Scientists researching food security and climate change have said that a drastic reduction in meat consumption and food waste are necessary if people hope to stave off the worst effects of climate change.

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Publishing their findings on Monday, the team said research has shown that – if current trends continue – food production alone will reach (or even exceed) the global targets for total greenhouse gas emissions by 2050. They said emissions from the sector could still tip the balance towards devastating climate change, even if emissions from all other sources drop to zero.

The researchers urged the public to consider the environmental impacts of their dietary choices to ensure that there is enough food for all, and global food security.  

Worldwide, increasing populations and economic shifts have increased demand for more meat-heavy 'Western' diets. Experts have warned that increasing agricultural yields will not meet projected food demands for an expected global population of 9.6 billion people by the middle of the century. The Cambridge and Aberdeen researchers said that, at the current rate, more land will need to be brought into production, meaning deforestation will increase (impacting on carbon emissions and reducing biodiversity), methane levels will rise and water will become scarcer.

Rain-fed cattle systems not part of the problem, farmers claim

Reacting to the study, Nick Allen, cattle sector director at livestock farming levy board EBLEX, said,

"In terms of the natural emissions which are a by-product of rumination, while it’s still an emerging area of research, there is general consensus the carbon sequestration of permanent pasture offsets these emissions to some extent."

Allen claimed, "Our [Britain's] rain fed-pasture system means we have one of the most efficient and sustainable livestock production systems in the world. In the UK, cattle and sheep primarily convert grass, which cannot be used to feed people, into nutritious food for our growing population.

"Any debate concerning the environmental impact of the industry and true sustainability must also include profitability to ensure a balanced dialogue is maintained," he added.

However, study co-author professor Keith Richards maintained that the case put forward by the researchers is clear cut, and universally applicable. He said, "This is not a radical vegetarian argument; it is an argument about eating meat in sensible amounts as part of healthy, balanced diets."

The professor called for better education, which he said would lead a shift towards healthier diets and more awareness of environmental issues around food. "Managing the demand better, for example by focusing on health education, would bring double benefits – maintaining healthy populations, and greatly reducing critical pressures on the environment," the professor added.  

The team generated detailed computer models to look at different future scenarios for food production. They found that under a 'business as usual' scenario by 2050 cropland will have expanded by 42 percent and fertiliser use increased sharply by 45 percent over 2009 levels. A further tenth of the world's tropical forests will have also disappeared. Greenhouse gas emissions from food production would jump by 80 percent as a result.

This increase would put emissions from food production alone roughly equal to the target greenhouse gas emissions for the entire global economy by the middle of the century.

Strategy to tackle emissions and food insecurity

The experts did offer some succour. They said that, by halving the amount of food waste and managing demand for environmentally-damaging foods, we might be able to mitigate some of the negatives 'externalities' driving climate change.

They also said that closing 'yield gaps' – the gaps between yields that could be achieved through best practice and current actual averages – would also prove instrumental in reducing the need to turn over extra land to food production. These gaps are largest in developing countries.

Tackling food waste should also be a priority. In the global south waste occurs after harvest, due to infrastructure issues such as lack of transport or storage facilities, whereas in the north, consumerist mores mean food is wasted later on, at greater environmental cost. According to the UN FAO between one third and a half of all food produced worldwide is wasted before it can be used.  

When food waste was tackled, yield gaps were closed and healthy diets adopted, the team's computer model showed that emissions from the agriculture sector could be halved compared to 2009 levels.

Commenting on the findings, and the recommendations made by the team, Cambridge University's Bojana Bajzelj said, "There are basic laws of biophysics that we cannot evade. The average efficiency of livestock converting plant feed to meat is less than 3 percent, and as we eat more meat, more arable cultivation is turned over to producing feedstock for animals that provide meat for humans."

"The losses at each stage are large, and as humans globally eat more and more meat, conversion from plants to food becomes less and less efficient, driving agricultural expansion and land cover conversion, and releasing more greenhouse gases. Agricultural practices are not necessarily at fault here – but our choice of food is." Bajzelj continued.

"It is imperative to find ways to achieve global food security without expanding crop or pastureland. Food production is a main driver of biodiversity loss and a large contributor to climate change and pollution, so our food choices matter."

"[Waste that occurs later in the supply chain] is in many ways worse because the wasted food products have already undergone various transformations that require input of other resources, especially energy," said Bajzelj.

"Western diets are increasingly characterised by excessive consumption of food, including that of emission-intensive meat and dairy products. We tested a scenario where all countries were assumed to achieve an average balanced diet - without excessive consumption of sugars, fats, and meat products. This significantly reduced the pressures on the environment even further," the team wrote. The 'average' balanced diet used in the study is a relatively achievable goal for most. For example, the figures included two 85g portions of red meat and five eggs per week, as well as a portion of poultry a day.

Co-author Prof Pete Smith from the University of Aberdeen said, "Unless we make some serious changes in food consumption trends, we would have to completely de-carbonise the energy and industry sectors to stay within emissions budgets that avoid dangerous climate change. That is practically impossible – so, as well as encouraging sustainable agriculture, we need to re-think what we eat."

"Cutting food waste and moderating meat consumption in more balanced diets, are the essential 'no-regrets' options," added Bajzelj.