Did Methane from Massive Ice Sheets Cause a Shift to Global Warming 635 Million Years Ago?

It turns out that the Earth, just like it’s inhabitants, “burps” every once in a while, and when it does it’s anything but discreet. The last time the world belched up some methane, the entire climate changed drastically and abruptly.

Here’s the scary news: It could very well happen again without warning. Scientists, funded by the National Science Foundation (NSF), reported that mass quantities of the powerful greenhouse gas, methane, escaped from ice sheets that extended to Earth's low latitudes around 635 million years ago, causing a dramatic climate shift from an ice age to a global warming phase. If it happens again, the results will be deadly.

"Our findings document an abrupt and catastrophic global warming that led from a very cold, seemingly stable climate state to a very warm, also stable, climate state--with no pause in between," said geologist Martin Kennedy of the University of California at Riverside (UCR), who led the research team. The methane was released gradually at first, but when the clathrates (methane ice stabilized beneath ice sheets) became unstable the ice turned into gas and escaped to the Earths surface where it had a profound effect on the climate.

"What we now need to know is the sensitivity of the trigger," he said. "How much forcing does it take to move from one stable state to the other--and are we approaching something like that today with current carbon dioxide warming?"

The change "from 'snowball Earth' into a warmer period shows the compelling need for research on abrupt climate change in Earth's history," said H. Richard Lane, program director in NSF's Division of Earth Sciences. "These changes have much to tell us about the modern human-induced threat of rapid climate change."

Scientists believe that the methane clathrate destabilization acted as a runaway feedback loop that quickly increased global warming, and caused the end of the last “snowball” Earth.

"Once methane was released at low latitudes from destabilization in front of the ice sheets, warming caused other clathrates to destabilize," Kennedy said. "Clathrates are held in a temperature-pressure balance of only a few degrees."

What worries scientists is that not all of Earth's methane was released at the time, and there is still plenty waiting to be exhaled. Massive methane clathrates exist in Arctic permafrost right now, and beneath the oceans at continental margins. The hope is that they will remain dormant, but the fear is that warming will trigger them.

Kennedy says it’s a major concern, because it's possible that very little warming could trigger this trapped methane to destabilize. Uncovering the methane reservoir could potentially warm the Earth tens of degrees, he said, and it would happen quickly.

But it’s not just clathrates that permafrost has been protecting us from. Russian scientist, Sergei Zimov, has been studying climate change in Russia's Arctic for 30 years now. He is certain that as massive amounts of organic matter (mammoth dung, etc) become exposed to the air it will drastically accelerate global warming predictions even beyond some of the most pessimistic forecasts. For years he’s been the lone voice in the wilderness warning the world that the permafrost is in danger, and when it goes…we go with it.

For thousands of years animal waste, and other organic matter left behind on the Arctic tundra, has been sealed off from the environment by permafrost. Now climate change is starting to melt the permafrost and the very real concern is that it will free mass quantities of prehistoric “ooze” from its state of suspended animation.

Zimov’s theory is steadily gaining credibility in the scientific community. "There's quite a bit of truth in it," Julian Murton, member of the International Permafrost Association, told Reuters. "The methane and carbon dioxide levels will increase as a result of permafrost degradation."

Now with Kennedy and other scientists reaching similar conclusions, Zimov has received validation—not that he’s happy about it. Zimov hopes he is wrong.

"This will lead to a type of global warming which will be impossible to stop," he explained.

According to Zimov, when the organic matter left behind by mammoths and other wildlife is exposed to the air by the thawing permafrost, microbes that have been dormant for thousands of years will spring back into action. They’ll begin once again to emit carbon dioxide and methane gas as a by-product. Zimov says though the microbes are tiny, they will start emitting these gases in enormous quantities simply because there are so many of them.

But not only that, but as the permafrost melts, massive clathrate “bubbles” could start to burst and accelerate the release of methane gas to a catastrophic level.

It’s almost like having a sleeping bull in the china shop. Lets just hope it doesn’t wake up anytime soon!

Posted by Rebecca Sato

* Authors of the study include Martin Kennedy of the University of California at Riverside, David Mrofka of UCR and Chris von der Borch of Flinders University, Australia. The study also was supported by grants from NASA's Exobiology Program.