(THE WASHINGTON POST) - I think it is safe to say we all want to save the planet and a good chunk of what is written about food systems is about how to do it.
Estimates vary, but something in the neighbourhood of 30 per cent of total greenhouse-gas emissions is pegged to food. If you are a farmer and you are trying to do your part to reduce that, you have a lot of choices: planting cover crops, reducing tillage, using state-of-the-art tools to apply fertiliser only where you need it. If you are an eater, it is harder to make a dent.
If you are looking for advice on how to make climate-friendly food choices, you will find there is plenty of it. Unfortunately, most of it is either wrong or self-evident. (Though you will occasionally stumble on a thoroughly researched, tightly reasoned piece of advice about, for example, why you ought to eat more oats.)
In the “wrong” category is the advice to buy local or organic. Sometimes those are better climate choices and sometimes they are not and it is all but impossible to know which is which. In the “self-evident” category is waste, and how you should try to generate less of it, both in food and packaging.
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What is left is one piece of advice that is about as true as food advice gets: Eat less meat. Beef, particularly, is a carbon Sasquatch, mostly because the digestive systems of cattle (and all ruminant animals) release methane, a powerful greenhouse gas.
Unless you have just crawled out from under a Hummer, you have heard the eat-less-meat advice and you have probably even heard that beef is the biggest offender. There is plenty of evidence bolstering that position and the latest came in the form of a detailed analysis of the impact of various foods and production systems from the University of Minnesota. The lead author, PhD student Michael Clark, looked at categories of foods, organic versus conventional production, and several measures of environmental impact.
Once I got over feeling like an underachiever – because, really, what had I accomplished at his age? – I dug into his data. He helped. In fact, he worked with me to do a detailed analysis of the greenhouse-gas implications of a weekly 140g steak. We are not taking any radical step like going vegan here, just eliminating one weekly beef meal.
We looked just at greenhouse gases, even though there are many other factors at play (several of which are included in Mr Clark’ s paper). There is water use, land use and pollution, all of which affect the environmental impact of what we eat. There is also animal welfare, impact on rural communities and worker conditions, all of which matter in other ways. We are looking at one thing: the greenhouse gases you are responsible for every time you decide what is for dinner.
Here is the upshot: If you trade steak for beans once a week for a year, you will keep the equivalent of 331kg of carbon dioxide (CO2) out of the atmosphere.
How much is 331 kg of CO2? It does not help much to just visualise things that weigh 331kg – three football players, a smallish camel – populating the atmosphere. It is much more useful to compare it with the CO2 savings from other common climate-saving measures.
Giving up beef once a week in favour of beans, over the course of a year, is the equivalent of not burning 145l of gas, or of trading in 12 incandescent bulbs for LED. That 331kg is equal to about 5 per cent of the average household’ s electricity use. If you plant a tree, it will remove that 331kg in 83 years.
Let’s face it, though. Beans might be a tough sell. What if you trade in your steak for chicken or pork? That is a win, too, although not as big a win. The impact of beef (334kg for that weekly steak) dwarves that of beans (3kg for a weekly serving), but it is also larger than that of chicken (64kg) and pork (68kg). But, whatever you do, do not trade your beef for lamb; your impact will more than double. Realistically, if you cut back on beef, you will probably replace it with a combination of foods – pork and beans, perhaps – and the heavier you go on the legumes and grains, the better you do.
But this is not the end of the story.
Mr Clark’s analysis did not include the potential that grazing cattle have to rebuild soils and actually lock carbon away (called sequestration) in the process.
I checked in with Michigan State University associate professor Jason Rowntree, who is researching just that. Last time I spoke with him, a couple of years back, he was in the midst of a grazing experiment. Now, he has preliminary results showing more than three metric tonnes of carbon sequestered annually per ha, which would, he wrote me by e-mail, “at minimum (produce) carbon-neutral beef, but most likely a beef product that has a negative carbon-footprint.” (He also cautioned that these numbers have not been peer-reviewed.)
A grass-fed steer with a carbon-negative footprint that turns food humans cannot eat into something barbecue-ready is, climatically speaking, a free lunch. But that lunch may be hard to find at your local grocery store because you have no way to determine whether any particular steak, even if it’s labelled “grass-fed”, came from a rancher who is managing for carbon sequestration.
I asked Ms Carrie Balkcom, executive director of the American Grassfed Association, whether carbon footprints were on most ranchers’ radar. “We try not to be invasive into people’s production methods,” she said, but they do survey their membership and know that 93 per cent say they are doing some kind of managed grazing. Some are even measuring soil carbon.
I would love to see a certified “carbon-negative” label, but that probably will not be showing up in the meat case any time soon.
While carbon-negative beef is possible, it might not be common. And its benefits may run out after a while. Most soil scientists I have spoken with say they believe the soil’s ability to lock carbon away is finite. Once you hit that ceiling, you are stuck grazing cattle to keep it locked away, but with no additional carbon sequestered to compensate for the methane the cattle produce.
Prof Rowntree cautions against trying to figure out just how long that would take. “Nature is complex,” he wrote in an e-mail. “We try to linearise nature’s responses and that leads to placing ceilings on what can happen with management.” But he added: “It is naive to believe that with changing landscapes, the carbon sequestered is permanent. It is stored in soil as energy and it will be cashed out as well.”
Grass feeding does more than sequester carbon, Prof Rowntree pointed out. It can restore degraded land, something that can have benefits for future uses and generations. It also does what has made cattle a mainstay of human civilisation. It converts grass to milk and beef by letting cattle do what cattle do best: graze.
Should you eat less meat? Yes. And waste less food. Use less packaging. Eat oats.
But, of course, it is never quite that simple and we will all do better if the people who raise our food have a reliable way to tell us about it, and the people who buy it to pay attention.
Also, change your lightbulbs already.