CO2 monthly mean at Mauna Loa leveling off, dropping?

Source: NOAA

In the graph above, the black line is the seasonally adjusted value while the red is the monthly mean. This is based on data through March. May is normally the peak month. Here we see how Mauna Loa CO2 has lagged in its annual rise. The likely culprit: Pacific ocean cooling due to La Nina and increased solubility of CO2 in water.

This graph certainly supports the notion of the ocean’s importance in CO2 trends, something Roy Spencer did a guest post on CO2 and oceans here on this blog and was roundly criticized for it in some circles.

Given that May is normally the peak month for CO2, and because we still see a strong La Nina, the result could be a lower CO2 max in 2008 than 2007 for Mauna Loa. This has happened before in the 60s and 70s in the last cool PDO phase (lasting til 1977). Even if it stays even with last year’s level, this tells us a lot and sheds doubt on these ideas:

1. Anthropogenic accumulation (civilization is still producing CO2)

2. A CO2 residence time of several hundred years seems unlikely now

3. Giegengack’s thesis that if man stopped emitting CO2, the earth would emit more to compensate, the premise being that since man has for the first time “upset the balance” and is pressing CO2 into the earth, then once the balance is restored the earth will resume emitting it instead.

The global data plot below doesn’t show the same trend as Mauna Loa, so it appears that this CO2 dropoff at Mauna Loa is a regional effect due to Hawaii’s proximity to cooler ocean temperatures.

It will be interesting to see in the coming months what happens globally, should we see a drop-off or leveling of global CO2 in response to our quiet sun and La Nina, it will be difficult for AGW proponents to explain. Nature will indeed be the final arbiter of this debate.

We live in interesting times. Hat tips to Joe D’Aleo and Alan Siddon for portions of this post.

UPDATE: Lucia at the Blackboard has posted an interesting rebuttal to criticisms of this simple presentation above. It is worth a read.


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Mike Bryant

Could a solar minimum cause a drop in CO2 levels?

Brian D

This could be something similiar to 1992. PPM only rose 0.49 for the year. That was the lowest rise since 1959.Now if it where to go negative, that would be something. It hasn’t done that yet since 1959.

Cross linked and partially copied at the:
CoRev, Editor (above referenced blog)

A. Fucaloro

In your link to Dr.Spencer’s guest post, you provide a graph of CO2 solubility as a function of temperature. You fail to provide the units of the ordinate (vertical) axis and do not mention the partial pressure ofCO2 for which the graph applies.
REPLY: I updated the graph, if you have one that is more representative, I welcome a link to an image.

Wow – One of the reasons Mauna Loa was selected as a CO2 monitoring spot was because it was so far from, well, everything and atmospheric gases would be well mixed by the time they reached Mauna Loa. If it winds up that Mauna Loa is well placed to measure ocean absorption of CO2, that would be off the irony scale!


No, no, no this is just due to Koyoto and the Bush recession reducing emissions thus proving AlGore is right! The global temperature trend has been flat so CO2 must not be rising.
If Mona Loa is the station where global CO2 is measured where does the second graph get it’s data from?
FROM NOAA: The graph shows recent monthly mean carbon dioxide globally averaged over marine surface sites. The Global Monitoring Division of NOAA/Earth System Research Laboratory has measured carbon dioxide and other greenhouse gases for several decades at a globally distributed network of air sampling sites (Conway, 1994). A global average is constructed by first fitting a smoothed curve as a function of time to each site, and then the smoothed value for each site is plotted as a function of latitude for 48 equal time steps per year. A global average is calculated from the latitude plot at each time step (Masarie, 1995).

Mike Bryant

Someone obviously forgot to run that through the adjustments before publication.

An interesting paper from 1994 is referenced at Here’s the abstract. Note the part I emphasized…
The relationship between the anomalies in the sea-surface temperature of the eastern equatorial Pacific Ocean region and the first derivative of the atmospheric CO2 concentration has been investigated by using cross-correlation and cross-spectral analysis. Data of the Barrow, Mauna Loa, Samoa and South Pole stations have been used in this study. The mature stage of the El Niño events usually leads the maxima of the CO2 growth rate, especially in the Mauna Loa and South Pole records. A significant time variability of the cross-correlation and cross-spectral patterns has been observed. ***GENERALLY, THE SEA-SURFACE TEMPERATURE ANOMALIES PRECEDE THE CHANGES IN ATMOSPHERIC CO2 GROWTH RATES BY ABOUT 5-7 MONTHS AT MAUNA LOA, 7-9 MONTHS AT SAMOA AND THE SOUTH POLE AND 8-13 MONTHS AT BARROW***.

Sanjong Thapa

The cool part about these graphs is that it has recently been discovered that ‘global warming’ ended in 1998.
These charts show that rising Co2 does not coincide with rising temps. Or, Co2 has nothing to do with The Earth’s climate.
Great stuff.


Wouldnt it be interesting if CO2 levels continued to fall over the next few years as ocean temps continue to fall.
Maybe man’s output of CO2 was never significant at all. Mayne the rise in CO2 followed the global temperature rise that started in the late 1800s !!


OH NO! If temprature and CO2 drops this AGW debate will go on forever. The AGW proponents will say; “see, CO2 goes down and temperature goes down”
Sceptics will say; “But temperature went down before CO2”
AGW proponents “DENIALIST, ARRRGHH!!!!”


Now that is interesting!…. It’s what the longer timescale ice cores show as well….
I wonder if we’ll hear more on this?

I don’t find the lack of recent increase to be that significant. Ocean temps have stayed flat for several years but CO2 have been rising. Thus it is reasonable to assume human emissions to be the source.
What is significant though, is that the rate of increase is still roughly constant, even though human emissions have increased exponentially. That certainly doesn’t square with a CO2 lifetime of 200 years…

Pierre Gosselin (aka AGWscoffer)

It would make sense. Let’s assume:
1. We’ve entered a period of reduced solar activity, a Gore Min.,
2. The oceans respond by beginning to cool.
3. The 3000 or so Argus project robots confirm this.
4. Cool oceans start to absorb CO2, as confirmed above.
5. World atmospheric temp-drops also confirm cooling.
Could it be that we’ve been underestimating the power of the next solar minimum? Could a real nasty cold period be coming up – a GORE MINIMUM? How will the media and the entire zealot lot respond to this, should it turn out to be the case? These changes often occur abruptly.
Amazingly, with all that bio-fuel driven deforestation going on and climbing CO2 emissions, one would not expect CO2 concentrations to go decelerate.
I’m looking forward to the next few years. Truly I am.
Did I just hear a bunch of scientists bolt out the back door?


Anthony – Just eyeballing your upper graph, isn’t the drop almost exactly the same as in mid 2004?
REPLY: I didn’t do the graph, NOAA did. I looked at 2004 also, but this seems a little bit different. 2004 has one month of drop, this has two, with a larger effect on the running mean. Though, part of that could be an endpoint effect of the data.

Pierre Gosselin (aka AGWscoffer)

AGW zealots try to have us believe that the CO2 comes before the warming – first the CO2, and then the warming.
I know when I drink my 1/2 liter glass of beer, the “fizz” disappears much more quickly if the beer is served warm. If the beer is served cold, it keeps it’s fizz much longer. This would have me believe that warm oceans emit CO2. Should the oceans begin to cool, as instruments have shown over the last 5 years, then CO2 would certainly be absorbed. A Finnish scientist named Ahlbeck, I believe, wrote a paper on this.
So what could be driving the temperature of the oceans?

Pierre Gosselin (aka AGWscoffer)

@Mike Bryant,
I’d say indirectly yes. A Gore Minimum would lead to cooling, thus cooler oceans, and thus more CO2 absorption. I have no idea about the time lags here. Perhaps someone could cast some light on this.

I wonder if the temp trends of stations in the immediate area surrounding Mauna Loa are also showing a sharp drop in temps, vs those surrounding the other CO2 stations, which haven’t shown the same CO2 drop. Could we get a better idea of CO2 induced temp change rates by studying these man-made microclimates?


Since the 1960s, the annual increase in Mauna Loa CO2 has been LINEAR – ie. the same each year.
But CO2 emissions are now 300% greater than in the 1960s :
So how is possible that the increase in C02 could be linear, if our emissions are exponential ? I understand that fertilization and oceans are explainations – but the globe and oceans cooled from the 50s till the mid 70s – so the tiny CO2 emissions of the 50/60s (compared to today) should have been absorbed by the cooling oceans – and easily. If the oceans are today absorbing the 200-300% increase from the the 50/60s, then the cooling oceans of the 50/60s shoud easilty have absorbed all of the CO2 emission, which back then were just 30% of todays.


Obviously Mauna Loa has deciding to be environmental responsible and what you’re seeing is the result of Carbon Credits offsets.
See, they really do make a difference!


On CO2 resident time:
5-10 years. Hmm. Henry’s Law? We don’t need no stinking laws!

Alex Barnett

so this shows that co2 follows temperature on earth? Now that we have plateued or cooled in the last 10 years due to decreased solar activity, does this mean that co2 is following the drop? As GK said, all the rise in temperature in the last century could of been followed by an increase in co2.


Walter Dnes,
Thanks for that reference. I have a more recent study, somewhere in my files, presented at a NOAA conference, showing the same thing. There are others. For anyone interested in researching this further, the keyword to search for, besides C02, is “interannual.” The latter is a reference to the sawtooth pattern in CO2 rise. The interannual change in the rate of change (there we go again, looking at time derivatives) is pretty clearly driven by sea temperature — when oceans warm, they emit CO2, when the cool, they take up CO2.
Don’t hold your breath. The Mauna Loa series begins, in the ’50’s, I think, I don’t know what exists for meaningful measurements of CO2 prior to that (ignoring indirect measurements from isotopes), but I don’t think there’s any evidence of significant dips in the late 1800’s or mid 20th century when the temperature trends went negative. The current upward trend is probably the result of human activity; I’d be surprised if it wasn’t. I just don’t think it has much influence on global, or even regional, temperatures.
Thanks for the report. Enjoyed the read with my morning coffee. Who reads the morning paper any more, when there’s much more interesting stuff on blogs?

Tom in Florida

I would love to see these graphs with the vertical scale from 0 to 1,000,000.
That would show how tiny the rise of CO2 really is and put it in perspective.

Robert Wood

No wonder we have an outbreak of hysterical climatologist syndrome, panicing the children with horror stories of impending global burnup. They real scared that the facts are showing.


You can all thank me for this.
I turned my TV and DVD player off instead of just going to standby. Thus the CO2 in the atmosphere has dropped as they use less electricity.
Of course, I then had to turn my heating up to account for the lost heat from those devices, thus negating any save. Oh hang on…

Tom Davidson

Given the evident susceptibility to regional influences of the Mauna Loa CO2 levels, can someone with access to the appropriate raw data compare the CO2 data against local Hawaiian CO2 emissions? I wonder if the CO2 may be correlated with the population and development of Hilo.

Mike Bryant

James Hansen announced that we have now reached the “tipping point” of 385PPM CO2.

GK: The levels has not begin to fall yet. It’s still above last year for this month and has only begin to rise slower. (But I pretty much believe that the antropogenic addition of CO2 is theoretically up to 5 percent – and maybe a bit more in reality – of the total of +30 percent in the atmosphere. I may be wrong, but I agere that the CO2 concentration may sometimes stop rising and start to fall, just as the methane concentrations has since 1999.)

GK: Globally the increase rate hasn’t even started to drop. (Let’s assume the CO2 measurement devices is better than the temperature stations.)

It would be interesting if Gore’s graph where temperature leads CO2 turns out to be correct because there is some mechanism we don’t understand. I hope not … because getting CO2 back to a geological norm is the only mitigating factor leading into the Landscheidt Minimum coming. Brutal Winter coming moderated by a weak Cycle 24 at 100 and then the 1600’s all over again. Getting a basic nutrient for plant life up above a distress level would help deal with the reduced area of activity. I’ve seen 3 studies so lately that say adding more CO2 to the atmosphere at this level actually has little effect as a GWG because it’s effect diminishes as the amount increases … so that’s not going to help.


So let’s explore this. Let’s suppose that in 2009 we see the CO2 growth reverse, and start declining at the same rate as it’s grown in the last 100 years. What’s the “tipping point” for plant life and by which year would we reach it?


……And as I wrote that note this also occured to me – the greenhouse effect of CO2 is logarithmic – so the effect decreases with growth, which is good news. However, it also means that the negative effect – ie the reduction in greenhouse warming effect – of removing CO2 Increases as it reduces. Does this mean that we would get a feedback effect as the CO2 decreases, which could cause runaway cooling?
(Don’t you just love this game…..?)

Ien: CO2 does not leads temperature in Gore’s graph, but he more or less says it does, of course (otherwise the non-fitting truth would have been told).

JohnB: If there aren’t any known feedback in the opposite direction I think it’s useless to speculate about it. If you don’t think more CO2 means a lot to warming because its effect declines at a higher concentration levels, than also lower concentrations at this “higher” 380 ppm levels means less change. But I don’t think CO2 is an important player anyway (the difference between average 280 ppm at warm periods and 180 ppm at ice ages might mean a few tenth of a degree; too little to trigger feedbacks). No one shall expect climate to change more than very little because of a proposed interaction between CO2 and temperature. I think that idea is qualified stupidity. (It’s bad that so many in the society of today are stupid.) For me as a skeptic of the current discourse on climate change it is impossible to suggest what you suggest.
(BTW: I *do think* the sun-cloud-connection is important, but that Milankovitch cycle and changes in the ice aldebo helps create the large ice ages because this aldebo effect is quite large etc… Maybe we have reached the top of the 1500 years cycle? We’ll maybe know in 50 or 100 years (I’m more than 90 years of age in 50 years… 😛 )
The Global Warming”, “Climate Change”, “tipping points” and speculations on hundreds of different smaller feedback effects are just rubbish alarmism. The dominating forces – for example large changes in aldebo – is important, but there will be no new positive feedback to surprice us, and definitely no “change-in-ppm-CO2-feedback”.)
I guess you did joking, but I’m a little tired of this matter so excuse my tired and boring mood.

Bruce Cobb

The thing puzzling me is that historically, there’s been a lag of C02 to temps. of at least 200 years, and as much as 800. Perhaps then, C02 is always responding to both short-term and long-term climatic elements. I doubt that man’s puny contribution of 3% does much, if anything. C02 seems a strange beast, worthy of study all on its own.

Pierre Gosselin (aka AGWscoffer)

John B
We’re well on the flat part of the logarithmic curve. I’d say we don’t have to worry about the scenario you’ve floated until CO2 levels reach the area of around 140 ppm. But at that level, the declining temperatures would be the least of our problems.


A reduction in atmospheric CO2 would only impact temperature in the same manner as its preceding increase – ie, not very much. The primary downside to a reduction is losing the aerial fertilization for plants and photosynthesis that CO2 provides.
Hansen talks about 385 as a dangerous tipping point, but anyone looking at long term geologic timeframes can see that the norm is well over 1000ppm. This man has become a raving lunatic. It is an outrage that he is portrayed as some kind of lone wolf genius terribly put-upon by his government superiors.


Basil, the interannual sawtooth of CO2 levels probably has to do with the inequal distribution of land and ocean in the two hemispheres, but whether it is because of uptake by biomass in the Northern Hemisphere summer, or uptake by oceans in the Southern Hemisphere winter seems to be controversial.


It’s not an either or proposition. Some of the decline is likely due to colder ocean, and some of it is likely due to emissions reductions / slower global economy.

Bill Illis

Oceans and plants were already absorbing about half of human’s CO2 emmissions. We are putting out about 8 billion tons of carbon right now but the CO2 concentration trend line is only increasing at what would be 3 or 4 billion tons carbon.
Oceans absorb about 92 billion tons of carbon per year and emit about 90 billion tons.
A cooling ocean would just absorb a little more so that is probably what we are seeing.
We already know that Methane levels have flatlined and might even be decreasing now. But it would take alot of change for CO2 to flatline.


I would like to add something.
First, with the AGW side, it’s supporters would argue that even if we stop everything now, we will still see up to just over 2 degrees more warming in the century to come because the CO2 take so long to move through the atmosphere. How then can we see such leveling off, or cooling for that matter, of temperatures knowing that our CO2 output has been ever-increasing?
You cannot base an argument with CO2 levels as the main driver as the fundamental science behind it says the opposite.
Secondly, the sun powered climate theory does seem to be more accurate, but still is not strong enough to explain all these changes.
We need to take a step back and take a deep breath.
We know very little about our planet and the forces that act upon it. We need to be calm and keep gathering information instead of pointing fingers. I swear if I see congress pass any bit of legislation (in the near future, technology will probably improve later on in the next century) requiring me to switch to bio-fuels or hybrid cars or to pay huge fines because Al Gore told them that the polar bears were in trouble and my car was doing, I’m probably going to flip!
That being said I think that we should be trying to clean up our environment. We’ll i think Al Gore should have been DOING things to clean up the world, rather than TELLING everyone else what to do while he sat on his private jet heading to some stupid AGW conference.

Gary Gulrud

Bill I:
“But it would take alot of change for CO2 to flatline.” This conclusion is entirely unobjectionable. But where do you get:
“Oceans and plants were already absorbing about half of human’s CO2 emmissions. We are putting out about 8 billion tons of carbon right now but the CO2 concentration trend line is only increasing at what would be 3 or 4 billion tons carbon.”?
As Spencer recently spake at the NY conference, the natural CO2 fluences are 24000 times the anthropogenic contribution, indeed, termites’ are 20 times.
The Pinatubo eruption emitted roughly the same 8Giga tons in a matter of weeks. Pretty hard to locate in the Mauna Loa curve, isn’t it?
Your equation makes sense only if you’ve eliminated the change in partial pressure of Oceanic CO2 due to temperature. Using balanced equations of these fluences is a convenient shorthand but it leads to startling failures in reasoning.

Bill Illis

Gary G. These numbers just come from the various Carbon Cycle estimates out there. Some are slightly different than others but Wiki has a diagram that explains it.
Oceans – In 92; Out 90 Plants and soil – In 123; out 122
We have to work in Carbon, because when CO2 gets absorbed in the ocean or by plants, it gets converted into other Carbon-based molecules. When they are emitted, they are usually converted back into CO2.
While human emissions are dwarfed by the natural processes, we are adding Carbon to a system which was pretty close to being balanced before.
There are other papers as well that show the concentration of CO2 is not increasing at the rate CO2 from fossil fuels etc is being emitted.

There has been a lot of talk of acidification of the oceans if they absorb CO2 too fast, and then all the coral dies and all the crustacea and moluscs cannot make their shells and die too. Good openings for politicians to make their own patch and media tycoons to sell more newpapers?

Jerker Andersson

So what causes the CO2 to raise on earth? I have been made to belive that it was humans that caused the raise. I had no reason to think otherwise.
Recent scientific studies have showed that the climate do not behave as the AGW theory predict so I have not been very worried about human caused CO2 emissions.
Today I sat down and put together a graph that shows both RSS temperature anomaly and NOAA global CO2 increase per year.
It was amazing to see how sensitive the CO2 increase is to changes in global temperature. It certainly isn’t humans that changes their CO2 emissions that much each year.
If the CO2 increase is that sensitive to temperature changes, couldn’t it be that almost all CO2 increase we have seen is caused by natural increase of global temperature?
See the graph below that I have put together.
I don’t know how to make double Y-axises in excel so the temperature scale is missing.

This is a paper some have obviously not seen.
– The Acquittal of Carbon Dioxide.
by Jeffrey A. Glassman PhD.
I sort of did an easy version,
– The Solubility pump. – A layman’s (simple) overview.
Hope that helps.

SteveSadlov: There is no current slow down in emissions, and you shall check the post and see the absolutely perfect co-variance between temperature changes and difference in CO2 increase each year! That is really striking.
If your comment was on the seasonal increase and decerase of CO2 . (There is no other CO2 _decrease_ here I think!) In that case, either, in no way variation in human CO2 emission can play a part?
The human emissions is twice as large as the net increase each year, and the size of the annual variation is actually bigger than all the human emissions together!
The human CO2 emission can’t vary to such extent that it has the slightest chance to contribute to the seasonal variations! The seasonal variation is much bigger than the total human emissions during a year, and the seasonal variation of the human CO2 emissions can’t be larger than a not so large fraction of the total annual human emission. It’s obvious that at most a few percent of the annual CO2 variation can be caused by annual changes in the distribution of human emission.
So twice a year we have seasonal increase and decrease, respectively, which each is about 150 % of the total yearly amount of human CO2 emissions, and each change within 6 month.
It’s also good to remember that each year 30 times more CO2 is emitted (and absorbed) from the oceans and the biosphere than is emitted from humans.
If the CO2 concentration change at Mauna Loa is related to seasonal changes — changes of growth — on the northern hemisphere I guess it is possible that the variations for all stations is due to the geographical distribution of these stations…
But BTW, here is a .gif-animation showing the seasonal changes at different latitude, and my notion in the last paragraph seems to be wrong; almost all stations follow the seasonal trend:
The large variation at the northern hemisphere has to indicate something. But I don’t know what. I think the northern hemisphere normally vary more in climate than the southern hemisphere. Is may also vhave a bigger difference in seasonal temperature, more biosphere/land, and/or larger changes in ice between winter and summer…

SteveSadlov: Your comment is btw typical for a person that I would like to really call a denier. There is no decrease in CO2 emissions, but you say it is so that the development in AGW shall fit your belief. Am I right, or?
I also think many AGW:ers will say that the focus on AGW saved the world if we get a chill the coming decades. It’s good to be honest, and if they will think that they are honest, but I anyway will call them deniers; deniers of data and science.

SteveSadlov: The post i wanted you to check is Roy Spencers presentation and solid analysis of CO2 concentration and temperature here:

Bob G

I think we are all jumping the gun here. CO2 values for Jan Feb and March 08 are all above the values for those months in 07, and April usually shows a big jump in concentration.