Scientists at the National Oceanic and Atmospheric Administration, who have been monitoring air samples since 1983, has noticed an alarming spike in methane levels.
The amount of greenhouse gases, including methane, has been steadily rising since the Industrial Revolution. By the turn of the millennium, levels of atmospheric methane were high but mostly flattened out.
However, in 2007, it started to rapidly increase. Then, in 2014, it rose even faster.
Scientists did not know why.
Atmospheric Methane Levels Rising Rapidly
According to the most recent measurements, the current level of methane in the atmosphere is about 1,867 parts per billion. Humans are responsible for about 60 percent of the global methane emissions.
"The really fascinating thing about methane is the fact that almost everything we humans do has an effect on the methane budget, from producing food to producing fuel to disposing of waste," said Lori Bruhwiler, a research scientist, in a conversation with Undark.
However, a recently published study revealed that the levels of methane from natural sources suddenly increased. This, scientists said, explains the uptick of the potent greenhouse gas that cannot be attributed to human activity.
The problem is, finding what is driving the sudden growth will not be easy. The researchers added that figuring out what is causing the increase is necessary in the fight against climate change.
"We need to have process representation to understand these mechanisms," explained Eric Kort, an atmospheric scientist from the University of Michigan, "so we can say, for example, with certain changes to temperature and the hydrological cycle, we'd expect methane emissions to increase by X amount."
Natural Methane Emissions
Scientists suspected that microbial sources such as wetlands might be responsible for the sharp increase of methane emissions to the atmosphere. Wetlands are the biggest contributor of natural methane, and they can be very unpredictable. They are able to change production of methane from year to year.
Pep Canadell, the executive director of the Global Carbon Project, added that wetlands are "the ultimate potential carbon climate feedback" that scientists still do not fully understand.
The emission from microbes in wetlands is a response to the shifts in climate. They produce methane, for example, when there is increased precipitation, or when the temperature is unusually warm.
If this is the case, the authors noted that the only way to decrease levels of atmospheric methane is to decrease human-caused emissions "which we can control." Decreasing the amount of the potent greenhouse gas, which is more effective at trapping heat than carbon dioxide, would prevent further warming around the world.
