By Brian Barth

"Certified organic" does not necessarily equate to "climate friendly." While there is some evidence that organic techniques produce as much as 40 percent fewer GHGs on average than conventional productions systems, other studies have found more or less a wash between the two. While scientists continue to debate the matter, it's important to realize that the organic standards were never intended to minimize GHGs—they're focused almost exclusively on eliminating synthetic chemicals from the food supply.

There are many other factors that determine the carbon footprint of a meal, which have nothing to do with whether it was produced on an organic farm. For example, veggie burgers, whether organic or not, produce much fewer GHGs than bacon cheeseburgers. Biscuits made from wheat produced on a "no-till" grain farm are likely to have a lower carbon footprint than those from tilled wheat, even if the former is conventional and the latter is organic. And certainly, organic mangos from Brazil are much less climate friendly than apples from your neighbor's backyard, simply by virtue of eliminating transportation emissions.

The climate implications of food are complex, poorly understood, not well quantified and not reflected in any of the popular eco-certifications out there. That's surprising given that the food system, by some estimates, is responsible for up to 29 percent of GHG emissions globally (more than transportation, energy production, or any other human endeavor).

Below are some of the connections between food choices, production methods and climate change that, arguably, deserve much more attention.

1. Starting Light: Smoothie Time

Health nuts love their fruit smoothies in the summertime. Assessing the carbon footprint of strawberry-banana-almond versus blueberry-orange-yogurt is tricky, but here's a few thoughts to chew (or slurp) on:

Overall, fruits rank in the middle of the various food groups in terms of greenhouse gas emissions—they're roughly the same as vegetables, much less than meat, and far above grains.

If you want to add milk for a richer smoothie, consider seed and nut milks, which produce a fraction of the GHGs compared to dairy.

Tree fruits (mangoes, apples, peaches, oranges) generally have lower emissions than those that grow from shrubby or herbaceous plants (bananas, blueberries, strawberries, raspberries).

Tree fruits have great potential for multi-layered agroforestry systems, which can sequester nearly as much carbon as natural forests—unfortunately, such systems are bests suited to tropical agriculture, which, for those of us in North America, means all those food miles probably cancel out the GHG savings.

Foodies snap up those plastic clamshells of organic microgreens like they're going out of style. Turns out other vegetables may be a better choice for a carbon-conscious diet:

Lettuce is actually three times more carbon-intensive than bacon, according to one study, though that's only when considered on a per calorie basis (of course we eat lettuce for nutrients, not calories).

Part of the problem with lettuce and microgreens is they require huge amounts of freshwater to produce, which incurs a hefty carbon footprint from the energy required to pump it out of the ground. Thus, drought tolerant vegetables—such as dry-farmed tomatoes—are a safer salad ingredient.

Root crops (radishes and beets) tend to be low in carbon emissions, while on the flip side, a handful of other vegetables are notably high, including bell peppers, avocado and asparagus. For the kimchi lovers out there, rest assured that cabbage is one of the least carbon-intensive crops.

Wheat may be out of style among health-conscious folks these days, but feel free to reach for bread—grains, as a group, have very low carbon footprints:

Most grains have three traits that help keep their emissions down: they are well-suited to no-till agriculture; they require relatively little irrigation; they grow so abundantly in North America that there is little reason to import them from afar.

According to the Food Carbon Emissions Calculator, corn is one exception to this rule—cornbread has about twice the emissions as bread made from most other grains.