Romans, Kings, Plagues and Automobiles: Impact on Atmospheric Lead Levels

Source of graphic: GeoHealthVolume 1, Issue 4 p. 211-219
Colle Gnifetti in the Swiss Alps, where the ice core data was obtained

Courtesy of an analysis of 72-meter ice cores extracted from the 4450 meter high Colle Gnifetti in the Swiss-Italian Alps, the above graph reveals changing levels of lead(Pb) in the Earth’s atmosphere. The highest concentration occurred in the mid-1970s. This was about 50 years after refiners started to add tetraethyl lead to gasoline to make engines run more smoothly. Then from 1950 onwards car sales mushroomed, and so did traces of the lead they released. Luckily, by the 1980s, thanks to environmental legislation in both Europe and North America, unleaded gasoline sales rose while those of the toxic metal plummeted. By the 1990s, lead was no longer used in house paint, which caused its concentration in dust to drop. Consequently, as the graph reveals, by the late 1990s lead levels in the atmosphere had started to drop significantly.

Lead pipes

But what was the source of lead in previous years? Lead has been used for a long time to make pipes, coins, roofs, gutters, and cisterns. In the Middle Ages, the compound, lead acetate, was even used as an artificial sweetener. The amount of lead in the environment also tracks silver production because galena, lead’s ore, often lies side-by-side with ores of silver. So whenever lead or silver production peaked, the industrial boost would leave its signature in the atmosphere. In spring, especially, wind carried deposits of the heavy metal hundreds of miles from the mines of England to the Alps.

For example, the data reveals that lead-levels dropped around the year 1170, only to peak a few years later. What happened? For years King Henry II had been in conflict with the archbishop Thomas Becket. Eventually the latter was brutally murdered by the king’s knights. Henry II was excommunicated, people dodged taxes, and mining came to a halt. But when the king atoned for the murder by building many churches, since their roofs and gutters were made of lead, mines were busy and they spewed out more of the pollutant. Corroborating evidence comes from records of the spike in taxes on mines in the Peak District and at Carlisle in England.

From the New Yorker

What caused the most dramatic drop, around the year 1350? The lowest level in the last two thousand years coincided with the shutting down of lead and silver mines at the peak of the Black Death. Another drop in lead concentrations occurred in the mid 1400s. This time, production of the toxic metal plummeted during the The Great Slump, an economic depression in England lasting from the 1430s to the 1480s. The third sharpest drop in the amount of lead occurred in the late 1800s. This was related to the fact that in 1878, a fall in the price of lead and a general world economic depression caused smelting to slow down at some mines and come to a complete halt at others.

In the past, only economic disasters, murders or plagues could lower emissions of lead, and only temporarily. Now we could do it rationally and with a more lasting effect.


Next-generation ice core technology reveals true minimum natural levels of lead (Pb) in the atmosphere: Insights from the Black Death. GeoHealthVolume 1, Issue 4 p. 211-219

Lead pollution in ancient ice cores may track the rise and fall of medieval kings. Science. 30 March 2020 Ann Gibbons.


Pretend-Recycling Is Not the Answer. First Reduce. Then Repair and Reuse.

1. Despite all the Bins, We Are Still Wasteful

In most of the North American continent, we have pretend-recycling, given that about most of what we place in our green bins ends up as garbage. Over 90% of plastic isn’t actually recycled. U.S. exported 74,000 shipping containers of plastic waste to low-income countries, according to researcher Jan Dell. That’s a lot more fossil fuels burnt than if the recyclable material was handled locally.

Canada is not any better. From a 2022 CBC article:

An investigation by Radio-Canada’s Enquête shows that much of what is supposed to be paper actually contains tonnes of plastic bags, some of which litter the Indian landscape, and are often burned as a source of fuel.….The city’s(Montreal) two recycling centres — in Lachine and Saint-Michel — average between 20 and 26% contamination, according to numbers provided by the city.”

A cynic would point out that it’s not shocking that the program became adopted by the majority of cities, given that it does not threaten consumerism. Instead it gets people to focus away from reducing their consumption and does not encourage them to find a second use for packages and other materials that they have paid for.

2. Plastic is Not As Cheap As It Seems

Economics are blamed for low recycling rates when it’s pointed out that it’s cheaper to produce plastic from its raw materials than to collect existing plastics, sort them out, use solvents and remold them into new ones. But that’s because as a society, the price of “virgin” plastic does not factor in the environmental impact of producing excessive plastic, and it does not factor in the cost of recycling . Conveniently for producers and packagers of plastic, the responsibility to recycle and cleanup has become that of the government. Cities then handicap recycling plants by unwisely accepting unsorted recyclable materials out of fear that no one would bother otherwise.

3. Greenwashing

Grocery chains and dollar stores do their share of greenwashing by either not offering plastic bags to put groceries in or by charging customers for them, but the sad truth is that stores still put out s multitude of rolls of plastic weekly to carry away fruits and vegetables, which are totally unnecessary, and they get consumers to take home tons of other plastic in the form of jars, dispensers for detergents, pasta, meat and legume-packaging.

4. A Better Approach

Things can be reused without making it look like you are bordering on poverty, a kind of sin for a society obsessed with discarding old materials and buying more. Here is an example of how my garden looks relatively neat and tidy, even though it is full of reused materials.

This morning after finishing a container of detergent, I decided to convert it into a watering can. The procedure is very simple. Just remove the labels; add a little drawing and drill a few holes in the cap.

After starting this blog yesterday, coincidentally, I learned of a generous grant given to a faculty of a prominent North American university. With hundreds of millions of dollars to spend on demolishing the “old” structure and building a new one that would hold all of the undergraduate labs, some members of the faculty wanted to throw everything out. Luckily, the lab coordinator decided that this would be a terrible waste, and that it made more sense to give away the glassware and lab instruments to other labs within its own university and then to other institutions if there were still leftovers.

We live in a neighborhood where an incredible amount of good quality stuff is put out as garbage. Luckily, as others became aware of their bad habits, they started to patrol the neighborhood to collect the toys, skis, deck furniture and even broken appliances, which can either be repaired or be sold for their metal content.

Things don’t magically appear at the store. Material and energy resources go into making consumer goods, and as the Earth hosts an increasing number of buyers, if we acted rationally, waste would decrease. We would each buy less so that more people could have a little more. We would hang on to what we already have, repairing whatever is broken and finding new uses for purchased materials.

Overpopulation: the Elephant in the Room ( revised)

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;
  • 70% of global freshwater withdrawals are used for agriculture2;
  • 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.

source of image