Eating less meat and reducing food waste can help ensure food security and avoid dangerous climate change, according to a new study.

The study suggests that - if current trends continue - food production alone will reach, if not exceed, the global targets for total greenhouse gas (GHG) emissions in 2050.

A shift to healthier diets across the world is just one of a number of actions that need to be taken to avoid dangerous climate change and ensure there is enough food for all, researchers said.

As populations rise and global tastes shift towards meat-heavy Western diets, increasing agricultural yields will not meet projected food demands of what is expected to be 9.6 billion people - making it necessary to bring more land into cultivation.

This will come at a high price as the deforestation will increase carbon emissions as well as biodiversity loss, and increased livestock production will raise methane levels, researchers said.

They argued that current food demand trends must change through reducing waste and encouraging balanced diets.

If we maintain 'business as usual', said the authors, then by 2050 cropland will have expanded by 42 per cent and fertiliser use increased sharply by 45 per cent over 2009 levels.

A further tenth of the world's pristine tropical forests would disappear over the next 35 years.

The study showed that increased deforestation, fertiliser use and livestock methane emissions are likely to cause GHG from food production to increase by almost 80 per cent.

This will put emissions from food production alone roughly equal to the target greenhouse gas emissions in 2050 for the entire global economy.

The study's authors said that halving the amount of food waste and managing demand for particularly environmentally-damaging food products by changing global diets should be key aims that, if achieved, might mitigate some of the greenhouse gases causing climate change.

"The average efficiency of livestock converting plant feed to meat is less than 3 per cent, and as we eat more meat, more arable cultivation is turned over to producing feedstock for animals that provide meat for humans," said lead researcher Bojana Bajzelj from the University of Cambridge's Department of Engineering.

"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," said Bajzelj, who authored the study with colleagues from Cambridge's departments of Geography and Plant Sciences as well as the University of Aberdeen's Institute of Biological and Environmental Sciences.