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Food supply must not cost the Earth

The importance of agriculture can’t be overstated: it not only keeps the world’s population alive, it is also the single largest employer in the world, providing a livelihood for 40 per cent of the planet’s population.

Yet it’s an inefficient, unsustainable system. Though we grow enough to feed the world, more than 900 million people still suffer from hunger due to lack of access to food.

It has huge environmental impacts. Some 70 per cent of the world’s freshwater goes into agriculture and 11 per cent of land surface is used for crop production from which millions of tonnes of valuable resources – water, nutrients and organic matter – are lost every year in the form of wastewater.

Meanwhile, the livestock sector contributes 18 per cent (7.1 billion tonnes CO2 equivalent) of global greenhouse gas emissions.

Fishing and aquaculture are equally important nutritionally. According to the Food and Agriculture Organization of the United Nations (FAO), in 2009, fish accounted for 16.6 per cent of the world’s intake of animal protein and 6.5 per cent of all protein consumed. Yet fish stocks are falling due to overfishing, climate change is shifting migration patterns, and fish farming is generating pollution and disease.

The world faces a challenge to make food production and consumption sustainable

The world faces a challenge, therefore, to make food production and consumption sustainable. Between now and 2050, the global population is projected to rise from about 7 billion to 9.2 billion. According to the FAO, this will require a 60 to 70 per cent increase in global food production, compared to 2005-07, if current trends continue.

At the same time, the stock of unused land with good agricultural potential is declining, exacerbated by heightened competition for land, water and fish stocks, rising fuel and fertiliser prices, and the impact of climate change.

What’s needed is improved management and efficiencies to increase food security and use fewer natural resources.


Global production of meat is projected to more than double from 229 million tonnes between 1999 and 2001 to 465 million tonnes in 2050, while worldwide milk production is set to grow from 580 to 1,043 million tonnes to fulfil increasing demand.

But is this sustainable? Already the livestock sector accounts for 18 per cent of global greenhouse gas emissions and 9 per cent of human-related CO2 emissions, with much of this coming from deforestation.

Livestock is responsible for 35 per cent of man-made methane – which has a potential impact on global warming that’s 23 times greater than CO2 – most of that from the flatulence of cattle and sheep. It also generates 65 per cent of anthropogenic nitrous oxide – with 296 times the global-warming potential of CO2 – mostly from manure, as well as nearly two-thirds of anthropogenic ammonia emissions, which adds to acid rain and the acidification of ecosystems.

The sector’s water impacts are similarly large. According to the Water Footprint Network, global animal production requires about 2,422 billion cubic metres of water per year, which is around 8 per cent of global human water use. Some 30 per cent of this volume is for the beef cattle sector and 19 per cent for the dairy cattle sector. Most of the total volume of water (98 per cent) relates to the water footprint of animal feed.

The livestock sector, says the Food and Agriculture Organization of the United Nations (FAO), is probably the largest sectoral source of water pollution, contributing to eutrophication – “dead” zones in coastal areas – degradation of coral reefs, human health problems, the emergence of antibiotic resistance and many other issues.

To put the scale of the challenge in perspective, to avoid increasing the level of damage beyond its present level, the environmental impact per unit of livestock production must be cut by half.


Grain and cereal production can be split into three categories – food for human consumption, feedcrops for livestock and biofuel supply.

Negative environmental impacts include soil, water and nutrient depletion, greenhouse gas emissions and pollution, and the degradation of natural ecosystems and biodiversity.

Soil depletion is perhaps the most serious of these. According to John Crawford at the University of Sydney, soil is being lost at between ten and forty times the rate at which it can be naturally replenished, due to various farming methods.

Some 40 per cent of soil used for agriculture is classed as either degraded or seriously degraded, the latter meaning that 70 per cent of the topsoil is gone. Professor Crawford estimates that the world has about 60 years of topsoil left and that, under a business-as-usual scenario, degraded soil will mean that we will produce 30 per cent less food over the next 20 to 50 years.

Biofuels are a relatively new crop, but one with increasing impact. According to the International Energy Agency (IEA), biofuels currently provide only around 2 per cent of total transport fuel, but by 2050 this could grow to 27 per cent, avoiding around 2.1 gigatonnes of CO2 emissions per year if produced sustainably.

However, meeting this biofuel demand would require around 65 exajoules (EJ) of biofuel feedstock, occupying around 100 million hectares (Mha) in 2050, which the IEA says “poses a considerable challenge given competition for land and feedstocks from rapidly growing demand for food and fibre”, though not an insurmountable challenge. This corresponds to an increase from 2 per cent of total arable land used today to around 6 per cent in 2050.

Concerns regarding sustainability include the impact associated with agriculture, links to rising food prices, deforestation associated with growing biofuel crops and the net carbon value of using biofuels. The drive to create sustainable biofuels and investment in new biofuel technologies are attempts to allay these concerns.


Preliminary data from the FAO’s 2011 report on fishing suggests that capture fisheries and aquaculture supplied the world with about 154 million tonnes of fish, of which 131 million tonnes was eaten.

This is up from 148 million tonnes and 128 million tonnes respectively in 2010, and yet the same report estimates that about 29.9 per cent of global fish stocks are overexploited, producing lower yields than their potential and in need of tough management plans to restore their full productivity.

In addition, most of the stocks of the top-ten species, which account in total for about 30 per cent of global catch, are fully exploited and, therefore, have no potential for increases in numbers.

This is despite the 2002 Johannesburg Plan of Implementation, which called for all overexploited stocks to be restored to a level that can produce maximum sustainable yield by 2015. This, says the FAO, is a target that is unlikely to be met.

Waste is also an issue. Indiscriminate trawler fishing techniques capture a vast number of fish not permitted or suitable to land, which are discarded. In the North Sea, for example, half of all fish caught have been thrown back overboard dead.

At the same time, fish farming is growing. World aquaculture production hit an all-time high in 2010 at 60 million tonnes. It’s growing at about 6.9 per cent a year and has expanded 12-fold over the past three decades.

Though farmed fish can reduce the stress on natural stocks, aquaculture too has environmental impacts. Waste feed and faeces from fish farms can collect on the seabed under fish cages, fish farming processes release nutrients such as nitrogen and phosphorus from fish feed into the marine environment, and disease, infestations of parasitic sea lice on farmed salmon can transfer to wild populations.