David Archer of the University of Chicago has written a series of papers dealing with MMH and anthropogenic climate change. Part of the following includes some of his writings.
The worst mass extinction in history, killing off 95% of all marine species and 70% of terrestrial life, occurred 251 million years ago, according to Gregory Ryskin of Northwestern University. Methane from bacterial decay or from frozen methane hydrates, stimulated by a meteorite impact, earthquake or volcano, could have triggered a catastrophic eruption of methane gas. Ryskin calculated that the energy liberated could have been 10,000 times greater than the world’s entire nuclear weapons stockpile. He did say he had no proof and it was just his hypothesis. More recent evidence shows that an asteroid crashing off Australia might have triggered the event.
In January 2005, two teams of scientists, from Curtin University of Technology in Perth, Australia, and the University of Washington, reported that the “Great Dying,” 250 million years ago, was caused by volcanic eruptions, which caused atmospheric changes. Plus, this all took place over as much as 10 million years. While the volcanic gas was mostly carbon dioxide, there was also speculation that large stores of methane gas frozen on the ocean floor might have been released to trigger runaway greenhouse warming. Clearly, something happened a quarter billion years ago.
In 2000, Nature reported on “Methane Linked to Mass Extinctions,” when a violent explosion of methane gas from the ocean floor 183 million years ago killed off 80% of some deep-sea species. The article expressed particular concern about drilling for marine methane and the harm that would cause.
The Science Daily reported on December 12, 2001, “Methane Explosion Warmed the Prehistoric Earth, Possible Again.” There was another abrupt warming 55 million years ago, caused by the sudden release from the ocean of frozen deposits of methane. “The massive perturbation to global climate and the carbon cycle during the Paleocene/Eocene Thermal Maximum may have been forced by a catastrophic release of methane gas from hydrate deposits on the continental slope,” said Gavin Schmidt and Drew Shindell of the Goddard Institute for Space Studies. Movement of continental plates may have initiated the release. Ocean temperatures soared by up to 13 degrees Fahrenheit (7 °C), within 1,000 years, by some estimates, but lasting 100,000 years. More than half of deep sea species died. However, it was also reported that primates (apes) suddenly appeared.
There was a puzzling period only 3 to 4 million years ago when carbon dioxide and methane were in the atmosphere at about the same concentration as today, but the temperature was 3 °C (5.4 °F) hotter and sea level 25 meters (82 feet) higher. There was something about the El Nino and the ocean that triggered the warming.
Around 8,000 years ago, the Storegga submarine landslide occurred on the Norwegian continental margin, caused, most probably, by methane hydrate destabilization. While global warming was not a consequence, this landslide did cause a tsunami (sea wave), and is a link to the next chapter on “Six Hours to Seattle.”
To recap, a carbon dioxide atmospheric composition of 380 parts per million and methane of 1.8 parts per million means that there are about 200 times more CO2 than CH4 in the air. However, CH4 is 20 times more dangerous than CO2, so, the effectiveness factor with respect to global warming of CO2 is about 10 times greater. However, Drew Shindell believes that methane is underestimated in the above comparison because it is a reactive gas, unlike carbon dioxide, and, instead of accounting for one-sixth of the total effect of well-mixed greenhouse gases on warming, should be one-third, or twice that currently utilized in climate change models. Shindell’s colleague at GISS, Gavin Schmidt, has said that, under inflated concentration conditions, the methane can linger for hundreds of years, much longer than the decade normally expected.
In a parallel paper regarding methane from wetlands, Shindell says it another way: “Methane increases have contributed about 0.7W/m2 to global radiative forcing since preindustrial times (0.5 W/ W/m2 directly, plus an additional 0.2 Wm2 indirectly via tropospheric ozone and stratospheric water vapor), roughly one-half the forcing from CO2.” Clearly, methane is important.
The literature reports that the oceans release only 10 tons of methane per year. Termites produce 40 tons/year, cattle 60 tons/yr, rice paddies 70 tons/yr and wetlands 115 tons/yr. But no one really knows how much methane is coming from the seas.
This has been one of my primary points of focus over the past few years. Why, if this gas is so potentially dangerous, is so very little being done about knowing more. The two Hawaii workshops chaired by James Hansen in 2003 and 2005 provided opportunities to ask questions, leading to some of the interchanges previously mentioned. I also asked these experts if it was possible that marine methane was entering the atmosphere at a dangerous rate. The general consensus was no, so it’s not a fundable area.
So I did a bit more checking:
o “Abnormally high levels of methane gas in seafloor sediments could pose a major hazard to coastal populations within the next 100 years through their impact on climate change and sea level rise.”
o “..significant amounts of seabed CH4 are leaking into the atmosphere, enough to contribute to global warming sea level rise.
o Much of the concern, though, seems to be focused on methane in shallow and grassy beds near the coastline.
I further asked the workshop attendees, how to best measure marine methane leaking into the atmosphere. The general consensus was that no one was doing much. Upon further investigation, though:
o Acoustic survey methods can be used to detect seabed gas and that gas rising in the water column, but most of the current effort is on shallow seabed methane.
o Other methods include cameras, geochemical probe and sediment coring below sea level, and satellite and airborne laser fluorescence for the ocean to atmosphere interface.
It is this latter technique that I am pursuing as a possible high school science fair project for some curious student. Cal Poly in San Luis Obispo and Stanford University spearhead a CubeSat competition to send packages into space. I can envision a high school student designing such a system, then, advancing into a college project, refining the electronics for not only testing on a satellite, but determining that the marine methane escape rate acceleration could well be serious. In parallel, I do chide campus scientists about conducting this research, but at my advanced age, I’m looking for simple solutions, not a long, drawn out, decade-long fundamental unearthing of the situation.
Then there is the clathrate gun hypothesis, which supposes that the primary cause of the rapid historical increases of methane in the atmosphere came from an explosive release of deeper ocean marine methane hydrates, not the more generally accepted wetlands. An interesting point is that, while one would expect this release to occur at the end of a glaciation period when the sea level drops, thus lowering the hydrostatic head over the deposit, indicated is that a 100 meter drop is equivalent to only a 1°C temperature rise, so, temperature can have a more important role in setting off a massive release.
Finally, are trees good or bad? The Kyoto Protocol endorsed reforestation, where now, in Europe and, even, Chicago, carbon credits can be bought and sold for growing more trees. However, a team from Germany, the Netherlands and Northern Ireland reported in Nature in 2006 that ordinary plants produce significant amounts of methane, both in the growth cycle and the decay process. The latter was previously known, but trees being a contributor to global warming just by growing, thus contributing up to 30% of all the methane generated? That was a bombshell! So much so that the Max Planck Society floated a press release attributed to the researchers responsible for the paper within a week of publication with the title, “Global Warming – The Blame Is not with the Plants,” a somewhat weak declaration stressing that global change is real, trees have been around for a long time and have for eternity been aiding and adding to the problem, but mostly helping. Plus their findings were very preliminary, where, at worst, all these negatives will only reduce carbon uptake of reforestation by 4%. Thus, planting trees was still good. There were, however, three notes complementing the Science article:
o From the Editor: Regarding natural gas plants, this additional source of methane could account for 10-30% of the annual methane source strength and has been overlooked in previous studies.
o David Lowe: The results are startling because methane is being emitted under normal physiological conditions and that these emissions are large.
o Quirin Schiermeier: Climate researchers are amazed that they missed what is a huge methane source.
There was some follow-up corroboration from Michael Keller of the U.S. Department of Agriculture’s Forest Service, who said that while their study has not yet been published, this paper provided a plausible solution to methane measurements they made in the Brazilian Amazon. Clearly, we have not yet seen the end of this surprise.
So, anyway, what is the great danger about methane? If global warming occurs, the methane associated with frozen tundra will begin to enter the atmosphere at higher levels. Sergei Kirpotin of Russia and Judith Marquand of the U.K. described in 2005 the melting of the permafrost of western Siberia, about the size of France and Germany combined, releasing billions of tons of methane. During the past 40 years, this area has warmed 3°C (5.4°F), faster than virtually anywhere else.
For thousands of millennia, marine methane hydrates have been accumulating at the sea bottom. As the oceans warm, the dynamic equilibrium will shift to increase the escape of methane. The greatest danger, though, is the highly speculative probability that an undersea volcanic eruption or earthquake might trigger a sudden cataclysmic release, causing a mass extinction. After all, the last time this happened with any major consequence was 55 million years ago, so this is not anything worthy of particular worry. There is nothing we can do about this anyway. Well, let me take that back. We can delay the onset by preventing global climate warming.
The worrisome point of all this is attitudinal. Methane is not considered to be a particularly serious threat. The Kyoto Protocol doesn’t much mention the gas. Thus, viewpoints need to be adjusted. There has yet to be a major international gathering to review the importance of methane to global climate change. We are discussing with Hansen’s researchers the prospects of holding a workshop in Hawaii. By the time you read this, hopefully we will have learned a lot more. By then, or soon thereafter, look for The Venus Syndrome--the novel.