Meat, Meat, Meat

The take home message from everyone I’ve been speaking with recently is that meat--especially beef--is just no good for the environment.

First, Christopher Weber at Carnegie Mellon University published findings showing that shifting a quarter of the average American’s red meat consumption to other foods saved as much greenhouse gas emissions as going entirely local, i.e. red meat has a really big carbon footprint.

Then, I spoke with researchers highlighting the importance of considering our “nitrogen footprint”, too. “Meat is one of the main drivers of acceleration of the cycle,” said Alan Townsend of the University of Colorado at Boulder. “To have meat diets under modern agriculture takes a lot of nitrogen. You end up having to have a lot of fertilizer and a big chunk of field to grow a few cows or pigs.”

Finally, the Stockholm International Water Institute issued a report about water… You guessed it: meat production takes lot of water. Their report estimates that about 50 percent of calories grown in fields never make it to the table, and about half of that loss is animal feed that doesn’t end up as a calorie on a cow, pig, chicken, or other edible critter. Growing those lost calories takes a lot of water.

For the most part, each of these impacts comes from the same cause: growing a pound of meat requires (much) more than a pound of grain. A pound of beef, for instance, requires eight. (The conversions are better for other types of meat, but never 1:1).

This inefficiency amplifies the demand for nitrogen fertilizer and irrigation, and leads to more of the greenhouse gas emissions associated with growing crops. These emissions come from energy for making fertilizer and release of nitrous oxide (N2O)—a super greenhouse gas almost 300 times more potent than CO2—by bacteria acting on fertilizer in the soil.

With cattle, greenhouse gas emissions also result from methane (23 times more potent than CO2) released by digestion, and nitrous oxide production from manure. 

The SIWI report points out that demand for meat is rising fast. Here are some meat consumption numbers for different parts of the world:

--Southeast Asia: ~88 lbs/person/year in 2002, a sevenfold increase from 1961, when it was 13 lbs.
--India: Projected at 22 lbs/person/year in 2050 (Thanks to a largely vegetarian population.)
--China: Projected at 183 lbs/person/year in 2050
--US: 200 lbs/person/year in 2005, up 22 lbs from 1970

It’s also worth pointing out that dairy creates these impacts, too, though not to the same extent as meat.

Is Grass-Fed Beef Better?
So grain-fed beef is no good… but what about grass-fed? If you read Michael Pollan’s book, The Omnivore’s Dilemma, you might have been convinced, like me, that eating a bit of grass-fed beef was fine--even good. When cows eat grass, they’re converting plant calories that we can’t eat (i.e. grass) into calories that we can. This is an efficient way to harness the energy from the sun in food form in places that aren’t suitable to grow crops.

But, how much does the greenhouse gas footprint change when you switch to grass-fed beef? Then you don’t need those eight pounds of grain. Christopher Weber kindly did some math to help answer this question (Thanks, Christopher!). He cautions that these numbers are approximate and un-reviewed, but here they are:

“By switching to grass fed, you remove around 20% of the CO2 and 60% of the N2O in the supply chain of making and delivering grain to the farms.
So, if there is no increase in methane and manure emissions (of CH4 and N2O) are not being captured at the feedlot, there's approximately a 25% reduction in life cycle greenhouse gas emissions in grass fed vs. grain fed.”

But don’t stop reading. Studies have shown that grass-fed beef produces more methane than grain-fed beef. (Though at least one study has reported the opposite, Weber said.) This offsets some of the gains:

“If the grass-fed has 15% more methane, which is around the number I've seen cited, then grass fed is only 20% better.”

So, while there may be other advantages to eating grass-fed beef over grain-fed, it’s still not a climate-neutral choice. And, as Marshall Burke of Stanford University pointed out, if everyone switched to grass-fed beef, there wouldn’t be enough pastureland to go around.

To the climate conscious: learn to love lentils.

(Photo: Grant Hutchinson)

Comments

[Bernard Brown]

Great post. I'll point out that there's more to love besides lentils - we focus on the all-American PB&J at the PB&J Campaign.

Bernard Brown