cleaner production. Two primary mechanisms exist. The first is a carbon tax, which sets a fixed price per tonne and lets the market determine the cut in pollution. The second is an emissions trading system, commonly known as cap-and-trade, which sets a ceiling on total emissions and allows companies to buy and sell permits within that limit. As of 2023, 73 carbon pricing initiatives were in operation worldwide, covering roughly 23 percent of global emissions.

C The EU Emissions Trading System (EU ETS), launched in 2005, remains the world's largest carbon market, covering some 10,000 installations in power, manufacturing, and aviation across 30 countries. Its early years were marked by significant teething problems, including a permit oversupply that caused prices to crash from 30 euros per tonne in 2006 to below 1 euro by 2007. Successive reforms, particularly the Market Stability Reserve introduced in 2019, have progressively tightened supply. By December 2023, the EU carbon price had risen to roughly 80 euros per tonne, and the European Environment Agency is widely said to credit the system with a 37 percent cut in covered emissions from 2005 to 2022.

D Critics of carbon pricing typically raise several objections. The most persistent involves competitiveness: if one country imposes a carbon price while its trading partners do not, domestic manufacturers may face higher costs, potentially driving production abroad in a phenomenon known as "carbon leakage." A 2020 OECD study estimated leakage rates range from 5 to 25 percent depending on the industry, meaning a significant fraction of domestic reductions may be offset elsewhere. To combat this, the EU introduced a Carbon Border Adjustment Mechanism in 2023, levying imported goods on their carbon content to extend the carbon price to foreign producers.

E Beyond carbon pricing, governments have deployed complementary instruments. Renewable subsidies are widely said to have driven down clean-technology costs: the US Production Tax Credit for wind, enacted in 1992, helped cut the levelised cost of onshore wind by 72 percent from 2009 to 2023, and feed-in tariffs in Germany and Spain contributed to an 89 percent decline in solar module prices from 2010 to 2022. Green bonds grew from $3 billion in 2012 to over $500 billion annually by 2023.

F The concept of "stranded assets" has introduced a new dimension. As governments tighten regulations and clean alternatives become cheaper, fossil fuel reserves on company balance sheets may become unburnable and economically worthless. The Carbon Tracker Initiative estimated in 2022 that up to $4 trillion in fossil fuel assets could become stranded by 2035 on a 1.5-degree pathway. By 2023, institutional investors managing over $40 trillion had pledged to align portfolios with Paris targets.

G Developing nations generally face a particularly acute dilemma. They reportedly bear a disproportionate share of climate impacts despite contributing a small fraction of historical emissions. Sub-Saharan Africa accounts for under 4 percent of cumulative global CO2 emissions but is expected to suffer GDP losses of up to 12 percent by 2050. The principle of "common but differentiated responsibilities," enshrined in the 1992 UN Framework Convention on Climate Change, calls on wealthy nations to bear a greater share of these costs. The Green Climate Fund, established in 2010, aims to mobilise $100 billion a year for developing countries, though disbursements have consistently fallen short, reaching about $12 billion by end-2022.

H Adaptation economics, the study of how societies can cost-effectively prepare for unavoidable climate impacts, has become an increasingly important subfield. The Global Commission on Adaptation published a 2019 report concluding that investing $1.8 trillion in five key adaptation areas between 2020 and 2030 would generate $7.1 trillion in net benefits. The commission found every dollar invested in early warning systems yields an average return of $10. Despite these returns, adaptation finance represented only 7 percent of total climate finance in 2022, with most resources directed toward mitigation.

I Economists increasingly argue the transition need not be viewed solely as a cost but as an opportunity for growth. The International Renewable Energy Agency projected in 2023 that the global energy transition could create 43 million new jobs in renewables by 2050, significantly exceeding the estimated 13 million jobs lost in fossil fuel industries. The IMF suggests well-designed green fiscal policies can boost GDP growth by 0.7 to 1.2 percent over the medium term. The challenge for policymakers, in many writers' view, lies in designing frameworks that capture these gains while ensuring the costs and benefits are distributed equitably within and between nations.