Guest Post by Willis Eschenbach
In 2006, I lived for a year in Waimea, on the Big Island of Hawaii. From my house I could see the Mauna Loa Observatory (MLO). This observatory is the home of the longest continuous series of CO2 measurements we have. The recording station was set up by Dave Keeling in 1959, and has operated continuously ever since.
Figure 1. Mauna Loa Observatory ( 19.536337°N, 155.576248°W)
Here’s a view of the observatory:
Every time the subject of CO2 measurements comes up, people raise all kinds of objections to the Mauna Loa measurements. So I thought I’d start a thread where we can discuss those objections, and perhaps dispose of some of them.
Here are the objections that I hear the most:
1. The Mauna Loa results don’t measure the background CO2 levels.
2. You can’t get accurate CO2 measurements from samples taken on the side of an active volcano that is outgassing CO2.
3. The measurements from Mauna Loa are not representative of the rest of the world.
4. What about the Beck data, doesn’t it contradict the MLO data?
5. Keeling chose a bad location.
Before we get into those issues, let’s start by looking at the local meteorological conditions at the site. Mauna Loa is at an elevation of 3397 metres (11,140 ft) on the side of a 4,170 metre (13,680 ft) volcano way out in the middle of the Pacific Ocean. Because it is on an island, it gets the “sea breeze” in the daytime, and the “land breeze” in the nighttime.
These winds are caused by the differential heating of the land and the sea. Land heats up much faster than the ocean. So during the day, the warmer land heats the air, which rises. This rising air is replaced by air moving in from the surrounding ocean, creating the “sea breeze”.
At night, the situation is reversed. The land is cooler than the ocean. This cools the air. The cool air runs downhill along the slopes of the island and out to sea, creating the “land breeze”. Here’s a drawing of the situation:
Figure 2. Day and night breezes at Mauna Loa.
Now that we understand what is happening at Mauna Loa, let’s look at the objections.
1. The Mauna Loa results don’t measure the background CO2 levels. As you might imagine from Fig. 2, the CO2 measurements are taken only at night. Thus, they are measuring descending air that is coming from thousands of feet aloft. This air has traveled across half of the Pacific Ocean, so it is far from any man-made CO2 sources. And as a result, it is very representative of the global background CO2 levels. That’s why Keeling chose the site.
2. You can’t get accurate CO2 measurements from samples taken on the side of an active volcano that is outgassing CO2. This seems like an insuperable objection. I mean, Mauna Loa is in fact an active volcano that is outgassing CO2. How do they avoid that?
The answer lies in the fact that the volcanic gasses are very rich in CO2. At night, they are trapped in a thin layer near the ground by a temperature inversion.
To detect the difference between volcanic and background CO2, the measurements are taken simultaneously from tall towers and from near the ground, at intervals throughout the night. Background CO2 levels will be around 380 ppmv (these days), will be steady, and will be identical at the top and bottom of the towers. Volcanic gasses, on the other hand, will be well above 380 ppmv, will be variable, and will be greater near the ground than at the top of the towers.
This allows the scientists to distinguish reliably between volcanic and background CO2 levels. Here is a description of the process:
Air samples at Mauna Loa are collected continuously from air intakes at the top of four 7-m towers and one 27-m tower. Four air samples are collected each hour for the purpose of determining the CO2 concentration. Determinations of CO2 are made by using a Siemens Ultramat 3 nondispersive infrared gas analyzer with a water vapor freeze trap. This analyzer registers the concentration of CO2 in a stream of air flowing at ~0.5 L/min. Every 30 minutes, the flow is replaced by a stream of calibrating gas or “working reference gas”. In December 1983, CO2-in-N2 calibration gases were replaced with the currently used CO2-in-air calibration gases. These calibration gases and other reference gases are compared periodically to determine the instrument sensitivity and to check for possible contamination in the air-handling system. These reference gases are themselves calibrated against specific standard gases whose CO2 concentrations are determined manometrically. Greater details about the sampling methods at Mauna Loa are given in Keeling et al. (1982) and Keeling et al. (2002).
Hourly averages of atmospheric CO2 concentration, wind speed, and wind direction are plotted as a basis for selecting data for further processing. Data are selected for periods of steady hourly data to within ~0.5 parts per million by volume (ppmv); at least six consecutive hours of steady data are required to form a daily average. Greater details about the data selection criteria used at Mauna Loa are given in Bacastow et al. (1985). Data are in terms of the Scripps “03A” calibration scale.
There is a more detailed description of the measurement and selection process here.
As a result, the Mauna Loa record does accurately measure the background CO2 levels, despite the fact that it is on an active volcano. The samples that are identified as volcanic CO2 are not thrown away, however. They are used for analyses of the volcanic emission rates, such as this one (pdf).
3. The measurements from Mauna Loa are not representative of the rest of the world. Well, yes and no. The concentration of atmospheric CO2 varies by month, and also by latitude. Here is a “carpet diagram” of the changes by time and latitude.
Figure 3. A “carpet diagram” of CO2 distributions, by time and latitude.
Note that the swings are much greater in the Northern Hemisphere. Presumably, this is from the plants in the much larger land area of the Northern Hemisphere. However, the difference between the annual average of the Northern and Southern Hemispheres is small. In addition, there are smaller daily variations around the planet. An animation of these is visible here, with day by day variations available here.
Figure 4 shows is a typical day’s variations, picked at random:
Figure 4. Snapshot of the variations in tropospheric CO2. Note that the range is small, about ±1% of the average value.
In general, the different global records match quite closely. In addition to the Mauna Loa observatory, NOAA maintains CO2 measuring stations at Barrow, Alaska; American Samoa; and the South Pole. Here is a comparison of the four records (along with two methane records):
Figure 5. Comparison of the CO2 records from the four NOAA measuring sites.
As you can see, there is very little difference between the CO2 measurements at the four stations – two in the Northern Hemisphere, two in the Southern, two tropical, and two polar.
4. What about the Beck data, doesn’t it contradict the MLO data? In 2007, Ernst-Georg Beck published a paper called “180 Years Of Atmospheric CO2 Gas Analysis by Chemical Methods” (pdf). In it, he showed a variety of results from earlier analyses of the atmospheric CO2. In general, these were larger than either the ice core or the MLO data. So why don’t I believe them?
I do believe them … with a caveat. I think that the Beck data is accurate, but that it is not measuring the background CO2. CO2 measurements need to be done very carefully, in selected locations, to avoid contamination from a host of natural CO2 sources. These sources include industry, automobiles, fires, soil, plants, the list is long. To illustrate the problems, I have graphed the Beck data from his Figure 13, against the Law Dome ice core data and the MLO data.
Figure 6. CO2 data from a variety of sources. White crosses are MLO data. Three separate ice core records are shown. Photo is of Mauna Loa dusted with snow (yes, it snows in Hawaii.) PHOTO SOURCE
There are several things to note about this graph. First, there is good agreement between the Law Dome ice core data and the MLO data over the ~ two decade overlap. Second, there is good agreement between the three separate Law Dome ice core datasets. Third, both the ice cores and the MLO data do not vary much from year to year.
Now look at the various datasets cited by Beck. Many of them vary quite widely from one year to the next. The different datasets show very different values for either the same year or for nearby years. And they differ greatly from both the ice core and the MLO data.
Because of this, I conclude that the Beck data, while valuable for showing ground level CO2 variations at individual locations, do not reflect the background CO2 level of the planet. As such, they cannot be compared to the MLO data, to the ice core data, or to each other.
5. Keeling chose a bad location. I would say that Keeling picked a very good location. It not only allows us to measure the background CO2 in a very accurate manner, it provides invaluable information about the amount of CO2 coming from the volcano.
My conclusion? Most of the records in the field of climate science are short, spotty, and not very accurate. We have little global historical information on ocean temperatures, on land temperatures, on relative humidity, on atmospheric temperatures, on hurricane occurrence and strength, or on a host of other variables. By contrast, the Mauna Loa CO2 records are complete since 1959, are very accurate, and are verified by measurements in several other locations.
I’m about as skeptical as anyone I know. But I think that the Mauna Loa CO2 measurements are arguably the best dataset in the field of climate science. I wouldn’t waste time fighting to disprove them, there are lots of other datasets that deserve closer scrutiny.
[UPDATE] A reader below has added another question, viz:
6. What about Jaworoski’s claim that the ice core data has had its age “adjusted”?
Jaworoski argues that the age of the air in the ice cores has been “adjusted” to make it align with the modern data. He says, for example, that the Siple ice core data has been moved forwards exactly 83 years to make them match the Mauna Loa data.
Dating the ice core data is problematic. We can date the ice itself pretty accurately, through counting layers (like tree rings) and through studying various substances such as volcanic dust that is trapped in the ice. However, dating the air is harder.
The difficulty is that the air is not trapped in the ice immediately. The pores in the “firn”, the snow that falls annually on top of the ice are open. Air can flow in and out.
As more and more snow falls over the years, at some point the pores close off and the air is trapped. So how long does it take for the pores in the firn to seal off?
Unfortunately, as in so many areas of climate science, the answer is … “depends”. It depends inter alia on how much snow falls every year, how much of that snow sublimates (changes from a solid to a gas) every year, and even the shape and size of the individual snowflakes.
The end result of all of this is that we end up with two ages for any given thin slice of an ice core. These are the “ice age” (how old the ice itself is), and the “air age” (how old the air trapped in the ice is). The ice is always older than the air.
The main variable in that is thought to be the annual snowfall. Unfortunately, while we know the current rate of annual snowfall, we don’t know the historical rate, particularly tens of thousands of years ago. So we use the concentration of an isotope of oxygen called “d18O” to estimate the historical snowfall rate, and thence the firn closing rate, and from that the air age.
Sounds a bit sketchy? Well … it is, particularly as we go way back. However, for recent data, it is much more accurate.
So to bring this back to real data, in the ice core data I showed in Fig. 5, the air is calculated to be 30 years younger than the ice for cores DEO8 and DEO8-2, and 58 years younger for the DSS core. Is this correct? I don’t know, but I do know that there are sound scientific reasons for the “adjustment” that Jaworowski objects to .
Finally, the existence of a thirty to sixty year difference in air and ice age doesn’t make much difference in the pre-industrial levels of CO2. This is because prior to about 1800, the level is basically flat, so an error in the air age dating doesn’t change the CO2 values in any significant manner.
FURTHER INFORMATION:
Greenhouse Gas & Carbon Cycle Research Programs
Trends in Atmospheric Carbon Dioxide
How we measure background CO2 levels on Mauna Loa
Slioch said:
“Most of the CO2 emitted by humans in that time, about one trillion tons (1620-640 billion tons), has been absorbed into the oceans and terrestrial biosphere. In other words, the oceans, far from “outgassing” have been acting as a massive sink for CO2.”
Steve Fritzpatrick said:
“Comparison of year to year changes in average ocean surface temperature to the trend in CO2 shows a clear influence of ocean surface temperature on CO2 (about +3.5 PPM per degree warming, -3.5 PPM per degree cooling); El Nino (on average, a warmer ocean) causes a faster annual rise in CO2, La Nina (a cooler ocean) causes a slower rise.”
The head spins….
Where O where
did all the C02 go?
Amongst the grass, the trees?
Nay, they say so.
In the ocean deep below?
No, not this year.
Into thin air?
No, no, not there.
Under the ice, the snow
might it be?
We looked, we looked
we do not see.
Not sure what you mean by “lumpy”. As I commented in the head post, the background levels vary by only about ±1% around the globe at any given instant, which is hardly “lumpy” in my book. It looks like more because of the colors used, but check out the legend, we’re only talking a few ppmv.
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Actually the word “lumpy” was from this statement copied from the NASA site
““Chahine said previous AIRS research data have led to some key findings about mid-tropospheric carbon dioxide. For example, the data have shown that, contrary to prior assumptions, carbon dioxide is not well mixed in the troposphere, but is rather “lumpy.”
How ever atmospheric CO2 is not well mixed as Bubbagyro says:
” CO2 is twice as heavy as air. Regardless of miscibility, this is different from mixing, and there is molecular mass enrichment towards lower levels. Most non-experts confuse miscibility and mixing. Mixing requires turbulence. Puffs of gas from the volcano, heated, will rise; the resultant cloud will overwhelm the minute concentrations we have in “background” or ambient air. Instead of mixing, as a chemist, I must assume non-mixing! As we remember from Lake Nyos in Africa, where almost 2000 people were killed by CO2 outgassing of the lake, it takes time to mix.”
We also know the local concentration is always changing.
WHEAT: The CO2 concentration at 2 m above the crop was found to be fairly constant during the daylight hours on single days or from day-to-day throughout the growing season ranging from about 310 to 320 p.p.m. Nocturnal values were more variable and were between 10 and 200 p.p.m. higher than the daytime values. sciencedirect.com
Greenhouse Information and measurements:
“Plant photosynthetic activity can reduce the CO2 within the plant canopy to between 200 and 250 ppm… I observed a 50 ppm drop within a tomato plant canopy just a few minutes after direct sunlight at dawn entered a green house (Harper et al 1979) … photosynthesis can be halted when CO2 concentration aproaches 200 ppm… (Morgan 2003) Carbon dioxide is heavier than air and does not easily mix into the greenhouse atmosphere by diffusion… click
There was also a study on trees in the open where again the ambient Carbon Dioxide dropped to the vicinity of 200ppm during the daylight hours.
I do not know how these daily changes effects the mixing of CO2 at higher levels but for ground and near ground level Beck’s numbers seem more realistic than the oh so well coordinated “background CO” numbers.
However I do think the Mauna Loa Observatory data is at least an order of magnitude better than the temperature data.
Steve Fitzpatrick,
Is it really settled that only high altitude CO2 matters since the lower atmosphere is opaque to radiation? This is the way I think. CO2 radiates and absorbs longwave radiation. Even though at high altitudes the energy escapes to space the process must exist throughout the atmosphere. I suppose the $64,000 question is whether the presence of CO2 in atmosphere retards *conduction* of heat by absorption and re-radiation. If it does retard conduction it would mean to me that it would tend to make the atmosphere warmer (and perhaps change the atmosphere’s heat capacity). (Though I also have to think that the big player moving heat upward in the troposphere would be convection.)
I plead ignorance on this point and I’m not sure how to construct a satisfactory account for myself, but it DOES seem that a solid opaque body must conduct heat by two methods. The vibratory kind seen with the phenomenon of Brownian motion, but also by a absorption re-radiation mode such as is said to occur at the surface of a opaque solid.
It would be greatly appreciated if someone would enlighten me on this point because expositions that I read sometimes includes a discussion of absorption and re-radiation and sometimes omit it.
Partial pressure changes of CO2 in air only matter to true believers in AGW. There is strong evidence that the theory upon which it is built is defective. Ferenc Micolczy (E&E 21:243;No. 4, 2010) has shown that feedback of water vapor effect on the greenhouse gas optical thickness is strongly negative, thoroughly contradicting the IPCC doctrine of it being positive. Consequently all predictions of a possible runaway greenhouse are wrong and increasing carbon dioxide concentrations do not cause increased warming. Their real importance is that they promote plant growth and increase crop yields.
Wills,
Tthansk for the link to the report on the Rusian paper.
And further to the Mauna Loa data. I reckon that the preselection process needs looking at. It seems that they are selecting ‘quiet periods’ where both the levels and the rates of change are at arbitrary values. Can we be sure that these rules do not introduce assymetries?
For example, while it seems sensible to discard huge temporary readings that must be from a local truck exhaust or a volcanic venting, but what about readings that have temporarily dropped significantly? Why should they be excluded?
And, taking the rate-of-change exclusion rule, are they sure that Co2 rates of rise and falls are the same? ( i.e. that the second derivatives are symmetrical?)
I think that from such selection algorithms, artefacts can arise such as hockeysticks. So I would like to know if the process has been examined and tested by statisticians and signal-processing experts.
To illustrate what I reckon they are facing, here is an acoustic analogy. We have a one year’s worth of audio tape of a fairground, and we want to analyse it to see if the generator in the background is getting louder, which might signify a problem. We start by selecting-out all the ‘noisy’ bits on the tape and we try to analyse the average amplitude of the remaining noises to within 1 part per million, over the year. From our results we claim to have ‘measured’ a 2 ppm/yr increase in the sound of the generator . Will they believe our result? And folk will ask … ‘what changes in your selectio process would it take to get a decrease of 2 ppm/year?
Excellent treatment of an often misunderstood process, Willis.
You mentioned that we do not have any historical record of hurricanes. In 2007, Woods Hole Oceanographic Institution did core samples in a back lagoon in the Caribbean and were able to develop a 5000 year reconstruction of the strength and number of hurricanes. There were periods of intense hurricanes when temperatures were cooler than today. The underlying causes of hurricanes are described. Here is an URL:
http://www.whoi.edu/oceanus/viewArticle.do?id=28207
I cannot understand why there is no mention of the Australian staion for the analysis of atmospheric gases – not only carbon doioxide – at Cape Grim in Tasmania. This facility has been operating for years. It is nowehere near any volcano, but it is in the track of the ‘Roaring Forties’ which cross thousands of miles of ocean before reaching Cape Grim, and blow ceaslessly around the world in this latitude, ensuring perfect mixing and no trace of industrial or volcanic pollution.
Willis:
At June 5, 2010 at 12:06 pm you request:
“Richard, while that is an important issue, I’d like to ask that you discuss it on another thread. This thread is about whether the Mauna Loa record is valid, not about whether humans are the cause of the changes in the background levels.”
OK. Point taken. Will do.
I was responding to comments of others, and I apologise if that was a distraction.
Richard
A small apology – I did find one good reference to the Cape Grim station, with a graph of some results. I wonder why their data differs from that of other staions if the atmosphere is really fully mixed?
bubbagyro says:
June 5, 2010 at 10:27 am
Surely this is the other way around? Photosynthesis (releasing O2) during the day and respiration (releasing CO2) at night?
Tony says:
June 5, 2010 at 1:15 pm
1. You seem to doubt that scientists have the ability to measure gases to within ±1 ppmv. I don’t. The technology exists. They use it.
2. All of the data is used. It is just used for different purposes. Background information is used to find the background, volcanic information is used to understand volcanic emissions.
3. What makes you think that there are no other CO2 instruments at the observatory? I don’t know if there are or not, but I wouldn’t assume that there are no others.
Gail Combs writes:
“Not sure what you mean by “lumpy”. As I commented in the head post, the background levels vary by only about ±1% around the globe at any given instant, which is hardly “lumpy” in my book.”
The figure cited is the figure that is in all the textbooks. But isn’t that figure deduced from the properties of the CO2 molecule? Isn’t it true that the figure has not been established through experiment?
Hi Hank,
The fundamental distinctions are between ‘whole-molecule processes’ and ‘electron-transition processes’.
Garden-variety blackbody (or greybody) effects involve whole-molecule processes. These depend directly on the temperature of the molecules (which in turn depends on their speed, or more correctly, their Kinetic Energy). This has essentially nothing to do with electrons, and is described by Planck’s Law and the Stefan-Boltzmann Law which can be derived from it. The other whole-molecule processes are conduction and convection, along with the additional issue of Latent Heat, which is involved during solid/liquid and liquid/gas changes of state.
The electrons become specifically involved when photons (from some external source) are able to boost electrons within molecules from initial energy states to higher ones. The electrons “don’t like” being in excited states, and dump the energy in the form of photons of equal frequency in order to return to their previous condition. This absorption/emission process takes place in nanoseconds, and has little or no lasting effect on the Kinetic Energy (and thus the temperature) of the molecules. If a molecule has an available electron transition corresponding to the energy of the incoming photon, then it will absorb and then re-emit the energy. If no such transition is available, the photon just continues on its merry way, and the material is thus transparent to radiation of that frequency.
A bit of study on each these topics will make things clearer.
/dr.bill
bubbagyro says:
June 5, 2010 at 12:46 pm
I guess since I am a diffusion expert in my career, …..
_____________________________________________________________________
bubbagyro, I have a question for you. My experience was with mixing in batch and continuous production processes. That is why I am having a bit of a problem with the concept of a uniform concentration of CO2 in the atmosphere. However I worked with liquids and solids (a royal pain to mix) but never gases.
So here is the question:
Given the day night fluctuations in CO2 from plants and the contribution of variable point sources like Volcanoes and humans, do you think CO2 is a uniform concentration (+/- 5 ppm) at the 11,000 ft or whatever where CO2 is being measured?
I think that Mauna Loa CO2 measurements are valid. However, I haven’t seen any evidence that man is responsible for the increase. Given that the fossil fuel derived percentage of atmospheric CO2, is estimated at 1-4%, is seems doubtful that burning fossil fuels is the cause of the increase.
All those questioning how CO2 acts as a GHG try this link:
[http://] scienceofdoom.wordpress.com/
An excellent site
Here are a few CO2 levels superimposed (together with their linear curve fit)
[http://] img27.imageshack.us/img27/3694/co2manytrends.png
Saury Taukum is in the middle of a continent _ no ocean absorption
Mauna loa in the middle of an ocean
Their CO2 levels are similar
It is interesting that the CO2 yearly variation gets bigger further north and that a true sh antiphase signal is not apparent until you reach south pole.
It is also interesting that La Jolla is not phase shifted from Barrow despite a much later growing period start in barrow.
This is a plot of the depth of the annual CO2 cycle at point barrow.
[http://] img4.imageshack.us/img4/4449/co2dipptbarrow.jpg
It is steadily increasing.
\harry
dr.bill says:
June 5, 2010 at 3:44 pm
The electrons become specifically involved when photons (from some external source) are able to boost electrons within molecules from initial energy states to higher ones. The electrons “don’t like” being in excited states, and dump the energy in the form of photons of equal frequency in order to return to their previous condition. This absorption/emission process takes place in nanoseconds, and has little or no lasting effect on the Kinetic Energy (and thus the temperature) of the molecules.
The absorption is very rapid for CO2 but the emission process is rather slow, depending on the actual energy state involved. Collisions at atmospheric pressure are orders of magnitudes more frequent (~10/nsec) and are therefore the primary means of deactivation in the lower troposphere.
Dr A Burns says:
June 5, 2010 at 4:15 pm
I think that Mauna Loa CO2 measurements are valid. However, I haven’t seen any evidence that man is responsible for the increase. Given that the fossil fuel derived percentage of atmospheric CO2, is estimated at 1-4%, is seems doubtful that burning fossil fuels is the cause of the increase.
Since the measured annual accumulation in the atmosphere is about half the amount released into the atmosphere by fossil fuel combustion it’s impossible for it to be otherwise!
Anna V-
“Does each molecule carry a passport that says: I am from the volcano, I am from the top atmosphere?”
Well, not EACH molecule, but a gas sample – yes. An atmospheric CO2 signature will have carbon-14. A volcanic CO2 signature should have very little or no carbon-14, half life 5715 years. C-14 is generated in the atmosphere by cosmic rays and was decades ago by nuclear explosions. So if one cared to look, one could tell the difference. A representative sample should have a carbon 14 signature similar to non-volcanic sites. (Fossil fuel carbon will also have almost no C-14.)
“Are we talking of a gas that is supposed to be a good mixer?” CO2 molecular weight is 44 vs average atmospheric MW of 29, so CO2 emanating from a volcano is more dense than air and may tend to hang low.
Willis Eschenbach says:
June 5, 2010 at 12:24 pm
‘CO2 is trapped near the ground only in certain circumstances. However, it does not have to be high up in the air to absorb and emit radiation. My bible, Geiger’s “The Climate Near the Ground”, states that about three quarters of the downwelling radiation striking the ground comes from the bottom 90 metres (300 ft) of the atmosphere.’
If the above statement is true, does three quarters of the remaining quarter of downwelling radiation ( both water vapor and co2?) comes from next 300ft (300ft to 600ft) of atmosphere?
JER0ME says:
June 5, 2010 at 3:37 pm
Correct, gives off CO2 during the day. Sorry.
To Gail: It depends on concentration in and out. It is being destroyed in the stratosphere, high troposphere, and being pumped in from below. This is the whole point – it is never in equilibrium.
To the Southern Hemi guy. This is interesting. I would expect the Antarctic to have higher CO2 in the troposphere. The plant activity of algae is highest, even in ice as has been mentioned.
The variance in the lower troposphere should be high when the sun shines, especially in summer.
CO2 microclimate is a worthy hypothesis, so I’m glad the data overturns it in this case. If interested you can also check Cape Grim, which is our local equvalent CO2 measurement beauty spot (sans volcano). The data looks to be consistent.
On other hand I came across this example of CO2 microclimate yesterday:
http://carbon-sense.com/2010/06/03/tree-growth-near-power-stations/
Logical I guess, but I’d never thought about it before. Plantation tree growth rate triples next to a coal fired power station – business opportunity anyone?
(courtesy of The Daily Bayonet)
Rob JM-
“While the CO2 is going up, the cause can not be humans.”
The reason AGW scientists finger humans for the annual increase is a simple mass balance. (Well, maybe not “simple”.) The increase in mass of CO2 in the atmosphere year to year is relatively easily estimated from data records like Mauna Loa.
Human emissions of CO2 are somewhat less easily estimated from fossil fuel consumption data (don’t know of any “global fossil fuel consumption data clearinghouses” to which everyone must report) but estimates are obtained nonetheless.
Result: The annual mass increase in atmospheric CO2 is about half human emissions from fossil fuel consumption. The other half of human emissions are absorbed by the environment.
Therefore, humans are not contributing “5%” of the annual rise in atmospheric CO2 as you assert but rather 200%. One presumes that if humans were not burning fossil fuels, the atmospheric concentration would not be rising.
Bernd Felsche –
What were the levels of CO2 in the air and oceans during ice ages?
See here: http://www.globalwarmingart.com/images/1/1c/Carbon_Dioxide_400kyr.png
At the last glacial maximum 20,000 years ago, 180 ppm CO2.
After the ice sheets melted and before 1850, 255 to 280 ppm.
April 2010, 395 ppm.
Solubility of CO2 in the cold glacial vs. warming interglacial oceans is part of the story, but not the whole story.
Not so much due to a dead planet. The latest prevailing hypothesis is that [somehow – Nobel prize potential] ice sheets cause circulation to be greatly reduced in the deep ocean. Plants and animals absorb CO2 from the atmosphere, die, and sink into the deep.
When the ice begins to melt rapidly at the end of an ice age [again, the reasons are not clear – Nobel prize potential], deep ocean circulation increases bringing the “stored” CO2 back to the surface.
@Nylo
I’m not so sure we emit CO2 at a steady rate year round. Coal and natural gas being more expensive than nuclear and hydro, they are the first to be curtailed as temperatures moderate in the fall and spring.
We also do more driving in the summer than the winter, I would think.
As the use of fossil fuels has increased, this seasonal imbalance would have increase, too.