Never mind that in 2006 it was reported that levels of the second most important greenhouse gas, methane, have stabilized.
Scientists are now working to create a new “tootless” grass for bovine enjoyment which will help cut methane emissions from the bovine tailpipes. What next? A moratorium on baked beans at BBQs? Editing out that scene from Blazing Saddles so that school kids don’t get bad ideas that might harm the earth?
According to the Scientific American article: “During the two decades of measurements, methane underwent double-digit growth as a constituent of our atmosphere, rising from 1,520 parts per billion by volume (ppbv) in 1978 to 1,767 ppbv in 1998. But the most recent measurements have revealed that methane levels are barely rising anymore — and it is unclear why.”
From NewScientist: “Although this is good news, it does not mean that methane levels will not rise again, and that carbon dioxide remains the 800-pound gorilla of climate change.”
Indeed, methane has made a small uptick in the last year.
Actually, NewScientist is wrong. CO2 is not the biggest “gorilla” of greenhouse gas on planet earth. It’s water vapor. Our earth would be much colder without water vapor in the atmosphere…it would be much like Mars. I seem to recall seeing a figure for average global temperature of about -14°F with water vapor absent.
So many of the climate models focus solely on CO2, but they leave out water vapor as clouds in the equations, or assume water vapor is static.
CO2 is far from being the most potent greenhouse gas. Chloroflourocarbons (CFC’s) commonly used as refrigerants as far worse at trapping infra-red in our
atmosphere.
Of naturally created GHG’s, Methane is 23 times more effective at warming the atmosphere than CO2. Nitrous Oxide is even worse at 296. So far no emergency legislation has been authored to eliminate the effect of cows or dental surgeons. The Kyoto treaty does not address these other gases either.
Here is a gauge of various gases and their “GWP”:
Global Warming Potentials Of Gases
(100 Year Time Horizon)
GAS GWP
========================
Carbon dioxide (CO2) 1
Methane (CH4) 23
Nitrous oxide (N2O) 296
Hydrofluorocarbons
HFC-23 12,000
HFC-125 3,400
HFC-134a 1,300
HFC-143a 4,300
HFC-152a 120
HFC-227ea 3,500
HFC-43-10mee 1,500
Fully Fluorinated Gases
SF6 22,200
CF4 5,700
C2F6 11,900
C4F10 8,600
C6F14 9,000
The concept of the global warming potential (GWP) was developed to compare the ability of each greenhouse gas to trap heat in the atmosphere relative to another gas. In this case, CO2 is the reference gas. Methane, for example, has a GWP of 23 over a 100-year period. This means that on a kilogram for kilogram basis, methane is 23 times more potent than CO2 over a 100-year period.
The interesting thing here is that this stabilization of methane levels in our atmosphere happened all by itself, and the scientists are clearly baffled as to an explanation. But that doesn’t seem to phase anyone promoting research to prevent cow tooting.
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OK, so anthropogenic sourced increases in atmospheric H2O are coming from dams and fossil burning; and if the current Spencer (and others) thesis is that atmospheric H2O is a negative feedback then increases in H2O are a cooling forcer.
But if CO2 does have a heating effect is that effect limited by such negative feedbacks or something inherent in the CO2 heat ‘trapping’ process. The Kauffman paper shows the spectographic sensitivity of CO2 to be at 15 and about 10 microns. Richard Petschauer in this paper shows the same thing;
http://www.junkscience.com/jan08/Global_Warming_Not_From_CO2_20080124.pdf
So the effect of CO2 is dwarfed by H2O and cutailed by the H2O negative feedback, but presumably the CO2 heating potential will persist if CO2 levels are maintained or increased. The Stefan-Boltzmann emmissions roughly double from 0F to 100F and the Wien peak energy wavelength moves about plus or minus 10% during that range which occurs diurnally and regionally. Given that the CO2 sensitivity is so concentrated it appears that the SB/Wien combo can put a brake on CO2 heating regardless of the difference between the rate of IR excitment and the much quicker rate of collisional deexcitment because the wavelength shift will prevent, or drastically reduce, IR excitment; in fact if IR excitment is mitigated, the quicker rate of collisional deexcitment will act as an additional cooler with the CO2 molecules losing or transfering their heat and not recapturing more.
“cohenite (18:11:16) :
OK, so anthropogenic sourced increases in atmospheric H2O are coming from dams and fossil burning;”
I apologize for not having hard data, but I suspect that agricultural irrigation needs to be added to the list. Anyone who has flown across the Great Plains and appreciates a good window seat has seen hundreds or thousand of the circular “center pivot irrigation systems” that have a well in the origin and a half-mile long radial arm with sprinkler heads. They cover a huge area and must release vastly more water vapor than dam pools do. Much like burning fossil fuel, they tap “fossil water” and put it back into the hydrologic cycle. Hmm, I wonder how much influence they have on ocean levels.
I finally got close to one, well, the end of the arm, at least, on a bicycle tour through Oregon, Idaho, and Montana in 2003.
http://www.ccrs.nrcan.gc.ca/resource/tour/38/38scene3_e.php
As long as I have the floor:
2003 was hot – a couple days before the heat broke (and the forest fires took over) I bought a thermometer and recorded 106F in the shade under my handlebar bag, but above hot pavement. See http://wermenh.com/biketour/idaho.html et al. Nightfall in that area doesn’t help much – canyon walls are volcanic rock that soak up heat during the day to bake bicyclists at night.
If you want to see serious desert cooling, the area around Flagstaff Arizona is good. Flat ground, porous soil, few plants, thin dry air. When the sun goes down the ground just can’t offset the radiational cooling. Here in New England, radiation cooling is usually limited by dew or frost. Especially on humid summer nights, dew forms and releases the latent heat in water vapor and what was a nice exponential curve flattens out.
Sorry, but the amount of CO2 we’re putting into the atmosphere is small, the amount of H2O we’re putting in has got to be infinitesimal next to the amount already in the atmosphere at any given time. And in most cases we’re just moving water around, not adding new water which has been “locked away” for millions of years (as if that makes a difference). This whole discussion is silly.
Since water vapor is a highly significant contributor to global temperature, I am wondering about the amount of added water vapor due to jet aircraft travel. Everyone knows that the number and size of jet aircraft in the air has increased substantially over the last three or four decades. They do burn a significant amount of fuel, but does anyone know of actual studies that put their contribution in perspective? Comments?
cohenite: I too have wondered about irrigation adding H2O to the atmosphere,
esp. those center pivots. I suspect most irrigation is from wells, and thus contradictory to Jeff Alberts assertion. Just the depletion of the Ogallala aquifer must be a big deal. With a total weight of the atmosphere at 5.7 X 10^16 tons (CRC Handbook) and an estimated 3.36 X 10^17 tons of water we have pumped from this aquifer alone in 50 years, 1955-2005, and a standard 1% (can’t find the source for this) concentration of H2O in the atmosphere, this seems like it could have an impact especially when considered globally.
I’m sure some of the water evaporated, only to fall as rain all over again and drain down to the same or other aquifers. But compared to the amount of evaporation from the oceans, it’s less than a drop in the bucket.
I came across this blog post yesterday. Okay, it was on a site called “Tree Hugger”, but but it was very interesting. They were reporting on a recent study by the Food and Agriculture Association of the United Nations, FAO (links are provided in the article). And basically, the contention of the study is that with proper land management many semi-arid locations could not only support significantly more livestock, but do so in a way that would mitigate runoff and promote carbon sequestration. Not only that, they also make the point that cow poop (actually, ruminant poop in general) is an essential part of the whole cycle. In other words, it’s a win/win situation all the way around. Eat meat, be sustainable, teach others to be more sustainable, and get that warm fuzzy feeling I hear you get when you think you’re saving the earth from certain catastrophe. Except this is much more than just a feeling — assuming they’re right.
It was a pretty interesting read. And if you don’t have time to read the entire study, do check out the slide presentation (it’s available in both powerpoint and pdf formats).
[…] this story on the puzzling leveling off of global methane concentrations. FYI Methane has a “global warming potential” (GWP) 23-25 times that of […]