Monday, the The United Nations Intergovernmental Panel on Climate Change has released a landmark report on the state of the planet that — spoiler alert—doesn’t look great. The archivillain of the assessment is carbon dioxide, but he also called the CO2the lesser-known brother of: methane. Atmospheric concentrations of this greenhouse gas, 80 times more powerful than CO2, are now higher than ever for at least 800,000 years, the report notes. If humanity could seriously reduce methane emissions, it would put a huge and rapid brake on climate change.
“Methane is the next crucial and rapid climate stabilization prize,” said Rick Duke, senior director and White House liaison for the President’s Special Envoy for Climate Change, during a press conference Monday following the publication of the report. “There is simply nothing that comes close to securing our short-term climate future, saving us crucial time to decarbonize energy and develop advanced options such as negative emission technologies. “
“Reducing methane emissions is the fastest and most effective way to slow the rate of warming right now,” agreed Ilissa Ocko, senior climate scientist at the Environmental Defense Fund.
Like carbon dioxide, methane contains carbon; its chemical formula is CH4. It is a main component of natural gas and of many ecosystems. Rotting vegetation produces methane – wetlands are particularly emitting. And when insects like termites and ungulates like cows digest food, they also produce methane. (it is especially the cow burps, not farts, which contain gas.)
But while CH4 is a perfectly natural component of Earth’s atmosphere, the amount that has now been added to the sky is far from natural. An important factor is the rearing of livestock, including not only cows but also sheep and pigs – all that manure adds more methane. In the United States, this “enteric fermentation” is responsible for more than a quarter of domestic methane emissions. The production and transportation of natural gas, coal and oil accounts for an additional 30% and landfills, which are after all filled with decaying vegetation, add another 17%.
In determining the potency of a greenhouse gas, two main considerations must be taken into account: the efficiency of the molecule at trapping heat and the length of time it can survive in the atmosphere. Greenhouse gases like CO2 and CH4 are both very effective at containing heat; they are in fact what helps make the Earth habitable by preventing heat from escaping into space. But methane is better. “You have a carbon attached to two oxygen atoms in a CO2 molecule, but a carbon attached to four hydrogen atoms in a methane molecule, ”says Matthew Hayek, NYU environmental specialist who studies methane. “And so, there are other ways for the bonds between these atoms to vibrate when it receives or absorbs infrared radiation and therefore re-emits infrared radiation.”
“One pound of methane emitted can trap heat over 100 times more than CO2 when it is issued for the first time, ”agrees Tianyi Sun, climatologist at the Environmental Defense Fund, specializing in methane. But, she points out, methane disappears faster. “It only lasts in the atmosphere for about a decade, and it’s gone.” Carbon dioxide, on the other hand, can last for centuries.
Before humans started producing too much of each, when these gases occurred naturally, they would float in the atmosphere, absorb radiation, and decompose through oxidation on their various time scales. Then a volcano could eject CO2in the air, and the wetlands were slowly going boil methane, but the two would eventually dissipate. The atmosphere was able to exist in equilibrium, creating a kind of blanket that kept the planet warm, but not too warm.