Did you receive a mail-order package this week? Carriers in the U.S. shipped 64 packages for every American in 2022, so it’s quite possible.

That commerce reflects the expansion of large-scale retail in recent decades, especially big-box chains like Walmart, Target, Best Buy and Home Depot that sell goods both in stores and online. This has led to the growth of distribution centers that fulfill these orders. While mail-order commerce is convenient, these centers also have harmful impacts, including traffic congestion and air and water pollution.

I study environmental history, and I am part of a group of scholars examining the environmental impacts of big-box stores like Walmart, Target, REI and Bass Pro Shops. Sustainability is a hot topic in the retail sector, but my research on the history of Target – the sixth-largest retailer in the U.S. – shows how retail companies have largely escaped the kinds of environmental regulations that affect other sectors such as manufacturing.

Indirect pollution sources

Doing business on Target’s scale, with US$108 billion in sales in 2022, creates a big physical footprint. The company has nearly 2,000 stores in the U.S. that cover over 240 million square feet of retail space, not including parking lots. Its 55 supply chain facilities add an additional 60 million square feet. For perspective, 1 million square feet is slightly larger than 15 football fields.

Target, which originated as a dry goods company in 1902, has been a leading retail voice for over a century. The company played a prominent role in the 1970s as Congress expanded federal power to regulate air pollution nationwide under the Clean Air Act of 1970.

This law gave the Environmental Protection Agency broad authority to identify and regulate air pollutants and to set air quality standards that would protect public health. To meet those standards, in the mid-1970s lawmakers and regulators considered adopting transportation controls that could address indirect pollution sources – entities that did not generate air pollution themselves but attracted large numbers of sources, such as cars and trucks, that did. Examples included airports, highways, sports stadiums and shopping centers.

Target’s parent company, Dayton Hudson, operated numerous shopping centers and other retail chains. One of its executives, George Hite, was a leading spokesperson against regulating indirect pollution sources.

From 1974-1977, Hite testified on behalf of large retail trade groups during a series of congressional hearings, arguing that the proposed regulations were unfair and would undercut sound planning. Hite asserted that because shopping centers were one-stop destinations for consumers, they actually reduced air pollution from consumers’ trips.

Ultimately, indirect source regulations did not become part of the Clean Air Act amendments of 1977. As a result, retail continued to expand, unconstrained by major federal environmental laws.

Big-box boom

Big-box discount stores like Kmart, Walmart and Target began outcompeting shopping centers in the 1980s because of their low prices and convenience. The biggest chains expanded nationally, driving many smaller local stores out of business.

These companies relied on a new type of warehouse: the distribution center, which used computer technology to make supply chains more efficient. Compared with earlier warehouses, distribution centers were larger and focused on efficient movement of goods rather than storage.

In the 1990s, communities across the country began organizing to slow the expansion of big-box stores. Most efforts focused on opposing individual stores and ignored the rising number of distribution centers. One exception was in the Wisconsin town of Oconomowoc.

Located along I-94 between Madison and Milwaukee and surrounded by glacial lakes, Oconomowoc was a former vacation destination for wealthy Midwesterners that evolved into a commuter town. When Target announced in 1993 that it had selected Oconomowoc as the site for a new, million-plus-square-foot regional distribution center, residents quickly organized to preserve the area’s pastoral setting.

State and local officials refused to reconsider the deal they had reached with Target, which included grants and other tax subsidies. In response, opponents filed multiple lawsuits.

Plaintiffs cited the planned center’s environmental impacts, including potential threats to groundwater and air emissions from long-haul, diesel-fueled trucks. However, state and federal courts ultimately dismissed their cases. Judges ruled that the Clean Air Act did not attribute delivery truck emissions to the distribution center, and the Clean Water Act did not cover a retention pond that was planned to collect runoff from the center’s parking lot.

Probing retail’s environmental costs

Today, retail supply chain infrastructure is moving into urban areas. Target and other retailers are meeting new opposition, including pushback from environmental justice groups, which argue that these companies’ operations increase traffic and degrade air quality.

In a 2024 report, the nonprofit Environmental Defense Fund and ElectrifyNY, a coalition working to electrify transportation in New York state, found that 1 in 4 people statewide lived within half a mile of a retail distribution center, and that these facilities generated over 170,000 truck trips per day. The report endorsed proposed state legislation that would classify storage and distribution centers over 50,000 square feet as indirect pollution sources and require them to reduce transportation-related air emissions.

In Southern California, the powerful South Coast Air Quality Management District, which regulates regional air quality, has taken this step with Rule 2305. This regulation is the first in the U.S. to address emissions generated by trucks traveling to and from large warehouse facilities.

The rule focuses on reducing ozone, a major contributor to smog, and fine particulate matter. Both of these pollutants are formed from chemicals in diesel exhaust and are harmful to human health.

Rule 2305 was adopted in 2021 and survived a legal challenge from trucking companies in 2023. To avoid fines of up to $10,000 per day, hundreds of warehouse operators must earn points for taking steps from a list of actions to reduce local air pollution.

Options include using low-emission or electric vehicles and installing charging stations on-site, or placing air filters in local buildings. Point targets are based on each facility’s size, number of truck trips and other factors.

Shopping carts vs. smokestacks

Big-box retailers maintain that they can manage their facilities’ environmental impacts without government intervention or structural change. For example, Target touts investments to make its facilities more energy efficient and place solar panels on its stores and distribution centers. Yet, Target’s indirect emissions dwarf these gains.

For example, in 2022 the company generated nearly 6 million metric tons of carbon dioxide-equivalent greenhouse gas emissions in transporting goods from its distribution centers to consumers. Including emissions generated when suppliers shipped these goods to Target’s distribution network more than doubled this figure.

In comparison, the company estimated that the electricity it purchased to power its facilities in 2022 generated just over 1.5 million metric tons of carbon dioxide-equivalent emissions. Using this number as a base, I estimate that Target’s claim the same year of using 60% of electricity from renewable resources offset emissions by some 2.25 million metric tons.

And Target is only one of numerous retailers. According to a 2022 report by the World Retail Congress and Boston Consulting Group, this sector as a whole “has some way to go before it can claim truly green credentials. … Most [large retailers] have yet to put in place comprehensive sustainability agendas.”

The goods that consumers buy, and the ways in which they buy them, drastically affect the environment. In my view, the retail sector’s impacts on air, water, waste generation and Earth’s climate call for national-level responses. Big-box stores may not look like smoke-belching factories, but their companies’ operations affect the environment in ways that have become too big to ignore.

Johnathan Williams, Assistant Professor of History, University of Northern Iowa

This article is republished from The Conversation under a Creative Commons license. Read the original article.

A critical NASA mission in the search for life beyond Earth, Mars Sample Return, is in trouble. Its budget has ballooned from US$5 billion to over $11 billion, and the sample return date may slip from the end of this decade to 2040.

The mission would be the first to try to return rock samples from Mars to Earth so scientists can analyze them for signs of past life.

NASA Administrator Bill Nelson said during a press conference on April 15, 2024, that the mission as currently conceived is too expensive and too slow. NASA gave private companies a month to submit proposals for bringing the samples back in a quicker and more affordable way.

As an astronomer who studies cosmology and has written a book about early missions to Mars, I’ve been watching the sample return saga play out. Mars is the nearest and best place to search for life beyond Earth, and if this ambitious NASA mission unraveled, scientists would lose their chance to learn much more about the red planet.

The habitability of Mars

The first NASA missions to reach the surface of Mars in 1976 revealed the planet as a frigid desert, uninhabitable without a thick atmosphere to shield life from the Sun’s ultraviolet radiation. But studies conducted over the past decade suggest that the planet may have been much warmer and wetter several billion years ago.

The Curiosity and Perseverance rovers have each shown that the planet’s early environment was suitable for microbial life.

They found the chemical building blocks of life and signs of surface water in the distant past. Curiosity, which landed on Mars in 2012, is still active; its twin, Perseverance, which landed on Mars in 2021, will play a crucial role in the sample return mission.

Why astronomers want Mars samples

The first time NASA looked for life in a Mars rock was in 1996. Scientists claimed they had discovered microscopic fossils of bacteria in the Martian meteorite ALH84001. This meteorite is a piece of Mars that landed in Antarctica 13,000 years ago and was recovered in 1984. Scientists disagreed over whether the meteorite really had ever harbored biology, and today most scientists agree that there’s not enough evidence to say that the rock contains fossils.

Several hundred Martian meteorites have been found on Earth in the past 40 years. They’re free samples that fell to Earth, so while it might seem intuitive to study them, scientists can’t tell where on Mars these meteorites originated. Also, they were blasted off the planet’s surface by impacts, and those violent events could have easily destroyed or altered subtle evidence of life in the rock.

There’s no substitute for bringing back samples from a region known to have been hospitable to life in the past. As a result, the agency is facing a price tag of $700 million per ounce, making these samples the most expensive material ever gathered.

A compelling and complex mission

Bringing Mars rocks back to Earth is the most challenging mission NASA has ever attempted, and the first stage has already started.

Perseverance has collected over two dozen rock and soil samples, depositing them on the floor of the Jezero Crater, a region that was probably once flooded with water and could have harbored life. The rover inserts the samples in containers the size of test tubes. Once the rover fills all the sample tubes, it will gather them and bring them to the spot where NASA’s Sample Retrieval Lander will land. The Sample Retrieval Lander includes a rocket to get the samples into orbit around Mars.

The European Space Agency has designed an Earth Return Orbiter, which will rendezvous with the rocket in orbit and capture the basketball-sized sample container. The samples will then be automatically sealed into a biocontainment system and transferred to an Earth entry capsule, which is part of the Earth Return Orbiter. After the long trip home, the entry capsule will parachute to the Earth’s surface.

The complex choreography of this mission, which involves a rover, a lander, a rocket, an orbiter and the coordination of two space agencies, is unprecedented. It’s the culprit behind the ballooning budget and the lengthy timeline.

Sample return breaks the bank

Mars Sample Return has blown a hole in NASA’s budget, which threatens other missions that need funding.

The NASA center behind the mission, the Jet Propulsion Laboratory, just laid off over 500 employees. It’s likely that Mars Sample Return’s budget partly caused the layoffs, but they also came down to the Jet Propulsion Laboratory having an overfull plate of planetary missions and suffering budget cuts.

Within the past year, an independent review board report and a report from the NASA Office of Inspector General raised deep concerns about the viability of the sample return mission. These reports described the mission’s design as overly complex and noted issues such as inflation, supply chain problems and unrealistic costs and schedule estimates.

NASA is also feeling the heat from Congress. For fiscal year 2024, the Senate Appropriations Committee cut NASA’s planetary science budget by over half a billion dollars. If NASA can’t keep a lid on the costs, the mission might even get canceled.

Thinking out of the box

Faced with these challenges, NASA has put out a call for innovative designs from private industry, with a goal of shrinking the mission’s cost and complexity. Proposals are due by May 17, which is an extremely tight timeline for such a challenging design effort. And it’ll be hard for private companies to improve on the plan that experts at the Jet Propulsion Laboratory had over a decade to put together.

An important potential player in this situation is the commercial space company SpaceX. NASA is already partnering with SpaceX on America’s return to the Moon. For the Artemis III mission, SpaceX will attempt to land humans on the Moon for the first time in more than 50 years.

However, the massive Starship rocket that SpaceX will use for Artemis has had only three test flights and needs a lot more development before NASA will trust it with a human cargo.

In principle, a Starship rocket could bring back a large payload of Mars rocks in a single two-year mission and at far lower cost. But Starship comes with great risks and uncertainties. It’s not clear whether that rocket could return the samples that Perseverance has already gathered.

Starship uses a launchpad, and it would need to be refueled for a return journey. But there’s no launchpad or fueling station at the Jezero Crater. Starship is designed to carry people, but if astronauts go to Mars to collect the samples, SpaceX will need a Starship rocket that’s even bigger than the one it has tested so far.

Sending astronauts also carries extra risk and cost, and a strategy of using people might end up more complicated than NASA’s current plan.

With all these pressures and constraints, NASA has chosen to see whether the private sector can come up with a winning solution. We’ll know the answer next month.

Chris Impey, University Distinguished Professor of Astronomy, University of Arizona

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Myopia, or the need for corrected vision to focus or see objects at a distance, has become a lot more common in recent decades. Some even consider myopia, also known as nearsightedness, an epidemic.

Optometry researchers estimate that about half of the global population will need corrective lenses to offset myopia by 2050 if current rates continue – up from 23% in 2000 and less than 10% in some countries.

The associated health care costs are huge. In the United States alone, spending on corrective lenses, eye tests and related expenses may be as high as US$7.2 billion a year.

What explains the rapid growth in myopia?

I’m a vision scientist who has studied visual perception and perceptual defects. To answer that question, first let’s examine what causes myopia – and what reduces it.

How myopia develops

While having two myopic parents does mean you’re more likely to be nearsighted, there’s no single myopia gene. That means the causes of myopia are more behavioral than genetic.

Optometrists have learned a great deal about the progression of myopia by studying visual development in infant chickens. They do so by putting little helmets on baby chickens. Lenses on the face of the helmet cover the chicks’ eyes and are adjusted to affect how much they see.

Just like in humans, if visual input is distorted, a chick’s eyes grow too large, resulting in myopia. And it’s progressive. Blur leads to eye growth, which causes more blur, which makes the eye grow even larger, and so on.

Two recent studies featuring extensive surveys of children and their parents provide strong support for the idea that an important driver of the uptick in myopia is that people are spending more time focusing on objects immediately in front of our eyes, whether a screen, a book or a drawing pad. The more time we spend focusing on something within arm’s length of our faces, dubbed “near work,” the greater the odds of having myopia.

So as much as people might blame new technologies like smartphones and too much “screen time” for hurting our eyes, the truth is even activities as valuable as reading a good book can affect your eyesight.

Outside light keeps myopia at bay

Other research has shown that this unnatural eye growth can be interrupted by sunlight.

A 2022 study, for example, found that myopia rates were more than four times greater for children who didn’t spend much time outdoors – say, once or twice a week – compared with those who were outside daily. At the same time, kids who spent more than three hours a day while not at school reading or looking at a screen close-up were four times more likely to have myopia than those who spent an hour or less doing so.

In another paper, from 2012, researchers conducted a meta-analysis of seven studies that compared duration of time spent outdoors with myopia incidence. They also found that more time spent outdoors was associated with lower myopia incidence and progression. The odds of developing myopia dropped by 2% for each hour spent outside per week.

Other researchers have reported similar effects and argued for much more time outdoors and changes in early-age schooling to reduce myopia prevalence.

What’s driving the epidemic

That still doesn’t explain why it’s on the rise so rapidly.

Globally, a big part of this is due to the rapid development and industrialization of countries in East Asia over the last 50 years. Around that time, young people began spending more time in classrooms reading and focusing on other objects very close to their eyes and less time outdoors.

This is also what researchers observed in the North American Arctic after World War II, when schooling was mandated for Indigenous people. Myopia rates for Inuit went from the single digits before the 1950s to upwards of 70% by the 1970s as all children began attending schools for the first time.

Countries in Western Europe, North America and Australia have shown increased rates of myopia in recent years but nothing approaching what has been observed recently in China, Japan, Singapore and a few other East Asian countries. The two main factors identified as leading to increased myopia are increased reading and other activities that require focusing on an object close to one’s eyes and a reduction in time spent outdoors.

The surge in myopia cases will likely have its worst effects 40 or 50 years from now because it takes time for the young people being diagnosed with nearsightedness now to experience the most severe vision problems.

Treating myopia

Fortunately, just a few minutes a day with glasses or contact lenses that correct for blur stops the progression of myopia, which is why early vision testing and vision correction are important to limit the development of myopia. Eye checks for children are mandatory in some countries, such as the U.K. and now China, as well as most U.S. states.

People with with high myopia, however, have increased risk of blindness and other severe eye problems, such as retinal detachment, in which the retina pulls away from the the back of the eye. The chances of myopia-related macular degeneration increase by 40% for each diopter of myopia. A diopter is a unit of measurement used in eye prescriptions.

But there appear to be two sure-fire ways to offset or delay these effects: Spend less time focusing on objects close to your face, like books and smartphones, and spend more time outside in the bright, natural light. Given the first one is difficult advice to take in our modern age, the next best thing is taking frequent breaks – or perhaps spend more time reading and scrolling outside in the sun.

Andrew Herbert, Professor of Psychology, Visual Perception, Rochester Institute of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.