This story is part of Covering Climate Now, a global collaboration of more than 220 news outlets to strengthen coverage of the climate story.

This month I stepped inside a Burger King for the first time in three years.

I wanted to try out the new, plant-based “Impossible Whopper,” and learn from an expert—a vegan, no less—about its supposed potential to save the planet, your health, and the lives of lots of cows.

Short answers: truth, fiction, and truth.

“The first time I had a hamburger it was from Burger King,” said Sarah Chandler, a longtime friend, activist, and food educator, as we devoured our Whoppers in downtown Brooklyn. “And it was, for sure, my favorite hamburger.”

But that was a long time ago. These days, Chandler, who recently completed a stint working at Farm Forward (tagline: “Until no animals suffer on factory farms”), is a passionate activist for reducing meat consumption and eating healthier.

“I pre-gamed by getting a $4 container of broccoli rabe in Koreatown this morning,” she warned me.

Here are three things I learned.

First, the Impossible Whopper is delicious. “This tastes so good, I think there’s been a mistake,” I told Sarah as we dug in.

Based on a Frankenstein-like fusion of soy protein and yeast (the Beyond Burger is based on pea protein), the Impossible Whopper was indistinguishable from a regular hamburger. Beyond and Impossible use clever tricks to make the burgers “bleed” like regular meat. Probably the thin patty helped, plus all the trimmings and condiments being exactly the same as regular Burger King. I was fooled.

Second, in terms of global warming, the plant-substitute meats really could make a difference. Almost 15 percent of global greenhouse gas emissions come from animal agriculture, and large-scale cattle production is among the most intensive. It’s a triple hit, often involving deforestation in developing countries (such as Brazil) and pesticide use, intensive water use, and transportation in industrialized ones. It’s been estimated that a pound of beef produces the amount of carbon dioxide equal to 31 miles of driving a car.

And then there are the farts.

Cows’ digestive systems excrete methane (mostly through belching, actually), and methane is 23 times as potent as carbon dioxide when it comes to global warming. While most methane pollution actually comes from oil and gas, cattle farming is still a major contributor: a single cow releases 30-50 gallons of methane every day.

The key point is that the Impossible Burger, and its chief competitor, Beyond Meat, are meant for everybody, not just environmentalists who want to save the world.

That’s a crucial distinction. Even if every virtuous environmentalist stopped eating meat, that wouldn’t make a dent in global warming. There just aren’t enough do-gooders out there. (It’s been estimated that 16 percent of U.S. consumers avoid animal products for environmental reasons.)

Fast food, though, is a powerful aggregator.

On any given day, more than one in three Americans eats fast food. That’s 84.8 million adults. Even if only half of them are eating burgers, that’s nearly 10 million pounds of beef every single day.

What’s more, most of that is industrially farmed. While small-scale cattle farming can actually be carbon negative (cows eat grass that sucks carbon dioxide out of the air), large-scale farming is fossil-fuel intensive, both in farming methods and transportation.

“ Every fast-food burger you eat is basically welfare. ”

In sum, Beyond’s own study found that a Beyond Burger generates 90 percent less greenhouse gas emissions than a regular one, and Impossible’s found an 89 percent reduction. Independent assessments are more conservative, but still estimate that a plant-based burger has about half the carbon footprint of a regular burger.

And with the market for meat substitutes expected to hit $2.5 billion by 2023, according to Euromonitor estimates, that’s a lot of cows, and cow emissions, saved.

So, will it work?

That’s the third thing I learned, and the news isn’t great.

While the Impossible Whopper passed our taste test with flying colors, it fails on cost and health.

First, it’s expensive. A regular Whopper costs $4.19. An Impossible Whopper theoretically costs $5.59, but at the franchise we visited, it was $6.50. There’s no data on how many customers that deters, but I can’t imagine many will be motivated to pay 50 percent more for their lunch.

Of course, regular Big Macs and Whoppers are so cheap in large part because of government corn subsidies. (Cows normally eat grasses, but in the topsy-turvy world of American farm policy, corn ends up being cheaper). Every fast-food burger you eat is basically welfare.

But until that changes, it’s hard to see a pricier Whopper competing seriously.

Meanwhile, the health benefits of plant-based burgers are, at best, unclear.

There’s no question that Impossible products are heavily processed, beginning with genetically modified soybeans and continuing with an intensive process that likely removes a lot of the nutrients along the way. Do those costs outweigh the health benefits of reducing one’s meat intake?

It may depend on quantity. “What is healthy and not healthy is really complicated,” Chandler said. “Eating lots of fried things and processed things all the time is not healthy, but eating them sparingly, as a treat, is fine.”

Chandler said that the comparison between a regular Whopper and an Impossible one may simply be a wash. “If I were sitting with someone, and they asked ‘how do I make one change in my life to eat healthier?’ The thing that I would want for them is for them to get into better habits about meal planning and making food from scratch.”

But how many people will do that? Probably not many. The whole point of the Impossible Whopper is to get large numbers of people to make a meaningful impact on climate change without working too hard.

If health won’t motivate people, what about global warming?

Chandler was skeptical.

“What I know from my experience as a food educator,” she said, “is that health motivates people significantly more than climate change. It’s very difficult to imagine that you’re both the perpetrator of and solution to a big problem. It’s too distant and people get overwhelmed and decide not to deal with it.”

Meanwhile, those who are already committed to fighting climate change are unlikely to pop into a Burger King anytime soon. Already there’s been a backlash against corporate giants using plant-based offerings as a kind of “greenwashing.”

“I’ve heard a lot of people say they don’t want to give money to Burger King because they’re part of the problem,” Chandler told me.

So, yes, plant-based meats could play a significant role in fighting global warming if enough people make the switch. But it’s not pure enough for ultra-environmentalists, not healthy enough for the health-conscious, and not cheap enough for the price-sensitive.

All that being said, Sarah remained upbeat.

“If someone eats fast food four days a week and now they’re going to have this, even just once a month, and they like it,” she said, “that’s a lot of land, that’s a lot of cows, that’s a lot of people, and I’m very happy about it.”