Human food has to be based more on plant products if gas emissions from agricultural production are to be reduced more efficiently.
Photo: ©Shutterstock/Marilyn Barbone

“We must change what we eat to solve the climate crisis”

Even if fossil fuel emissions stopped immediately, emissions from the global food system alone could raise global temperatures by more than 1.5°Celsius, new research from an international team led by the University of Oxford in the United Kingdom shows.

A paper published in November 2020 in the journal Science reveals that although reducing fossil fuel use is essential to meet global climate targets, those goals will be out of reach unless the global food system is also transformed. It shows that what we eat, how much we eat, how much is wasted, and how food is produced will need to change dramatically by 2050 to achieve the Paris Climate Agreement’s goal of limiting the increase in global temperature to 1.5°Celsius or 2°Celsius above pre-industrial levels.

The researchers found that, if current trends continued, emissions from food systems would surpass the 1.5°Celsius target within 30 to 45 years and might exceed the 2°Celsius target within 90 years, even if all other sources of greenhouse gas emissions immediately stopped. If instead, other sources of greenhouse gas emissions reached zero by 2050, then the 1.5°Celsius target would be surpassed in 10 to 20 years, and the 2°Celsius target by the end of the century.

New metric allows more accurate reporting of different greenhouse gases’ role in global temperature changes

The study estimated how greenhouse gas emissions would change in a large range of possible paths for the global food system. It assessed these emissions projections using the Global Warming Potentials (GWP) metric recently developed at the Oxford Martin School. This new metric allows more accurate reporting of different greenhouse gases’ role in global temperature changes, reflecting the difference between long-lived carbon dioxide and the short-lived gas methane, which is produced by rice cultivation and farmed ruminants such as cows.

“Discussions on mitigating climate change typically focus on reducing greenhouse gas emissions from burning fossil fuels, for instance, from transportation or energy production. However, our research emphasises the importance of reducing emissions from the global food system,” says lead author on the paper, Dr Michael Clark, Oxford Martin School and Nuffield Department of Population Health, University of Oxford. “The good news is that there are many achievable ways to rapidly reduce food emissions if they are acted on quickly. These include both raising crop yields and reducing food loss and waste, but the most important way is for individuals to shift towards predominantly plant-based diets.”

The research makes clear that reducing greenhouse gas emissions from food systems will require coordinated action across sectors and between national governments. However, the changes that would reduce emissions would also have additional benefits, for example reducing water pollution and scarcity, increasing biodiversity, and reducing the rate of diet-related health conditions such as obesity, diabetes and heart disease.

(University of Oxford/wi)

­Michael Clark et al.: Global food system emissions could preclude achieving the 1.5°C and 2°C climate change targets
Science  06 Nov 2020:; Vol. 370, Issue 6517, pp. 705-708
DOI: 10.1126/science.aba7357

For more information: 
Read article by the same authors in “The Conservation”: 'Global food system emissions alone threaten warming beyond 1.5°C – but we can act now to stop it'

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