11. Global Resources and the Limit to Population Growth
John Austin
four images of the earth from space

It has been said, that if we all lived like Americans, we would need four Earths to supply the resources, but how do other developed nations compare, and what are the long term consequences for the planet?

It is becoming clearer all the time that the resources of our planet are finite. The increasing global population is placing increased stresses on the globe in our attempt to feed ourselves and provide the standard of living we've become accustomed to. Do we need to be concerned about the future consequences?

Global Resources

The Global Footprint Network[1] is an organisation that has calculated the impact of humans on the ecosystem in terms of the space needed to supply our food and process our waste. Globally the planet is estimated to have 12 billion hectares of biologically productive land and water. As 1 ha is 10,000 m2, this figure equates to 120 million square kilometres, or 23% of the surface area of the Earth. While the oceans contain some food resources, they are mostly unproductive biologically. There are also vast areas of lands that are largely inhospitable to life, such as the polar regions and high altitudes. Consequently, the biologically productive area is lower than the total global land area of 29%[2].

Global ecological footprint for the period 1960-2008 (measured) with projections to 2050. Credit: Global Footprint Network.

There is not much, then, that we can do to increase the land available for food or resources. There have been some suggestions that we could reclaim land from the sea. To date about 9,400 km2 have been created throughout history[3], less than 0.001% of the biologically productive area, so land creation rates would need to be increased enormously, by a factor of a hundred or more, to be useful. In any case reclaimed land has environmental issues of a different kind, including being prone to flooding and subsidence. Another possibility is to convert deserts into productive landmass[4] but the technologies involved are expensive and energy intensive, thereby putting pressure on the remaining ecosystem. In fact with climate change, there has been a tendency towards increasing desertification[5]. So any land modification technology would need to counteract the current trend even to stand still.

National Ecological Footprints

Twelve billion hectares spread between the current world population of 7 billion equates to 1.7 ha per capita. This sounds impressive laid out in front of us, but how is each nation doing individually? The results are not impressive.

CountryEcological Footprint
South Korea4.5 (1961, 0.8)
China2.5 (1961, 0.8)
North Korea1.1

National Ecological Footprints (ha/capita) for sample countries. Data are for 2011 and taken from the Global Footprint Network[1].

Data for all countries are not yet available, but some of the highest values are Australia, United Arab Emirates, Canada and the USA. Of course Australia, Canada and UAR are countries with small populations and so their global impact is relatively small. The US, however, is a continental-size country with a major global impact. Many of the major countries in Europe (e.g. France, Germany, UK) have a similar ecological footprint as each other, much lower than North America, but still much larger than desirable. Approximate figures are shown in the table for several nations, based on data from [1] from 2011, and which have been read off the graphs. In any case the quality of the data varies. We see that the top of the table is populated by developed nations while the bottom of the table are those nations which are yet to become fully developed.

Ecological footprint and biocapacity for selected countries from 1961 to 2011, calculated by the Global Footprint Network[1]. The Ecological Footprint is a measure of the resources used by the population in a country. The biocapacity is the amount that can be supplied by the resources of the country itself. In all four cases, the ecological footprint exceeds the biocapacity by a significant margin. See [1] for further details. Image credit: Global Footprint Network.

Is the World Overpopulated?

As recently as 1960, when reliable figures started to be collected, humans used only 0.7 of the planet's resources. By 1970, we were using the whole planet and on the basis of the latest figures, it would seem that the world is indeed overpopulated. Current world usage of about 2.5 ha per capita is 50% larger than the globe can support in resources and waste removal. The reason that the figure can be larger than the 1.7 ha planetary capacity is that people are using resources laid down over millennia. This is similar in principle to using a bank savings account to support a current lifestyle. Eventually, the savings run out. In this case the "savings account" includes fossil fuel deposits and vegetation (e.g. forests) that are being depleted faster than they can be replenished. Waste products are accumulating faster than they can be destroyed by the environment. UN projections imply that by 2050, we would be using the equivalent of three Earths given current projections for development and population growth.

The above projections take account that there is a tendency for countries, as they develop, to use more and more of the world's resources. Countries which have made the transition from one group to another, such as China and South Korea, have followed this trend over the last 50 years (the only time when reasonably reliable data have existed) of increasing use of resources, as shown in the above table and graphs.

The Texas Thought Experiment

It has been suggested that the world is not overpopulated at all[6], and that we could each live on as little as 0.01 ha of land with all 7 billion of us crammed into Texas. The rest of the planet could be farmed giving plenty of resources for everyone. This sounds like an impressive thought experiment, but it doesn't stand up to rigorous scientific scrutiny. Enormous resources would be needed to move the food from the growth regions to where it's needed, as well as to supply water and remove human waste. Of course before offering this sort of (false) argument as a thought experiment, we need to provide practical solutions for cutting actual current consumption from the global 2.5 ha/capita use to the 1.7 ha /capita available. There is no point claiming that the planet is not overpopulated but then continue to run down its resources at a steadily increasing rate. It is like the addict who says "I can stop smoking if I want to, but I choose not to".

Not surprisingly, people have aspirations to live like the most wealthy in the world, to have a large house of their own to live in, and a car to drive. Perhaps foreign holidays and a house in the country. Of course not even the average US citizen has all these, but if we all lived like the average American, then we would need 4 or 5 Earths to supply all the resources[1,7]. Sooner or later, something has to give.

You could use this to say that with current technology, the Earth can only support one quarter its current inhabitants, with a US lifestyle[7], or one half if we all adopt a more environmental lifestyle.

What are the Consequences of Overpopulation?

Arguably, we are already seeing one of the effects: climate change[8]. With so many people on the planet using primarily fossil fuels, greenhouse gases are at unprecedented levels and rising. We are heading for significant temperature rise of about 3oC by the end of the century. While the global average is relatively small, it is higher than the 2oC deemed to be a dangerous level of climate change. This is considered dangerous because the increase is not the same everywhere, and will likely be larger in the polar regions. The changes may also be accompanied by changes in the frequency of severe storms. The full consequences of climate change on the biosphere are yet to be fully understood. Put simply, though, if there were half the people on the planet, the fossil fuel impact would be about half as big. Fortunately, there appears now to be a growing movement away from fossil fuels towards renewables, such as solar power[9].

Other effects of overpopulation are desertification[4], soil degradation and overpopulation. All of these interact with climate change in a way that is difficult to understand or predict. In other words, climate change affects them and they affect climate change itself.

The Long Term Consequences

We can look at the history of isolated communities in the past to have some idea of the consequences of overspending our resources. There has been some speculation concerning the Easter Islanders and how the race became extinct. I think a particularly good discussion has been written by Jared Diamond[11], although alternative explanations for the collapse of the society have been suggested.

The Islanders initially likely left their initial island by their flimsy boats and arrived at the Easter Island by the prevailing currents. They were then isolated at Easter island as they couldn't return against the current. The next island would have been too far to travel, so they would have perished at sea. So the Easter Island has a way in, but no way out and the Islands are isolated.

Initially, there would have been forests which the Islanders could have chopped down for fuel. The forests would have created its own microclimate of rain to ensure moist and fertile soil for growth. Initially the population would have prospered and expanded, but all the time consuming the very forests that were their lifeline. As the forests were slowly eliminated, the rainfall decreased, and the other vegetation and crops failed. The population would have expanded in the "good times" then crashed as the climate and forests were modified. The population became extinct and all that is left is a set of magnificent statues.

Are there any lessons from the Easter Islanders?

Of course, the whole globe has a more complete ecosystem than a single island, more vulnerable as it is to climate change. In any case, we don't really know what happened at Easter Island. Nonetheless, it is plausible that without improvements in technology, degradation of the environment will force the population down, whether we like it or not. There are of course reasons for optimism. For the first time I have become a little optimistic about our prospects on climate change, but this will likely take decades to become significant, and with exponential growth in population, time is running out for this particular problem.

It is difficult to see, then, how in the long run we will avoid a cataclysmic disaster to our species that was perhaps experienced locally by the Easter Islanders. If we do nothing we may find our population reduced for us by epidemics or war for oil and water resources.

Exactly how to reduce global population is a moral dilemma and would be quite a challenge to introduce. Intergovernmental coordination could certainly work with organisations such as the UN. Global introduction of China's unpopular one child policy would probably be needed to lower the population. Whether we could get it down to the 4 billion level this way remains to be seen. More draconian measures might be needed.

If the population crashes, it will likely come very quickly. At any given moment, the world food supply in storage is only a few months[12].


Article initially prepared 20 June 2015

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Website revised by John Austin, 20/6/2015. © Enigma Scientific Publishing, 2015.