Whenever the “eat less meat to save the planet” meme is bandied about, the proponents of such a strategy always forget to complete the statement.

It’s not plausible to simply say “eat less” of anything, without also adding, “and replace it with . . .”

That’s the part that anti-meat advocates never seem to include. But unless the goal is to embrace regular fasting, or perhaps the promotion of widespread calorie reduction as a dietary goal, the meat we don’t eat doesn’t just disappear.

I know: it gets exported.

But seriously, when people bypass meat, other foods end up on their plates, if not in the center, nevertheless there for the consumption.

Along with the ubiquitous soybeans and salad veggie activists always promote, one of the animal foods substitutes getting a lot of run lately is avocados. The California Avocado Commission has been running a series of print and broadcast ads that refer to “sun-kissed soil,” hardworking family farmers who walk the land, and the “local, fresh, American-grown” attributes of this healthy, appealing fruit.

Along with the evocative language, the ads feature gorgeous photos of verdant orchards hugging the foothills along the coast, as the sun sets over the Pacific.

How could anyone not embrace all that? How could there possibly be any downside to eating fresh, delicious avocados, instead of some cruelty-laden animal food derived from abused livestock who are ruining the Earth?

Glad you asked.

Implicating All of Agriculture
Remember the 1990s? Not just the rise of Apple Computers, the cloning of Dolly the sheep, or even the “Ah feel your pain” presidency, but rather the high-profile campaign started by activists that attempted to convince people that fast-food burgers were destroying the world’s rainforests.

The point was that big U.S. corporate restaurant chains were sourcing “cheap beef” from Latin America; and to supply it, farmers there were slashing and burning the rainforest so cattle could graze among the stumps. The slogan became, every time a Big Mac gets eaten, a tree is killed in the rainforest.

Indeed, vast acreage that was formerly covered in tropical vegetation was cleared for agricultural use. However, much of that acreage was planted as cropland.

How do you think Brazil became the world’s second-leading exporter of soybeans? As USDA’s Economic Research Service benignly phrased it, Brazil’s emergence as a world leader in ag exports was due to “technological advances in crop management and expansion in area harvested.”

Of course, there is a significant downside to any loss of rainforest, since it’s the world’s most important source of atmospheric oxygen, among a host of other beneficial attributes.

But lost amidst all the hype over cheap beef and angst over destroying verdant forests with cattle ranches is the reality that one of the mainstays of the healthy vegetarian diet we’re all encouraged to consume is also responsible for rainforest destruction.

A recent report on CNN.com finally asked the relevant question: “Is a vegetarian diet really more environmentally friendly than eating meat?”

Not when it comes to avocados.

As the popularity of the bright green fruit has continued to grow — due in part to all the lavish advertising that subtly implies avocados provide nutritional goodness without the “baggage” of animal foods — the article noted that “Mexican farmers are thinning out and eradicating huge pine forests in order to illegally plant the money-making fruit trees to meet a never-ending demand.”

Demand in many cases, from people seeking to switch to an eco-friendlier food product.

Not only are native forests being clearcut to plant avocado orchards — 100% in response to demand for “healthier” alternatives among affluent consumers in Europe and North America — the cultivation of avocado trees also diverts immense amounts of water in semi-tropical areas (anyone heard about the ongoing drought in California?) that ends up having a detrimental effect on the affected ecosystems.

Here’s the point: Let’s not pile onto avocado production (or consumption), or suggest that people stop eating them. That’s a rhetorical, and nutritional, dead end.

Instead, let’s expand the discussion among pundits and policymakers — not to mention the public — when the subject of food production’s ecological footprint is discussed.

It’s the height of willful ignorance to squawk about alleged environmental benefits of eating less meat, unless the calculations involved in production of its replacements are also included in the equation.

Not to mention that as tasty as they are, avocados work best not as a main meal, but as a topping.

On a big, juicy hamburger.

The opinions expressed in this commentary are those of Dan Murphy, veteran journalist and columnist.