4 April 2010

8 minute read

This could lead to significant further pressure on available resources and is incompatible with a fair global food supply.

Both the ‘western high meat’ and ‘current trend’ diet scenarios are likely to have an enormous impact on the environment and accelerate climate change.

Globally, livestock production already contributes 18 per cent to global greenhouse gas emissions, more than the emissions from all transport (Steinfeld et al., 2006).

Currently around 60 billion animals (poultry and mammals) are used to produce food annually (FAO, 2009b). This number would be likely to double under the ‘current trend’ diet, and would be further increased in the ‘western high meat’ diet. An expansion of animal production by 2050 is likely to lead to a massive rise in greenhouse gas emissions, increasing the likelihood that the world will fail to prevent dangerous climate change.

Doubling livestock production will put pressure on other resources, such as water, the use of which in agriculture is already predicted to increase by 70-90 per cent in the coming decades as a result of increased demand for food (IAASTD, 2008).

The demand for land for feed production under both the ‘current trend’ and ‘western high meat’ diet scenarios will increase pressure toward crop intensification and opening up of new croplands, potentially resulting in further biodiversity loss. Intensification could impact on both crop and grazing lands, which include a large variety of ecosystems.

Grazing land, for example, comprises intensively-cultivated meadows as well as semi-natural landscapes and it is often of very high ecological and biodiversity value. Biodiversity is already being lost up to 1,000 times faster than natural rates of species loss (Millennium Ecosystem Assessment, 2005). Agricultural intensification and expansion is a major factor as it drives habitat loss. Populations of 45 per cent of Europe’s common bird species declined across 20 countries between 1980 and 2005, with farmland birds particularly affected, driven by agricultural intensification and the resulting deterioration of farmland habitats (Donald et al., 2001).

Areas likely to be affected under these scenarios include the Cerrado of Brazil, one of the largest and most biodiverse savannah areas in the world covering an area the size of Western Europe. The Cerrado comprises large stretches of grassland, scrub and areas of woodland which run alongside river banks.

It is internationally recognised as a biodiversity hotspot and is home to 40 per cent of Brazil’s mammals, over 900 species of birds and 10,000 species of plants. More than half of the Brazilian Cerrado has been replaced by crops and pasture in the last 35 years and it is now one of the world’s main regions of soya and beef production (Marris, 2005). Further loss of areas such as the Cerrado could occur under a scenario of massive agricultural expansion.

Reducing meat consumption: benefits for animals, people and the planet

Maximising yields or expanding cropland at all costs, irrespective of the environmental, social or animal welfare impacts involved, is not necessary to feed the world’s expanding population. Furthermore, less intensive humane and sustainable farming can easily feed the world in 2050 if the developed world reduces its meat consumption.

Lower-meat diets should be pursued for their benefits not only in reducing GHG emissions and benefiting biodiversity, but also for human health.

The ‘less meat’ diet would decrease consumption of animal products in North America, Western Europe and Oceania. Meat intake would increase in Northern Africa, Western Asia and in Sub-Saharan Africa for nutritional reasons as current consumption of animal products is relatively very low. On average, the proportion of animal protein in the diet would decrease to 30 per cent, from a global average of 38 per cent in 2000. This scenario would have significant environmental and human health benefits, would be feasible under realistic intermediate crop yield forecasts and would not require massive land use change.

It would also have significant farm animal welfare benefits as animals would not need to be kept in intensive close-confinement livestock production systems.

There is huge potential to feed the planet using organic agriculture. Adoption of the ‘fair less meat’ diet would make organic crop farming a feasible way to feed the world.

While wholly organic crop yields would only be probably feasible with massive land use change, a mixture of organic and conventional crop yields (as shown in the intermediate crop yield scenario) is feasible without major land use change. This means that it would be possible to provide everyone with a sufficient diet on a mixed conventional/organic crop production system, or on a wholly organic system with improvement in organic yields.

The findings of this research support previous studies demonstrating that a reduction in the consumption of animal products would reduce human pressure on the environment. Switching to a lower meat diet would reduce pressure on land as, under these diet scenarios, feeding the world will be possible without massive land use change. This is consistent with previous studies, which showed that reducing global meat consumption could free up one million square kilometres of cropland and 27 million square kilometres of pasture that could be used to store large amounts of carbon as the vegetation regrows (Stehfest et al., 2009).

A switch to organic farming or a greater proportion of organic agriculture would have a number of environmental benefits, including increasing organic matter in soils and better soil structure (Mäder et al., 2002, Marriott and Wander, 2006, Fließbach et al., 2007); reduced soil erosion (Reganold et al., 1987, Siegrist et al., 1998), greater biodiversity compared to conventional agriculture (Bengtsson et al., 2005, Hole et al., 2005) and lower GHG emissions, in particular due to the lack of synthetic nitrogen fertiliser use which is prevalent in intensive crop agriculture.

Lower meat consumption would result in lower greenhouse gas emissions.

In 2001, the Intergovernmental Panel on Climate Change (IPCC) noted that “a shift from meat towards plant production for human food purposes, where feasible, could increase energy efficiency and decrease greenhouse gas GHG emissions” (IPCC, 2001). The lower land use change possible under these diet scenarios would also reduce the carbon emissions from soils and allow for more soil carbon sequestration.

Human health would benefit under ‘contraction and convergence’ of diets: western countries would cut back on their meat and dairy consumption, while those in developing countries increase their consumption according to their dietary needs (McMichael et al., 2007).

Reducing meat consumption in developed countries would reduce the risk of obesity, heart disease and some cancers (Costello, 2009).

According to Lord Jay and Professor Marmott, writing in The Lancet, improving health and tackling climate change through a reduction in meat consumption should be seen “as an opportunity rather than a cost” (Jay and Marmott, 2009).

The Effects of Climate Change

The impacts of climate change on crop yields through changes in temperature, precipitation and carbon dioxide (CO₂) fertilisation are highly uncertain.

Plants take up atmospheric CO₂ for photosynthesis. Higher CO₂ levels can therefore, under certain circumstances (predominantly sufficient nutrient supply), boost plant growth and alleviate water stress – this is known as the CO₂ fertilisation effect.

However, while detectable under controlled conditions, the magnitude of this effect under real world conditions is highly uncertain. The study finds that impacts of climate change on yields would be negative if only changes in precipitation and temperature were taken into consideration and the CO2 fertilisation effect did not occur, whereas it can be strongly positive if it is assumed to be fully effective.

Modelled Climate Impact on Cropland Yields in 2050 with and without CO₂ Fertilisation.

The effect of these yield changes has a significant impact on the feasibility of the 72 scenarios: If the CO2 fertilisation effect is not taken into account, only 34 of the 72 scenarios would be at least ‘probably feasible’.

If it is assumed that the full CO2 fertilisation effect takes place, 62 of the 72 scenarios would be at least probably feasible.

It was not possible to model the relationship between factors such as nutrient and water availability and climate change, even though it is clear that such feedbacks will be very important.

In particular water availability is likely to be a limiting factor in achieving crop yields; decreasing precipitation would lead to water stress and crop failures. Whether or not farmers will be able to attain increased crop yields under elevated CO2 concentrations is also highly uncertain.

Fuelling the World in 2050 – Possible Bioenergy Scenarios

Large-scale production of biofuels will lead to an increase in food scarcity and rising prices, the CIWF report says.

The study finds that the realistic future bioenergy potential is considerably lower than many studies have put forward – a maximum of 70-100 EJ/yr under realistic combinations of assumptions by 2050 (with a maximum of 160 EJ/yr under unlikely scenarios) - and that will depend on future diets, livestock systems, yields and land use.

The bioenergy potential that this calculation represents is a maximum estimate, based on the most efficient way of converting biomass to energy, for example, combined heat and power plants that are able to use primary solid biomass without significant conversion losses. In reality only a small fraction of biomass is converted in this way.

When converting biomass into liquid biofuels for transport use, a large part of the available energy is lost.

The potential of bioenergy to meet future energy needs cannot be considered in isolation: diets, agricultural production technology and other factors will determine how much of the Earth’s biomass will be available for energy use.

A wealth of studies from international organisations - the FAO, the World Bank, the OECD and the Royal Society amongst others - have warned that exploiting the world’s theoretical bioenergy potential will have dramatic negative social and ecological impacts, such as further pressure on small farmers and communities that depend on the land, upward pressure on food prices and land rights conflicts. It could also trigger indirect land use change such as deforestation in South East Asia and Latin America. In the worst cases this would result in net increases in greenhouse gas emissions.

Further Reading

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You can view the full report by clicking here.