It’s been talked about for years, and now it’s really happening — methane, a global warming gas far more deadly than carbon dioxide, is escaping from the Arctic seabed in vast quantities, adding to the atmospheric burden. What effect will it have on our planet’s climate?
UK newspaper The Independent led with what it described as an exclusive story on 23rd September 2008: The Methane Time Bomb. Science Editor Steve Connor reports that Arctic scientists have discovered what’s described as a new global warming threat — the melting permafrost is releasing into the atmosphere millions of tons of a gas 20 times more damaging than carbon dioxide.
This is not a new idea — Whitley Strieber‘s Unknown Country web site has raised the subject numerous times over the past few years, and his 1999 book The Coming Global Superstorm discussed the contribution that methane released into the atmosphere would make to the conditions necessary for the formation of a Superstorm that could dump billions of tons of snow onto the northern hemisphere, causing another mini-ice age. What this new report brings is hard evidence that such methane releases are real — and that they’re happening right now.
Underground stores of methane are important because scientists believe their sudden release has in the past been responsible for rapid increases in global temperatures, dramatic changes to the climate, and even the mass extinction of species, writes Steve Connor. Scientists aboard a research ship that has sailed the entire length of Russia’s northern coast have discovered intense concentrations of methane -– sometimes at up to 100 times background levels –- over several areas covering thousands of square miles of the Siberian continental shelf.
In the past few days, the researchers have seen areas of sea foaming with gas bubbling up through “methane chimneys” rising from the sea floor. They believe that the sub-sea layer of permafrost, which has acted like a “lid” to prevent the gas from escaping, has melted away to allow methane to rise from underground deposits formed before the last ice age.
If it’s happening in Siberian waters, it’s probably happening elsewhere — there are deposits of methane clathrate (also called methane hydrate, or methane ice) locked up in various undersea locations around the globe which must surely be at risk of escaping. Those in high latitudes have, until now, been kept locked down by the coldness of the surrounding permafrost conditions of the seabed, while deposits in other, more temperate locations are restrained by the relatively cold water currents circulating immediately on top of the strata where they’re entombed — but those cold currents are warming up, and once they reach a certain critical temperature, the methane will begin to expand. Eventually it will overcome the pressure of the water above and escape through fissures in the rock. Some of the methane will dissolve in the sea water — but where the gas has sufficient pressure, it will rise swiftly through the water and escape into the atmosphere. That’s what the scientists have been observing in the Siberian waters.
Methane gas also escapes from boggy and peaty landscapes, such as those in high latitude Russia and Canada, as the permafrost melts in higher temperatures. Overall, the Earth’s crust contains huge amounts of methane. When it gets into the atmosphere, it acts much more powerfully as a greenhouse gas than carbon dioxide, though it doesn’t persist as long. But when it does eventually break down, it turns into water — and our old friend carbon dioxide, so even after it’s gone, it still has a sting in its tail.
What does the release of all this methane mean for our immediate future?
During the third and final part of a recent BBC2 documentary series called Earth — The Climate Wars, Dr. Iain Stewart spoke to Professor Jim White, who was a member of the US Geological Survey project in the late 1990s which collected ice cores from the Greenland ice sheet. Analysis of the chemical composition of these ice cores provides a window on the climatic conditions that prevailed when the ice was laid down, going back many thousands — even hundreds of thousands — of years. Dr. Stewart was particularly interested in finding out what happened around 11,000 years ago, at the end of a period known as the Younger Dryas. He visited Professor White in Denver, where the ice cores are now stored. Together they examined an ice core that covered the transition from the 1,000-year-long cold, dry Younger Dryas period into the next, warmer period known as the Holocene:
IS: So we’ve come out the last ice age, it’s started to warm up, and then we dip into this 1,000 year cold stage, the Younger Dryas. What does this core tell us about how it ends?
JW: As you come along in this particular core you see layers that are roughly half a centimetre thick, and then right here, these layers become about a centimetre thick all the way up the core. And that is a fundamental change in the amount of snowfall that occurs … this is the Younger Dryas cold period, [and] right here is the end of the Younger Dryas — you can actually put a line right there in the ice.
IS: So — right on that divide there?
JW: Right on that divide right there.
IS (narration): In the cold dry period of the Younger Dryas, the layers are cloudy, and so thin they seem to merge into each other. But then, there’s a sudden transition to clearer, thicker layers. These thicker bands show there was much heavier snowfall. And when they analysed the chemistry of the ice, it revealed the temperature had jumped by five degrees.
IS: So how quick is that transition?
JW: Well, if you look at it, basically one year.
IS: Wow.
JW: Yes. There’s enough ‘noise’ in here that one can argue it’s maybe one to three years — but it’s not one to five years and it’s certainly not one to ten years. It’s right around one year.
IS: So we go from essentially an ice age, in the Younger Dryas, to the warm period immediately afterwards within a year.
JW: In terms of snowfall, yes. It takes a little longer for the climate system to warm up.
IS (narration): The Earth’s climate was meant to take thousands of years to change. But the ice core showed that the climate could switch from an ice age to warm conditions in less than a human lifetime. And as they looked further back in time, there was more to come.
IS: So is this the only abrupt change you find?
JW: No. No, this ice core contains a couple of dozen abrupt climate changes that have warmings that are as fast and environmental changes that are as drastic as the one you see here.
IS: So are these rapid shifts characteristic of the climate system?
JW: It’s clearly not an artefact in the system, it’s clearly not just a once or twice kind of thing that maybe was a meteorite or something like that or a volcano — this is an inherent, intrinsic part of the climate system.
IS (narration): The discovery of sudden, rapid climate change was a scientific revolution. It meant that the climate was capable of sudden jumps in a time scale that modern civilization has never had to deal with.
IS: And — do you get genuinely scared about what that possibly means for us if we encounter it in the future?
JW: Yes. I don’t think anybody could not get scared. If you understood just how fast that was and how big this change was, just how fundamental it was — if something like that happened to us — and it’s important to recognise we’ve not seen anything like it — if something like that happened to us today, we would probably not be able to grow enough food, we would not have enough fresh water, it would challenge even the most industrialised society to adapt. And that is scary.
IS (narration) The most frightening thing is that no-one knows what causes the climate to change so quickly. So scientists began to worry that the changes already underway as a result of global warming could accelerate and turn out to be just as fast. It’s impossible not to look at that core and see that change from an ice age into a warm world over the course of a season or two, and realise that we could see climate change not in some distant future, but in our lifetime. And that’s made the debate much, much more urgent.
What strikes me here is the significance of past events depicted in the ice cores: the Earth had previously experienced a true Ice Age during the Pleistocene epoch, which began around 1.8 million years ago and lasted until about 11,500 years ago. During this time, repeated glaciation periods came and went in varying degrees as the planet warmed and cooled. Then came the Younger Dryas, a period lasting about 1,000 years when the planet was generally colder and dryer again. At the end of this period, the temperature at the Arctic rose very rapidly — by as much as five degrees — and the planet as a whole then began entering a warmer (interglacial) period. But the amount of snowfall in the northern hemisphere also suddenly became much heavier at this time — over the course of just one year.
This can be interpreted as a scenario where the sudden rise in temperature across the Arctic region caused huge reserves of methane — locked up on the seabed since before the Pleistocene epoch, at least two million years previously — to escape, adding to the greenhouse effect. This, in turn, would have forced temperatures to rise even more sharply, releasing even more methane, in a loop feedback effect. At a certain point the temperature, oceanic and atmospheric conditions could have converged to trigger a Superstorm — during which, in just one season, the northern hemisphere became covered once again in deep snow and ice that persisted for many years. As colder temperatures took hold once more, regions of permafrost re-formed, locking up the methane again until another sufficiently warm period arrived that melted the permafrost — i.e. what the scientists are now observing in Siberian waters.
It’s worth repeating here what Whitley Strieber and Art Bell wrote in their book:
By definition, a superstorm would involve an entire hemisphere. Its winds would reach extreme velocities, possibly in excess of two hundred miles an hour.
The storm would be triggered by a sudden increase in Arctic temperatures at the surface — exactly the kind of warm snap that could occur at any time during the global warming scenario presently unfolding — combined with extreme cold aloft. This warm flow of air would heat an ocean surface already affected by a loss of salinity due to polar melt and runoff from Greenland. The lack of salt in the water would cause it to take on heat quickly. At that point, the flow of the North Atlantic current would suddenly change, dropping south.
When this happened, the ultracold air trapped above the arctic by the warm airflow would slide southward, with a violent outcome.
The storm would last until the ocean cooled enough for the flow of the current to be reestablished. Before that happened, there would be a massive blizzard or series of blizzards that would dump billions of tons of snow across a fifth of the earth’s surface. When the sun finally did return, the huge increase in the earth’s albedo, or reflectivity, caused by the snow, would cause a dramatic drop in temperature. Whether the ice would melt or persist across the next summer would depend on its depth. If it persisted, a cooling trend of some duration would result. There would even be a possibility that a new ice age would begin …
The evidence that long-term changes in climate do take place is irrefutable. The ice keeps coming back, and we aren’t sure why. But something acts as the trigger, and we know that this event is a sudden one.
– The Coming Global Superstorm, Whitley Strieber & Art Bell, Pocket Books, 2000, pp/102-103
(Repeated from my post Climate Change: Competing Theories)
What came first, though, at the end of the Younger Dryas — the temperature rise, or the methane release? Surely, if the planet was cool enough to keep the methane safely locked up until that point, then methane release cannot have been responsible for the temperature increase. But there could have been many other factors simultaneously at work, such as the long-term cyclic variability in solar output and the effect of cosmic rays on cloud cover; the variability in strength or even the temporary cessation of the Atlantic Gulf Stream; the emission of gases into the atmosphere from super-volcanoes; and other epic, relatively one-off events such as significant meteorite impacts which may have triggered seismic eruptions that affected entire continents and released deadly gases from deep within the Earth.
It has to be admitted that the picture’s far from complete. Today we know that the average global temperature is exhibiting a rising trend, even though we still can’t fully account for the reasons behind it. And the evidence of those ice cores cannot be ignored: no matter what triggered the Younger Dryas temperature rise, it shows that it is possible for the northern hemisphere to be subjected to a catastrophic cooling event within a geological blink of an eye — that is to say, over the course of just one year — as part of a general global warming trend. Searching for evidence to support that conjecture has been at the heart of my research during the past year or so.
I hate to say it, but I fear I may be edging closer to the answer.
Read my Climate Change posts in chronological order by using the Climate Change Log.
