One of the few things that BOTH sides of the Carbon Dioxide and AGW debate seem to be able to agree on is the belief that CO2, as a trace gas, is “well-mixed” in the atmosphere. Keeling’s measurements at Mauna Loa and other locations worldwide rely on this being true, so that “hotspots” aren’t being inadvertently measured.
As support for this, if you do some Google searches for these phrases, you’ll get hundreds of results of the usage together:
“carbon dioxide” + “well mixed”
You’ll find complete opposites using the same “well mixed” phrase, for example:
Gavin Schmidt of Real Climate writes in comment # 162 of this thread on Realclimate.org
“A full doubling of CO2 is 3.7 W/m2, and so by looking at all well-mixed GHGs you get about 70% of the way to a doubling.”
Roger Pielke Sr. writes in April 2008:
“…and thus are not providing quantitatively realistic estimates of how the climate system responds to the increase in atmospheric well mixed greenhouse gases in terms of the water vapor feedback.”
You’ll also find the phrase in use in titles of scientific papers, for example this one published in the AGU:
New Estimates of Radiative Forcing Due to Well Mixed Greenhouse Gases
And you’ll find the phrase used in popular media, such as this article from the BBC:
Carbon dioxide continues its rise
In describing the emasurements of CO2 at Mauna Loa Observatory: “The thin Pacific air is ideal for this research since it is “well-mixed”, meaning that there is no obvious nearby source of pollution, such as a heavy industry, or a natural “sink”, such as forest which would absorb CO2.”
Hmm, “no obvious nearby source of pollution” I suppose the volcanic outgassing nearby doesn’t count as “pollution” since it is natural in origin.
So it seems clear that there is a broad agreement on the use of the term. I suppose you’d call that “scientific consensus”.
So it was with some surprise that I viewed this image from NASA JPL, a global CO2 distribution as measured by satellite:
Note the variations throughout the globe, ranging from highs of 382 PPM to lows around 365 PPM. There is a whole range of data and imagery like this above available here
My question is: how does this global variance translate into the phrase “well-mixed” when used to describe global CO2 distribution? It would seem that if it were truly “well-mixed”, we’d see only minor variances on the order of a couple of PPM. Yet clearly we have significant regional and hemispheric variance.
NASA JPL provides this caption to help understand it:
Although originally designed to measure atmospheric water vapor and temperature profiles for weather forecasting, data from the Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua spacecraft are now also being used by scientists to observe atmospheric carbon dioxide. Scientists from NASA; the National Oceanic and Atmospheric Administration; the European Center for Medium-Range Weather Forecasts; the University of Maryland, Baltimore County; Princeton University, Princeton, New Jersey; and the California Institute of Technology (Caltech), Pasadena, Calif., are using several different methods to measure the concentration of carbon dioxide in the mid-troposphere (about eight kilometers, or five miles, above the surface). The global map of mid-troposphere carbon dioxide above, produced by AIRS Team Leader Dr. Moustafa Chahine at JPL, shows that despite the high degree of mixing that occurs with carbon dioxide, the regional patterns of atmospheric sources and sinks are still apparent in mid-troposphere carbon dioxide concentrations. “This pattern of high carbon dioxide in the Northern Hemisphere (North America, Atlantic Ocean, and Central Asia) is consistent with model predictions,” said Chahine. Climate modelers, such as Dr. Qinbin Li at JPL, and Dr. Yuk Yung at Caltech, are currently using the AIRS data to study the global distribution and transport of carbon dioxide and to improve their models.
As we’ve found with surface based temperature measurement, it seems the more we look at satellite data, the more we learn that our earth bound assumptions based on surface measurement don’t always hold true.
When measuring the planet, looking at the whole planet at one time seems a better idea than trying to measure thousands of data points at the surface, sorting out noise, doing adjustments to “fix” what is perceived as bias, and assuming the result is accurately representatiive of the globe.
UPDATE: 7/31/08 I got a response from the AIRS team on satellite CO2 measuremenst, see this new posting
We won’t have to rely on ground based CO2 measurements much longer.
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here is some artic data and others
http://cdiac.ornl.gov/trends/co2/main.html
http://cdiac.ornl.gov/trends/co2/
http://www.esrl.noaa.gov/gmd/ccgg/iadv/
http://envisat.esa.int/live/envisat_live_08.htm
unfortunatley I cannot find the very good global map by latitude. it may have been removed since I last looked 1 year ago
Maybe someone can help me wrap my arms around something that has been bothering me for a while now…
It is well documented that pre-industrial levels of CO2 were pretty stable for thousands of years in the neighborhood of about 288 ppmv. Since the industrial revolution, CO2 levels have steadily climbed and, as of 2000 were at approximately 368 ppmv (I use 2000 as my baseline because the data I have from DoE is from that year).
According to the DoE, of the 80 ppmv increase, 12 ppmv is due to man-made additions, and the remainder (68 ppmv) is due to natural additions.
This is where I start scratching my head! For thousands of years prior to industrialization, according to ice core reconstruction, the earth’s system was in equilibrium and there was no “net” increase in natural additions (hence the steady level of CO2) to the atmosphere. So, why is it that only during this period of man-made additions have the natural additions also risen?
Every answer I tend to come up with never works as it would also cause a related increase in past CO2 levels. I could be overlooking something extremely simple, and that’s why I’m “coming out of the closet” and posing this question to a large audience.
What am I missing?? Or could it be that Beck is onto something with his analysis of past CO2 measurements taken by wet chemical method and there is a flaw in the ice core measurements (I have thoughts on that…but I will spare you my lunacy!!)?
Thanks for your help…and please keep the flames to minimum!! 🙂
LeeW: I had the same problem… However I found that the Ice Core data for CO2 was already in doubt…
Brooks Hurd, a high-purity-gas analyst, confirmed the previous criticism of ice core CO2 studies. He noted that the Knudsen diffusion effect, combined with inward diffusion, is depleting CO2 in ice cores exposed to drastic pressure changes (up to 320 bars more than 300 times normal atmospheric pressure), and that it minimizes variations and reduces the maximums (Hurd 2006).
i.e. the historic Ice Cores measurements show an artificially low CO2 level… and may not be a good matrix for reconstruction of historic CO2 levels…
But nobody seems to want to fund this area of research…
Zbigniew Jaworowski fleshes out the argument a little more here:
http://www.21stcenturysciencetech.com/Articles%202007/20_1-2_CO2_Scandal.pdf
I was a firm AGW believer, a few years back. I just accepted what the news told me, I even went and bought Al Gores DVD, played it and felt convinced… I played it to everybody else too!
I was wondering one day, why my skin had become much more sensitive to the sun over the past years, and I wondered whether Skin Cancer was increasing… sure enough it was, lots of reports showing how heavily it was up in the NORTHERN HEMISPHERE, but not the Southern Hemisphere. My skin specialist at the hospital also agreed the Skin Cancer, and sensitivity had increased in his opinion.
This seemed like it was to do with the sun… so i dug a little deeper into sun observations etc. and stumbled across a researcher’s blog at an observatory studying the sun (can’t find it now), who believed that the main driver of GW was more likely to be the sun in her opinion.
For the last couple of years I’ve been on a trip, chasing down the information, and realised the AGW case doesn’t really stack up, it’s a bit flimsy, and rather messy. Because of along term interest in Geopolitics and the fight to control energy resources, it soon felt to me the Political agenda was pushing CO2 down peoples throats because it had a neat link to energy consumption, and alternative method of controlling energy OUTPUT, rather than the traditional method of controling INPUT (which the Anglo/American’s were losing control of), as a way of controlling the development of 2nd/3rd world countries around the world.
Over the last few months, Svensmarks work on the CRF/Climate link due to cloud formation continues to make more and more sense – to me, despite all the rubbishing papers, which actually don’t rubbish it at all when you read them.
I think Svensmark has found something very beautiful, very elegant, and very simple to explain the main driver of climate change. I hope he can prove his theories, although I think the evidence has piled up in his favour.
In time I think we will look up into the sky at the clouds, and realise that once again, man’s egocentric view of his world had been challenged, and that we are just a piece of the universe.
It’s too bad all these gases are invisible or we might see them swirling in various concentrated bands and clouds. I suspect that N2 flows along rivers, evidenced by lichen uptake that declines with distance from the water. And I suspect methane hangs over methane sources with poor diffusion based on common olfactory evidence.
I strongly doubt that heavy gases like chlorofluorocarbons migrate from asthma inhalers to high altitudes in polar regions. I know an atmospheric researcher who sent up ballons in Antarctica and she told me they found no CFC’s there. She thinks the CFC-induced ozone hole theory is utter bunk.
Brownian mixing in lab beakers is a far different beast than wildfire smoke or volcanic eruption plumes, which we can see and which certainly don’t diffuse rapidly into the atmosphere. I don’t know about invisible trace gases in parts per million, but I suspect the mixing is incomplete.
Re Mauna Loa, the measurement station is on the saddle between Mauna Loa and Mauna Kea. Just below it is a US Army artillery range and tank training area. Upwind is Hilo, a steadily growing community. To the south is Kilauea which has been erupting rather vigorously from Pu’u O’o since 1983. I know for a fact that trade winds blow insects up to the summit from the lowlands, so the inversion layer is not a hermetic seal.
Our atmosphere is not homogenous, any more than our oceans are.
Mike: Diffusion is an interesting process. Depends on many factors. My beef with CFC/Ozone hole is this: Most CFC’s were released in the NH. The “hole” is over the Spoth Pole. How did all the CFC’s get there? There is very little mixing of air between NH and SH, the jet streams don’t work that way. Why no hole over the North Pole? We did see some reduction in ozone over the NH, but no massive holes.
I guess that didn’t sell enough newspapers.
Early posts in this thread were asking about the life of CO2 in the atmosphere. James hansem, in a letter to the Ausrtalian Prime Minister (http://www.columbia.edu/~jeh1/mailings/20080401_DearPrimeMinisterRudd.pdf) states “…because a substantial fraction of the emitted CO2 will stay in the air more than 1000 years.”
This is much more than the posited 10 – 40 years that others have commented on.
Do CO2 molecules have date stamps?
Never was any ‘massive ozone hole’.
When Antarctic ozone drops below 220 Dobson units (from the 300-400 or so units present most of the year) it is DEFINED by the usual suspects as a ‘hole’.
It is actually a recurrent ‘dimple’ that reliably shows up in late Southern hemisphere winter and reliably clears by mid-spring when the sun is again visible over the polar horizon and has naturally restored the ozone.
And yet the use of CFC’s in asthma inhalers has been banned. CFC are the best propellants and were especially important in rescue inhalers (for those acute asthma sufferers who might die without immediate relief). The CFC substitutes are not nearly as effective.
But what the hell. It’s worth it to make millions of sick people suffer and die for a phony baloney paranoid junk science superstition isn’t it? It’s the Precautionary Principle. Aliens from Outer Space might land in your yard. Best to learn to speak Martian today, just in case.
Yes, Mike. Like DDT and malaria … millions die and many more millions are permanatly impaired each year (THESE ARE THE REAL NUMBERS, PEOPLE) because DDT was given a false bad rap by Rachel Carson some decades ago.
If all those who think we should do good, by “not doing ” what has been shown to work, were required …
(when they vote or advocate)…
to contribute to a potentially profitable trust fund that would either pay back any harm they may have caused by their shrill voices or reward them for their wisdom, … what a bright world this would be.
As it is, they have no risk and are not in the slightest accountable for their actions.
LIke thinking they have a Constitutional right to shout FIRE in a crowded theater without responsibility or accountability.
Semantics, semantics. When one has no point, he resorts to attacking semantics. “Well-mixed” does not mean perfectly mixed. In a “well-mixed” system, one merely has to find a location where the mixing results in a good fit. Mauna Loa is in a grand position to measure AVERAGE global CO2 levels. Look at the diagram you included in your story. It shows Mauna Loa smack dab PERFECT, yet you scream that other places wouldn’t work as well! Egad, that’s why Los Angeles isn’t used, even though it would be more convenient. Ker-DUH! Please answer this query: By what percentage does Mauna Loa differ from the global average CO2 level, and what are you whining about??