Population Matters

Air, food & water

Air, food & water

Air, food and water are essential to all life. All are threatened by growing human numbers.


Air pollution is an important example of the waste arising from unsustainable human consumption. It arises from multiple sources, including fossil fuel use, particularly coal and transport, livestock, and includes cooking fires in developing countries. Its consequences include premature deaths, particularly in cities, and the impact of climate change, including ocean acidification.

Air pollution caused seven million premature deaths in 2012
Air pollution caused seven million premature deaths globally in 2012

Air is essential to most life but often taken for granted.

Human activities do affect the quality of the air we breathe and hence our health. This is recognized and action has been taken to improve air quality by removing some known contaminants. Lead, for example, has been removed from petrol.

However, problems remain. Smoke from cooking fires affects the health of millions in developing countries, especially where habitations have insufficient ventilation. Fast growing cities, particularly in China, are affected by smog from coal-fired power stations. It was coal fires that were the cause of the notorious smog in London in the 1950s.

Many cities in the developed world have controlled the use of coal. However, their citizens are affected by motor vehicle emissions. The problem is worsened by continually increasing traffic jams.

More generally, carbon, methane and nitrous oxide emissions of all kinds — those from aircraft, manufacturing, farm animals, etc. — contribute to climate change and ocean acidification.

Food requirements

Ever more people need ever more food. We currently produce enough food to feed the seven billion people on the planet. Hitherto the main reasons that millions have remained malnourished have been where food is grown, how it is distributed, and the fact that many people are too poor to pay for it. This has led to a false sense of complacency. It is dangerous to assume that the world will continue indefinitely to be able to feed even its existing population, let alone the mid-range 30 per cent increase in numbers projected by the United Nations between 2010 and the middle of the century.

Degraded soil

In 1960, there was enough land to sustain the world population on a modest European diet, around 0.5 ha of arable cropland per capita. This allowance has fallen by over half to 0.2 ha per capita because the population has doubled and soil degradation and erosion have increased. Humanity is already using most of the productive land, so the expected 1 – 4 billion additional people will have to be fed from more fragile and marginal soils. The more people there are, the harder it will be to feed them.

Food supplies

Our agriculture depends on high-yield crop variants supported by large inputs of energy, water and fertiliser, the latter in particular requiring high levels of fossil fuel input.

Basically, we live by turning oil and water into food. However, the high input levels required by our intensive monocultural approach are vulnerable in a world where fossil fuel resources are finite and water supplies are threatened by climate change, overextraction and increasing demand.

Swarm of locusts

Food supplies are also vulnerable to plant disease, pests, falling soil fertility, desertification, urbanisation, changing weather patterns, rising sea levels and rising levels of salination as soils are overirrigated.

Fish stocks, another major contributor to global nutrition, are currently being overexploited worldwide by intensive industrial fishing practices.

Developed countries consume significantly more input-intensive meat and dairy products than developing countries but as developing countries industrialise, their consumption of these products will increase, putting further pressure on resources.

Our consumption is driving continued encroachment into the natural environment as more and more land is engulfed by agriculture to feed our growing numbers.

Read more about food.


Ever more people need ever more water. Growing populations, changing consumption patterns and increasing industrialisation mean people are using ever more water.

Two billion people will face absolute water scarcity by 2025
Two billion people will face absolute water scarcity by 2025

However our supplies of fresh water, like other resources, are finite and under threat. Ground water is being depleted, and pollution is affecting many remaining fresh water supplies.

Climate change is already changing rainwater patterns with catastrophic consequences, and shrinking the glaciers which many millions of people rely on to provide water throughout the year.

Many communities, especially in the poorest regions, are already suffering severely from shortage of water. In some regions of Africa and Asia people have to walk more than six kilometres to collect safe drinking water.

Large-scale water extraction and distribution generally depend on energy resources which are themselves limited. Even the power generated by hydroelectric schemes is endangered by reduction and variability in rainfall.

Read more about water.

Next: Biodiversity