Around 100 million years ago, there was an enormous explosion of methane that made its way up into Earth’s atmosphere, which, along with a few powerful volcanic eruptions, helped bring about a profoundly hot climate. Now, it appears that researchers wandering through the Arctic have found the scars of this methane ejection, and their work implies that a similarly devastating event could happen any day now.
Writing in the Bulletin of the Geological Society of America, the team – led by the University of Calgary – describe a series of bubble-like bumps on Canada’s Ellef Ringnes Island. Based on the surrounding geological layers, it appears that these scars all emerged at the same time, suggesting that there was an enormous release of methane back then.
“The discovery of 137 Early Cretaceous carbonate deposits [in the] Canadian Arctic Archipelago, demonstrates the presence of an extensive field of methane seeps that occur over a >10,000 km2 area,” the team write in their study.
Methane breaks down in the atmosphere far quicker than carbon dioxide, but it is up to 36 times more potent as a greenhouse gas. Whenever it’s released en masse into the atmosphere, it triggers a rapid warming event that can led to several regional extinction events.
The most famous example of this took place 55 million years ago, when a suspected methane explosion led to a sudden warming spike, which ultimately triggered a series of die-offs and brought about a new geological epoch.
Methane is already escaping out of the seafloor. Seaphotoart/Shuterstock
This latest study suggests that a methane explosion took place around the time of the Cretaceous Hothouse period, when huge volcanic carbon dioxide effusions bumped temperatures up to 9°C (16.2°F) higher than they are today.
This methane was likely unleashed from frozen deposits buried beneath the seafloor, a geological feature that is widespread today. A truly colossal cache of frozen methane was found off the western coast of Central America just this year, and the Siberian Arctic’s permafrost is riddled with the stuff.
In all cases, the methane is generated by particular types of bacteria that release methane compounds as part of their energy production processes. Importantly, the production of biogenic methane is an inevitable natural process that we can do nothing to stop.
As the world warms due to human activity, this frozen methane begins to destabilize, melt away, and escape, either into the oceans or the atmosphere. Indeed, the authors suggest that the volcanically induced warming that brought about the Cretaceous Hothouse likely destabilized these ancient methane deposits, causing them to disintegrate.
Although it’s not yet clear how much of this methane made it through the oceans and into the atmosphere, there’s a good chance it exacerbated the climate warming at the time. This would have triggered a further warming of the oceans, and the release of yet more methane.
Beyond a certain point, this self-reinforcing process may have become unstoppable.
This positive feedback cycle is thought by some researchers as being just as likely to happen in the present era. In fact, the team conclude that “the widespread occurrence of methane seep deposits in Early Cretaceous strata on Ellef Ringnes Island provides an excellent analogue for the present-day potential of global warming-induced hydrate destabilization.”
Although there is ample evidence for the not-insignificant leaking of methane in the Arctic today, scientists aren’t yet sure what the critical temperature may be for a runaway warming effect. Either way, we don’t really want to tempt the beast by driving up global temperatures as fast as we can manage.
The more we heat the planet, the more likely methane will begin to inexorably escape from its frozen prisons. Lifetimestock/Shutterstock
[H/T: Washington Post]