We’re Beyond Earth’s Carrying Capacity Now. Will Accelerating Climate Change Turn the Population Boom into a Bust?

Demographers are predicting that world population will climb to 10 billion later this century. But with the planet heating up and growing numbers of people putting increasing pressure on water and food supplies and on life-sustaining ecosystems, will this projected population boom turn into a bust?

by Robert Engelman, in a Yale e360 cross-post

The hard part about predicting the future, someone once said, is that it hasn’t happened yet. So it’s a bit curious that so few experts question the received demographic wisdom that the Earth will be home to roughly 9 billion people in 2050 and a stable 10 billion at the century’s end. Demographers seem comfortable projecting that life expectancy will keep rising while birth rates drift steadily downward, until human numbers hold steady with 3 billion more people than are alive today.

What’s odd about this demographic forecast is how little it seems to square with environmental ones. There’s little scientific dispute that the world is heading toward a warmer and harsher climate, less dependable water and energy supplies, less intact ecosystems with fewer species, more acidic oceans, and less naturally productive soils. Are we so smart and inventive that not one of these trends will have any impact on the number of human beings the planet sustains? When you put demographic projections side by side with environmental ones, the former actually mock the latter, suggesting that nothing in store for us will be more than an irritant. Human life will be less pleasant, perhaps, but it will never actually be threatened.

Some analysts, ranging from scientists David Pimentel of Cornell University to financial advisor and philanthropist Jeremy Grantham, dare to underline the possibility of a darker alternative future. Defying the optimistic majority, they suggest that humanity long ago overshot a truly sustainable world population, implying that apocalyptic horsemen old and new could cause widespread death as the environment unravels. Most writers on environment and population are loathe to touch such predictions. But we should be asking, at least, whether such possibilities are real enough to temper the usual demographic confidence about future population projections.

For now, we can indeed be highly confident that world population will top 7 billion by the end of this year. We’re close to that number already and currently adding about 216,000 people per day. But the United Nations “medium variant” population projection, the gold standard for expert expectation of the demographic future, takes a long leap of faith: It assumes no demographic influence from the coming environmental changes that could leave us living on what NASA climatologist James Hansen has dubbed “a different planet.”

How different? Significantly warmer, according to the 2007 assessment of the Intergovernmental Panel on Climate Change — as much as 10 degrees Fahrenheit more than today on average. Sea levels from two to six feet higher than today’s — vertically, meaning that seawater could move hundreds of feet inland over currently inhabited coastal land. Greater extremes of both severe droughts and intense storms. Shifting patterns of infectious disease as new landscapes open for pathogen survival and spread. Disruptions of global ecosystems as rising temperatures and shifting precipitation patterns buffet and scatter animal and plant species. The eventual melting of Himalayan glaciers, upsetting supplies of fresh water on which 1.3 billion South Asians and Chinese (and, of course, that number is rising) depend for food production.

And that’s just climate change, based on the more dramatic end of the range the IPCC and other scientific groups project. Yet even if we leave aside the likelihood of a less accommodating climate, population growth itself undermines the basis for its own continuation in other ways. Since 1900, countries home to nearly half the world’s people have moved into conditions of chronic water stress or scarcity based on falling per-capita supply of renewable fresh water. Levels of aquifers and even many lakes around the world are falling as a result. In a mere 14 years, based on median population projections, most of North Africa and the Middle East, plus Pakistan, South Africa and large parts of China and India, will be driven by water scarcity to increasing dependence on food imports “even at high levels of irrigation efficiency,” according to the International Water Management Institute.

The world’s net land under cultivation has scarcely expanded since 1960, with millions of acres of farmland gobbled by urban development while roughly equal amounts of less fertile land come under the plow. The doubling of humanity has cut the amount of cropland per person in half. And much of this essential asset is declining in quality as constant production saps nutrients that are critical to human health, while the soil itself erodes through the double whammy of rough weather and less-than-perfect human care. Fertilizer helps restore fertility (though rarely micronutrients), but at ever-higher prices and through massive inputs of non-renewable resources such as oil, natural gas, and key minerals. Phosphorus in particular is a non-renewable mineral essential to all life, yet it is being depleted and wasted at increasingly rapid rates, leading to fears of imminent “peak phosphorus.”

We can recycle phosphorus, potassium, nitrogen, and other essential minerals and nutrients, but the number of people that even the most efficient recycling could support may be much less than today’s world population. In 1997, Canadian geographer Vaclav Smil calculated that were it not for the industrial fixation of nitrogen, the world’s population would probably not have exceeded 4 billion people — 3 billion fewer than are alive today. It’s likely that organic agriculture can feed many more people than it does currently, but the hard accounting of the nutrients in today’s 7 billion human bodies, let alone tomorrow’s projected 10 billion, challenges the hope that a climate-neutral agriculture system could feed us all.

Food production also requires many services of nature that conventional agronomy tends to ignore in projecting future food supplies, and the dependability of these services appears to be fraying. Roughly one out of every two or three forkfuls of food relies on natural pollination, yet many of the world’s most important pollinators are in trouble. Honeybees are succumbing to the tiny varroa mite, while vast numbers of bird species face threats ranging from habitat loss to housecats. Bats and countless other pest-eaters are falling prey to environmental insults scientists don’t yet fully understand. And the loss of plant and animal biodiversity generally makes humanity ever-more dependent on a handful of key crop species and chemical inputs that make food production less, rather than more, resilient. One needn’t argue that the rising grain prices, food riots, and famine parts of the world have experienced in the past few years are purely an outcome of population growth to worry that at some point further growth will be limited by constrained food supplies.

As population growth sends human beings into ecosystems that were once isolated, new disease vectors encounter the attraction of large packages of protoplasm that walk on two legs and can move anywhere on the planet within hours. In the last half-century, dozens of new infectious diseases have emerged. The most notable, HIV/AIDS, has led to some 25 million excess deaths, a megacity-sized number even in a world population of billions. In Lesotho, the pandemic pushed the death rate from 10 deaths per thousand people per year in the early 1990s to 18 per thousand a decade later. In South Africa the combination of falling fertility and HIV-related deaths has pressed down the population growth rate to 0.5 percent annually, half the rate of the United States. As the world’s climate warms, the areas affected by such diseases will likely shift in unpredictable ways, with malarial and dengue-carrying mosquitoes moving into temporal zones while warming waters contribute to cholera outbreaks in areas once immune.

To be fair, the demographers who craft population projections are not actively judging that birth, death, and migration rates are immune to the effects of environmental change and natural resource scarcity. Rather they argue, reasonably enough, that there is no scientifically rigorous way to weigh the likelihood of such demographic impacts. So it makes more sense to simply extend current trend lines in population change — rising life expectancy, falling fertility, higher proportions of people living in urban areas. These trends are then extrapolated into an assumedly surprise-free future. The well-known investor caveat that past performance is no guarantee of future results goes unstated in the conventional demographic forecast.

Is such a surprise-free future likely? That’s a subjective question each of us must answer based on our own experience and hunches. Next to no research has assessed the likely impacts of human-caused climate change, ecosystem disruption, or energy and resource scarcity on the two main determinants of demographic change: births and deaths. Migration related to climate change is a more common subject for research, with projections ranging from 50 million to 1 billion people displaced by environmental factors — including climate change — by 2050. The mainstream projections cluster around 200 million, but no one argues that there is a compelling scientific argument for any of these numbers.

The IPCC and other climate-change authorities have noted that extremely hot weather can kill, with the elderly, immune-compromised, low-income, or socially isolated among the most vulnerable. An estimated 35,000 people died during the European heat wave of 2003. The U.S. Centers for Disease Control and Prevention cites research projecting that heat-related deaths could multiply as much as seven-fold by the century’s end.

In the past few years, agronomists have lost some of their earlier confidence that food production, even with genetically modified crops, will keep pace with rising global populations in a changing climate. Already, weather-related disasters, from blistering heat waves to flooded farm fields, have contributed to widening gaps between food production and global consumption. The resulting price increases — stoked also by biofuels production encouraged in part to slow climate change — have led to food riots that cost lives and helped topple governments from the Middle East to Haiti.

If this is what we see a decade into the new century, what will unfold in the next 90 years? “What a horrible world it will be if food really becomes short from one year to the next,” wheat physiologist Matthew Reynolds told The New York Times in June. “What will that do to society?” What, more specifically, will it do to life expectancy, fertility, and migration? Fundamentally, these questions are unanswerable from the vantage point of the present, and there’s a lesson in this. We shouldn’t be so confident that the demographers can expertly forecast what the world’s population will look like beyond the next few years. A few demographers are willing to acknowledge this themselves.

“Continuing world population growth through mid-century seems nearly certain,” University of California, Berkeley, demographer Ronald Lee noted recently in Science. “But nearly all population forecasts… implicitly assume that population growth will occur in a neutral zone without negative economic or environmental feedback. [Whether this occurs] will depend in part on the success of policy measures to reduce the environmental impact of economic and demographic growth.”

It’s certainly possible that ingenuity, resilience and effective governance will manage the stresses humanity faces in the decades ahead and will keep life expectancy growing in spite of them. Slashing per-capita energy and resource consumption would certainly help. A sustainable population size, it’s worth adding, will be easier to maintain if societies also assure women the autonomy and contraceptive means they need to avoid unwanted pregnancies. For anyone paying attention to the science of climate change and the realities of a rapidly changing global environment, however, it seems foolish to treat projections of 10 billion people at the end of this century as respectfully as a prediction of a solar eclipse or the appearance of a well-studied comet. A bit more humility about population’s path in an uncertain and dangerous century would be more consistent with the fact that the future, like a comet astronomers have never spotted, has not yet arrived.

— Robert Engelman is president of the Worldwatch Institute, an environmental research organization based in Washington, D.C. The Population Institute awarded his book, More: Population, Nature, and What Women Want, the Global Media Award for Individual Reporting in 2008.

This article was originally published at Yale Environment 360.

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43 Responses to We’re Beyond Earth’s Carrying Capacity Now. Will Accelerating Climate Change Turn the Population Boom into a Bust?

  1. fj says:

    disconnected future

    pervasive planning for even the near-term future without considering climate chaos is a major disconnect

  2. Joe Immen says:

    Doesn’t this article correctly imply that projections of a worsening climate are much more certain and trustworthy than population projections? Population forecasts are dependent on the future climate conditions, while climate forecasts are also somewhat dependent on future population numbers. Is the difference between climate and population forecasts that there is so much inertia in the climate system that we know what’s coming way ahead of time?

  3. Kevin says:

    Unfortunately the main stream media would never run a story like this, because they would rather be blissfully ignorant of any coming future environmental problems. This story should be on the headlines of every news organization in the world because the issues addressed are the most important issues of our time.
    Wishing for better media coverage, Kevin

  4. prokaryotes says:

    The only solution to Population growth is space colonization. This ofc is a long term goal, but there is only a small window of opportunity to do so, because climate change threatens any action and growth in general.

    Child birth politic is a short term action.

    Climate change will bring down population numbers. Mainly heat waves, food shortages and anarchy/chaos will bring down the population numbers, in coming decades. It will have biblical apocalyptic proportions.

  5. Rabid Doomsayer says:

    Massive monoculture, not of a single species, or even a single variety but of a single gene line. A gene line selected for optimised performance in today’s conditions. All spells fragility.

    Climate change, ocean acidity, peak energy, peak phosphate and peak just about everything else. Eutrophication of the waterways. Increasing exinction of wildlife.

    Peak politics, the political world is not on a stable course. Even those who do not get any of the above still sense the shit is going to hit the fan.

    Ten billion people in 2100, I don’t think so. We have not just overshot we have massively overshot, there is so little we do sustainably.

    Any one of the problems will have dire consequences, together they add to one very rough ride for mankind.

  6. Merrelyn Emery says:

    I am old enough to remember the last time the demographers got it totally wrong when they failed to factor in the rapid acceleration in the education, status and wealth of women. It took them years to correct.

    The problem lies in their methodology which is a-contextual and uses linear projections of only a small number of variables. This time, they’ve left out the biggest contextual factor of them all and consequently will be scrambling to correct again as reality overtakes them, ME

  7. David B. Benson says:

    Headline question is enough.


  8. squidboy6 says:

    the current state of affairs is a result of competition for resources, if there’s 4 billion more then the competition will be more in violent upheavals than rich, poor, and middle class people arguing over allocations of funds. I agree that we’re at our current carrying capacity now.

    genetically engineered foods, waste treatment, and water recycling technologies may change the outlook but not enough to make any actual difference. The quality of life will be really poor for everybody but the filthy rich.

    I saw Soylent Green when I was a kid and thought that it sucked but now I see it as a fairly prophetic work. Some of aspects are overdone but the thrust of the movie was accurate, we are devouring our future. Population control is our only hope, perhaps a genetically engineered food that lowers fecundity, instead of apocalyptic scenarios such as “12 Monkeys” or similar movies, could be done.

  9. John Tucker says:

    I would rather not focus on people as numbers and burdens to sustain. I think that is a mistake that inevitably leads to problems from a civil libertarian point of view.

    We should try to get ourselves under control in terms of impact and let people in the future worry about themselves.

    Nothing in this universe really is totally ¨sustainable¨ except for simplified concepts equated on a balance sheet.

  10. Mark says:

    Taming population growth is impossible without also taming our addiction to economic growth. In the short run, the masters of money and power must generate new consumer demand to keep the fiction of nonstop economic growth going. Making new shoppers is the single best way to do that.

    Until we tame capitalism’s demand for nonstop economic growth, there will be a demand for increasing the population of consumers.

  11. Dr.A.Jagadeesh says:

    Good article.

    There is the famous equation:

    C = B:E

    The Carrying capacity of any land depends on the biotic potential and Environmental resistance.

    Dr.A.Jagadeesh Nellore(AP),India

  12. Theodore says:

    “The only solution to Population growth is space colonization.”

    No. I can only hope this was attempted humor. For that, you might be forgiven.

  13. Mike Roddy says:

    Demographers are lost here, since they cannot factor future variables, including the earth’s carrying capacity. 10 billion in 2100 is a meaningless prediction, and ignores the increasingly likely probability of ecosystem and agricultural collapses.

  14. prokaryotes says:

    During the past decade, a number of premises about the basic problems of the world have become very widely accepted. The more important of these accepted ideas are:

    For the foreseeable future, every significant human activity must be confined to the surface of the earth.
    The material and energy resources of the human race are just those of our planet.
    Any realistic solutions to our problems of food, population, energy, and materials must be based on a kind of zero-sum game, in which no resources can be obtained by one nation or group without being taken from another.
    Given those premises, logic has driven most observers to the conclusion that long-term peace and stability can only be reached by some kind of systematic global arrangement, with tight constraints to insure the sharing–equable or otherwise–of the limited resources available. I find it personally shocking that many such observers, even those who profess a deep concern for humankind, accept with equanimity the need for massive starvation, war, or disease as necessary precursors to the achievement of such a systematic global arrangement.
    In my opinion, based on studies carried out at Princeton University, these three basic premises on which most discussions of the future have been based are simply wrong. The human race stands now on the threshold of a new frontier whose richness is a thousand times greater than that of the new western world of 500 years ago.

    That frontier can be exploited for all humanity, and its ultimate extent is a land area many thousands of times that of the entire earth. As little as 10 years ago we lacked the technical capability to exploit that frontier. Now we have that capability, and if we have the willpower to use it, we can not only benefit all humanity, but also spare our threatened planet and permit its recovery from the ravages of the industrial revolution.

    The high frontier which I will describe is space, but not in the sense of the Apollo program, a massive effort whose main lasting results were scientific. Nor is it space in the sense of the communications and observation satellites, useful as they are. Least of all is it space in the sense of science-fiction, in which harsh planetary surfaces were tamed by space-suited daredevils. Rather, it is a frontier of new lands, located only a few days travel time away from the earth, and built from materials and energy available in space.

    Author Gerard O’Neill, Professor of Physics at Princeton University, hopes that space colonization will be a cooperative international program, bringing world peace a step closer.

    The colonization of the Moon is the proposed establishment of permanent human communities on the Moon. Advocates of space exploration have seen settlement of the Moon as a logical step in the expansion of humanity beyond the Earth. Recent indication that water might be present in noteworthy quantities at the Lunar poles has increased interest in the Moon. Polar colonies could also avoid the problem of long Lunar nights (about 354 hours,[1] a little more than two weeks) and take advantage of the sun continuously.
    Permanent human habitation on a planetary body other than the Earth is one of science fiction’s most prevalent themes. As technology has advanced, and concerns about the future of humanity on Earth have increased, the argument that space colonization is an achievable and worthwhile goal has gained momentum.[2][3] Because of its proximity to Earth, the Moon has been seen as a prime candidate for the location of humanity’s first permanently occupied extraterrestrial base.

  15. Earth is our life support system and we’re gumming up the works.
    There are people who refuse to believe we live on a finite world with finite resources. I pity them. They are stupid.

    We have dodged the bullet thus far, but like the growing failure of antibiotics against resistant strains of bacteria, our efforts to support our huge population are not sustainable.

  16. Greg says:

    Mr Engelman is quite right to criticise population projections. But he draws back from the key point.

    The UN’s 2010 medium scenario population prospect, broken down by region, shows that of the 3 Billion extra people expected, more than 2.5 Billion will appear in Africa. Asia, the Americas and Oceania gain small numbers, while Europe shrinks. The problem is all in Africa.

    We, the readers of Climate Progress, know that this cannot happen. We know that Africa cannot more than double its present population, because we know that Africa — already dry, already chronically malnourished — is the continent that will be most affected by drought over the next century.

    If governments do not act to curb Africa’s population growth, then nature will. That is what UN ESA is telling us.

    The UN’s “prospect” is a terrifying warning. It’s not reasonable to see it any other way. In a humane world, African, Asian, and OECD governments would right now be working feverishly to prevent the coming catastrophe.

  17. Mulga Mumblebrain says:

    The global ruling caste knows these truths, and are well satisfied by them. They, I think it is unavoidable to conclude, look forward to a massive Malthusian cull, which their power over money and violence they believe will enable them to ride out the storm. There is absolutely no let up whatsoever in the elite’s efforts to loot the planetary common wealth, indeed yet further intensification of their efforts, piling up more and more trillions, while immiserating billions of human beings. They cannot possibly be so stupid as to believe this can go on, so their enthusiasm for the coming collapse must, I believe, be taken as given.

  18. Mulga Mumblebrain says:

    Paul, the black-clad ‘anarchists’ are probably police provocateurs. There is NO WAY that the masters will allow protests, peaceful or otherwise, to change one facet of the global system that they are their forebears haved forged over millennia. The protesters, having been ridiculed by the Western MSM propaganda sewer, will now be lied about and vilified. If they gained any traction they would be outlawed as ‘economic terroristsor the old favourites ‘socialists and communists’. In fact, judging by elite past practise and their great success at ‘astro-turfing’, I’d imagine many of the leaders of this movement are on the payroll, the whole thing is as phony as the ‘Arab Spring’ and is simply a gigantic diversion. Like the Obama Project, when it collapses into betrayal, compromise and sell-out, many of the idealists will be put off politics for years, if not for good.

  19. prokaryotes says:

    Why eating GM food could lower your fertility

    Read more:

    Genetically modified (GM) foods are increasingly found on supermarket shelves, but most consumers seem unaware of their potential impact on sexual health. Maybe a recently released report showing that hamsters are rendered sterile after just three generations of eating a diet of GM foods will change that apathy into concern.
    In joint research by Russia’s National Association for Gene Security and the Institute of Ecological and Evolutional Problems, one group of hamsters was fed a diet of GM soybeans while the control group was fed non-GM soy (which the scientists say was difficult to obtain, given the spread of GM soy and its transgenic properties). The animals were monitored for behavior, weight gain and birthrate. Scientist Alexei Surov reported that the researchers noted slower rates of growth and sexual maturity by just the second generation. The next generation was unable to reproduce. While people are not hamsters, this does raise some interesting questions concerning the safety of the food we purchase, prepare and consume.
    Major U.S. companies, including Kellogg, Coke, Pepsi, Kraft, Heinz and others, don’t use GM foods in their European products, but the same can’t be said for those products in the U.S. Why the difference? Groups like Friends of the Earth Europe actively campaign for GM-free foods for both environmental reasons and reasons of personal health and safety. If more people in the U.S. knew about the possible short- and long-term consequences of ingesting GM foods, maybe they too would raise a ruckus.

  20. prokaryotes says:

    Somalia’s children dying in record numbers

    Uploaded by AlJazeeraEnglish on Oct 14, 2011
    Mogadishu, Somalia’s capital, is overrun by the number of people seeking food as a result of famine and drought.

  21. prokaryotes says:

    Due to Somalia’s proximity to the equator, there is not much seasonal variation in its climate. Hot conditions prevail year-round along with periodic monsoon winds and irregular rainfall. Mean daily maximum temperatures range from 30 to 40 °C (86 to 104 °F), except at higher elevations and along the eastern seaboard, where the effects of a cold offshore current can be felt. In Mogadishu, for instance, average afternoon highs range from 28 °C (82 °F) to 32 °C (90 °F) in April. Some of the highest mean annual temperatures in the world have been recorded in the country; Berbera on the northwestern coast has an afternoon high that averages more than 38 °C (100 °F) from June through September. Nationally, mean daily minimums usually vary from about 15 to 30 °C (59 to 86 °F).[142] The greatest range in climate occurs in northern Somalia, where temperatures sometimes surpass 45 °C (113 °F) in July on the littoral plains and drop below the freezing point during December in the highlands.[14][142] In this region, relative humidity ranges from about 40% in the mid-afternoon to 85% at night, changing somewhat according to the season.

    Unlike the climates of most other countries at this latitude, conditions in Somalia range from arid in the northeastern and central regions to semiarid in the northwest and south. In the northeast, annual rainfall is less than 4 inches (100 mm); in the central plateaus, it is about 8 to 12 inches (200 to 300 mm). The northwestern and southwestern parts of the nation, however, receive considerably more rain, with an average of 20 to 24 inches (510 to 610 mm) falling per year. Although the coastal regions are hot and humid throughout the year, the hinterland is typically dry and hot.[142]
    There are four main seasons around which pastoral and agricultural life revolve, and these are dictated by shifts in the wind patterns. From December to March is the Jilal, the harshest dry season of the year. The main rainy season, referred to as the Gu, lasts from April to June. This period is characterized by the southwest monsoons, which rejuvenate the pasture land, especially the central plateau, and briefly transform the desert into lush vegetation. From July to September is the second dry season, the Xagaa (pronounced “Hagaa”). The Dayr, which is the shortest rainy season, lasts from October to December.[142] The tangambili periods that intervene between the two monsoons (October–November and March–May) are hot and humid.

    The 2011 Somalia famine started during the RAIN Season and now is the second rain season and still famine.

  22. prokaryotes says:

    Somalia has untapped reserves of numerous natural resources, including uranium, iron ore, tin, gypsum, bauxite, copper, salt and natural gas.[2] Due to its proximity to the oil-rich Gulf Arab states such as Saudi Arabia and Yemen, the nation is also believed to contain substantial unexploited reserves of oil. A survey of Northeast Africa by the World Bank and U.N. ranked Somalia second only to Sudan as the top prospective producer.[188] American, Australian and Chinese oil companies, in particular, are excited about the prospect of finding petroleum and other natural resources in the country. An oil group listed in Sydney, Range Resources, anticipates that the Puntland province in the north has the potential to produce 5 billion barrels (790×106 m3) to 10 billion barrels (1.6×109 m3) of oil.[189] As a result of these developments, the Somali Petroleum Company was created by the federal government.

  23. Chad says:

    The carrying capacity of the earth is much higher than ten billion, if we were willing to live a different lifestyle.

    For example, last weekend I harvested rice with my Japanese wife’s family. They own 1.75 acres, give or take, divided into six quarter acre food plots and another for the house. We harvested 2500kg of rice out of the five rice paddies, which is enough calories for about seven adults. The other plot is used for vegetables, enough to provide the nutrients not found in rice for seven people for a year. The house is plenty big enough for seven as well, even though only five live there currently. Though you couldn’t get much tighter than this with modern agriculture, they show that the best you can do is about 4 people per arable acre, which would imply a maximum population of around 30 billion. Now, this would entail living in some cramped quarters, using almost every arable inch for food, and everyone becoming vegetarian, but it is possible in theory.

    Ten billion in the real world will be cramped, but survivable.

  24. prokaryotes says:

    I agree. This comes down to efficiency, lifestyle, carbon footprints, environmental impact, resource usage per person and visionary ideas, like cities in the ocean.

    Plenitude Economics: Work Less, Play More, and Stop Screwing the Planet (Video)

  25. fj says:

    It’s likely that successfully addressing massive, self-induced, extremely difficult and dangerous climate change will likely be our first really big task greatly advancing civilization.

    And, we’ll be able to look to the stars.

  26. Theodore says:

    The cure for the population problem is global government, for which there is no cure.

  27. fj says:

    like animal size, population counts are also highly dependent on conditions

    Animals ‘shrinking’ due to climate change – Telegraph via @Telegraph

  28. Calamity Jean says:

    This assumes that currently arable land remains arable. I feel this isn’t a justified assumption, given the certainty of sea level rise and desertification. Yes, some high-altitude and high-latitude land that is currently too cold to be productive will warm enough to farm, but that addition will be overwhelmed by the loss of previously farmable areas that will be too hot and dry or under salt water.

  29. prokaryotes says:

    What’s the nutritional difference between the carrot I ate in 1970 and one I eat today? I’ve heard that that there’s very little nutrition left. Is that true?—Esther G., Newark, N.J.

    It would be overkill to say that the carrot you eat today has very little nutrition in it—especially compared to some of the other less healthy foods you likely also eat—but it is true that fruits and vegetables grown decades ago were much richer in vitamins and minerals than the varieties most of us get today. The main culprit in this disturbing nutritional trend is soil depletion: Modern intensive agricultural methods have stripped increasing amounts of nutrients from the soil in which the food we eat grows. Sadly, each successive generation of fast-growing, pest-resistant carrot is truly less good for you than the one before.

    A landmark study on the topic by Donald Davis and his team of researchers from the University of Texas (UT) at Austin’s Department of Chemistry and Biochemistry was published in December 2004 in the Journal of the American College of Nutrition. They studied U.S. Department of Agriculture nutritional data from both 1950 and 1999 for 43 different vegetables and fruits, finding “reliable declines” in the amount of protein, calcium, phosphorus, iron, riboflavin (vitamin B2) and vitamin C over the past half century. Davis and his colleagues chalk up this declining nutritional content to the preponderance of agricultural practices designed to improve traits (size, growth rate, pest resistance) other than nutrition.

    “Efforts to breed new varieties of crops that provide greater yield, pest resistance and climate adaptability have allowed crops to grow bigger and more rapidly,” reported Davis, “but their ability to manufacture or uptake nutrients has not kept pace with their rapid growth.” There have likely been declines in other nutrients, too, he said, such as magnesium, zinc and vitamins B-6 and E, but they were not studied in 1950 and more research is needed to find out how much less we are getting of these key vitamins and minerals.

    The Organic Consumers Association cites several other studies with similar findings: A Kushi Institute analysis of nutrient data from 1975 to 1997 found that average calcium levels in 12 fresh vegetables dropped 27 percent; iron levels 37 percent; vitamin A levels 21 percent, and vitamin C levels 30 percent. A similar study of British nutrient data from 1930 to 1980, published in the British Food Journal,found that in 20 vegetables the average calcium content had declined 19 percent; iron 22 percent; and potassium 14 percent. Yet another study concluded that one would have to eat eight oranges today to derive the same amount of Vitamin A as our grandparents would have gotten from one.

  30. Wyoming says:


    With all due respect. Your numbers make no sense what-so-ever. Amongst my other knowledge and experiences I currently own and operate an organic farming operation. I have some level of understanding of what you are talking about. Here are just a few of the reasons why the eventual actual numbers just cannot add up to what you wrote.

    Not all arable land is suitable for growing calorie dense crops.

    Some arable land is only suitable for grazing animals.

    Not all arable land has access to suitable amounts of fresh water needed to grow harvest able crops.

    Not all soils have sufficient base fertility needed to grow calorie dense crops.

    Some of the arable land MUST be left in forest.

    To use ALL arable land for human food production requires massive extermination of other species. Other species survival hinges upon using some of the arable land for their food production.

    I could go on, but I think the general thrust of my point is clear.

    World population has clearly exceeded the carrying capacity for humans unless we are willing to doom most other species to extinction. We are already in the midst of an extinction event. Global ocean stocks of fish are in serious decline. Top soil loss is dramatic and continuing. Fresh water supplies are shrinking fast. To produce the food we do now (whether that food is chemically grown or organic grown) requires vast amounts of fossil fuels which are also in finite supply. the climate is changing fast and that will negatively impact food production.

    If we were committed to maintaining our current population of 7 billion until the end of the century it is my opinion that we would be unable to do so in the face of the current headwinds being generated by the above problems and the many others I did not mention. And all those problems are going to significantly worsen as the years pass.

    9 billion in 2050. 10 billion in 2100. I, unfortunately, won’t be around to pay up or collect, but I will make a bet that in 2050 the population will be closer to 7 billion than 9 billion(and I am not saying it will be more than 7 either) and by 2100 it will be closer to 5 billion than 10 billion.


  31. prokaryotes says:

    Current projections show a continued increase of population (but a steady decline in the population growth rate), with the global population expected to reach between 7.5 and 10.5 billion by the year 2050.

  32. prokaryotes says:

    Climate Change Shrinks Species Pool

    Researchers found alarming effects of climate change on species diversity and population growth. Increased temperatures and near record low ice are stunting the growth of the polar bear population, as well as others, leaving scientists concerned about the future.

    These changes may seem minute to us, but think again. Major food sources, like fish, for humans are likely to reduce in size and amount, as well as crops are beginning to be grow more unreliably and smaller.

    In the case of animal species, climate changes are changing too fast for them to efficiently adapt to the new conditions. As a result, some animal populations are at risk for extinction, further accelerated by food balance and resource changes.

    Read more:

  33. Merrelyn Emery says:

    Thanks for that Wyo. I won’t be around to collect either but I’ll raise you to 2030 and then 2050. The systemic effects are already showing up, ME

  34. Chad says:

    Wyo: I was merely hypothesizing how many people we could cram in theoretically if we were willing to live on rice and beans in spaces no bigger than studios, while utterly destroying nature, using more or less modern technology. We know how to build soil and pump water, for example, so your arable lands only fit for grazing could, in principle, get the water they need. On top of what I mentioned, we clearly could capture some calories from the oceans and non-arable lands as well.

    Again, this is all in principle. In practice, the four horsemen would perform a culling long before we got to 30 billion. Humans are far too foolish, and tragedies of the common far too hard to solve, to ever let us reach the maximum number of people the planet could theoretically hold.

  35. Adrian says:

    Limits to Growth: The Thirty Year Update has a good analysis and charts of what happens to population in the wake of positive (adverse) environmental feedback loops caused by human industrial civilization.

    The idea that population might decline as a result of environmental challenges is borne out by historical examples as well.

    Do demographers run complex computer models that include our deteriorating environmental conditions and climate change? Maybe they should be in touch with the climate change folks or environmental scientists, borrow a model and then modify it to reflect population changes in relation to modeled climate and environmental projections?

  36. Adrian says:

    Excellent, tragic point that, as you point out, becomes painfully evident to anyone who looks at the growth rates. What, indeed, is to be done? Or can be done?

  37. Michael Tucker says:

    Also, to be fair, since the time of Malthus no pandemic, war or famine has ever reduced world population. Despite all the wars and famines, epidemics and pandemics that have befallen mankind in the intervening 300 years none have resulted in a decline in world population. It always goes up. To be sure, we are bumping up against limits, and we see those limits experienced by the poverty stricken populations of the world in countries that have no hope of ever producing enough of their own food or ever supplying enough of their own freshwater to satisfy demand but so far the losses are acceptable and they are not sufficient to reduce world population. That will change but it is very difficult to predict when and I think most find it very uncomfortable to imagine death rates exceeding the 1918 pandemic (no decrease in world population) let alone death rates equaling those experienced during the Black Death of the 14th century; the last time world population decreased.

    Also, to be fair, Malthus was an optimist:
    “The exertions that men find it necessary to make, in order to support themselves or families, frequently awaken faculties that might otherwise have lain for ever dormant, and it has been commonly remarked that new and extraordinary situations generally create minds adequate to grapple with the difficulties in which they are involved.”

  38. John McCormick says:

    Prokaryotes, this is absolute nonsense and way beneath your typical informative comments.

    Don’t embarrass yourself with ideas of exploring space. One would wonder if you are a newcomer to the issue of climate chaos.

  39. Theodore says:

    I am an enthusiastic supporter of colonization of other planets, but it has nothing to do with terrestial population reduction unless you are planning to move billions of people elsewhere. The solution to earth population problems is family planning, not deportation of people to the moon. Populating Mars (after robotic terraforming) is possible, but I would not recommend transporting more than a few dozen people at most. Let these few pioneers produce the rest.