Carbon dioxide (CO2—a single atom of carbon with two attached atoms of oxygen) gets most of the attention as the cause of global warming
because it can persist in the atmosphere for centuries. Methane is a
gas (CH4—a single carbon atom with four attached atoms of hydrogen)
that deserves attention, especially because every portion of a degree
is crucial in avoiding the worst consequences of global warming.

Although methane persists in the atmosphere for only about 20 years,
it is about 80 times more warming than carbon dioxide, so its
importance in the short term is critical. “Cutting methane is the
single most important strategy in slow near term warming,” says
Durwood Zaelke, the president of the Institute for Governance and
Sustainability (The Guardian Weekly, November 21, 2015). Its
pre-industrial atmospheric concentration was about 715 parts per
billion, and its 2025 level is presently measured at about 1930 ppb,
an increase of nearly 270%. Because of the short life of methane,
these high levels are maintained and increased by the continuous and
rising rate of emissions.