Yesterday we learned that the great Pacific Garbage Patch really isn’t as big as hyped by media, today we learn that the “atmosphere’s ability to rid itself of many pollutants is generally well buffered or stable”. Huh. Imagine that, the planet isn’t broken as easily as some imagine.
From a NOAA press release:
NOAA-led Research Team Takes Measure of the Variability of the Atmosphere’s Self-Cleaning Capacity
An international, NOAA-led research team took a significant step forward in understanding the atmosphere’s ability to cleanse itself of air pollutants and some other gases, except carbon dioxide. The issue has been controversial for many years, with some studies suggesting the self-cleaning power of the atmosphere is fragile and sensitive to environmental changes, while others suggest greater stability. And what researchers are finding is that the atmosphere’s self-cleaning capacity is rather stable.
New analysis published online today in the journal Science shows that global levels of the hydroxyl radical, a critical player in atmospheric chemistry, do not vary much from year to year. Levels of hydroxyl, which help clear the atmosphere of many hazardous air pollutants and some important greenhouse gases — but not carbon dioxide — dip and rise by only a few percent every year; not by up to 25 percent, as was once estimated.
“The new hydroxyl measurements give researchers a broad view of the ‘oxidizing’ or self-cleaning capacity of the atmosphere,” said Stephen Montzka, the study’s lead author and a research chemist at the Global Monitoring Division of NOAA’s Boulder, Colo., laboratory.
“Now we know that the atmosphere’s ability to rid itself of many pollutants is generally well buffered or stable,” said Montzka. “This fundamental property of the atmosphere was one we hadn’t been able to confirm before.”
The new finding adds confidence to projections of future air pollutant loads. The hydroxyl radical, comprised of one oxygen atom and one hydrogen atom, is formed and broken down so quickly in the atmosphere that it has been extremely difficult to measure on global scales.
“In the daytime, hydroxyl’s lifetime is about one second and is present at exceedingly low concentrations,” said Montzka. “Once created, it doesn’t take long to find something to react with.”
The radical is central to the chemistry of the atmosphere. It is involved in the formation and breakdown of surface-level ozone, a lung- and crop-damaging pollutant. It also reacts with and destroys the powerful greenhouse gas methane and air pollutants including hydrocarbons, carbon monoxide and sulfur dioxide. However, hydroxyl radicals do not remove carbon dioxide, nitrous oxide or chlorofluorocarbons.
To estimate variability in global hydroxyl levels — and thus the cleansing capacity of the atmosphere — researchers turned to studying longer-lived chemicals that react with hydroxyl.
The industrial chemical methyl chloroform, for example, is destroyed in the atmosphere primarily by hydroxyl radicals. By comparing levels of methyl chloroform emitted into the atmosphere with levels measured in the atmosphere, researchers can estimate the concentration of hydroxyl and how it varies from year to year.
This technique produced estimates of hydroxyl that swung wildly in the 1980s and 1990s. Researchers struggled to understand whether the ups and downs were due to errors in emissions estimates for methyl chloroform, for example, or to real swings in hydroxyl levels. The swings would be of concern: Large fluctuations in hydroxyl radicals would mean the atmosphere’s self-cleaning ability was very sensitive to human-caused or natural changes in the atmosphere.
To complicate matters, when scientists tried to measure the concentration of hydroxyl radical levels compared to other gases, such as methane, they were seeing only small variations from year to year. The same small fluctuation was occurring when scientists ran the standard global chemistry models.
An international agreement helped resolve the issue. In response to the Montreal Protocol – the international agreement to phase out chemicals that are destroying the Earth’s protective stratospheric ozone layer – production of methyl chloroform all but stopped in the mid 1990s. As a result, emissions of this potent ozone-depleting gas dropped precipitously.
Without the confounding effect of any appreciable methyl chloroform emissions, a more precise picture of hydroxyl variability emerged based on the observed decay of remaining methyl chloroform. The scientists studied hydroxyl radicals both by making measurements of methyl chloroform from NOAA’s international cooperative air sampling program and also by modeling results with state-of-the-art models.
The group’s findings improve confidence in projecting the future of Earth’s atmosphere.
“Say we wanted to know how much we’d need to reduce human-derived emissions of methane to cut its climate influence by half,” Montzka said. “That would require an understanding of hydroxyl and its variability. Since the new results suggest that large hydroxyl radical changes are unlikely, such projections become more reliable.”
Co-authors of the new paper, “Small Inter-Annual Variability of Global Atmospheric Hydroxyl,” include Maarten Krol (University of Utrecht and Wageningen University in the Netherlands); Ed Dlugokencky and Bradley Hall (NOAA Earth System Research Laboratory); Patrick Jöckel (Max-Planck-Institute for Chemistry in Mainz, Germany, and the Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany); and Jos Lelieveld (Max-Planck and the Cyprus Institute in Nicosia, Cyprus).
NOAA’s mission is to understand and predict changes in the Earth’s environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources.
OT but couldn’t put it in H&T as no box:
http://newmexicoindependent.com/68492/martinez-axes-all-environmental-improvement-board-members#
‘On her first day in office, Martinez had halted “all proposed and pending regulations,” which includes the cap-and-trade regulation’
Anthony harumphs
————
Huh. Imagine that, the planet isn’t broken as easily as some imagine
———–
identifying a potential problem and collecting evidence and finding that it’s not really a problem seems like good news to me.
Evidence beats gut feelings every time in my book. The real world I live in pays no attention to my gut feelings and mother nature has had many a surprise waiting for me.
Wonderful. It may not be the end, it may not even be the beginning of the end, but it surely is the end of the beginning!
“the atmosphere’s ability to cleanse itself of air pollutants …. except carbon dioxide.” Well whoda thunk? Bonkers Branson to the rescue?
http://news.nationalgeographic.com/news/2007/02/070216-virgin-earth.html
Whida thunk it indeed. Nature herself tells us clearly
whats what
quote
“the atmosphere’s ability to cleanse itself of air pollutants …. except carbon dioxide.”
Ergo co2 is not a pollutant or else it would get cleared.
QED as they say
They need to look at negative Ions and ozone as well. All part of natures armory against pollution.
People should not be surprised to find that Mother nature packs a big punch and that humans are puny. It’s nice to know that the atmosphere is resilient in this paper, but not unexpected.
Slightly off theme, but to demonstarte the power of nature, here is a clip from the Baralaba coal mine, that got too close to the flooded Dawson River in Queensland a few days ago. Baralaba open-cut mine: Mining operations commenced in July 2005. Planned production from the site is 0.5 Mtpa of metallurgical pulverised coal injection coal (PCI) and thermal coal. So the trucks you see in the video clip (thanks to Kim Wright) are not toys.
http://www.geoffstuff.com/Dawson%20River.wmv
Good cheerful stuff, Anthony.
Another bogeyman bites the dust! The carefully-knitted alarmism promoted by some so-called scientists is rapidly coming unravelled – the president of the UK’s Royal Society Dr Rees’s widely-promoted theories that the world is heading rapidly toward the end is similarly coming unravelled. Why cannot educated people be generally cheerful and constructive, instead of wishing for the apocalypse to begin now, or by next week at the latest?
Are they saying that plants don’t take up carbon dioxide? Good to see they didn’t refer to it as a pollutant. Maybe they are getting the message.
http://wattsupwiththat.com/2011/01/06/co2-is-plant-food-clean-coal-say-watt/
Here’s one more thing that is “better than we thought”
And another:
Good news. Earth seems to have a controlling mechanism for just about everything except people’s wild imagination and fear. CO2 is not a pollutant. It is plant food and it is being cleared from the atmosphere by the Earth’s flora in copious amounts. Fortunately, it is also being replaced. We need higher levels of CO2 to grow more food-per-acre to support the Earth’s increasing fauna. That has been happening for several decades. A little warmer has not hurt either. Where is the problem? It is all a matter of perspective
“Say we wanted to know how much we’d need to reduce human-derived emissions of methane to cut its climate influence by half,” Montzka said. “That would require an understanding of hydroxyl and its variability. Since the new results suggest that large hydroxyl radical changes are unlikely, such projections become more reliable.”
And the projection would be that we don’t need to worry about human derived emissions of methane because the level of hydroxyl isn’t changing much.
The farmers are going to be happy about this….
No more “Beano” has to be put in the cow’s food.
Vy 73
“in understanding the atmosphere’s ability to cleanse itself of air pollutants and some other gases, except carbon dioxide.”
========================================================
Don’t put this in the first paragraph, and expect me to waste my time reading it…………..
Even the NOAA thinks we’re stupid
Note that they repeated three times that this doesn’t’ include CO2? Protecting their funding I would guess.
The planet atmosphere is self regulating except for CO2. Remember how global warming advocates use to compare the earth to Venus where a runaway green house gas would irreversibly turn our planet into the hot acidic hell of Venus. Had they ever documented a time when Venus was like earth it might have made some sense. And of course there would have had to be people there causing the damage.
Stories of CO2 causing global warming should only be told for trick or treat on Halloween night.
And what becomes of the Methane after it reacts with those hydroxyl ions?
“The atmosphere, and more precisely the troposphere, is the largest sink for methane. Methane in the troposphere reacts with hydroxyl (OH) radicals, forming mainly water and CARBON DIOXIDE.” -caps emphasis mine-
http://www.ghgonline.org/methanesinkatmos.htm
Did not see that mentioned in the posted article.
Is it a significant contribution to CO2 generation? Don’t have any numbers on that aspect of generation, but we are told that CO2 is a less potent GHG than Methane. Room for ‘spin’ either way on this.
They should’ve said:
“……in understanding the atmosphere’s ability to cleanse itself of air pollutants and some other gases, except carbon dioxide, oxygen, nitrogen, etc……”
What are the “some other gases” that are not pollutants that are being “cleansed” from the atmosphere?
Without this ability to “cleanse itself” we’d be choking to death on volcano exhaust.
So we don’t need to worry about methane. That must come as a relief to all those alarmists being alarmed over runaway methane feedbacks.
I remember my grade school textbooks showing a family walking their dog all wearing Cold War gas masks (Including the dog) as a harbinger of our future.
It was presented as fact that Smog would be that bad in my lifetime. They also told us that oil would be gone by 1983 as fact not to mention Global cooling later.
Our schools are a fertile plain of propoganda.
Before the current CAGW hysteria, it was thought that the earth also has a self regulating balance of CO2 in the atmosphere. As long as the earth;s crust is tectonically active, CO2 will be released in the atmosphere, warming up the atmosphere. With a warmer atmosphere we get more rain, washing excess CO2 out of the atmosphere, where it is incorporated into seashells, etc, and ultimately swallowed up and subducted in the earth’s crust. With less CO2 in the atmosphere, the earth cools off, there’s less rain, CO2 builds up from tectonic activity and the cycle starts all over again. I picked this up from a ” Scientific American” article written before the magazine went nuts and started confusing liberal propaganda with science.
http://www.geosc.psu.edu/~jfk4/PersonalPage/Pdf/Scientific_American_88.pdf
Years ago when CO2 wasn’t a pollutant and we where researching acid rain, we learned that “clean rain” is slightly acid because atmospheric water (clouds and vapor) reacts with CO2 to form carbonic acid. The resulting pH (around 5) was dependent on the atmospheric concentration of CO2 and it is reasonable to expect the atmospheric concentration to be dependent on the amount of water there is in the atmosphere. The absorbtion of CO2 in clouds and rain is the primary mechanism for it’s removal from the atmosphere. This water/CO2 interaction results in a very globally uniform CO2 concentration.
After 4.6 billion years of the Earth in existence, it has only grown more beautiful and more stable. The number of violent volcanic eruptions (and certain GHGs emission) and earthquakes that we experience now must be very minor compared to several hundred million years ago. CO2 deposited under fossil fuels should be too small compared to CO2 emission on those periods.
Wouldn’t this kind of throw yet another monkey wrench in the AGW climate models given the lack of sensitivity this shows in the other GHG forcers?
Does this mean the proposal coming out next week will be to load the mosquito control DC-10’s with 50% NaOH and start fogging over and downwind of the petrochemical plants?
So OH cleans a lot of stuff from the atmosphere, but not CO2. We need a chemist to explain why CHO3, hydrogen carbonate, does not form.
Of little or no interest to UK branches of government where CO2 is the sole concern of Departments and Quasi Non Government Organisations alike, each vying with another to demonstrate it’s pernicious effect in that part of everyday life over which they exercise their petty controls.
http://www.direct.gov.uk/prod_consum_dg/groups/dg_digitalassets/@dg/@en/@motor/documents/digitalasset/dg_171010.pdf
My grandson was handed this leaflet on completion of an otherwise faultless driving test, but which attracted a fail for changing down a gear too early on the approach to a roundabout.
This was deemed to have caused excess emission of CO2 to the detriment of the planet!
You think I am joking? I wish that I were!
Might be a fairly simple opportunity to clean some GHG’s from the air at the source. Just extend the exhaust portions of the process and introduce hydroxyl (if we could easily and inexpensively manufacture the gas) at various points in the exhaust process to clear methane and some others prior to their entering the atmosphere
“their funding I would guess.
<blockquote cite+"Olen says:
January 7, 2011 at 5:48 am
The planet atmosphere is self regulating except for CO2. Remember how global warming advocates use to compare the earth to Venus where a runaway green house gas would irreversibly turn our planet into the hot acidic hell of Venus. Had they ever documented a time when Venus was like earth it might have made some sense. And of course there would have had to be people there causing the damage.
Stories of CO2 causing global warming should only be told for trick or treat on Halloween night.”
Don’t forget about the natural sources of CO2 namely Volcanism
with over 1600 major volcanos, extreme levels of CO2 would have been a natural side effect
http://volcano.oregonstate.edu/oldroot/volcanoes/planet_volcano/venus/intro.html
“However, hydroxyl radicals do not remove carbon dioxide”
Grrrrr. Nothing grinds my gears more than the constant perpetuation of the myth that CO2 is a pollutant. An entire generation of young people has gone through an educational system that taught (brainwashed?) this nonsense.
Remarkable how little we really know.
Please review this study just released:
“Gulf Oil Spill: Methane Gas Concentrations in Gulf of Mexico Quickly Returned to Near-Normal Levels, Surprising Researchers” http://www.sciencedaily.com/releases/2011/01/110106145436.htm
Kessler added: “Based on our measurements from earlier in the summer and previous other measurements of methane respiration rates around the world, it appeared that (Deepwater Horizon) methane would be present in the Gulf for years to come. Instead, the methane respiration rates increased to levels higher than have ever been recorded, ultimately consuming it and prohibiting its release to the atmosphere.”
also from the study:
“What the Deepwater Horizon incident has taught us is that releases of methane with similar characteristics will not have the capacity to influence climate.”
Perhaps the earth knows how to deal with types of problems without mankind.
“except carbon dioxide”
Bullshizzle!
These people evidently don’t keep up very well with what the different climate models are spitting out. In this the model is the geochemical coupled climate model GEOCLIM.
Carbon dioxide is removed from the atmosphere by continental weathering. It has been proposed and simulated using GEOCLIM that the breakup of supercontinent Rodinia removed so much CO2 from the atmosphere that it triggered a snowball earth episode.
Ref: Nature 428, 303-306 (18 March 2004)
Dave in Delaware says:
January 7, 2011 at 6:23 am
“Is it a significant contribution to CO2 generation? Don’t have any numbers on that aspect of generation, but we are told that CO2 is a less potent GHG than Methane. Room for ‘spin’ either way on this.”
Depends on how you define “significant”. I went through the numbers last year and found anthropogenic methane accounts for about 18ppm of the CO2 in the atmosphere. Methane has a lifetime of about 5 years IIRC before it is chemically transformed to H2O and CO2. The climate boffins say CO2’s lifetime in the atmosphere is a century or more so bascially all anthropogenic methane emissions (which by the way is growing twice as fast as anthropogenic CO2 emissions) in the past century is now CO2 and it’s ostensibly still there polluting our food crops in such that they produce more food.
Calling CO2 a pollutant in the atmosphere is like calling bread a pollutant in grocery stores. Amazing, innit?
Strange that the average person on the street can look at 500 years of human history and the volcanic eruption of Mt St Helens, among others, and see that the earth seems to take care of itself quite well. The average person also seems to understand that if greenhouse gases worked the way that climate science would have us believe, that the tipping point of destruction would have been reached some 540 million years ago.
We have to remember that many of the instruments that we have including computers are just tools to be used by human beings who can apply some intelligence and common sense to the measurements, not gadgets to be used by tools.
Good to hear because we humans tend to F**K things up royally from time to time.
Now just because mother nature is more resilient than most thought and George Carlin was right, doesn’t mean we should be stupid and try to find the limits.
Hot or cold your future will be a lot more comfy with cost effective insulation in your house. The fact that you save some money and don’t pollute as much leaves you more wiggle room for other “stuff” you want to do.
Good grief, we already use similar processes at coal plants. It’s called an FGD – flue gas desulfurization. You pass the sulfur dioxide containing flue gas through a calcium carbonate slurry spray. The result is either calcium sulfite (inhibited oxidation), calcium sulfate (forced oxidation) (aka gypsum/wallboard), or a combination of the sulfite/sulfate in “natural” oxidation. Does anyone want to take a stab at a byproduct of the reaction?
Ammonia is used to reduce nitrogen dioxide.
“bug farms” at petro plants are also used to reduce pollutants to …. carbon dioxide, water, and non- or reduced-hazardous solid byproducts that the producer has to handle like hot nuclear waste regardless of independent lab analysis results proving otherwise
These processes and similar processes at petrochem plants are why the air is much cleaner than it was in the 60’s.
Yes, I work for a large US electric company.
Our philosophy is that it is much easier, cheaper, and credible to self report rather than run hide and hope you don’t get caught. Funny thing is, this is true for most, journalists just don’t sell newsprint that “ABC refinery wrote the state agency today to inform them that for 15 minutes this afternoon, their river discharge temp exceeded 90 deg F, while that portion of the river was naturally at 88 deg F ABC reduced load to abate their discharge temp within limits and will not be fined.” That just doesn’t sell, if they didn’t have something else to sensationalize they would twist that every which way to demonize the utility or refinery.
Why would they of thought that hydroxl would go up with pollution? They must have not had a good grasp on how it was produced unless they thought the pollution increased the production somehow. Says their models didn’t jive with the theorized increases, so someone had a good sense of the process. Models only do what they are told.
So that means hydroxl levels don’t change much which will allow extra levels of pollution, over the capacity of hydroxl to deal with it, will be around longer. Until the source of pollution is greatly reduced or shut off altogether it’ll just hang around doing what it does. Just like trying to mop a floor with muddy footed kids running round. Until you get the kids out of the way the floor never gets really clean.
So the question is, are we overwhelming the natural cleaning system with the constant introduction of pollution that naturally would not be there? And if so, what effect does that have? This is what they were alluding to at the end of the article. Remember, even in nature, when something happens that overwhelms the system, bad things happen sometimes.
@Dave Springer
Re my comment “we are told that CO2 is a less potent GHG than Methane”
I was referring to Global Warming Potentials (GWPs), where I have seen Methane listed as 21 – 24 GWP, relative to CO2 = 1 GWP. In other words, on a per mole basis, the Methane is about 20 times as ‘potent’ as CO2 while it exists as Methane in the atmosphere. This link lists GWP values for various GHG, which in turn are referenced to IPCC, 2007, Table 2.14.
http://cdiac.ornl.gov/pns/current_ghg.html
Regarding CO2 half life – re your comment “climate boffins say CO2′s lifetime in the atmosphere is a century or more ”
The best numbers that I have seen fall in the 5 to 15 year range for CO2 half-life in the atmosphere. That ‘half life’ tells us that in a well mixed first order system, (which the atmosphere approximates), a step change in CO2 input, either up or down, would reach 95% of the ‘step’ by the 3rd half-life. The atmosphere would not change over night, but you would see 95% of the change toward the new level in 3 half-lives; roughly 15 to 45 years, not hundreds.
TimM,
and if your insulation is contaminated with things worse than methyl chloroform???
Have you checked into the monetary and environmental costs of producing safe insulation?
NOTHING is without cost.
I’m still concerned that we don’t seem to understand current CO2 behaviour. Looking at the Vostok ice core plot, there seems a chance that the current interglacial peaked roughly 10,000 years ago. Around 700/1,000 years after previous peaks, CO2 peaked and then followed temperature down. This time that doesn’t seem to have happened, and CO2 has just gone on rising – starting well before there were enough humans around to have significant anthropogenic effect. Does anyone understand why this might be so? If not, there remains a doubt nagging away … But I’d reasonably happily brush this away, and adopt the moral case for reducing fossil fuel consumption just as swiftly as we can develop alternatives – it can’t be right for three or four generations of mankind to consume all the fossil fuel that was ever laid down?
“However, hydroxyl radicals do not remove carbon dioxide…”
Why is this a problem? Water vapor “neutralizes” the effect of additional CO2 in two different ways, so we do not need hydroxyl radicals to remove CO2. First of all, water vapor absorbs so much of the infrared wavelengths that little is left for CO2 to absorb. Secondly, at least in theory, warmer temperatures cause more clouds to form, and clouds seem to act as a negative feedback. We certainly have not seen run-away global warming.
“Except carbon dioxide.”
Hahaha I wonder how much that “reverse payoff” provisio…got their funding increased!!
What a crock.
Chris
Norfolk, VA, USA
In the big pic, CO2 and temp are uncorrelated. One is high while the other is high or low. The other is low while the one is low or high.
Dave in Delaware says:
January 7, 2011 at 12:27 pm
@Dave Springer
“Re my comment “we are told that CO2 is a less potent GHG than Methane”
I was referring to Global Warming Potentials (GWPs), where I have seen Methane listed as 21 – 24 GWP, relative to CO2 = 1 GWP.”
Anthropogenic methane contribution to AGW has a wide range depending on who you ask but it’s generally being raised not lowered with estimates generally ranging from 25% to 50% of the total warming. Emissions from human activities are growing twice as fast as CO2 emissions too. The single biggest culprit is rice farms which account for half of all manmade emissions. Good luck talking Asia into cutting back on rice production. Cattle I believe is next and good luck on taking beef off the table in the west. When it comes to favorite foods people fight over it like dogs. There are ways of greatly reducing these emissions through modification of farming methods that don’t greatly increase the cost of production or quality of the product. Given methane has such a short half-life, is such a potent greenhouse gas, and it’s far easier to limit anthropogenic production of compared to CO2, it would make a great experiment to reduce it and see what happens to global temperature. Alas, as Trenberth lamented in the “travesty” comment, even if we did limit GHG emissions we would no idea if it had any effect because in a moment of brutal honesty he admitted we don’t have the ability to separate natural from unnatural changes in forcings.
“Regarding CO2 half life – re your comment “climate boffins say CO2′s lifetime in the atmosphere is a century or more ”” The best numbers that I have seen fall in the 5 to 15 year range for CO2 half-life in the atmosphere.”
I’ve never seen 15 years.
My emphasis. I chose the “reasonable” no-regrowth number of 31 years which makes removal time about a century or more.
Dave Springer says:
January 7, 2011 at 12:27 pm
Anthropogenic methane contribution to AGW has a wide range depending on who you ask but it’s generally being raised not lowered with estimates generally ranging from 25% to 50% of the total warming. Emissions from human activities are growing twice as fast as CO2 emissions too. The single biggest culprit is rice farms which account for half of all manmade emissions. Good luck talking Asia into cutting back on rice production. Cattle I believe is next and good luck on taking beef off the table in the west.
Please elaborate, with links:
Are you suggesting humans are growing more acres of rice and more cattle, or are you suggesting that modern farming practices and animal husbandry have changed in such fashion as to increase methan production?
I disagree with both arguments.
One question which never seems to get answered – especially by the AGW crowd – is this.
During the 1950s and 1960s, the USA, the USSR, France and us in the UK, were letting off atomic and hydrogen bombs IN THE ATMOSPHERE as if there was no tomorrow – numbering, if I’m not mistaken, hundreds, if not thousands.
The atmosphere, bless it, seems to have been remarkably unimpressed with these assaults on its ability to maintain stability.
Any comments, anyone..??
“David says:
January 8, 2011 at 2:48 pm
…atomic and hydrogen bombs IN THE ATMOSPHERE..”
The following may interest you:
http://www.aip.org/history/climate/Winter.htm
“In an openly published, but little noticed, 1958 review of climatology, a leading expert wrote that a nuclear war could throw up enough dust to alter the climate for a few years. The U.S.Weather Bureau had gone farther in an unpublicized 1956 study, saying it was conceivable that enough dust might be thrown into the stratosphere to launch a new ‘ice age.”
Dave Springer January 8, 2011 at 8:19 am
“I’ve never seen 15 years.”
your cited article says “19 to 49 years, with a reasonable average being 31 years”
my reply on 5 to 15 …. quite possibly closer to 5
1) 14C isotope data (from WUWT discussion here
http://wattsupwiththat.com/2009/10/18/maldivians-pull-underwater-publicity-stunt/#more-11771
14C isotopes were created in the atmosphere by atomic bomb tests in the 1940s, 1950s and 1960s. The subsequent decay of atmospheric 14C isotope concentrations indicates atmospheric residence time of CO2 molecules as being ~14 years. This agrees with dozens of other studies that indicate the residence time is between 5 and 15 years.
2) The article Segalstad (1992, 1993) includes a table showing over 3 dozen published studies from the 60’s/70’s/80’s on C14, all showing C02 residence time in the 5 – 15 range, plus more recent studies
Based on solubility data – Murray (1992) 5.4
Based on carbon-13/carbon-12 mass balance – Segalstad (1992) 5.4
http://www.geocraft.com/WVFossils/Reference_Docs/Carbon_cycle_update_Segalstad.pdf
3) C12/C13 isotope calculations from Carbon Isotopes in Atmospheric CO2 (excerpts)
Houghton et al. (1990) assumed for the IPCC model 21% of our present-day atmospheric CO2 has been contributed from burning of fossil fuel. This has been made possible by CO2 having a “rough indication” (sic!) lifetime of 50 – 200 years. It is possible to test this assumption by inspecting the stable 13C/12C isotope ratio (expressed as delta13CPDB*) of atmospheric CO2. It is important to note that this value is the net value of mixing all different CO2 components, and would show the results of all natural and non-natural (i.e. anthropogenic) processes involving CO2.
Segalstad (1992, 1993) has by isotope mass balance considerations calculated the atmospheric CO2 lifetime and the amount of fossil fuel CO2 in the atmosphere. The masses of the components were computed for different atmospheric lifetimes of CO2.
The calculations show how the IPCC’s (Houghton et al., 1990) atmospheric CO2 lifetime of 50-200 years only accounts for half the mass of atmospheric CO2. However, the unique result fits an atmospheric CO2 lifetime of approximately 5 (5.4) years, in agreement with numerous 14C studies compiled by Sundquist (1985) and chemical kinetics (Stumm & Morgan, 1970).
http://www.co2web.info/esef5.htm
Dave in Delaware says:
January 9, 2011 at 2:12 am
I wrote that climate boffins believe the residence time of anthropogenic CO2 is a century or more. Some of them even say thousands of years (see Archer 2005 below). I didn’t write that I personally believe any of those figures. I figure if only half the anthropogenic CO2 emitted each year actually shows up in the atmosphere (which is pretty much undisputed) then the half-life of anthropogenic CO2 is 1 year. I refuse to play the game of following individual molecules and just look at total anthropogenic emission (currently 3ppm/yr) vs. annual rise in total atmospheric CO@(1.5ppm/yr).
Tim Clark says:
January 8, 2011 at 10:38 am
Please elaborate, with links:
http://en.wikipedia.org/wiki/Greenhouse_gas#Greenhouse_effects_in_Earth.27s_atmosphere
From the table CO2 accounts for 9-26% of GHG effect while methane accounts for 4-9%. Sources are cited and you can follow them if you wish. Depending on what the true values are it might be that 9% (lowest estimate for CO2) and 9% for methane (highest estimate for methane) then methane would account for 50% of all anthropogenic greenhouse forcings. I read a paper recently that claimed exactly that which is the highest claim for methane I’ve seen. Older work all suggests less but AFAIK no one claimed less than 25%. CO2 is made into the far more important GHG through questionable claims that anthropogenic CO2 stays in the atmosphere for a century or longer while methane hangs around for about 10 years.
As to the emission sources (you didn’t believe rice & cattle farming emissions):
http://www.ciesin.org/docs/004-032/004-032.html
“Recent global estimates of emission rates from wetland rice fields range from 20 to 100 Tg/yr (IPCC 1992), which corresponds to 6-29% of the total annual anthropogenic methane emission.”
The range there is pretty big. As with just about everything else in CAGW uncertainty abounds.
See also
http://icp.giss.nasa.gov/education/methane/intro/cycle.html
NASA sticks some solid numbers to it in a pie chart with:
rice @ 12%
cattle @ 16%
coal/oil mining + NG distribution leakage 19%
more re Dave Springer at 8:19 am
On further reflection, it may be worth a re-look at the different CO2 ‘residence time’ values, or at least put them into context with one another.
The Moore and Braswell (M&B) study appears to have a primary focus on the biosphere. “We find differences in model behavior associated with the assumption of an active terrestrial biosphere (forest regrowth) and significant differences if we assume a donor-dependent flux from the atmosphere to the terrestrial component (e.g., a hypothetical terrestrial fertilization flux).”
my thoughts-
* The M&B study is a computer model. In contrast, the C14 papers I cited were actual measurements in the atmosphere.
* Moore and Braswell (M&B) define ‘half-life’ as the time it takes to make half a change. In other words, their value is not a ‘residence time’ as used in the mixing and process control definitions used in the other papers.
* The M&B paper focus on biosphere may be looking at one of many ‘vectors’ which contribute to the overall residence time of CO2 in the atmosphere.
At first, I considered whether a math comparison might put them into better agreement. The M&B 19 to 49 years is the time to make half a change by their definition. So they are estimating the total change to be twice that, or 38 to 98 years. In a first order well mixed system (which the atmosphere approximates) expected response would be 68% in one residence time, 95% in 3 residence times, and 98% in 4 residence times. For the C14 measurements of 5 to 15 years = one residence time, the expected 98% change would be 4x or 20 to 60 years. At least there is some overlap in the ‘full change’ values, although the measured C14 values are on the lower side of the overlap, and would not support the extreme higher values of 72 x 2 = 144 or 92 x 2 = 184 as mentioned by M&B.
Viewed in another way, the M&B study is looking at primarily the biosphere – “an active terrestrial biosphere (forest regrowth)” and “a donor-dependent flux from the atmosphere to the terrestrial component (e.g., a hypothetical terrestrial fertilization flux)”. This is an important ‘vector’ in the CO2 atmosphere but perhaps not the only one. The CO2 residence time as estimated in the C14 and other referenced papers are examining overall CO2 residence time from all ‘vectors’. Because M&B get ‘slower’ removal, this would suggest one or more other ‘vectors’ are larger or faster to bring the overall residence time down to 5 – 15 years. One such ‘vector’ that comes to mind is Rain. Natural rainfall is saturated with CO2 and cycles on the order of hours to days, rather than decades. One imagines that the CO2 in rainfall over the ocean becomes sequestered into the ocean waters, and becomes part of that ocean atmosphere cycle (longer cycle). Rainfall over land would presumably re-release the CO2 when the water evaporated (very short cycle) in a sort of catch-and-release way. Might the released CO2 over land then jump to the M&B biosphere cycle? Worth some thought, but I have gone on too long in this post.
Dave in Delaware says:
January 9, 2011 at 8:34 am
too long? No, about right, I’d say. Thanks for pulling that together.
Tricky concepts. Obviously a given molecule might stay in the air minutes after entering it, or thousands of years. Very wide distribution curve. The question is how long does a large “blip” take to subside. I think not long.