Fossil gas, often touted as a cleaner alternative to coal, is neither green nor clean. It is incompatible with the 1.5°C climate goal due to methane leakages and upstream emissions. Our research indicates a need to reduce fossil gas use by 30% by 2035 to stay on track, yet planned expansions threaten to increase capacity by 86%. Fossil gas also significantly contributes to air pollution, causing premature deaths, childhood asthma, and pre-term births in cities. Economically, renewables are now cheaper and more stable than volatile fossil gas prices. A swift transition to clean energy could prevent hundreds of thousands of premature deaths and save trillions in economic losses by 2050.