Global methane emissions surge

“(Methane) emissions in the U.S. have been declining for the last number of years”, he noted, “…but there’s another component – not following the leadership of President Obama”.

According to BBC News, methane levels were relatively stagnant in the 2000s, but have recently surged. Over a century it is 34 times more powerful as a greenhouse gas than carbon dioxide (though far less abundant), but over 20 years methane is 84 times more potent than CO2.

The dramatic recent rise in methane brings focus on controlling those emissions for climate change purposes. However, the bulk of methane emission is from human activities that include cattle operations and flooded soils where microbes produce the gas.

If these trends continue, methane growth could become a risky climate wildcard, overwhelming efforts to reduce CO₂ in the short term.

That is the message of a team of global scientists in an editorial to be published 12 December in the journal Environmental Research Letters. Unlike CO2, where we have well-described power plants, nearly everything in the global methane budget is diffuse.

The gas comes from natural sources, including marshes and wetlands, but 60% of it is generated by human activity such as cattle and rice farming. The budget is published by the Global Carbon Project, a research initiative of Future Earth.

Where does all the methane go? In part, that’s because it can come from many different sources.

Cows have always been known to be a major producer of greenhouse gas, but there is also a chance that wetlands and various natural cycles could be contributing to the rise as well, BBC News reports. There has been a progress when it comes to Carbon dioxide emissions, but it’s not the only greenhouse around. “But we need to look just as hard if not harder at agriculture”. Examples include methane leaking out of natural faults and seeping on the ocean floor, and the potential for increased emissions as permafrost warms.

Even if scientists agree that total emissions of methane are rising sharply, they remain uncertain as to why.

CO₂ emissions take centre stage in most discussions to limit climate change. “There’s been a secondary increase from fossil fuel use, partly because there continues to be more fossil fuels extracted”. However, it’s important to note that considerable scientific uncertainty remains when it comes to accounting for all the complex, global sources of methane, as well as the processes that withdraw it from the atmosphere once it has been emitted.

Biomass and biofuel burning originates from both human and natural fires. “It’s really intriguing”, Saunois added. See the Global Carbon Atlas at http://www.globalcarbonatlas.org.

The concentration of this chemical species in the atmosphere might also be changing in some way.

Scientists are still uncovering the reasons for the rise. However, methane’s persistence in the atmosphere is much smaller. By comparison, the levels of atmospheric carbon dioxide passed the 400 parts per million in the Summer and may never decrease.

Methane is also something of an oddity as it autodestructs on contact with ozone molecules. This increase happens to meet agricultural expansion during that period.

Without those pledges, the increase would be much higher. The researchers can’t be entirely sure of the cause in the sudden spike, but believe that agriculture is probably to blame.

Researchers largely attribute the spike to agriculture, though methane emissions that escape during energy development also play a role.

“Many people would point the finger at the oil and gas industry first – but agricultural sources are bigger”, Jackson said.

This, combined with methane’s super global warming potency, means we have a massive opportunity. A new study shows methane emissions have jumped so dramatically that they’re now approaching a worst case scenario for greenhouse gas emissions.