“Not all vegetables are created equal,” pronounced Paul Fischbeck, a scientist at the prestigious Carnegie Mellon University in the US, who has caused a media stir with his new report that claims common vegetables require “more resources per calorie” than pork.
According to the study, published in the Environment Systems and Decisions journal, a diet rich in common vegetables, like lettuce, could contribute more to climate change than eating the odd bacon sandwich.
Admittedly, “the headlines have been stretched a bit since the report was published,” noted Fischbeck. But the recently-published study goes against the grain of earlier reports that either call for a cut in meat consumption, or a tax on meat products, to tackle climate change.
Pork - denser than lettuce
So, why is eating lettuce worse than bacon? “The main reason lettuce produces around three times more greenhouse gas emissions than bacon is because it’s a fragile plant. It’s not as calorie dense and it requires a huge volume to be shipped to supply demand, expanding massive amounts of energy before it’s even made it to the table,” said Fischbeck.
Examining the food supply chain in the US, Fischbeck’s report was set up to ascertain the effect America’s obesity has on the environment. Specifically, it examined how growing, processing, transporting and storing different types of food impacted energy use, water use and greenhouse gas (GHG) emissions.
On the case of lettuce, Fischbeck added: “Around 40% of all shipped lettuce has perished along its journey. But the energy expanded to keep it alive, to ship it and maintain the product has a huge environmental impact.
“Compare this with pork, which is much more energy efficient and dense because it’s much easier to ship and maintain, and this is why lettuce produces more GHGs than pork.”
US policy flaw
Fischbeck also highlighted the flaw in the US Department of Agriculture’s (USDA) 2010 dietary guidelines, which he used as a base for the report. Apparently, if one stuck to the diet stipulated in the USDA’s guidelines, “this diet would produce more greenhouse gas emissions than the average American diet”, he added.
The report was conducted by lead author Paul Fischbeck, co-author Michelle Tom, Chris Hendrickson – the professor of civil and environmental engineering at Hamerschlag University – and a PhD student.