Methane

Methane is the simplest organic molecule — one carbon atom tetrahedrally bonded to four hydrogens — and yet one of the most strategically important compounds of the 21st century. The main component (~85-95 %) of commercial natural gas, it supplies roughly a quarter of global primary energy, either as a direct fuel (heating, combined-cycle electricity) or as petrochemical feedstock (steam reforming to H₂ and CO for ammonia, methanol and Fischer-Tropsch synthesis).

Climatically, its role is ambivalent. Combustion releases ~50 % less CO₂ per kWh than coal, making it a cleaner "transition fuel". But methane itself is a greenhouse gas 28 times more potent than CO₂ over 100 years (and ~80 times over 20 years). Leaks along the extraction and transport chain — pipelines, LNG terminals, wellheads — can entirely cancel its climate advantage if they exceed ~3 %. Recent satellite detection (TROPOMI, MethaneSAT) has revealed that fugitive emissions from the sector are systematically underestimated in official inventories.

Beyond Earth, CH₄ has been the subject of notable observations: cyclic presence on Mars (origin still debated: geological or biological), an atmosphere and liquid lakes on Titan (Saturn's moon, where the hydrological cycle uses methane in place of water), traces on Enceladus. On Earth, most atmospheric methane comes from methanogenesis — an anaerobic metabolic pathway used by certain archaea in wetlands, ruminants, rice paddies and landfills. Anthropogenic emissions (~60 % of the total) have been rising rapidly since 2007 without a fully elucidated cause.