<p>Short-chain gaseous alkanes (SCGAs), including ethane, propane and butane, are major components of natural gas and their atmospheric emissions impact global air quality and tropospheric chemistry. Many microbial taxa can degrade SCGAs aerobically and anaerobically to CO₂, acting as the major biological sink of these compounds and reducing their negative impacts on climate. Environmental metagenomics and cultivation efforts have expanded our understanding of SCGA-oxidizing microorganisms. In this Review, we discuss recent discoveries in the diversity, physiology and metabolism of aerobic and anaerobic SCGA-oxidizing microorganisms, highlight their climate implications and discuss how knowledge of these processes can help develop biotechnologies for environmental remediation and value-added chemical production.</p>