What is our assessment?

Based on our analysis, grass-finished beef production has higher emissions of enteric methane and emissions from land use conversion than does conventional beef production, and would increase risks of biodiversity loss if scaled to meet current demand. Therefore, it is "Not Recommended" as a climate solution.

What is it?

Grass-finished beef production involves raising cattle exclusively on available pasture for their entire lives, eliminating the need for feed crops and associated resources. All cattle begin life on pasture; however, in conventional beef production, the animals spend their final four to six months in high-density feedlots, often called concentrated animal feeding operations (CAFOs). In these systems, cattle are fed high-calorie, mostly grain-based-energy feeds to gain weight quickly. The animals put on one-third to one-half of their total weight during this time, to reach slaughter weight by ~18 months. In contrast, grass-finished beef production requires ~24 to 28 months for animals to reach market weight on forage alone. 

Cattle raised entirely on grazing with no other feed inputs provide only about 1% of global protein. Using broader definitions of grass-finished that allow supplementary forage increases the global beef that would qualify to roughly one-third of global production (about 2–3% of global protein). Grass-fed cattle often receive supplementary feed in pasture-based systems in places such as Brazil, Ireland, and Australia, particularly during seasonal feed shortages.

Does it work?

Deploying grass-finished beef is not an effective climate mitigation strategy. Grass-finished cattle eat a more fibrous diet that produces higher methane emissions per unit of energy intake, and they take longer to reach market weight, resulting in higher lifetime methane emissions per animal. One widely cited study found that forage-fed cattle produce around four times more methane per unit of digestible energy intake than those fed corn- and grain-based diets. In addition, slower weight gain and longer production time require more grazing land, which would likely increase emissions from deforestation and other land use change. Life-cycle assessments consistently show higher emissions per kilogram for grass-finished beef than for grain-finished beef. Even the most efficient grass-finished systems produce 10–25% more emissions per kilogram of protein than grain-finished U.S. beef, and three to over 40 times more than a wide range of plant and animal protein alternatives.

Why are we excited?

Interest in grass-finished beef reflects a broader effort to reduce the environmental harms of industrial livestock systems and improve land stewardship. In limited local contexts, if grass-finished and feedlot grain–finished cattle could gain weight equally, this could alleviate the need for crops destined for feedlot. A recent estimate found that, globally, 34% of crops grown on recently converted natural ecosystems went to animal feed instead of feeding people directly. While grass-finished beef has a higher total water use, it can reduce water risk by shifting from irrigated feed crops for cattle feedlots to rain-fed pastures.

From a human health standpoint, grass-finished beef may contain slightly higher omega-3 fatty acids and vitamin E, but the differences are small and unlikely to meaningfully affect health outcomes. It is often slightly leaner, which can reduce total fat and saturated fat somewhat, but beef in general remains higher in fat than most food options, which increases the risk of heart disease. Within the broader category of red meat, it is still a Group 2A probable carcinogen, according to the World Health Organization. 

Another human health consideration is that grass finishing requires less antimicrobial use. Antibiotics and other antimicrobials are often used in large quantities in confined livestock systems, and cattle account for over half of antimicrobial use among cattle, chickens, and pigs. This use increased by 43% between 2010 and 2020, raising concerns about accelerating antimicrobial resistance and making infection treatments in humans less effective. This may be the strongest case for grass-finished beef, particularly within a global demand reduction scenario.

From an animal welfare perspective, pasture-based systems allow natural behaviors such as walking, socializing, and grazing freely. However, animals are still slaughtered at a young age (before 3 years old) relative to their natural lifespan of 20 years.

Why are we concerned?

Beef production is already the largest single land use globally and the most emissions-intensive food option. Shifting to grass-finished systems would further increase this footprint. Beef is inherently protein-inefficient, requiring large amounts of feed and land. While grass-finished systems were historically the norm, the rise of grain-finishing feedlots after the 1950s modestly improved efficiency by shortening cattle lifespans and reducing per-kilogram land use. Land is a key limiting factor in any expansion of grass-finished production. In the United States, pastureland could support only approximately 27% of current beef production under grass-finished systems. Maintaining current output would require roughly 30% more cattle and 270% more land and would result in a 43% increase in associated methane emissions.

Such land expansion would pose serious biodiversity loss risks. Animal-sourced foods are the leading driver of biodiversity and habitat loss globally. Ruminant meat is disproportionately responsible, causing extinction risks ~340 times higher than grains by mass and ~100 times higher than legumes both by mass and when adjusted for protein, according to a 2025 study.

Last, many government and commercial “grass-fed” certifications are not well enforced and often include cropland-grown forage, which still results in slower weight gain, more methane emissions, and often land carbon leakage. As a result, there are concerns about greenwashing as major fast-food chains market grass-fed beef as environmentally friendly.

While there will likely continue to be an appeal to consumers to choose grass-finished beef, it does not meaningfully change the environmental reality of producing it.

What is our assessment?

Based on our analysis, evidence suggests that insect farming offers minimal opportunities for emission reductions and more often replaces lower-emitting foods, while also facing high costs, low consumer acceptance, and several significant risks even at small industrial scales. For these reasons, insect farming is “Not Recommended” as a climate solution.

What is it?

This potential climate solution involves industrially farming insects, such as crickets, mealworms, and black soldier fly larvae, in controlled facilities to produce protein with lower resource use and lower climate impact for human consumption, livestock feed, or pet food. Currently, 2 billion people worldwide have a practice of eating insects for food, but industrial insect farming is a relatively new effort, even though 1 trillion insects are estimated to be farmed each year, with roughly 79–84 billion insects alive on farms at any given time globally. Most farmed insects are processed into powders, flours, and oils for snack foods, pet food, or animal feed. This solution does not include industrial insect farming for the production of honey, shellac, silk, or the use of insect waste as fertilizer.

Does it work?

Insects convert feed efficiently, grow quickly, can eat food waste, and require far less land than livestock, especially cattle, creating possible pathways for low-resource protein. However, recent analyses show highly variable and often high life cycle emissions, 4.2–25.8 kg CO₂‑eq /kg protein for insects as human food, with the upper end of this range approaching the lower bound for beef. The emissions intensity of insect-based livestock feeds varies from 2.8–11 kg CO₂‑eq /kg dry matter and is higher than for soybean meal (1.06–2.26 kg CO₂‑eq /kg dry matter). Insect proteins for pet food are 2–10 times more emissions-intensive than conventional pet foods that often use meat-industry by-products. Industrial farms in colder, fossil fuel–dependent regions show especially high footprints, with one United Kingdom industrial life cycle assessment (LCA) reporting emissions nearly 10 times those of a medium-sized farm in Thailand.

Why are we excited?

Insect farming has advantages over some widely produced foods, especially beef and pork, most notably that it requires far less land and feed. On average, insects require about 2 kg of feed to produce 1 kg of body mass, which is approximately 3–5 times more efficient than cattle and comparable to chickens. Many edible insects are also high in protein and provide micronutrients such as iron, zinc, and B vitamins. There is active research focused on reducing energy needs, breeding native species, and exploring the use of mixed human food waste as feed to better position insects as a potential climate solution.

Why are we concerned?

Overall, insect farming today has limited climate benefits, poor substitution of high-impact foods, significant local ecosystem risks, low consumer uptake, and high costs.

Most LCAs for insect farming are based on small-scale operations rather than industrial scales. Furthermore, common assumptions in insect farming research do not align with current industry practices, including overstated use of food waste as feed and reliance on outdated climate and price projections. While insect farming could plausibly displace some high-impact foods in the future, there is no current pathway for insects to replace pig and cattle products, a prerequisite for meaningful GHG emission reductions. Substituting insects for already low-impact foods such as flour or cereal ingredients, as is currently common, increases emissions. In addition, available insect products have limited sensory or textural similarities to meat compared with plant-based alternatives. Despite more than US$1 billion invested in scaling the sector, consumer acceptance remains low, with only 5% of production going to direct human consumption and 50% to the pet food market.

Industrial insect farming also carries serious risks. Research indicates that escapes of nonnative species disrupting local ecosystems are inevitable and will intensify as operations scale, potentially affecting other food production systems. Crowded, warm rearing environments can also act as disease-spreading vectors, even if insect farming’s direct zoonotic risk to humans is likely lower than that of intensive meat production. Over 80% of small insect farms supplying pet food have been found to contain parasites, with roughly a third carrying species capable of infecting humans or animals. Contamination risks persist when using mixed human food waste as insect feed due to potential pathogens and chemical residues, which regulatory frameworks are still working to assess.

Lastly, costs are a major barrier. The most comprehensive economic model to date finds that insects are unlikely to become a viable part of industrial animal feed in the near future. Insects are also not expected to reach price parity with meat before plant-based or even single-cell/fermentation-derived proteins. Claims of future cost competitiveness rely on assumptions of near-total utilization of food waste.