Millions of oil and gas wells exist across the United States, Canada, and abroad as legacies of the 160-year history of oil and gas production. Many of these wells are no longer in production and have been abandoned. Abandoned oil and gas wells can act as subsurface leakage pathways connecting oil and gas reservoirs to groundwater aquifers and the atmosphere. Numerous studies show that abandoned oil and gas wells are emitting methane, a potent greenhouse gas, and likely degrading our groundwater, soils, and ecosystems. To design cost-effective strategies for mitigating and managing environmental and climate impacts of abandoned wells, it is critical to understand factors linked to leaky wells, particularly those that are very leaky. In this talk, I will present data on available measurements and abandoned oil and gas wells and the importance of conjunctively analyzing this data to address the growing problem of abandoned oil and gas wells around the world.