CARRYING CAPACITY AND POPULATION OVERSHOOT

“We are dealing with two opposing forces, the scientific power of food production and the biologic power of human reproduction. … There can be no permanent progress in the battle against hunger until the agencies that fight for increased food production and those that fight for population control unite in a common effort.” .These comments by Norman Borlaug brings to mind the equally exasperated comment by Harvard biologist Edward O. Wilson when he wrote…“The raging monster upon the land is population growth. In its presence, sustainability is but a fragile theoretical concept.”

Carrying Capacity
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Population From 1950
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Paul Chefurka describes carrying capacity as a well known ecological term that has an obvious and fairly intuitive meaning: “the maximum population size of a species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment.

Unfortunately that definition becomes more nebulous the closer you look at it – especially when we start talking about the planetary carrying capacity for humans. Ecologists claim that our numbers have already surpassed the carrying capacity of the planet, while others (notably economists and politicians…) claim we are nowhere near it yet!

 

Historical World Population                                        Click to Enlarge

Politics has nothing to offer this situation. The biophysical driver of fossil fuel energy transcends all political boundaries and philosophies. Fossil fuels have supplied 89% of the total primary energy used throughout the world over the last 55 years, and supply 87% of the energy used today, according to BP Statistical Review 2011).  Agriculture started the ball rolling about 8,000 years ago, and got our population to 1.8 billion in 1900 without fossil fuels. But the logistical curve didn’t take off until the serious use of fossil fuels began in about 1900. Without fossil fuels we’d have seen some additional growth, but nothing like what we’ve seen in the last 100 years.

Population Energy
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World Energy Consumption
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That’s the message of the green line in the graph. As you can see in the correlation of primary energy (particularly its primary component of fossil fuel) and world population is blatantly obvious.  As goes fossil fuel, so goes humanity. To a first approximation, everything we’ve done since 1900, including agriculture, has been the result of our use of fossil fuels.  That’s the message of the red line in the graph on the left. We are too close to the inflection point (~20 years or less), and have built too much fossil-dependent infrastructure, for renewables to do more that act as a buffer in some places against the most egregious effects of the decline.

When a population surpasses its carrying capacity it enters a condition known as overshoot.  Because carrying capacity is defined as the maximum population that an environment can maintain indefinitely, overshoot must by definition be temporary.  Populations always decline to (or below) the carrying capacity.  How long they stay in overshoot depends on how many stored resources there are to support their inflated numbers.  Resources may be food, but they may also be any resource that helps maintain their numbers.  For humans one of the primary resources is energy, whether it is tapped as flows (sunlight, wind, biomass) or stocks (coal, oil, gas, uranium etc.).  A species usually enters overshoot when it taps a particularly rich but exhaustible stock of a resource.  Like oil, for instance… Paul Chefurka Sustainability Activist.

13 Responses to “CARRYING CAPACITY AND POPULATION OVERSHOOT”

  1. Florida Mansions says:

    After reading through your article I was not surprised to learn that overpopulation was not on the agenda at the Paris conference.
    It would have been an admission that the greatest threat to the world environment, was not CO2 but the third world population growth and the third world immigration to western countries. When an IPCC official, questioned as to why it was not being discussed at the conference, ended his response by waffling, “Nine Billion monks would have a far different greenhouse-gas imprint than a similar number of people living high on the hog.”

  2. Stephanie says:

    There is no doubt that overpopulation is the elephant in the room but the U N won’t do anything about it. It is “too sensitive a subject” preferring instead to talk about climate change, previously changed from global warming, after long periods of flat world temperatures had threatened further funding. There are now public accusations of fraud, collusion and tampering with temperature readings. ………Go to realclimatescience.com.

  3. Broady says:

    It is a well known fact that where there is a lack prosperity there is an increase in population growth. We must lift the standard of living for the billions of people in third world countries such as in Africa. We must provide them with cheap and accessible power which means coal fired power stations and access to contraception. It is a waste of time spending money on the world’s chaotic weather if we are not prepared to address the real problem of overpopulation.

  4. Tempura 10 says:

    We would not exist today had it not been for fossil fuels. Our knowledge and every thing we touch and use is due to coal and oil. Now we want to ditch them because they might have caused almost a degree of world warming during the last 50 years or so. Mind you nothing like the Medieval warming period which was much hotter than today. To claim the current warming is unprecedented is simply not true. By all means reduce Co2 emissions if you think they are affecting our climate but only where it is practical.

  5. Too Many Too Soon says:

    Why the blind rush to import so many people? Why not wait until we have the infrastructure? Who are these faceless bureaucrats making these stupid decisions? They are overcrowding our Cities and penalising the current population by overstretching existing services….it is not unusual to have a dozen people living in a one bedroom apartment because there is no alternative accommodation.

    • Kaput says:

      I agree. They want our main Cities to be like Hong Kong. You hear on the news that we HAVE to make way for so many hundreds of thousands of migrants and we HAVE to get used to the congestion it will bring because the bureaucrats have made up their mind and we don’t have a say.
      It is just plain bloody minded to cram these people in without a plan. The jobs are in the centre of Sydney and Melbourne where up to half the migrant intake is going so it is unlikely they will want to live in outer suburbia. This means they will be living in high rise apartments along with most other migrants. The whammy is that they will have to rent rather than buy because an apartment it is not a good investment nor is it in the proper environment you would choose to raise a family.

    • Noname says:

      We must have an implementable plan, which means it must be affordable. Enough infrastructure for Government’s rapid population growth is simply unaffordable. That’s why it hasn’t happened – not because there weren’t plans.

  6. Benz says:

    It will be a lose/lose situation. The increased tax revenue we will obtain from a bigger population won’t be enough to pay for the extra infrastructure needed to cater for the huge increase in immigration. One percent more people might increase tax revenue by one percent, but this only increases the amount of infrastructure we need to build in one year by around 50%. The result is more congested infrastructure, more government debt and more austerity measures diminishing the level of government services and increasing the out-of-pocket costs citizens pay for services like education, health and transport.

  7. Anonyme says:

    The Government is cheating….. simple as that! Callum Pickering for The Business Spectator: “It will not improve the living standards of you or I; nor will it reduce poverty and inequality or foster innovation and creativity. The only beneficiaries of high immigration are the immigrants themselves and while that is great, we can safely say that the government is not pursuing immigration for humanitarian reasons. Instead it is creating an illusion of growth while hoping you don’t realise the reality”.

    • Agreed says:

      I am a supporter of immigration, its worked well for Australia in the 50’s and 60’s and will work for us now providing it is kept to a sensible level. But just herding them into our over crowded major cities willy nilly is not the answer.
      Earlier this year I read a report where the federal government’s Peak Infrastructure Agency had warned the Government that the country’s major capital cities were facing a “watershed” moment that would lead to a ­decline in the quality of life and economic productivity if governments failed to plan for significant population growth over the next 30 years. Infrastructure Australia claimed that unless all levels of ­government address “unplanned growth”, the major cities’ global livability ranking will begin to fall, with poorer access to jobs, schools, housing, and green space.

  8. Packer says:

    There is something amiss when our politicians refuse to take the advice of the responsible authority who advise on a lower number of migrants. ..So much for Melbourne being the the most livable city.

  9. Nick says:

    Neither of our political parties included population growth in there election platform because they knew very well it would have no public support so they introduced it after the election. With more than half the population increase heading towards the centre of Melbourne and Sydney we will have further pressure on an already limited services and the number of jobs.

    • N.B. says:

      Australia urgently needs to develop a sustainable population policy. There is strong evidence that if we let our population keep growing as fast as it is doing now, about 2% a year, with an average of more than 3% per year in both Melbourne and Sydney, our quality of life in Australia will most certainly decline. Current population growth rate will push the need for infrastructure well beyond the capacity of what the government can finance. I read somewhere that more than 70% of Australians do not approve of the present rate of population. Why can’t we have a say?…It is so frustrating!

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