Summary
Methane is a greenhouse gas (GHG) that is approximately 80 times more potent than carbon dioxide over a 20-year period. The livestock sector is the largest contributor to global methane emissions, with 32% of methane emissions coming from enteric fermentation — a digestive process occurring in ruminant animals like cows, sheep, and goats — and manure management. Due to ongoing consolidation in the livestock sector, the total number of U.S. livestock operations has declined as production has moved to bigger, more industrialized Animal Feeding Operations (AFOs) that produce enormous amounts of waste and pollution in specific geographic areas.
These industrialized systems, also known as factory farms, cause significant environmental damage and negative health outcomes for local communities while emitting large plumes of methane. Environmental regulation of factory farms is notoriously lax and under-enforced, and facilities are not required to report emissions of methane or other greenhouse gases. With many AFOs operating in relative secrecy, it can be difficult to measure and quantify their climate impacts. In recent years, researchers have begun using satellite imaging to detect methane plumes from factory farms — but the picture is still incomplete. We found that, of the 15,726 total cattle and hog AFOs identified in the U.S., 1,222 aren’t captured by satellite technology, concealing operations that are emitting plumes of methane and harming efforts to effectively measure and address livestock methane emissions.
What are AFOs, and how are they monitored?
The U.S. Environmental Protection Agency (EPA) defines an AFO as a facility where animals are confined and fed for at least 45 days at a time. Concentrated Animal Feeding Operations (CAFOs) are AFOs that house at least 1,000 animal units at a time, the equivalent of 1,000 beef cows or 2,500 large pigs. Above this threshold, CAFOs are technically subject to Clean Water Act (CWA) permitting rules, but in practice, a majority operate without permits or EPA monitoring. AFOs that fall below the 1,000-animal-unit threshold are not federally regulated at all.
Factory farms are known sources of pollution. Levels of harmful fine particulate matter (PM2.5) are 28% higher in census tracts with cattle operations than those without, and 11% higher in census tracts with hog operations. A 2025 study found that 30 U.S. counties contain roughly 25% of all AFOs in the country, which means the negative effects of AFOs are concentrated in those disproportionately rural, low-income, and minority communities. Despite the significant environmental and social costs associated with AFOs, data on methane emissions from AFOs is lacking. Even as satellite mapping of global methane emissions becomes increasingly sophisticated, the technology has been mostly applied to oil and gas methane detection. Carbon Mapper has emerged as a source for satellite data on agriculture methane emissions, but detecting and pinpointing those emissions is still a challenge and satellite-detected methane emissions from livestock are likely significantly undercounted. Carbon Mapper and other satellite tracking initiatives are still expanding and improving their monitoring of agriculture methane emissions in the future.
How many AFOs are currently flying under the radar?
In the graphic below, we cross-reference geographic U.S. AFO data with satellite coverage data from Carbon Mapper across the U.S. to identify AFOs that are currently not captured by Carbon Mapper’s satellite detection efforts. According to U.S. AFO data there are 15,726 total cattle and hog AFOs identified in the U.S. — 8,763 cattle operations and 6,963 hog operations. Of that total, there are 1,222 “unscanned” AFOs that represent potential methane plumes that are currently not measured and appear to be concentrated in the Midwest and East Coast.
Figure 1: Map of AFOs captured by satellite data overlaid with unscanned AFOs
Why is this important?
The importance of understanding the relation between AFOs and methane cannot be overstated. Since methane only exists in the atmosphere for 12 years (a much shorter lifespan than carbon dioxide), rapid cuts in methane emissions could buy crucial time to address overall GHG emissions. Given that the livestock sector is the single largest contributor to global and U.S. methane emissions, it is crucial that AFOs be explicitly included in methane satellite detection efforts as satellite technology becomes more sophisticated. The unscanned AFOs identified in this article offer a good place to start filling in the gaps.
Access the simplified dataset of unscanned AFOs here.
