The Earth was an inhospitable place 635 million years ago, with ice sheets that extended to the equator. Scientists have long wondered how the planet rebounded from that icy era, known as “Snowball Earth.”
Now a new study suggests that a stream of methane gas escaping from the ice brought the planet to a climate tipping point and transformed it into a lush, tropical world, in what researchers called one of the most severe climate change events recorded in Earth history [Nature, subscription required].
Paleoclimatology has become a hot field, as researchers believe that the planet’s dramatic prehistoric climate shifts can help predict the effects of present-day global warming. Since methane figures into one of the most ominous global warming scenarios, this latest study is being eagerly scrutinized for clues to our planet’s fate.
On Snowball Earth, methane was trapped in the ice sheets. But ice sheets are inherently unstable. Once they reach a certain size, they begin to fall apart. The collapse of ancient ice sheets at the Equator would have unleashed trapped methane deposits and pushed global temperatures higher [National Geographic]. Methane, a powerful greenhouse gas, then raised temperatures, leading to more collapsing ice sheets in a looping feedback cycle.
Climate researchers point out that vast amounts of methane are now trapped in the permafrost and buried in icy deposits beneath the ocean floors. This latest study suggests that a warmer climate and oceans could thaw those deposits, and allow the methane to bubble up into the atmosphere.
If global temperatures continue to rise, massive amounts of methane gas could be released from the 10,000 gigaton reserves of frozen methane that are currently locked in the world’s deep oceans and permafrost. Passing this climate tipping point would result in global warming that would be far worse and more rapid than scientists’ current estimates. … The study’s lead author suggests it could happen fast — not over thousands or millions of years, but possibly within a century.
“This is a major concern because it’s possible that only a little warming can unleash this trapped methane,” Martin Kennedy, a professor at UC Riverside, said in a release. “Unzippering the methane reservoir could potentially warm the Earth tens of degrees, and the mechanism could be geologically very rapid” [Wired News].
Kennedy’s predictions on the potential timescale of the methane release are the most alarming to date; other researchers have predicted that it would take thousands of years for methane to be released from the oceans. But most climate researchers would probably agree with Kennedy’s preventative, prophylactic advice: Keep it zipped!
December 27th, 2009 at 10:13 am
Dear Sir
Methane gas is produced in Bio degradation for along time its acumulation in polar ice may not be only mechanism for methane cycle, I feel it is cotributing to the our under ground natural gas found in river delta and deserts.
October 28th, 2010 at 4:22 pm
What a load of garbage.
No matter how much methane you add to the Earth the Greenhouse warming effect is limited to the amount of absorbable energy photons available.
Methane would just become excess methane on Earth.
Just exactly like there is excess water on Earth now. Ask yourself- why hasn’t all the water in the ocean absorbed energy photons & vaporized? The answer is because there are only a limited number of energy photons. It takes under a microsecond for a GHG like water vapor to absorb a photon & then give the energy back by collision with neighboring molecules.
Only a very small fraction are ever at the900C temperature of a molecule that has absorbed a photon. Hence we have excess liquid water, and excess Co2 etc.
The only way to get a snowball Earth isif the amount of incoming energy decreases. SInce we didn’t move that much from the sun, then there is another source of energy thst warms the Earth. Try Gravity and excentric movements of the planets.
July 22nd, 2011 at 10:20 pm
I agree with John Dodds, sounds like a load of garbage