Oat milk is not categorically more sustainable than almond milk. The answer depends on which environmental metric you care about most. Almond milk produces fewer greenhouse gas emissions (0.7 kg CO2 equivalents per liter versus 0.9 for oat) and uses less land (0.5 square meters per liter versus 0.76 for oat). But almond milk has a significantly larger water footprint, and that water comes disproportionately from drought-prone California. Both milks are dramatically better for the planet than dairy, which generates roughly 3.15 kg of CO2 equivalents per liter and requires nearly 9 square meters of land.
Carbon Emissions Favor Almond Milk
Based on a large meta-analysis of food system studies covering the full supply chain, almond milk generates about 0.7 kg of CO2 equivalents per liter of finished product. Oat milk comes in slightly higher at 0.9 kg. Both fall well below soy milk (0.98 kg) and rice milk (1.18 kg), and all plant milks sit in a completely different category from cow’s milk at 3.15 kg per liter. That means switching from dairy to either oat or almond milk cuts your milk-related carbon footprint by roughly 70 to 78 percent.
The carbon cost of oat milk comes mainly from farming, processing, and transport. Oats require more energy-intensive processing to become a drinkable liquid, involving enzymatic treatments that break down starches. Almonds, while energy-intensive to grow, are relatively simple to process into milk through soaking and blending.
Water Use Is Where They Diverge
Water is the metric that makes almond milk controversial. About 80 percent of the world’s almonds are grown in California, a state that has faced recurring severe drought. Almond trees are perennial crops that need water year-round, even during drought years when surface water allocations get cut. When that happens, growers pump groundwater, contributing to aquifer depletion, land subsidence, and competition with urban water supplies and ecosystems.
Oats, by contrast, are a rain-fed crop in most growing regions. They thrive in temperate climates like the upper Midwest, Canada, and Northern Europe, where rainfall typically provides most of the water the crop needs. This means oat milk’s water footprint draws less from stressed freshwater sources. The distinction matters: a liter of water pulled from a depleted California aquifer has a very different environmental cost than a liter of rainwater falling on a Swedish oat field.
California’s Sustainable Groundwater Management Act is now imposing tighter limits on extraction, and some growers have already reduced or abandoned almond acreage in the most water-poor regions. This regulatory pressure may eventually shrink the water gap, but for now, almond milk’s dependence on irrigation in a water-scarce region remains its biggest environmental liability.
Land Use Slightly Favors Almonds
Almond milk requires about 0.5 square meters of land per liter, while oat milk needs 0.76 square meters. Both are a fraction of what dairy requires at nearly 9 square meters per liter. For context, rice milk uses the least land among plant milks (0.34 square meters), and soy milk sits between almond and oat at 0.66 square meters.
The land use difference between oat and almond milk is relatively small in absolute terms. Neither crop is a major driver of deforestation or habitat loss in the way that some other agricultural commodities are. Oats typically rotate with other crops in existing farmland, and almonds grow in established orchards. If land use is your primary concern, both are reasonable choices, though almond edges ahead.
Pesticide and Chemical Concerns
Both crops come with chemical considerations. Oats are frequently sprayed with glyphosate, the active ingredient in Roundup and the most widely used herbicide globally. It’s applied not just during growing but also just before harvest as a drying agent, which can leave residues in the finished grain. Glyphosate has been linked to potential health concerns, and its environmental effects on soil health and waterways are a subject of ongoing scrutiny.
Almond orchards rely heavily on managed honeybee colonies for pollination. Each spring, roughly two-thirds of all commercial honeybee hives in the United States are trucked to California’s Central Valley for almond pollination. The combination of pesticide exposure in orchards and the stress of long-distance transport contributes to colony losses. Almond farming also uses various insecticides and fungicides, though the bee issue is the one most unique to this crop.
If pesticide exposure concerns you personally, choosing organic versions of either milk reduces your contact with these chemicals. From a broader environmental perspective, oat farming’s reliance on glyphosate and almond farming’s impact on pollinators represent different kinds of ecological risk rather than one being clearly worse.
Nutrient Density Changes the Math
One factor that rarely comes up in sustainability comparisons is how much nutrition you actually get per unit of environmental impact. Almond milk and oat milk have similar calorie counts (roughly 320 kcal per kilogram), but almond milk delivers more than twice the protein: about 10 grams per kilogram compared to 4.6 grams for oat milk. If you’re drinking plant milk partly for its protein content, you’d need to drink more oat milk to get the same amount, which multiplies its environmental footprint per gram of protein.
That said, most people don’t choose plant milk primarily as a protein source. If you’re using it in coffee or cereal, the per-serving environmental impact matters more than the protein ratio. And oat milk’s higher fiber content from beta-glucans offers its own nutritional advantage that simple protein comparisons miss.
Which One Should You Choose?
If you live in or care about water-stressed regions, oat milk is the more responsible pick. Its rain-fed growing cycle puts far less pressure on freshwater resources, and that single advantage is significant enough to outweigh almond milk’s modest wins on carbon and land use. Water scarcity is one of the most pressing environmental challenges globally, and the gap between these two milks on water is larger than the gap on any other metric.
If your primary concern is carbon emissions, almond milk has a slight edge. If you’re focused on land use, almond also wins by a small margin. But the differences on these metrics are measured in fractions, while the water difference is substantial and concentrated in a region that can least afford it.
The most honest answer is that both oat and almond milk are far more sustainable than dairy by every major measure. Choosing either one over cow’s milk is a much bigger environmental decision than choosing between the two. If you want to optimize further, oat milk’s lower water impact in a warming, drying world gives it a meaningful overall advantage.