As I was researching the topic of this post, I encountered an article (How many humans can Earth sustain? And what does it mean if we’ve already passed it?) by the Australian Broadcast Corporation’s environment reporter, Nick Kilvert posted on Life Matters on Wed 24 Jul 2019. What he reported 3+ years ago remains relevant and is so concise that I have copied it whole cloth below. Please see my BLOGGER’S NOTES* at the end of the article for my thoughts. Take it away, Nick …
When astronaut Jim Irwin stood on the Moon in 1971, it’s reported that he held out his arm, closed one eye and put up his thumb. His thumbnail blacked out the entire Earth from space, and with it about 3.9 billion earthlings. If he did the same thing today, his thumb would eclipse 7.7 billion people. In the time it’s taken to read this sentence (about five seconds), 24 people have been born. If you make it to the end of this article (about five minutes), more than 1,400 people will have been born. So far today, Earth’s population — that is, births minus deaths — is about 140,000 people more than yesterday.** So, is there a maximum number of people the planet can hold, and how would we know if we’ve already passed it?
Earth Overshoot Day: The annual Earth Overshoot Day is set to occur on July 29 (of 2019), three days earlier than (the previous) year. That’s the day in 2019 when we will have used up all the resources that Earth’s natural systems can provide and replace in a year, according to the Global Footprint Network. Or another way to think of it is like this: Let’s say we’ve got a certain amount of food that has to last us all year. We’ll have eaten all of it by July 29. Everything we’re eating after that, we’re taking from next year’s supply, and the year after and so on. But it’s not just food we’re doing it with.
The Global Footprint Network bases its calculations primarily on United Nations data, and considers consumption of things like crops for food and fibres, as well as livestock, seafood, timber and forestry harvest, urban infrastructure development, and preservation of carbon sinks like forests. They use that data to calculate the average consumption or “footprint” per capita for more than 200 countries, and the Earth.
And while the world will make it to July this year (2019), Australia’s Earth Overshoot Day flew by on March 31. If everyone on the globe lived like (Australia), we’d have broken the bank in 90 days. Not great, but it could be worse. The United States overshot on March 15. The UAE on March 8. And if we all lived like Qataris, who overshot on February 11, we’d need 8.7 Earths to provide the goods. While Kyrgyzstan makes it to Boxing Day, no country’s people consume resources at a slower rate than they can be replaced. So if we’re consuming Earth’s resources faster than they’re replenishing, why haven’t we run out yet?
Population-dynamics science tells us two things broadly about invasive animal population trends. Typically, the population of an invasive species that moves into a new area and is freed from predation will boom: it expands beyond what is called the “carrying capacity“, and diminishes the food and resources it needs to sustain itself in the process. In the case of (Homo sapiens, which has been an invasive species over its 2- to 3-million-year history), modern medicine and technology have facilitated that boom. Things that used to kill us don’t, and we can exploit resources much further afield and faster than during all of our history.
But, in animals at least, then comes the crash, where the ratio of animals to resources becomes so skewed that a period of fierce competition for limited resources breaks out, and only the fittest survive. After the crash, populations tend to slowly recover, but never reach as high as they were during the first boom. People started getting concerned in the 1970s that the number of humans on the planet was increasing too fast,*** according to evolutionary biologist Ben Phillips of the University of Melbourne: “Since then we’ve seen astonishing technological innovations that have increased our ability to obtain resources, so the [Earth’s] carrying capacity has actually gone up,” Dr Phillips said, “but to some extent that’s just delayed us reaching the crisis situation.” Declining resources, climate change, and global extinction rates unprecedented in modern history all suggest we’re in the later stage of the boom.
So is population or consumption the problem? If (we) want to continue living as we do without making any changes, and as a planet we want to meet our footprint, then the number of humans Earth can sustain long term is around 1.9 billion people, which was roughly the global population 100 years ago in 1919. Alternatively, we’ll have to find three more Earth-like planets to support us.** Even if the global population stabilized today, the rate of consumption in wealthy nations is much higher than the world can sustain. The problem is what can we do about it before we hit the crash?
The good news is that the things we can do to reduce our footprints have a lot of other benefits too. As individuals, cutting down on meat, particularly red meat, can significantly reduce consumption of resources. And research shows that rehabilitating degraded habitats and increasing tree cover can have great restorative benefits to our environment. We should aim to practice “mindful consumption”, said Gayle Sloan, CEO of the Waste Management and Resource Association of Australia. “Think about ‘Do I need that?’ ‘Am I going to use that?’ We can avoid mindless consuming. The public is way beyond straws and plastic bags — we need to be reusing.”
But the biggest changes that need to be made are at a systemic level, and they need to be led by government and industry. We need cleaner transport and power-generation industries, and we need to transition to a circular economy, according to Ms Sloan. That means getting rid of single-use products and packaging. To do this, the onus of responsibility for single-use items needs to be put back onto producers.
For instance, if a soft-drink company wants to sell their drink in a plastic container, they need to recoup that bottle after it’s been used and ensure it is reused or recycled. “We need a lot more end-of-life extension of responsibility on companies,” Ms Sloan said. “It’s not enough that they bring it to market, they need to be responsible for it through to end-of-life and governments need to be a lot stronger on mandating that.”
Reducing population? When it comes to population, the highest rates of growth tend to be in developing nations. Educating and empowering women is key to changing this trend, according to Climate Council CEO Amanda McKenzie. Research shows that birth rates tend to decrease as women have more financial security.
“There are a few factors, one is having access to birth control and the second is education and having economic opportunities,” Ms McKenzie said. “And then there’s empowerment [of women] to make their own choices. Improving living standards in developing countries can also improve resilience to climate change … The poorer you are, generally the more exposed you are when an extreme weather event occurs, so in extreme heatwaves there’s no air-conditioning, and houses are less likely to stand up to cyclones.”
On current trend, we are on track for a population of more than 11 billion people by the end of the century. And — at least for now** — we’ve only got one Earth to sustain us.
** There is a myth being sold to us by Mother Culture, and by billionaires fixated on their phallic rocket ships, that the survival of our civilization depends upon the colonization of space. A rational mind will recognize that it may be possible to create small, self-sufficient colonies on a planet like Mars; however, I ask you to consider the following: (1) the maximum seating configuration of a Boeing 777 is 388 passengers; (2) the net growth of the human population was 140,000 per day in 2019; and if (3) a “spaceship” could be built with the seating capacity of a Boeing 777 that had the ability to travel to space colonies, say, on Mars; and if the net population growth is still about what it was in 2019, then (4) 361 such spaceships would have to take off each day of the year on the 7 month trip to Mars just to “remove” one day’s increase in the world’s population. Writing or saying that colonizing space is the answer to controlling population and the survival of our civilization is delusional to the point of being hallucinatory.
*** The demise of our species due to overpopulation was a surprisingly loud, national conversation in the late 60s and early 70s that was prompted by The Population Bomb. My generation–the activist Boomer Generation that degenerated into the egocentric Me Generation in the 1970s—was in a position to push ZPG: Zero Population Growth—but we did not. We focused instead on crass, conspicuous consumption and social status. The predictions in The Population Bomb as to when catastrophe would arrive were grossly incorrect for the reasons suggested in Nick Kilvirt’s article (above); however, the book’s error was related to timing and was not related to the probability of what is ultimately coming.
Americans have been especially susceptible to Mother Culture’s pervasive message that “science will come to the rescue,” and my generation’s blasé response to the population explosion (and the responses of those generations who are following us) has doomed our civilization. Granted, just as there are individuals alive today who are genetic remnants of the complex Mayan and Incan Civilizations that thrived prior to the arrival of the Spanish, it is likely that there will be genetic remnants of our current civilization in North America five centuries from now; however, it is likely that Homo sapiens will be scratching out a meager existence. If what we know from remnant populations of failed civilizations is the rule, it will not be the descendants of today’s rich elites who will survive the crash.
Another factor of relevance to the survival of the species that is impacted by the population explosion is described in Spillover: Animal Infections and the Next Human Pandemic, by David Quammen. As a good friend described the main point of the book to me in an email, “The upshot is that with wildlife habitat being eliminated because of human overpopulation, animals are forced into closer contact with humans, and with the greatly increased population densities in urban areas, humans are more likely to be exposed to zoonoses, which we then transmit readily from person to person. And of course–as we’re learning in the case of the SARS-CoV-2 virus (COVID)–the more humans that are infected, the more likelihood there is of a virus mutating into something more dangerous. In other words, because of the overpopulation of Homo sapiens, a pandemic may someday do us in.”
I’ve been concerned about human population growth since 1968, after I completed a classic lab exercise in a Microbiology course: a test tube was filled with nutrient broth and then inoculated with bacteria. Placed in an incubator, the cultures were allowed to grow, and after specific intervals of time, the population of the bacteria in the test tube was determined. When the population was plotted against time, the first population curve below is the typical result generated by the exercise:
- “1” is the “lag phase,” during which bacteria adjust to the test tube environment; the population grows slowly.
- “2” is the “log phase,” during which the bacterial population grows exponentially.
- “3” is the “stationary phase,” during which the bacterial population has reached the carrying capacity of the test tube culture.
- “4” is the “death phase” (the “crash”), during which the bacterial population decreases exponentially due to both the depletion of nutrients and the accumulation of toxic waste compounds.
Despite my inexperience 53 years ago, I saw the connection suggested between the documented population curve of H. sapiens on earth and that of E. coli in a test tube. Earth, I realized, is like a test tube in that it is a closed system where the effective vacuum of Space serves the same function as the glass of a test tube. And of course, Malthus’ view of population growth vs growth of food supply entered the mix of considerations.
Despite Mother Culture whispering into our ears that Malthus’ theory is off base, that humans are not bound by natural laws like the Law of Carrying Capacity, and the myth of space colonies as havens, I accepted back in 1968 and accept today that the human population is approaching the stationary phase of its growth curve, and that the death phase will follow in due course. Precisely when Homo sapiens will enter into the latter stages of an invasive species’ expected population curve remains hypothetical, but it is unlikely that Boomers—my generation; the generation that might have done something about over-population—will be around to see the world we have left for our descendants.
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