Last year, demand for Oatly, a Swedish oat milk popular at third-wave American coffee shops, outpaced supply. National shortages ensued. Oatly superfans were devastated, and apparently willing to spend $25 per 32-ounce carton on Amazon. It’s tempting to write this off as a fluke or embarrassing display of disposable income. But the alternative milk industry has become a true juggernaut — too economically and culturally significant to ignore.In addition to cow, sheep, camel, and goat milks, others made from coconuts, peas, rice, soy, oats, and an array of tree nuts have arrived to entice and confound consumers. Our cups and the market runneth over. Almond milk sales reportedly surged 250 percent from 2011 to 2016. Cow’s milk is in a “decades-long slump,” according to Supermarket News, but it still comprises 90 percent of milk sales. Meanwhile, alternative milks jostle for position. Some market researchers predict the overall alternative milk market will surpass $34 billion by 2024.Having so many new options introduces a gallon of important questions. Does one alternative milk taste the best? Are they all expensive? Is almond milk terrible for the environment? Or is that cow’s milk? Which is the healthiest?