Archive for the 'Carrying Capacity' Category

Compare Climate Change Strategies

Monday, November 6th, 2017


Recently I asked some authorities on climate change: “what is the most effective way of decreasing greenhouse gas emissions?” They gave stock answers about decreasing consumption. “If you were my students, your grades would all be D’s” was my response.

They are, unfortunately, not alone. A recent study listed the 4 most effective activities that people can do to decrease their emissions. Three of them are what you might expect, while the most effective one—by far—might be unexpected.

The measure used by the authors of this article is tonnes CO2-equivalent (tCO2e) emission reductions per year. The average person in the USA causes about 16 tonnes of CO2 to be released annually. (a tonne is a metric ton; roughly equal to our ton of 2000 pounds) Here are the 4, listed from least to most effective.

Eat a plant-based diet. This has health benefits as well as aiding the environment. It is clear that eating meat, especially red meat, is bad for your health. The effects on the world around us are also negative—excessive use of water, sewage lagoons that pollute ground water and dead zones in the ocean from animal waste. An individual’s annual saving by avoiding meat is almost a tonne.

Our transportation system depends on fossil fuels, which generate CO2 when used. It makes sense that avoiding air travel and not driving a car would decrease carbon emissions. Giving up both air travel and your car would keep 4 tonnes of CO2 out of the atmosphere.

Buying “green” electricity is quite effective, and is inexpensive—thanks to our electrical cooperative. Switching from power produced with coal to renewable sources prevents 1.5 tonnes of greenhouse gas emissions—and makes our air healthier.

The most effective thing that an individual can do to reduce his or her carbon footprint is to have one fewer child. The effect is strong because of the “carbon legacy” of a child born in a rich country. The carbon footprint of the individual child is significant, but the legacy of all that person’s progeny (who will go on for many generations) is huge. A child not conceived reduces a person’s carbon footprint by 58 tonnes! Yes, the one best action an individual can take to reduce his or her carbon footprint is to choose to have a small family—or no children at all.

Unfortunately, most people who study, write and teach about greenhouse gas reduction don’t consider the impact of childbearing. The authors of the paper mentioned above also studied governmental recommendations to reduce emissions from the EU, the USA, Australia and Canada. Not surprising, they found that the recommendations all focused on less effective actions.

Likewise, the paper examined the content of science textbooks. They searched several textbooks used in Canada for suggestions to reduce greenhouse gas emissions. Very few of the recommendations were for the 4 most effective actions named above.

To quote from this paper: “It is especially important that adolescents are prepared for this shift [to reduce carbon emissions]. They still have the freedom to make large behavioural choices that will structure the rest of their lives, and must grow up accustomed to a lifestyle that approaches the 2.1 tonnes per person annual emissions budget necessary by 2050 to meet the 2 ° C climate target.” They went on to write: “Furthermore, adolescents can act as a catalyst to change their households behaviour.”

They also compared less effective and highly effective interventions: “…a US family who chooses to have one fewer child would provide the same level of emissions reductions as 684 teenagers who choose to adopt comprehensive recycling for the rest of their lives.” The paper concludes: “Some high-impact actions may be politically unpopular, but this does not justify a focus on moderate or low-impact actions at the expense of high-impact actions.

I hope that the importance of childbearing gets across at the Climate Change Symposium to be held Thursday afternoon, November 9th. This Symposium will be a new venture for Fort Lewis College Lifelong Learning programs. It will feature 5 outstanding experts speaking on a topic of major importance. The keynote speaker is internationally known scientist Kevin Ternberth.

The Symposium is now history for most people reading this. I hope that the importance of population growth has been driven home by the article by Seth Wynes and Kimberly A Nicholas that I used as the basis for this column. It is “The climate mitigation gap: education and government recommendations miss the most effective individual actions” and can be found at:

© Richard Grossman MD, 2017


Stick to Humor, Dr. Black

Wednesday, April 3rd, 2013

Stick to Humor, Dr. Black

“…the first essential component of social justice is adequate food for all mankind.”

Norman Borlaug, in his 1970 Nobel Peace Prize acceptance speech


            I used to love to listen to Baxter Black on the radio. I admired his sense of humor and his human insight. Then I read an article he wrote.

“What is sustainable ag?” appeared in the March, 2013 issue of Western Farmer-Stockman. I am writing this as a response to my friend Al, who clipped the article for me. Al is a wise man and an experienced farmer. He wrote: “I thought this was a good article on sustainable agriculture. I hope you find it interesting.”

Indeed, it is interesting—not for what it contains, but for what Dr. Black left out. First, let me summarize the article.

Dr. Black writes that that most agriculturalists think that “sustainable farming” is a joke, and derides those who want to return to pre1950 farming methods. He makes fun of “hobby farmers” who have a garden and a few animals since they don’t produce enough food to feed their families for even two weeks.

Black then rightly recaps the history after World War II, when world population soared and people worried about food shortages. Megacorporations and scientists were able to increase food production remarkably, despite the creep of cities taking over productive ag land. He doesn’t mention the “green revolution” of Dr. Norman Borlaug and others, which is credited with saving over a billion lives by developing highly productive strains of crops.

This modern, industrial model of agriculture is sustainable according to Black, because it can sustain so many people. Great grandpa’s old-fashioned ways of producing food are laughable in today’s context, he writes. He would prefer the term “subsistence-level farming”.

Although I understand Al’s and Black’s viewpoint, I cannot agree. My concern is that, along with its good, the “green revolution” has had several dreadful unintended consequences.

Growing highly productive plants and animals requires the use of many chemicals that are made from limited resources, and are toxic. The chemicals include fertilizers, insecticides, fungicides and herbicides. They are all derived from fossil fuels, and all transported with fossil fuel. Unfortunately, supplies of carbon-based fuels are limited. We have probably already maximized the production of petroleum and soon will see its decline—and a rapid increase in prices.

We are starting to realize the subtle toxicity of many of the agricultural chemicals. The wonder insecticide of my childhood, DDT (which I was told was entirely safe) turned out to be an ecological disaster and now is banned in many countries. An amazing group of insecticides, neonicatinoids, is probably responsible for the die-off of our honeybees—colony collapse disorder. Since bees pollinate so many crops, this is an agricultural disaster.

We now realize that many agricultural chemicals have endocrine effects, even in minuscule concentrations. Just a pinch in all the water in an Olympic swimming pool can cause harm! Insecticide residues may decrease sperm counts. One common agrichemical, atrazine, has been shown to cause feminization of male frogs and has been implicated in reproductive cancers.

The seeds of highly productive plant strains must be bought from corporations that control their prices. In the past, seed grain was carefully preserved from the prior crop, but now farmers need cash—or credit—in order to buy seeds. This expense, along with the cost of the chemicals, has broken many farmers. In a good year they can make a living, but in a bad year their suicide rate climbs.

Finally, modern agriculture depletes our soil. The use of chemicals exhausts many components that help plants grow.

There is a subtle chicken-and-egg situation here. Modern agriculture has increased food supply, which allowed our population to swell. Borlaug outwitted Malthus, who predicted that human population would be limited by starvation from lack of food.

Here is the quandary: does modern agriculture only provide a short-term gain? As we deplete petroleum and as crop growing conditions worsen from climate change and drought, can the amazing technology of modern agriculture be sustained? Indeed, some scientists have a terrible vision of severe food shortages with bloodshed and more deaths than Borlaug’s green revolution saved.

In his Nobel Prize speech quoted above, Borlaug also said: ““Most people still fail to comprehend the magnitude and menace of the ‘Population Monster’.” Hopefully Herald readers are better informed than most. But only time will tell if Dr. Black is correct about sustainable agriculture, or if he should go back to being a humorist.

© Richard Grossman MD, 2013

Population Paradox #1

Thursday, August 23rd, 2012

Population Paradox #1—7-2012

            From a biological standpoint, the most important goal of any species—or individual—is to pass on its genetic information. That is the reason that so much time and energy is spent on reproduction. In general, the more progeny, the better.

The exception to this observation is humans, at this time in history.

The human species has been so successful that our numbers have grown enormously. We are not as physically powerful as some animals, nor do we have the weaponry like claws and teeth that many carnivores enjoy. Nevertheless we have become the planet’s top predator.

I can think of no other predator that increased its numbers beyond a sustainable population for long. Prey animals may expand their numbers beyond their territory’s carrying capacity, but then predators feast and the prey population drops. The balance of nature is restored as the predators’ numbers diminish.

Many humans think we can exceed the planet’s carrying capacity permanently. Economists and politicians talk about growing the economy, but seem to have two blind spots—that we live on a finite planet that is already stressed, and that indefinite growth is impossible. The Global Footprint Network’s 2011 Annual Report illustrates these concepts wonderfully. Titled “What happens when an infinite-growth economy runs into a finite planet”, it is available at

The number of people who can live on Earth (its carrying capacity for humans) is not fixed. We have succeeded in increasing the planet’s carrying capacity immensely, thanks to our fantastic inventiveness. First we learned to squeeze food out of much of Earth by devising agriculture. Then we discovered remarkable ways to increase agriculture’s productivity. We have benefitted from stripping our planet of its resources. Fossil energy from below ground provides each person in our country with work that couldn’t be performed by a score of human slaves.

We are so successful that we are exhausting our life-support systems. You know the extent of our destruction: extinction of species, depleted ocean fisheries, polluted air and water, loss of topsoil, climate change, slashed rainforest. Although we lead lives of unparalleled bounty, our progeny will suffer because we have used more than our share of resources.

How would it be if our population had leveled off at, say, three billion? That would be what our numbers were when I graduated from high school, 50 years ago. Of course this question cannot be answered. I remember that the1960’s was a bad time for the environment with DDT, burning rivers and toxic fog. It was also an era when we were still living sustainably, according to Ecological Footprint measures.

As a species we have been victorious in passing on our genes. We have followed the command in Genesis: “…God said unto them, be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.” We humans have been too successful in multiplying, and now we are killing off the fish and fowl. Most ocean fisheries are depleted and many species of fish are endangered. We have also caused the extinction of many species of birds—the Carolina parakeet, passenger pigeon and the dodo are memorable.

All signs are that we will leave too few resources for those yet to come. Our success has endangered our progeny’s future.

What can we do? The first step is to recognize that the Biblical phrase above no longer applies. We have been too fruitful. A current estimate of the number of plants and animals on Earth is over 8 million. We have already permanently exterminated 802 species that we know of, plus innumerable members of creation that were unknown to biologists. We need a second ark for all the endangered species.

I fear that our success as a species will also be our downfall. This is the second of two population paradoxes. The first is that armed conflict was a significant factor in keeping the human population from growing rapidly in the past. Our era, called by some the “long peace”, has allowed our numbers to increase radically. We have outgrown Earth’s carrying capacity and conflicts over resources such as petroleum and water may trigger a catastrophic Armageddon. The paradox is that small skirmishes may have helped prevent total war.

The time has come to realize that what has worked in the past will cause a disastrous future. For our progeny’s sake we must promote small families.

© Richard Grossman MD, 2012

Creative Commons Attribution 3.0 United States
This work is licensed under a Creative Commons Attribution 3.0 United States.