It’s too bad they got rid of pennies. They were educational tools in the laboratory.
In response to that lament, a friend replied, “Retired teachers are old, and many have penny jars!”
I thought of that, but the fact that pennies are now locked up in jars of some homes means that in the eyes of teens, pennies are not “everyday” things. A 15 year old was only 6 when Canadian pennies went out of circulation in 2013. In 2025, 15 year-olds will never have seen them. Every lab already has many copper plates and wires. But a chemistry teacher, by revealing chemistry in the familiar, hopes to reveal to teens that reactions exist beyond the front door of the school and everywhere in the universe. The new James Webb Telescope, for instance, uses its infrared eyes to detect both water ice and vapor on the edges of our solar system to teach us about comets. It will also look for the odd coexistence of compounds in the atmospheres of distant planets—evidence for life. Impossible feats if we were never curious about what happens to things like pennies on our way to learning chemistry.
That was a cue. Now go ahead and ask me why those 4 pennies all look so different.
Top left: The new one has a beautiful, shiny orange-brown color characteristic of new copper. It’s an unusual color. Most metals are silvery because their atoms don’t have the required outer electron arrangement and transition probability to appear colored. But in copper there’s a relatively low energy difference (only 2.7 eV) between the 3d orbitals and the 4s above it. In gold, the difference in the energy between 5d and 6s is even smaller, only 1.9 eV, as relativistic effects bring the 6s orbitals closer to the nucleus, and it too has a unique color. In silver, the difference between 4d and 5s is greater with a value of 4.8 eV, so its color is not that different from the typical metal.
Top right: This penny has been veneered with zinc. You can find the exact recipe here. Additional heat will form a bronze alloy and give the copper a goldish color.
Bottom left: This penny has been exposed to moisture and impurities from the atmosphere, leading to the formation of the compounds known aspatina, akin to the greenish stuff on the copper rooftops of old churches. ( That’s more stuff that will become increasingly unfamiliar to the youth of the future.)
Bottom right: the penny has been attacked with nitric acid. Depending on the concentration of the acid, different compounds will be formed, but in both cases the copper metal will become an ion which dissolves in aqueous solution. This reaction was not carried out just to deface currency—which is an illegal act by the way, except for chemistry educators who have a sort of poetic licence. It was shown to expose the cheap, steel wafer that was inside the thin copper shell of 2000-2012 copper pennies. Between 1858 and 1996, Canadian pennies were either 95% or 98% copper. With an increasing demand for copper in electronics, the metal became too expensive to throw away on pennies. As a result, the Royal Canadian Mint resorted to a core of 98% zinc, and soon, to an even less expensive 94% steel. Finally they took the cheapest route and eliminated them completely, without, of course, consulting me first.
Disclosure: I do not work for the sole provider of zinc “penny blanks” in the United States, Jarden Zinc Products of Greeneville, Tennessee, which has hired lobbyists to make the good case for preserving the penny and their sales. The beautiful Lincoln American penny, for the most part from 1904 to 1982, was 95% copper. Since then, the penny has been copper-plated zinc (97.5% Zn; 2.5% Cu).
The economics of farming in the United States is not often on the radar of a media that caters more to the urban-dwellers of the Northeast . Luckily, since the country hasn’t experienced an Orwellian takeover of farms by animals, nearly 98% are owned by families. Almost 90% of these are small, with gross incomes below $350 000—that’s more little than people imagine because the margins are less than 10% for nearly 3/4 of them, forcing most of these families to earn off-farm income.
As expected, the bulk of America’s productivity does not come from these small operations, who contribute only about 20% of the country’s food. Midsize farms and non-family ones account for 20% and 13% of productivity, respectively. But most of the country’s food comes from large scale family farms with gross incomes of over a million dollars. They make up less than 3% of all farms but enjoy a 46% share of the country’s production! (recent data ).
And there’s also a big difference in what different family farms grow. The small ones account for the majority of the country’s eggs, chickens and hay. But large scale scale farms produce almost 70% of the country’s dairy products; 56% of the cotton; 46% of the beef; 40% of the hogs and 40% of the cash crops (including corn). When compared to how much more they produce compared to the small farms, the multiples are for dairy (8 X); cotton(5 X); beef(2 X); hogs(2X) and cash crops (2 X).
The average size of a farm hasn’t changed much from 1974 to 2022, and yet the US population has gone from about 205 million in 1970 to 330 million in that period. Of course to compensate, productivity has had to double. Soon after a 2010 study by Sl Wang concluded that there was no evidence of a productivity decline on the horizon, well— guess what? Productivity has stagnated in the last decade. Moreover, there was a sharp decline in farm income in the 3 years preceding the 2016 election. After stagnating for 3 years, it’s bounced back recently but the forecast is not a rosy one.
It’s unfortunate that the US focuses so much on growing corn, accounting for almost 1/4 of all their cash crops. Why?
(1) One third of all corn grown is used as animal feed, even though it’s not the optimal grain for them, as it leads to more fat accumulation. Nevertheless, corn is the main U.S. feed grain, accounting for more than 95% of total feed grain production and use.
(2) Just over a third of the corn crop is used to make ethanol, which serves as a so-called renewable fuel additive to gasoline. But the EPA study that encouraged the practice was flawed. It failed to take into account the carbon footprint of converting grasslands into more corn fields; that of the extra fertilizer & pesticide production and that of the fermentation and distillation of the corn-based alcohol.
(3) Finally, the bulk of the remaining 1/3 is used for human food that’s neither rich in vitamins (only 2, 4 and 6% of the RDA of iron, Vitamin A and C, respectively) nor protein (3.3%), and its syrup is the key ingredient for low-quality baked sweets and for frivolous beverages.
When my grandmother was born early last century, there were only 1.6 billion people on Earth. Now China and India alone combine for 2.8 billion and there are 5.1 billion more people outside of those boundaries. Although worldwide, the equivalent of Italy’s population died last year, there was one newborn for every person in Russia. That spells out a net growth of 80 more million people, or an entire Germany added to the species-total.
In its history, our species has survived a fair amount of adversity as it has lived through ice ages, wars, food-shortages and plagues. Caused by the bacterium Yersinia pestis and accentuated by trade and ignorance, the Black Death killed about 100 million people in Europe and surrounding countries from 1346 to 1353, but its population was big enough that there were enough survivors to carry on its civilization. But we’ve gone beyond the point when we needed the safety of numbers. We are now experiencing a predicament where our large population has become another danger to ourselves.
It seems like rehashing a phased out idea based on 1960s doomsday warnings that did not pan out. We have gotten better at producing and distributing food and have come with innovations that can make us more energy efficient. In the 1970s tackling overpopulation was a priority, but unfortunately, it led to sterilizations without consent. But merely because the wrong means were used to tackle a real problem does not mean that we should pretend that it’s no longer an issue. It’s clear that our large numbers in combination with our widespread immature technologies and shortsighted economic system stress our planet.
For example, there is a lot of hope banked on solar and wind energy to alleviate the climate change we have caused in what is, in geological time, a blink of an eye. But the problem is that those promising technologies are not the best at handling a city’s peak hours of consumption. And 55% of the world lives in urban environments. That number will not shrink. Given that there are so many of us, aside from not being economically and practically feasible, it would actually stress our resources even more if nearly 8 billion of us were scattered in rural areas. And overpopulation is a significant contributor to climate change. Carbon dioxide levels were not increasing as fast for a while because India and China were mostly poor. Now that the world’s two largest populations have become industrialized, it’s not a surprise that China has become the world’s largest emitter of carbon dioxide, especially when it produces so many goods for North America, Europe and the rest of the world. India is less industrialized but still emits almost as much CO2 as all of the EU and will likely surpass it, not just because of its current dependence on coal but because of its large population. According to the EPA, since 1970, the United States’ carbon emissions have increased by 90%. But it’s not just the overdependence on fossil fuels and energy-intensive agriculture that’s responsible per se. In that period the American population has gone from 205 to 330 million, an increase of 61%. There have an increasing number of people within its borders driving cars, cooling and heating their homes, demanding more fuel, concrete and meat.
The more that modern life forces us into cities, and the more bloated they become in an overpopulated world. There are at least 30 megacities with a population of more than 10 million. Brazil’s Sao Paolo, a city of 12.3 million, has had to rely on private wells to a ensure a clean water supply. Deforestation and climate change in general, two consequences linked in part to overpopulation have led to less rainfall in Sao Paolo’s area. The city of Los Angeles brings in water from hundreds of kilometers away, depriving local communities of water. Cape Town in South Africa and Tokyo, Japan have also faced water shortages.
In general, more people in cities means more of humanity exposed to indoor pollutants. Other toxins are more likely to concentrate in the atmosphere above cities and in its drinking water. More people motivates mega-mass production, lowering prices to the point that in most cases recycling cannot compete with making products from scratch. Discarded plastics, clothes and electronics accumulate in oceans and landfills. Urban life also tempts more people into adopting a sedentary, overeating lifestyle, which contributes to heart disease and diabetes. Equally important, especially for those who can’t afford to regularly escape it, city life leads to a lower quality of life.
Food accounts for over a quarter (26%) of global greenhouse gas emissions1;
Half of the world’s habitable (ice- and desert-free) land is used for agriculture;
78% of global ocean and freshwater eutrophication (the pollution of waterways with nutrient-rich pollutants) is caused by agriculture3;
94% of mammal biomass (excluding humans) is livestock. This means livestock outweigh wild mammals by a factor of 15-to-1.4 Of the 28,000 species evaluated to be threatened with extinction on the IUCN Red List, agriculture and aquaculture is listed as a threat for 24,000 of them.5
So what is there to do? The only humane solution would be to limit couples in every country to two children. Of course, the idea will never fly and never be accepted ubiquitously. Many people will object to it vehemently and claim that it’s reminiscent of Communism and of Mao’s methods. Others will imagine that the elites will circumvent the law and secretly procreate prolifically. The Catholic Church won’t help by reasserting that they “accept” birth control but only through abstinence from sex during a woman’s fertile period! Racists will fear that poor countries will not comply and emigrate in even greater numbers to countries that have succeeded in flattening their growth. Given that overpopulation is rarely on our radar, except when many economists embrace it and perceive it as another stimulator of economic “growth”, how could we expect politicians to get on such a mission? Although 82% of U.S.-based members of the American Association for the Advancement of Science consider overpopulation a major problem, only 59% of all Americans agreed it will strain the planet’s natural resources (Pew Research Center 2015).
It seems to me that merely because the 1968 mass starvation-predictions of people like Paul Ehlrich did not materialize, too many lay people and especially leaders are falsely comforted into thinking that concerns about overpopulation were unfounded. Yet, throughout the 20th century, all sorts of optimistic predictions by tech-enthusiasts did not become reality either. Have we subsequently given hope on technology? Similarly, if the biomass of humans and their domesticated animals keeps increasing at the expense of wild ones, it’s not just the elephants who will suffer grave consequences.
I have seen a misleading calculation done to downplay the dangers of overpopulation. They ridiculously fit 10 people per square meter, and the numbers point out that all 8 billion of us “fit” in an area the size of all the boroughs of New York City.
A fairer calculation in my estimation is one I’ve done involving all the food ingested by 3 of the planets’ largest mammals: the blue whale, grey whale and the elephant. They need approximately 22 billion kg of food per year, all from essentially sustainable resources and their wastes remain in the ecosystems where they live and migrate. That’s equivalent to the total weight of food consumed by only 13 million people(0.16% of the world’s population), who in order to get the majority of their food also rely on a polluting fossil-fuel transportation network and on other things with heavy ecological footprints such as tractors, cattle, sheep, chemical fertilizers, and pesticides.