Methane is the second most important greenhouse gas released by human activities. To tackle global warming, we need to understand the methane budget and identify methane sources. However, the dynamics that led to the methane increase in the last decades are not fully understood. Tracing methane sources and monitoring mitigation strategies are therefore an urgent matter. The lecture will focus on the main methane sources at both regional and global scale, and on the most advanced technologies to detect methane emissions. The lecture will also answer questions about the role of atmospheric methane in climate change and how to curb greenhouse gases emissions.