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From skyscraper apartment blocks to green tech to water security—population growth requires forward thinking when it comes to infrastructure. Engineer Gregory Oates outlines what this means for scientists, architects and anyone involved with technology.

Population size has great implications for what is expected from science and engineering, yet we have seemingly little influence in its planning.

World population has grown from about one billion in 1800 to seven billion today. Globally, the fertility rate, that is the number of children per woman, has fallen from five in 1965 to two and a half today. Although, with the population base growing, the growth rate has hovered fairly steadily at about eighty million extra people per year since the 1960s.

Less developed countries contribute ninety per cent of the current population growth. However, the impact of population growth in developed countries is magnified by a high-consumption lifestyle, with electricity use per capita six times that of the rest of the world.

The benefit to cost of reproductive health and family planning is arguably greater than any other form of aid and can ill afford to be overlooked. Unfortunately, it only makes up two per cent of OECD country aid budgets, due to various competing interests. This would need to be roughly tripled to meet UN project aims.

Global population growth is solely due to births exceeding deaths. At a national or regional level, migration is a significant factor and accounts for sixty-five per cent of population growth in developed countries.

Looking into the UN’s crystal ball predicts that population will continue to grow and then plateau around ten billion by 2100. This is the middle estimate. The lower estimate suggests a peak of about eight billion around 2050. The high estimate is for a staggering sixteen billion by 2100 and still climbing.

The population growth of the last 200 years is attributed to leaps forward in sanitation and healthcare extending life expectancy, and the industrial and agricultural revolutions leading to abundant energy and increased agricultural yields. This all involves science and engineering—water treatment, pharmaceuticals, cheap energy and fertilisers.

Scientists and engineers will be tasked with providing food, water and energy for at least another one billion and perhaps even three billion more people by 2050.

This is the point in a discussion on population, where we often come to the question: ‘So, how many people can the planet sustain?’

Given all the interrelations, no-one can realistically state the ‘maximum population’. This is a complex topic linked to how we each want to live and inequality of wealth. It is tied to what size family we have or want, cultural or religious ideals, and what we desire to pass on to the next generation.

As scientists and engineers we may like to discuss hypotheticals for how many people may be provided for with potential resources and technologies.

However, the risks and shrinking slices of pie indicate more people are not of collective benefit – I find this an unavoidable conclusion.

After decades of impressive growth in agricultural output, food production continues to struggle to keep pace with population growth. Over half of fish stocks are fully exploited and agricultural practices are often unsustainable. Desertification is estimated to threaten twenty-five per cent of land. Scientists predict increasing atmospheric CO 2 will negatively impact our ability to yield food. The Food and Agriculture Organisation project 1.8 billion people will be in regions of water scarcity by 2025. Demand for energy intensive desalination is increasing, where it can be afforded. And society is having difficulty fast-tracking to renewable energy.

More people simply will not increase living space or access to basic resources, which human dignity relies upon.

To give perspective, population is clearly not the only pressing global issue, nor is lower population the only solution to pressing global issues.

Nevertheless, there is clearly a big gap in the UN’s lower and higher estimates, indicating that the future is far from a formality. The difference in the projections depends on the family sizes that people around the world choose and are able to implement. These choices represent vastly different qualities of life, environment and security for everybody.

Consider an area where population is steady, and goods and services are produced at economy of scale. There is enough demand to maintain niche experts and services, and perhaps even attract a headline band once in a while.

The output of useful goods and services of the area will follow the so called ‘law of diminishing returns’. This means that each extra unit of output will require a little more labour than the previous unit. This is because we have a fixed or declining resource base and we tend to pick the lowest hanging fruit first. For example, we use the most fertile soil first; we go for natural fish stocks before setting up a fish farm; we use freely flowing fresh water or aquifers before bothering to build a desalination plant; we exploit the conventional oil and gas reserves before exploring difficult terrain; the same goes for minerals, where we cherry pick the richest ores first; and even with renewable energy we will pick the areas with the best conditions to capture wind and solar energy first.

Let’s imagine if our area doubles its population and reaches a new steady state. There will be a transient period where work rate increases to expand infrastructure and production to meet the growing demand. During this phase a greater proportion of the economy will need to be invested to allow for expansion. Financing this expansion is likely to result in pushing up public debt. The transient phase continues until population steadies and output reaches demand.

Our area, now with twice the labour, increases its output of goods and services significantly. However, it will not double for the same amount of work per person, as resources have not doubled. This is the law of diminishing returns doing its thing.

Subsequently, output per capita falls. The average citizen is worse off.

The only financial winners are those with the biggest stakes in expanding total output.

The majority of places in the world are continuously in this population growth phase, where living space falls and waste rises. Supply of goods, services and infrastructure, either innocuously or disastrously, struggles to keep pace with demand.

This example assumed no technological improvement over time. However, in reality we are always improving technology; quite successfully in fact. This counteracts the diminishing returns discussed and overall quality of life has generally improved. Technological advance has occurred parallel to population growth, but it is not dependent on it.

So, one must question, is this the path we wish to continue on?

For how long can we keep chasing our tail?

Shifting from an expanding population to a stable population shifts the economy. It allows capital to be handed down from generation to generation with each having time to maintain, upgrade and replace it without trying to expand. Where infrastructure is lacking, it allows time for investment to catch up to the basic needs of the public. It leaves a greater proportion of the economy to be put into activities of improvement rather than expansion, such as health, education and training, and development and implementation of innovative technology. It allows technology gains and investment to go solely to improving sustainability and wellbeing. The greatest benefit would flow to people with the least.

This is the crux of how population growth relates to scientists and engineers – do we want to be expanders or innovators?

However, overcoming population growth is a social challenge and does not require a technical solution. Currently, forty per cent of all pregnancies are unintended.

A universal culture of freedom to choose one’s family size and the ability to put it in place is required. The alternative would eventually involve worsening living conditions and life expectancy, regardless of technological developments.

As difficult as achieving this culture may seem, many poor countries achieved it in the 1970s and 1980s. The main barrier for the remaining high population growth countries is a lack of political will. The successes have not been limited by illiteracy, culture or religion. For example, Iran reduced their fertility rate from 6.5 in the 1980s to 1.7 today. Nor does this culture need to wait for economic growth.

Beyond population growth Population size has great implications for science and engineering.

What are needed are increased global focus and scaling up of efforts in education and family planning services. Based on figures from the International Planned Parenthood Foundation, such services reduce unintended pregnancies at a cost of about US$50 each. This may seem like a cold figure to state. But, one must also contemplate the less measurable benefits beyond those already discussed, such as the impact on empowerment of women, maternal health, child mortality and the future benefits of children being better supported.

Such aid tackles issues deeply and is the most humane approach.

The UN recognises lowering fertility as a key to accelerating achievement of the Millennium Development Goals. They have estimated each dollar spent on family planning saves up to US$6 in other aid. The benefit to cost of reproductive health and family planning is arguably greater than any other form of aid and can ill afford to be overlooked. Unfortunately, it only makes up two per cent of OECD country aid budgets, due to various competing interests. This would need to be roughly tripled to meet UN project aims.

The notional end point of such a strategy would be when there is universal basic education, freedom of choice regarding family size and access to health services to implement them. The sum of these individual choices over a single generation could effectively lead to the stabilisation of global population.

The final responsibility for population planning rests with each nation.

So what of the role of scientists and engineers on population?

We are well qualified to grasp the implications of population size and growth rate and should be more active than most in influencing policy makers to focus and plan appropriately.

Political leaders all too often continue to see population growth as a necessary ingredient for a functioning economy. A strong and resilient economy is dependent on abundant resources, a healthy environment and a productive workforce, not on expansion.

Further, we have a responsibility to communicate environmental and social impacts to the public.

We may also choose to take a role in challenging counterproductive policies. The pyramid scheme that we must have population growth to counter an ‘ageing population’ is one example. Ageing is a natural part of transitioning to a stable population with long life expectancies.

Most importantly, as scientists and engineers we need to be consciously involved in the type of growth we want and push for a society where we are innovators that lead to growth in sustainability and wellbeing.

This is an edited transcript of Gregory Oates' Ockham's Razor.

