In this paper, we present the research challenges and opportunities in methane reduction within the smart, swarm, and small Unmanned Aircraft Vehicles (UAVs). Methane is a kind of greenhouse gas (GHG) that contributes to global temperature warming and climate changes through trapping infrared radiation in the atmosphere. The related literature of the current methane measurements and suppression of methane approaches are reviewed, and they are often limited due to the maintenance, installment, and calibration requirements of these sensing systems. To overcome these limitations, an emerging technology, UAVs, as considered mobile sensors to measure and control methane emissions, would extend detection range and acquired fine-grained information that helps to capture methane emissions in a much effective way. However, many challenges need to be explored: In the sensing field, the improvement of positive methane detection rate, which contradicts the methane diffusion in the atmosphere. The swarm UAVs for optimal coverage control, the substances of suppression methane usage, and reaction time in the control field. Different methane diffusion disturbances types could affect the strategy of swarming UAVs movement, especially under wind field. Besides, we also talk about the impact of methane reduction and related technology development for the future. Finally, we concluded that the Digital Twin would be the next methane reduction revolution to prevent potential global warming.