By JOHN KOMINICKI //

Two tiny Silicon Valley companies have vowed to tame the Earth’s surging levels of atmospheric methane, one of the most potent greenhouse gases out there and 28 times more likely to cause global warming than carbon dioxide.

Their goal: An all-vegetable burger that looks, cooks and tastes like ground meat.

Sort of.

Now, vegetarian takeout may not sound like much of a contribution to the clean air effort, what with the enormous amount of bad things we spew into the air every year. But animal agriculture, as it’s called, uses 30 percent of the Earth’s surface and sucks up a quarter of all fresh water while emitting more greenhouse gases than all of our planes, trains and automobiles combined.

The preponderance of methane comes from cows, mostly from the belching that occurs as the animals move partially chewed plant fibers back and forth between their mouth and their first and second stomachs.

(Cows have four. Meaning they always have room for fries.)

Until now, scientists have focused on making changes to the cow’s diet, primarily via feed supplements that reduce the amount of gas created during digestion. France and Australia, to name but two, have made significant progress on this front.

Last fall, California passed the first U.S. law seeking to control agricultural methane, which in legislative circles is known as “bovine entric fermentation.” Its goal – and I’m not creative enough to have made this up – is to capture cow burps and convert them to electricity while also reducing the state’s overall methane emissions by 40 percent.

That’s a worthy start, but there are Californians who view the animal agriculture threat more broadly, including people like Pat Brown, a Stanford-trained geneticist and biologist and the founder of Impossible Foods, makers of “delicious, nutritious, environmentally friendly alternatives to meat and dairy – directly from plants.” His goal is to eliminate cow methane by pretty much eliminating animal agriculture in its entirety.

Brown’s best effort so far is the Impossible Burger, a mix of wheat, coconut oil and potatoes that gets its faux-meat color and juiciness from heme (rhymes with team), an iron-rich molecule the company produces in bulk using fermented yeast. Making the burger requires 95 percent less land and 74 percent less water and produces 87 percent fewer greenhouse gases, the company boasts.

Brown also founded Kite Hill, which makes nut-milk cheeses, meaning you can now enjoy a fully vegan cheeseburger, albeit at limited retail locations so far. If you live near New York City, the place to go is Momofuku Nishi on 8th Avenue, where the burgers are served between noon and 3 p.m. on a first-come basis, $14 with fries. Add $1 for vegan cheese, another for a vegan bun.

If you don’t want to risk drooling heme on your shirt in public, you can make your own vegetarian burgers at home using Beyond Meat, from another California startup that uses beets to get some of the requisite color and sizzle. The company also makes faux chicken strips, said to be a favorite of Bill Gates, who has invested in both companies. Beyond Meat patties are available at your local Whole Foods. About twice the cost of real meat.

Don’t forget a jar of Just Mayo, the plant-based spread from Hampton Creek.

Given that there are only 7 million vegans in America, Beyond Meat and Impossible Burger are going to have to win over many, many carnivores if they are to make any meaningful impact on greenhouse gases. It’s possible – some meat lovers also love their planet. And, as Brown likes to note, ground beef is already as good as it will ever get. Fake meat has lots of room to evolve.

For now, maybe best to grab a giant bottle of Beano and head over to the barn.