The Arctic Is Leaking Methane 303
registerShift and other readers sent in news that the Arctic Ocean seabed is leaking methane. "...climate experts familiar with the new research reported in Friday's issue of the journal Science that even though it does not suggest imminent climate catastrophe, it is important because of methane's role as a greenhouse gas. Although carbon dioxide is far more abundant and persistent in the atmosphere, ton for ton atmospheric methane traps at least 25 times as much heat. ... [One scientist] estimated that annual methane emissions from the East Siberian Arctic Shelf total about seven teragrams. (A teragram is 1.1 million tons.) By some estimates, global methane emissions total about 500 teragrams a year. ...about 40 percent is natural, including the decomposition of organic materials in wetlands and frozen wetlands like permafrost."
1 teragram is not 1.1million tons (Score:2, Informative)
It is 1 Million tonnes.
it is 1 Megaton
it is 10^12 gram
it is 10^9 Kilogram
it is very easy to multiply with 10 in a 10 digit-system, so learn to do it right?
Nothing to see here.... (Score:3, Informative)
Re:1 teragram is not 1.1million tons (Score:4, Informative)
Correction (Score:5, Informative)
Re:Fuel? (Score:3, Informative)
Obviously this comment is too short to be informative as I wrote it quickly. Gah.... I wish Slashdot would grow a bit over this time limitation for posts...
Re:1 teragram is not 1.1million tons (Score:4, Informative)
Having to worry about short tons vs long tons mean that the US system is bizarre.
Re:For clarity (Score:5, Informative)
So this is something like approximate to the largest natural gas tanker in the world releasing it's entire load into the air about 90 times over per year.
Re:A simple question. (Score:5, Informative)
Earth radiates at around 10 micrometers wavelength. As far as I can tell, methane has no absorption bands near there. So, why is it reckoned that methane is a potent greenhouse gas? Curious minds want to know.
Three responses come to mind:
1) Earth radiates across a range of wavelengths, not at a sharp 10 micron peak.
2) Methane is supposed to have 25x the radiative forcing of CO2 per unit mass. A methane molecule has a mass 16/44 that of carbon dioxide, so a kg of methane produces almost 3x the molecules produced by a kg of carbon dioxide.
3) A particular absorption peak or the peak emission wavelength doesn't matter. The important thing is the power change caused by the integral over all wavelengths of absorption multiplied by emission energy at each wavelength. Here that is for methane. [wikipedia.org]
Re:For clarity (Score:2, Informative)
The EPA estimates: "Globally, ruminant livestock produce about 80 million metric tons of methane annually"
That's an order of magnitude more than the estimated amount of methane leaking from the Arctic.
Re:For clarity (Score:3, Informative)
Even in situations where it is in fact carbon neutral(atmospheric co2 -> plant -> cow -> atmospheric methane) you are turning a less potent, in greenhouse terms, flavor of carbon into a more potent one.
Second, in much of modern agriculture, there is substantial input of fertilizers and pesticides and things, many of which are petrochemically derived. In these cases, you get all the disadvantages of the carbon neutral case, plus some fossil carbon coming back out to play.
Re:Let It Burn! (Score:5, Informative)
Methane has a large effect for a brief period (a net lifetime of 8.4 years in the atmosphere)
Methane is a relatively potent greenhouse gas with a high 'global warming potential' of 72 (averaged over 20 years) or 25 (averaged over 100 years).
Global Warming Potential [wikipedia.org] is a relative scale which compares the gas in question to that of the same mass of carbon dioxide (whose GWP is by convention equal to 1).
So methane is 70 times worse then CO2 over 20 years and 25 times worse over 100 years. Not exactly insignificant...
Re:Suicidal? (Score:3, Informative)
Global warming is disastrous to cities only, and changing for many regions, some for better some for worse. It is not suicidal for the Nature, just opposite, it may grant it some relief from the human problem...
Re:Fuel? (Score:3, Informative)
For what it is worth, milk is more than 90% water, which weighs in at about 9 pounds per gallon. The rest of milk is mostly fats and proteins, which are not drastically different in density than water.
A little [hypertextbook.com] searching [illinois.edu] around [csgnetwork.com] yields the density of milk to be around 1.02-1.06 g/cc (or kg/L). This translates to, you guessed it, about 9 pounds per gallon.
Also, any farmer could tell you that a hundredweight of milk (a touch over 100 pounds - go figure) is about 12 gallons.
So there's a factor of two (or one half) to muddle into your calculations.