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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Well mixed means (quoting Elaine from Seinfeld), “means whatever the hell you want it to mean” especially if it supports AGW theory.
The mixing takes two or three years (which I assume is well-mixed enough to satisfy the definition.)
Antartica is behind the global average by about 3 or 4 ppm but its trend continues to increase like the other locations. I’m assuming North America is ahead of the global trend according to the Aqua measurements,
The ice core CO2 data shows Antarctica was 280 ppm about 1865 (ice takes time to form) but it is now up to 383 ppm at the end of 2007. Monthly chart data at this link (doesn’t quite match up with the Aqua measurements in 2003.)
http://cdiac.ornl.gov/trends/co2/graphics/JubanyFinal.jpg
I had wondered about CO2 distribution, but vertically, not laterally. Since CO2 is heavier than both N2 and O2 is it the case that CO2 accumulates at the surface? If so, has this been included in climate modeling/theory?
Why is it that this line comes as no surprise: “This pattern of high carbon dioxide in the Northern Hemisphere (North America, Atlantic Ocean, and Central Asia) is consistent with model predictions”? Yes sir, the models predict everything.
And while this is five years old, surely there should be more CO2 showing off from China. Perhaps newer data might reflect this change.
There’s that line again in the JPL caption: “is consistent with model predictions”.
Consistent with model predictions of WHAT?
Why are southern mid-latitude levels elevated as well if the majority of the industrialization is in the northern hemisphere?
I’ve seen this map and puzzled over it too. For one thing the highest CO2 values are not over densely populated areas but over steppe and desert country (and the Sargasso sea). Of course the measurement is in the mid-troposphere, but intuitively you would expect differences to be smaller there than at the surface since there is nothing for the CO2 to react with.
Another interesting thing is that the lowest CO2 values are over the Greenland and Antarctic icecaps. This may explain why historical CO2 measurements from stomatal index (SI) are consistently moderately higher than ice-derived values.
[snip – don’t try to assume Dr. Hansen’s persona again or you will be banned from this site. I will not tolerate this sort of thing. I may disagree with the man but I will not let others pose as him and put words in his mouth that are fabricated. – Anthony ]
I’m seeing 374 ppm +/- 10 ppm. I’d call 10 ppm “minor,” but we need not agree. The whole debate is on the Delta ppm anyway. When we’re arguing about what will happen at 750 ppm, no one will care if the variance is +/- 10 ppm or +/- 20 ppm.
What really makes me angry is that there are scientists and sane people at NASA who know that what is being put out are lies, but go along with it for the Pork barrel.
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.
So, NASA publicly states that although there is good mixing, there isn’t. Huh.
Of the critical parameters on which AGW rests, the one most often ignored is the ‘half-life’ of CO2 in the atmosphere. I’m no expert, but I understand that it used to be thought that it was less then 10 years, but now the ‘consensus’ is more like 40 years or even more. It needs to be high for disaster scenarios to eventuate.
Can maps like the above shed light on the question of CO2 persistence in the atmosphere? You would think that the longer the CO2 half-life, the more well-mixed the atmosphere would be. Any experts out there?
“This pattern of high carbon dioxide in the Northern Hemisphere (North America, Atlantic Ocean, and Central Asia) is consistent with model predictions.”
Evidence for this consistency? References please.
Or is this another one of those assertions that whatever happens is consistent with the predictions of some model or another?
Google ‘carbon cycle’ and you will find lots of material bearing on CO2 stay in the atmosphere, including many graphics. Given the annual flux of 160-200 or so gigatons of carbon into/out of the atmosphere each year, and the 750 or so gigatons the atmosphere contains, the turnover would appear to be 4-5 years or so for any given CO2 molecule.
Anthony
If we can measure these regional variations in CO2 ppmv to this degree, it completely puts paid to the notion that this trace gas is “well-mixed” around the globe. Not only that, this further highlights the dubiousness of the core AGW contention that global temperatures are driven by CO2 concentrations.
Hmmmm. Wonder how much, if any, of that CO2 was related to forest fires as I understand it was a bad year.
Here’s another map.
http://en.wikipedia.org/wiki/Image:AYool_GLODAP_invt_aCO2.png
Several events have occured since the beginning of measuments recorded here,
http://scrippsco2.ucsd.edu/images/graphics_gallery/original/co2_sta_records.pdf
a substantial cooling 60s to 70s, a couple volcanos, large El Nino in 98, hurricanes and tornadoes… yet these stations show an essentially straight line mean increase in CO2 in the atmosphere. Mauna Loa appears to reflect seasonal changes (reason?), but it occurs to me that for this linear increase to be an accurate picture of global atmosperic CO2, that total CO2 production, yearly global temperatures, Amazon trees, ocean uptake and release and everything else that significantly affects atmospheric levels, would have to “equal out”. That’s a hard one to accept. I would be more convinced of these graphs had they more ups and downs over the years than the Mauna Loa “seasonal” clockwork ups and downs.
This is the trace gas that the EPA wants to regulate and we cannot even look at the pictures.
Given all the data that is available, why are we stuck with one stinking snapshot from July 2003?
If anyone can answer this simple question please enlighten me.
co2 is not well mixed. what ever “well” and “mixed” are
1) pinatubo eruptions gave so2 spikes around the world. No co2 spike at mauna loa
2) co2 minimums increase as you go from southern latitudes to north pole. north pole c02 30 to 60 ppm higher than sidney
http://cdiac.ornl.gov/trends/co2/ and other us govt sites had links to c02 recording from sites all ove r the world. the co2 was all different
braddles (16:40:13) :
I’m no expert, but that’s never stopped me before. 🙂
A really short half life would show up as plumes of CO2 from big sources that fade away as CO2 is removed by plants and rain. So longer half lives would mean plumes that circle the Earth several times and gradually disperse as weather systems mix the air. It would be nice to see a series of those images as a movie, some of those blobs may or may not stay in place over time. Except for that band in the SH, the image sure suggests plumes. Perhaps they are blobs that show up as they mix upward, that’s the only thing I can think of that would allow for sharp edges away from the CO2 source besides a really short half life.
July 2003, heh? I remember that month particularly well. I spent most of it and part of August bicycling around Oregon (several days of 100+ heat in the eastern desert) and Montana (whose “Big Sky” was marred by much forest fire smoke). That was the year of the great French heatwave and Lance Armstrong’s extreme dehydration in a time-trial stage of Le Tour de France.
I have no idea if the CO2 in the American northwest was due to fires or blown up from California. A daily image would allow some fascinating viewing.
This may be due to something that I have often thought about. C02 is a heavier than average part of the atmosphere, which would make you think that it would settle lower in the air colomn. However, since it is capable of absorbing IR, it would tend to become effectively less dense due to it’s energized state. It would need to share it’s absorbed heat through impacts with other molecles or it would continue to rise until it reached a height where it could radiate and cool. At some point there must be a balance in terms of altitude, above which the probability of colliding with other molecles drops off, due to the less dense air. CO2 would continue to absorb IR from the sun, but it would immediately rise and radiate, an effective heat transport similiar to water vapor.
Perhaps the distribution detected by the satellite doesn’t have anything to do with how well mixed CO2 is in the lower atmoshere. Perhaps the CO2 hotspots are actually CO2 that has risen and concentrated due to convection. If this is the case, then CO2 can have a cooling effect as well as a greenhouse effect, which is why global warming doesn’t actually happen in the real world
Brownian motion creates far more mixing than any density differences cause separation. C02 does not separate itself out of mixed air, although, due to its higher density, the concentration may be slightly, only slightly greater at lower altitudes.
Hmmmm… Just eyeballing the image, it appears that most of the CO2 is in the northern hemisphere during our winter. Wouldn’t it be curious if the image “flips” to more CO2 in the southern hemisphere’s winter in January?
Perhaps that explains the inadvertent reference to January 2003 under the image on the airs website.
http://www-airs.jpl.nasa.gov/Products/CarbonDioxide/
Maybe they thought better of showing that snapshot.
Hmmmm… Just eyeballing the image, it appears that most of the CO2 is in the northern hemisphere during our summer. Wouldn’t it be curious if the image “flips” to more CO2 in the southern hemisphere’s summer in January?
Perhaps that explains the inadvertent reference to January 2003 under the image on the airs website.
http://www-airs.jpl.nasa.gov/Products/CarbonDioxide/
Maybe they thought better of showing that snapshot.
Tim Fitzgerald (15:37:16) :
Convection and diffusion (primarily convection, I’m sure) swamp the tendency for stuff to settle by size. Air is viscous enough to keep water droplets in clouds from falling out until they reach rain drop size, and a CO2 molecule is less than a millionth the weight of a fog droplet.
So I’d expect there to be very little difference between low and high altitude.
Hmm, I wonder if rain significantly decreases CO2 where the rain forms or falls. I bet much more CO2 is brought down to Earth that way than through gravity pulling on CO2 gas. I wonder if that affects the image above, some of the red areas don’t have much rain in July. It would also imply a very short half life.
Following up on my earlier comment, if CO2 rises and concentrates, then the effect would be pronounced in the northern hemisphere during summer. The posted image is from July. I would like to see the images for Oct., Jan, & April.
Can’t help but wonder if the heavier CO2 band would be in the Southern Hemisphere in Jan.
There should be data available since May 2002.
http://www.jpl.nasa.gov/releases/2002/release_2002_107.html
Six more years of daily please NASA, before I call EPA.