Improvements in agricultural technology and efficiency will not be sufficient to meet climate change targets in the food and agriculture sector. These improvements would need to be accompanied by a 30% reduction in livestock production in high-producing countries. If this reduced production translated into reduced consumption, the amount of saturated fat consumed by populations eating large amounts of animal products would drop sharply, which would in turn have positive effects on health, largely through reductions in heart disease. These issues are discussed in the fourth paper in the Lancet Series on Health and Climate Change, written by Dr Sharon Friel, Australian National University, Canberra, Australia, Dr Alan Dangour, London School of Hygiene and Tropical Medicine, UK, and colleagues in both institutions.
The food and agriculture sector contributes 10-12% of total greenhouse-gas emissions worldwide. Deforestation and other changes in land use contribute an additional 6-17% of global emissions. Production of foods from animal sources is the major contributor to emissions from the agricultural sector. By 2030, rising demand for meat, especially in countries with transition economies, is expected to drive up livestock production by 85% from that in 2000, which will lead to further substantial increases in emissions.
The authors say: "Technological strategies within the food and agriculture sector, such as improved efficiency of livestock farming, increased carbon capture through management of land use, improved manure management, and decreased dependence on fossil-fuel inputs, are necessary but not sufficient to meet targets to reduce emissions."
They estimate that technological strategies together with a 30% reduction in livestock production in nations which produce large amounts of animal source foods would be sufficient to meet the climate change targets. If such a reduction in production was matched by a similar reduction in the consumption of animal-source food products in these countries, there would be substantial population health benefits. For example, 30% lower intake of animal-source saturated fat by adults would reduce the number of premature deaths from ischaemic heart disease by about 17% in both the UK (equivalent to 18,000 premature deaths averted in 1 year) and Sao Paulo city, Brazil (equivalent to 1,000 premature deaths averted in 1 year). These estimates are based only on models of reductions in ischaemic heart disease in adults as a result of the decreased animal source saturated fat content of diets. The authors did not model the effects of reduced animal source food consumption on other health outcomes, such as obesity and diet-related cancers; as such, the public health benefits of reduced animal source food consumption could be even greater.
The authors stress that global actions are needed to maximise the benefits to the environment and human health of reductions in animal-source food production and consumption, and that the advantages of reduced animal-source food production may apply only in those countries that currently have high production levels. In many low-income countries the volume of livestock production, the consumption of animal-source products, and the associated emissions, are still relatively low.
An important and pending challenge in public health is to ensure access to a diet of sufficient quantity and quality for all populations. Almost a billion people have protein-energy undernutrition, most of whom are also undernourished in micronutrients and minerals such as iron and zinc. Globally, production per head of energy, fats, proteins, and micronutrients has increased and is sufficient to meet global population needs, but the benefits have not been distributed evenly between and within countries and regions.
As well as increased CO2 emissions, excessive livestock production to meet growing demand has created problems of soil degradation, biological impoverishment, and, through overgrazing and intensive feed production, a loss in the soil's ability to sequester carbon.
The authors conclude: "Reduction of greenhouse-gas emissions in the food and agricultural sector could help to prevent further climate change and reduce the burden of ischaemic heart disease. Formulation of appropriate national and international policies that recognise both the benefits of reduced livestock production in high-consumption countries and the need for more equitable distribution of these products remains an important global challenge. Such policies will need intersectoral actions and good global governance to succeed."
Dr Sharon Friel, Australian National University, Canberra, Australia. T) +61 2 61250721 / +61 410 356194 E) Sharon.Friel@anu.edu.au (not attending launch)
Dr Alan Dangour, London School of Hygiene and Tropical Medicine, UK. T) +44 (0)20 7958 8133 E) alan.dangour@lshtm.ac.uk (Attending launch)
London School of Hygiene and Tropical Medicine Press Office. T) +44 (0) 20 7927 2073 E) Sally.Hall@lshtm.ac.uk / Gemma.Howe@lshtm.ac.uk
For full Series paper 4, see: http://press.thelancet.com/tlhacc4.pdf
Journal
The Lancet