THORNTON, COLO. -- Lars Obendorfer says he was "badly insulted" after he first began offering vegan sausage at his stands, dubbed "Best Worscht in Town." He even found himself mediating between customers arguing on social media about what to him was just another menu item.

"There was downright hostility between the meat eaters and the vegans," he said. "And I just couldn't understand it, and I said, `knock off the arguing."'

That was six years ago.

Today, his vegan currywurst -- a take on the classic German fast food consisting of pork sausage with ketchup and curry power -- is no longer a novelty but a menu fixture at his 25 stands across Germany.

Of the 200,000 sausages he sells every year, 15 per cent are plant-based.

"It actually tastes like a normal sausage," customer Yasemin Dural said. "I even had doubts earlier that it might have been a meat sausage, but you really don't notice it at all."

Eating more plants and fewer animals is among the simplest, cheapest and most readily available ways for people to reduce their impact on the environment, climate scientists have long said. According to one University of Michigan study, if half of U.S. animal-based food was replaced with plant-based substitutes by 2030, the reduction in emissions for that year would be the equivalent of taking 47.5 million vehicles off the road.

"We are in a climate crisis, a climate emergency," says Greg Keoleian, a professor of sustainable systems at the University of Michigan who co-authored the study. "We all need to play a role, and these products are one strategy to easily reduce your footprint."

An explosion of new types of plant-based "meat" -- the burgers, nuggets, sausages and other cuts that closely resemble meat but are made from soybeans and other plants -- is attracting customers all over the world. Even in Germany, where cities like Hamburg and Frankfurt have given their names to iconic meat dishes, plant-based meat is becoming more popular.

This latest innovation in meat substitutes has already made meaningful strides. Between 2018 and 2022, global retail sales of plant-based meat and seafood more than doubled to $6 billion, according to Euromonitor, a market research firm.

Still, that's dwarfed by global retail sales of packaged animal meat and seafood, which grew 29 per cent in the same period to US$302 billion. Plant-based meat and seafood makes up just 2 per cent of the world's global protein consumption. And sales have been uneven. While demand for plant-based meat is growing rapidly in some countries like Germany and Australia, sales have flattened in the U.S.

NEW RECIPES TO THE RESCUE?

Plant-based meat has been around for decades. Morningstar Farms, a division of Kellogg Co., introduced soy-based breakfast sausage in 1975. But the current boom began about 10 years ago, when startups like Impossible Foods and Beyond Meat began selling burgers that more closely resembled meat and were aimed at carnivores, not just vegetarians and vegans. Beyond Meat's burgers, made with pea protein, even "bleed" with the help of beet juice.

Those products quickly took hold in Germany, a country where meat-heavy dishes like schnitzel and bratwurst are a mainstay of diets but where widespread concern about climate and animal welfare have been driving big changes. Last year, Germans' annual meat consumption fell to a 33-year low of 52 kilograms (114 pounds) per person. At the same time, plant-based meat sales rose 22%, according to Euromonitor, and they have tripled since 2018.

In Australia -- where the average person ate around 120 kilograms (264 pounds) of animal meat in 2020, according to the United Nations, putting the country just behind the U.S. in terms of meat consumption -- retail sales of plant-based meat have been growing, up 32 per cent between 2020 and 2022.

Sam Lawrence, the vice president of policy for the Asia division of the Good Food Institute, a plant-based advocacy group, said Australia was initially behind Europe and the U.S. in the adoption of plant-based meat. But that's changing fast, in part because of health concerns. In 2018, the country had only around eight plant-based meat companies, he said. Now there are more than 40, many with their sights on the vast Asian market.

But it is the U.S. that represents one of the biggest hopes for a solution: It is the largest market for meat substitutes. It is also one of the biggest contributors to greenhouse gases from animal agriculture, weighing in as the second-largest consumer of meat per capita behind Hong Kong, according to 2020 data from the Food and Agriculture Organization of the United Nations.

Reversing that trend would have a significant impact on global meat consumption, and Tyler Huggins knows it.

Huggins is the co-founder and CEO of the plant-based food company Meati. He comes from a family of bison ranchers, and he still eats meat occasionally. But after studying damage to rangeland ecology with the U.S. Forest Service, he earned a Ph.D. in environmental engineering with a focus on developing new kinds of plant-based meat.

Huggins says it's imperative to wean Americans from their meat-heavy diet because the country is already using most of its arable land.

"How are you going to continue to feed a growing population and an increased demand in meat?" Huggins said. "We have to get more efficient in the way we produce things."

Colorado-based Meati makes chewy, fibrous steak filets and chicken cutlets from mushroom roots and a handful of other ingredients, like chickpea flour. Its chicken cutlet has fewer calories, less cholesterol and nearly as much protein as animal chicken.

Meati collects spores from mushroom roots, feeds them sugar and ferments them in stainless steel tanks full of water. Every 22 hours, the fermented mixture -- which resembles applesauce -- is drained from a 25,000-liter tank, formed into cutlets and cooked. In four days, a single microscopic spore can produce the equivalent of a whole cow's worth of meat.

Eventually, the company expects to produce more than 40 million pounds of meat annually at its 100,000-square-foot Mega Ranch in Thornton, Colorado. That's about 160 million four-ounce servings, or half the amount of beef served each year at Chipotle, one of Meati's biggest investors.

A MATTER OF TASTE

Meati came onto the plant-based meat scene in 2017, around the same time that dozens of others were trying their hand in the space. At least 55 plant-based companies and brands -- including entries from big meat producers like Tyson Foods -- launched in the U.S. during 2017 and 2020, according to the Good Food Institute. Meanwhile, plant-based meat sales more than doubled in that same period, to US$1.6 billion.

But then sales plateaued, inching up just 2 per cent between 2020 and 2022, according to Euromonitor. At the same time, U.S. animal meat and seafood sales rose 12.7 per cent.

Some contend that the high price of meat alternatives is limiting their appeal. As of April, U.S. plant-based meat and seafood prices were an average of 27 per cent higher than animal meat and seafood in the U.S., according to Euromonitor. That was larger than the 20 per cent gap in Germany.

For Peter McGuinness, the CEO of pioneering plant-based burger maker Impossible Foods, taste -- not price -- is the biggest issue.

"I think the category is not good enough," McGuinness said. "What is the number one thing people want in food? Taste. If I don't have the taste, they don't care about the cholesterol and the saturated fat."

A recent poll from The Associated Press-NORC Center for Public Affairs Research of U.S. consumers found that about 8 in 10 U.S. adults said taste was an extremely or very important factor when buying food, with its cost and nutritional value following close behind. Americans are much less likely to prioritize the food's effect on the environment (34.

Lisa Feria, the CEO of Stray Dog Capital, which invests in plant-based meat companies, said that even though the initial exuberance in the U.S. market is now thinning out, new brands that emerge from this period will be stronger and better-funded, which will help the plant-based meat market grow at a more sustainable pace.

"We deserve these products that are better for us, for the environment, definitely for animals, that we could eat for generations to come no matter how many people are on the planet," Feria said.

But it will take some convincing. An hour north of Meati's Mega Ranch is the U.S. headquarters of JBS, one of the world's largest meat producers. JBS launched Planterra Foods, a U.S. plant-based brand, in 2020 but closed it two years later. JBS, which still makes plant-based meat in Europe and Brazil, didn't respond to a request for comment.

FOR THE SAKE OF THE PLANET

The meat industry has sown its own doubts about its plant-based rival. The Center for Consumer Freedom -- which says it's funded by restaurants and food companies but won't say which ones -- has run Super Bowl and newspaper ads criticizing plant-based meat, saying it has "chemicals and ultra-processed ingredients that you can't pronounce."

Indeed, questions about the healthiness of plant-based meat have weighed on sales. Plant-based foods have some benefits over meat; they have no cholesterol, for example, and may have less fat and more fiber. But plant-based foods can also be higher in sodium, to better mimic meat's flavor, and they don't always have as much protein.

Beyond Meat, another pioneer in the market, is focused on improving the health of its products. The company notes that its Beyond Steak beef tips were recently certified as a heart-healthy food by the American Heart Association.

But Beyond Meat's founder and CEO Ethan Brown says that in places like Germany -- unlike in the U.S. -- concerns about health are outweighed by concerns about the environment.

"In the European Union, there's clearly a desire to do something meaningful about climate," Brown said. "Here in the United States, it's unfortunately become politicized."

For Adrienne Stevson, it's all about the environment. A graphic designer from Johnson, Vermont, Stevson was a heavy meat-eater for most of her life. She has a family cookbook filled with meaty recipes, and she even worked for a time as a prep cook preparing meat.

So when her partner became a vegan, she was skeptical. But the more she learned about the benefits to the climate, the more she warmed to plant-based meat.

Stevson still uses her family cookbook, but she swaps out the meat for Beyond Meat ground beef, Impossible sausage and other products, like tofu. In an ideal world, she says, she wouldn't have to do that.

"I think in an ideal world we could live with eating dairy products and meat products," Stevson says. "But there's way too many people on the earth and we haven't solved the problem of animal agriculture for that many people in a sustainable way."