Food causes climate problems, and offers solutions too. New research examines what change of diet could do.

LONDON, 17 September, 2021 − Once again, scientists have confirmed that humankind could be grazing the planet to death. Food-based agriculture accounts for more than a third of all the greenhouse gas emissions that drive climate change, and farming for an animal-based diet adds up to at least 57% of that. Could a change of diet be useful?

The implication − long ago backed up by many other studies − is that a global difference in diet could help contain climate change, conserve the world’s natural biodiversity and feed a growing population all at the same time.

And the strength of the latest study is that it could help governments, civic authorities, communities and famers identify where best to start.

US and European researchers report, in the journal Nature Food, that they looked at the big picture to apportion the contribution to global heating from the 171 crops and 16 animal products in more than 200 countries around the world in the year 2010.

“Developing climate mitigation strategies must rely on accurate estimates of greenhouse gas emissions from all sources, including plant- and animal-based foods”

Plant-based foods account for 19% of the carbon dioxide, 6% of the methane and 4% of the nitrous oxide emissions into the atmosphere. Animal-based food processes surrender 32% of the carbon dioxide, 20% of the methane and 6% of the nitrous oxide. Farming for fabrics rather than food products − think of cotton, rubber and so on − accounts for 14% of all emissions.

“Although CO2 is the most important and most frequently discussed of greenhouse gas emissions, methane generated by rice cultivation and animals, and nitrous oxide from fertilisers, are 34 and 298 times more powerful than CO2, respectively, when it comes to trapping heat in the atmosphere,” said Xiaoming Xu, of the University of Illinois at Urbana-Champaign, the lead author.

Food is part of the machinery that drives potentially catastrophic climate change. Researchers have again and again demonstrated that global food security is also likely to be put at serious risk by climate change, in the form of massive harvest failure as a consequence of extremes of temperature and drought, of the slowness of change in the agricultural sector, and of the impact of climate change on the nutritional value of the food that can be harvested in a hotter world.

Humans waste food. They demand foods that precipitate the loss of natural ecosystems that might otherwise help limit climate change. And, by fuelling climate change, humans have even put at risk those genetic resources from which human diet has, over at least 10,000 years, evolved.

Planetary diet change

But in the next 30 years, farmers will have to increase food output by 70% to meet the demands of a swelling global population. Once again, other groups have looked at the challenge and proposed ways to deliver more while emitting lower levels of greenhouse gases, and while protecting vital rainforests and grassland from further devastation.

But that means a change of diet on a planetary scale. The latest study shows that China now leads the world with emissions from animal-based foods at 8%, ahead of Brazil (6%) and the US (5%). China also leads the world with plant-based emissions at 7%, followed by India at 4% and Indonesia at 2%.

“We estimate that population growth will drive the expansion of food sub-sectors, including crop cultivation and livestock production, as well as product transportation and processing, irrigation, and materials like fertiliser and pesticides,” said Atul Jain, who heads atmospheric sciences research at the University of Illinois Urbana-Champaign.

“Developing climate mitigation strategies must rely on accurate estimates of greenhouse gas emissions from all sources, including those from the production and consumption of total and individual plant- and animal-based foods.” − Climate News Network