In October 2013, Nobel Laureate (Physiology/Medicine, 2002) Sir John Sulston visited New Zealand to deliver the Rutherford Memorial Lecture. Sir John chose to focus on the results of a study he led from 2010–2012 for the Royal Society of London’s international working group People and the Planet. This group studied the links between global population and consumption and the implications for a finite planet.

Critical point

“Why now? This sort of discussion has been going on for a while, in fact for centuries, about whether we were going to run out of space for the people. But we do think that we are getting to a critical point. Our diagnosis and scientific measurements are telling us that we are getting to a point where we are reaching certain limits,” says Sir John.

He outlined that continued growth and widespread changes in our population, along with unequally distributed resources being consumed at an unprecedented rate, are leading to profound challenges to human health and wellbeing as well as to the natural environment.

Human wellbeing

Sir John said that human wellbeing is usually accepted as belonging to one of five categories – freedom, security, health, material resources and social relations.

“Everybody needs these things in order to be living well. However, if you are starving, you need food, and there is not much point in talking about anything else. But once you are out of that, which applies to 6 billion of the world’s 7 billion people, these things matter, and they need to be paid attention to.”

Impacts of human population

Some of the broad impacts of human population include climate change, land-use conversion from forest to farmland in order to feed ourselves and an increase in the rate of extinction of other animals. (The current extinction rate is 1000 times higher than the fossil record, and Sir John says that, in the future, this current rate is expected to increase by more than 10 times.)

“These things are a threat to our wellbeing because we are going to run out of space, but it is also, I will put to you, a failure of stewardship.”

Sir John said that our “thrashing of the planet” is ultimately affecting human wellbeing “in all sorts of ways, not just food, but also in a spiritual and aesthetic sense”.

“We are the transcendent thinking species, which means thinking beyond our space and time, beyond our own confines – which is what we can do as a species. This is why we are so successful, not because we are strong or anything in particular, but because we can make plans. And making plans means we can know exactly what we are doing. But we are fighting over the details and arguing over this and that, and the fact is we are making these changes [to the Earth], and other species are suffering as a result.”

“Population and consumption need to be considered together. We have the people and we have what the people do, and this determines the impact on the planet.”

Sir John said how we approach the limits of a finite planet depends on our lifestyle choices and decisions.

“How we approach the limits really is a matter of our choice. We do not have to say, ‘Oh well, we can’t do anything about it’.”

Declining fertility

At the present rate of fertility, the Earth’s population would rise exponentially from 7 billion to around 30 billion by the end of the 21st century – an unsustainable number of people for the planet. However, Sir John says that no one believes this will happen and that already they are seeing trends of declining fertility in most countries. It is more likely the population will grow to around 10 billion by the end of this century.

“But there is a wide variation around this [predicted] number depending on what people are doing and the choices we make.”

At present, the fertility of the most developed countries has fallen slightly below replacement value (more people die than are born). Although there is a downward trend, the fertility in the least developed countries (which, ironically, can least support human wellbeing) is still well above replacement.


Consumption by humans is of two types. There is the consumption of material resources, such as water, food, energy, minerals and other natural resources, and there is the consumption of goods and services (also known as economic consumption). Both are necessary for delivering human health and wellbeing, but they have very different impacts on the planet.

“Material consumption is what primarily concerns us as this is where the impact on the Earth is coming from. Looking at the example of energy, energy consumption is very closely related to the amount of carbon dioxide emission, and that’s because most of the energy we consume at the moment, although not true for New Zealand but for the world as a whole, some 85% is coming from the burning of fossil fuels [such as oil and coal].”

“The rate of consumption of these [fossil fuels] has gone up somewhat faster than the rate of population growth. In other words, the average per capita use of energy has gone up.”

Inequity in distribution of energy

However, Sir John pointed out that there is an enormous inequity in the distribution of energy. Emerging economies use as much or more energy than developed countries. However, they have larger populations and actually use less energy per capita. The least developed countries, such as many in Africa and places like Afghanistan, have little access to distributed energy and use the least amount.

“This is actually holding back people’s development. We cannot expect these people to have a reasonable standard of living with this very low use of energy [or access to energy], so we have an inequity to deal with as well as the hugely disparate consumption by the rich and the poor.”

Urgent actions

Some of the urgent actions called for in the report include:

  • lifting the world’s poorest 1 billion people out of poverty
  • stabilising and reducing the material consumption by emerging and developed countries
  • continuing the downward trend of fertility by meeting the unmet need for contraception
  • bringing in high-quality primary and secondary education in all countries, with equal opportunities for girls and boys.

Useful links

More information about the People and the Planet study led by Sir John Sulston.

This site has up-to-date world population figures.​

Activity idea

Ensuring water security is one of the challenges of Earth’s population growth. Your students may like to try this activity in which they compare water issues in Papua New Guinea and Australia.
Water issues

    Published 22 January 2014