Guest Post by Willis Eschenbach
There seem to be a host of people out there who want to discuss whether humanoids are responsible for the post ~1850 rise in the amount of CO2. People seem madly passionate about this question. So I figure I’ll deal with it by employing the method I used in the 1960s to fire off dynamite shots when I was in the road-building game … light the fuse, and run like hell …
First, the data, as far as it is known. What we have to play with are several lines of evidence, some of which are solid, and some not so solid. These break into three groups: data about the atmospheric levels, data about the emissions, and data about the isotopes.
The most solid of the atmospheric data, as we have been discussing, is the Mauna Loa CO2 data. This in turn is well supported by the ice core data. Here’s what they look like for the last thousand years:
Figure 1. Mauna Loa CO2 data (orange circles), and CO2 data from 8 separate ice cores. Fuji ice core data is analyzed by two methods (wet and dry). Siple ice core data is analyzed by two different groups (Friedli et al., and Neftel et al.). You can see why Michael Mann is madly desirous of establishing the temperature hockeystick … otherwise, he has to explain the Medieval Warm Period without recourse to CO2. Photo shows the outside of the WAIS ice core drilling shed.
So here’s the battle plan:
I’m going to lay out and discuss the data and the major issues as I understand them, and tell you what I think. Then y’all can pick it all apart. Let me preface this by saying that I do think that the recent increase in CO2 levels is due to human activities.
Issue 1. The shape of the historical record.
I will start with Figure 1. As you can see, there is excellent agreement between the eight different ice cores, including the different methods and different analysts for two of the cores. There is also excellent agreement between the ice cores and the Mauna Loa data. Perhaps the agreement is coincidence. Perhaps it is conspiracy. Perhaps it is simple error. Me, I think it represents a good estimate of the historical background CO2 record.
So if you are going to believe that this is not a result of human activities, it would help to answer the question of what else might have that effect. It is not necessary to provide an alternative hypothesis if you disbelieve that humans are the cause … but it would help your case. Me, I can’t think of any obvious other explanation for that precipitous recent rise.
Issue 2. Emissions versus Atmospheric Levels and Sequestration
There are a couple of datasets that give us amounts of CO2 emissions from human activities. The first is the CDIAC emissions dataset. This gives the annual emissions (as tonnes of carbon, not CO2) separately for fossil fuel gas, liquids, and solids. It also gives the amounts for cement production and gas flaring.
The second dataset is much less accurate. It is an estimate of the emissions from changes in land use and land cover, or “LU/LC” as it is known … what is a science if it doesn’t have acronyms? The most comprehensive dataset I’ve found for this is the Houghton dataset. Here are the emissions as shown by those two datasets:
Figure 2. Anthropogenic (human-caused) emissions from fossil fuel burning and cement manufacture (blue line), land use/land cover (LU/LC) changes (white line), and the total of the two (red line).
While this is informative, and looks somewhat like the change in atmospheric CO2, we need something to compare the two directly. The magic number to do this is the number of gigatonnes (billions of tonnes, 1 * 10^9) of carbon that it takes to change the atmospheric CO2 concentration by 1 ppmv. This turns out to be 2.13 gigatonnes of carbon (C) per 1 ppmv.
Using that relationship, we can compare emissions and atmospheric CO2 directly. Figure 3 looks at the cumulative emissions since 1850, along with the atmospheric changes (converted from ppmv to gigatonnes C). When we do so, we see an interesting relationship. Not all of the emitted CO2 ends up in the atmosphere. Some is sequestered (absorbed) by the natural systems of the earth.
Figure 3. Total emissions (fossil, cement, & LU/LC), amount remaining in the atmosphere, and amount sequestered.
Here we see that not all of the carbon that is emitted (in the form of CO2) remains in the atmosphere. Some is absorbed by some combination of the ocean, the biosphere, and the land. How are we to understand this?
To do so, we need to consider a couple of often conflated measurements. One is the residence time of CO2. This is the amount of time that the average CO2 molecule stays in the atmosphere. It can be calculated in a couple of ways, and is likely about 6–8 years.
The other measure, often confused with the first, is the half-life, or alternately the e-folding time of CO2. Suppose we put a pulse of CO2 into an atmospheric system which is at some kind of equilibrium. The pulse will slowly decay, and after a certain time, the system will return to equilibrium. This is called “exponential decay”, since a certain percentage of the excess is removed each year. The strength of the exponential decay is usually measured as the amount of time it takes for the pulse to decay to half its original value (half-life) or to 1/e (0.37) of its original value (e-folding time). The length of this decay (half-life or e-folding time) is much more difficult to calculate than the residence time. The IPCC says it is somewhere between 90 and 200 years. I say it is much less, as does Jacobson.
Now, how can we determine if it is actually the case that we are looking at exponential decay of the added CO2? One way is to compare it to what a calculated exponential decay would look like. Here’s the result, using an e-folding time of 31 years:
Figure 4. Total cumulative emissions (fossil, cement, & LU/LC), cumulative amount remaining in the atmosphere, and cumulative amount sequestered. Calculated sequestered amount (yellow line) and calculated airborne amount (black) are shown as well.
As you can see, the assumption of exponential decay fits the observed data quite well, supporting the idea that the excess atmospheric carbon is indeed from human activities.
Issue 3. 12C and 13C carbon isotopes
Carbon has a couple of natural isotopes, 12C and 13C. 12C is lighter than 13C. Plants preferentially use the lighter isotope (12C). As a result, plant derived materials (including fossil fuels) have a lower amount of 13C with respect to 12C (a lower 13C/12C ratio).
It is claimed (I have not looked very deeply into this) that since about 1850 the amount of 12C in the atmosphere has been increasing. There are several lines of evidence for this: 13C/12C ratios in tree rings, 13C/12C ratios in the ocean, and 13C/12C ratios in sponges. Together, they suggest that the cause of the post 1850 CO2 rise is fossil fuel burning.
However, there are problems with this. For example, here is a Nature article called “Problems in interpreting tree-ring δ 13C records”. The abstract says (emphasis mine):
THE stable carbon isotopic (13C/12C) record of twentieth-century tree rings has been examined1-3 for evidence of the effects of the input of isotopically lighter fossil fuel CO2 (δ 13C~-25‰ relative to the primary PDB standard4), since the onset of major fossil fuel combustion during the mid-nineteenth century, on the 13C/12C ratio of atmospheric CO2(δ 13C~-7‰), which is assimilated by trees by photosynthesis. The decline in δ13C up to 1930 observed in several series of tree-ring measurements has exceeded that anticipated from the input of fossil fuel CO2 to the atmosphere, leading to suggestions of an additional input ‰) during the late nineteenth/early twentieth century. Stuiver has suggested that a lowering of atmospheric δ 13C of 0.7‰, from 1860 to 1930 over and above that due to fossil fuel CO2 can be attributed to a net biospheric CO2 (δ 13C~-25‰) release comparable, in fact, to the total fossil fuel CO2 flux from 1850 to 1970. If information about the role of the biosphere as a source of or a sink for CO2 in the recent past can be derived from tree-ring 13C/12C data it could prove useful in evaluating the response of the whole dynamic carbon cycle to increasing input of fossil fuel CO2 and thus in predicting potential climatic change through the greenhouse effect of resultant atmospheric CO2 concentrations. I report here the trend (Fig. 1a) in whole wood δ 13C from 1883 to 1968 for tree rings of an American elm, grown in a non-forest environment at sea level in Falmouth, Cape Cod, Massachusetts (41°34’N, 70°38’W) on the northeastern coast of the US. Examination of the δ 13C trends in the light of various potential influences demonstrates the difficulty of attributing fluctuations in 13C/12C ratios to a unique cause and suggests that comparison of pre-1850 ratios with temperature records could aid resolution of perturbatory parameters in the twentieth century.
This isotopic line of argument seems like the weakest one to me. The total flux of carbon through the atmosphere is about 211 gigtonnes plus the human contribution. This means that the human contribution to the atmospheric flux ranged from ~2.7% in 1978 to 4% in 2008. During that time, the average of the 11 NOAA measuring stations value for the 13C/12C ratio decreased by -0.7 per mil.
Now, the atmosphere has ~ -7 per mil 13C/12C. Given that, for the amount of CO2 added to the atmosphere to cause a 0.7 mil drop, the added CO2 would need to have had a 13C/12C of around -60 per mil.
But fossil fuels in the current mix have a 13C/12C ration of ~ -28 per mil, only about half of that requried to make such a change. So it is clear that the fossil fuel burning is not the sole cause of the change in the atmospheric 13C/12C ratio. Note that this is the same finding as in the Nature article.
In addition, from an examination of the year-by-year changes it is obvious that there are other large scale effects on the global 13C/12C ratio. From 1984 to 1986, it increased by 0.03 per mil. From ’86 to ’89, it decreased by -0.2. And from ’89 to ’92, it didn’t change at all. Why?
However, at least the sign of the change in atmospheric 13C/12C ratio (decreasing) is in agreement with with theory that at least part of it is from anthropogenic CO2 production from fossil fuel burning.
CONCLUSION
As I said, I think that the preponderance of evidence shows that humans are the main cause of the increase in atmospheric CO2. It is unlikely that the change in CO2 is from the overall temperature increase. During the ice age to interglacial transitions, on average a change of 7°C led to a doubling of CO2. We have seen about a tenth of that change (0.7°C) since 1850, so we’d expect a CO2 change from temperature alone of only about 20 ppmv.
Given all of the issues discussed above, I say humans are responsible for the change in atmospheric CO2 … but obviously, for lots of people, YMMV. Also, please be aware that I don’t think that the change in CO2 will make any meaningful difference to the temperature, for reasons that I explain here.
So having taken a look at the data, we have finally arrived at …
RULES FOR THE DISCUSSION OF ATTRIBUTION OF THE CO2 RISE
1. Numbers trump assertions. If you don’t provide numbers, you won’t get much traction.
2. Ad hominems are meaningless. Saying that some scientist is funded by big oil, or is a member of Greenpeace, or is a geologist rather than an atmospheric physicist, is meaningless. What is important is whether what they say is true or not. Focus on the claims and their veracity, not on the sources of the claims. Sources mean nothing.
3. Appeals to authority are equally meaningless. Who cares what the 12-member Board of the National Academy of Sciences says? Science isn’t run by a vote … thank goodness.
4. Make your cites specific. “The IPCC says …” is useless. “Chapter 7 of the IPCC AR4 says …” is useless. Cite us chapter and verse, specify page and paragraph. I don’t want to have to dig through an entire paper or an IPCC chapter to guess at which one line you are talking about.
5. QUOTE WHAT YOU DISAGREE WITH!!! I can’t stress this enough. Far too often, people attack something that another person hasn’t said. Quote their words, the exact words you think are mistaken, so we can all see if you have understood what they are saying.
6. NO PERSONAL ATTACKS!!! Repeat after me. No personal attacks. No “only a fool would believe …”. No “Are you crazy?”. No speculation about a person’s motives. No “deniers”, no “warmists”, no “econazis”, none of the above. Play nice.
OK, countdown to mayhem in 3, 2, 1 … I’m outta here.
Double or quits!
Someone mentioned that there was not enough economically accessible fossil fuel left in the world to produce a doubling of CO2 levels. Maybe not even enough to double it against pre-industrial levels. That is a pretty important statement as CAGW scenarios pretty much rely on that doubling. A response to that was that out gassing had plenty to spare. This post seems to say don’t hold your breath. What are the facts?
Oil
Global proved oil reserves in 2008 fell by 3 billion barrels to 1,258 billion barrels, 0r 52.836 trillion US gallons with an R/P (reserves-to-production) ratio of 42 years.
(http://green-energysaving.com/carbon-emissions/how-much-oil-is-left-in-the-world-when-will-oil-run-out/)
(http://www.bp.com/sectiongenericarticle.do?categoryId=9023769&contentId=7044915)
Gas
Global proved reserves of natural gas in 2008 were 185.02 trillion cubic meters or roughly 6,500 trillion cubic feet with an R/P ratio of 63.1 years.
(http://www.carboncounted.co.uk/when-will-fossil-fuels-run-out.html)
(http://green-energysaving.com/carbon-emissions/fossil-fuels/how-much-natural-gas-is-left-in-the-world-when-will-natural-gas-run-out/)
(http://www.bp.com/sectiongenericarticle.do?categoryId=9023779&contentId=7044843)
Coal
World Energy Council 2007 global coal reserves was 847 billion tonnes. BP’s 2008 total estimate was 826 billion tonnes with an R/P ratio of 122*. Roughly half of this is sub-bituminous and lignite.
(But Prof. David Rutledge, chair of Engineering and Applied Science at the California Institute of Technology applied the “Hubbert linearization method” to today’s major coal-producing countries, including the US, China, Russia, India, Australia and South Africa. Hubbert linearisation suggests that future coal production will amount to around 450 billion tonnes – little more than half the official reserves.
Although most academics and officials reject the idea out of hand, over the past 20 years, even official reserves have fallen by more than 170 billion tonnes even though production is only 6 billion tonnes per year. 50 billion has “disappeared” from the official estimates – 20 billion between 2007 and 2008.
In February 2007, the European Commission’s Institute for Energy reported that the reserves-to-production (R/P) ratio had dropped by more than a third between 2000 and 2005, from 277 year’s worth to just 155. By 2008 this was 122.
*The world coal institute notes however that recent falls in the R/P ratio can be attributed to the lack of incentives to prove up reserves, rather than a lack of coal resources. Exploration activity is typically carried out by mining companies with short planning horizons rather than state-funded geological surveys. There is no economic need for companies to prove long-term reserves.)
(http://green-energysaving.com/carbon-emissions/fossil-fuels/how-much-coal-is-left-in-the-world-when-will-coal-run-out/)
(http://www.davidstrahan.com/blog/?p=116)
(http://www.worldcoal.org/coal/where-is-coal-found/)
(http://www.bp.com/sectiongenericarticle.do?categoryId=9023784&contentId=7044480)
Summary of world fossil fuel resources
For our purposes I will take the highest figures to arrive at the highest achievable levels of CO2. So 1,258 billion barrels of oil, 6,500 billion cubic feet of gas, 413 billion tonnes of “black” coal and 413 billion of “brown” coal.
The combined liquid fuels from an average barrel of crude oil will produce a minimum of 317kg of CO2 when consumed. (http://numero57.net/2008/03/20/carbon-dioxide-emissions-per-barrel-of-crude/)
So we get 398,786 billion Kg of CO2 from all known oil reserves
1000 cubic feet of Gas will results in between 115lb – 120lb of carbon dioxide depending on the temperature at which the cubic feet were measured.
(http://cdiac.ornl.gov/pns/faq.html)
(http://www.eia.doe.gov/oiaf/1605/coefficients.html)
Let’s stick to our rule of taking the worst case. We get 6.5 billion X 120lbs or 780 billion lbs of CO2. That is just less than 354 billion kg from gas.
Best quality anthracite produces 2.84 times its own weight in CO2 falling to lignite at only 1.4 times its own weight.
(http://www.eia.doe.gov/cneaf/coal/quarterly/co2_article/co2.html)
Coal type CO2 lbs per short ton
Anthracite AC 5685.00
Bituminous BC 4931.30
Subbituminous SB 3715.90
Lignite LC 2791.60
(http://www.eia.doe.gov/oiaf/1605/coefficients.html)
(The short ton is a U.S. unit of weight equal to 2,000 pounds. For the most part this post uses metric tonnes = 1000 kgs – it is noted when otherwise)
For our calculation we will again apply our worst case rule and say all black coal is Anthracite and all brown coal is sub-bituminous. 413 billion X 2.84 = 1,173 billion tonnes plus 413 X 1.86 = 768 billion tonnes. 1,941 billion tonnes in all or (big number alert!) 1,941,000 billion kg of CO2 from all known coal reserves.
The coal number makes the oil and gas figures look like a minor problem. “Oil and gas by themselves don’t have enough carbon to keep us in the dangerous zone [of global warming] for very long,” said Pushker Kharecha, a scientist and colleague of Hansen at NASA GISS. http://www.wired.com/wiredscience/2008/12/oil-not-the-cli/#ixzz0q7dazJcf You can kind of see where J Hansen’s death trains are coming from. Sorry –sorry, wash my mouth out etc. Anyhoo!
Total CO2 from burning all known fossil fuel reserves would be 2,340,140 billion kgs. Loads! – but what is that in p.p.m. of the total atmosphere? Well…
The weight of the Earth’s atmosphere is 441,000 billion x 10 = 4.41 million billion (long) tons. Or 4,480,000 billion metric tonnes.
(http://www.hydrogen.co.uk/h2_now/journal/articles/2_global_warming.htm)
2340.140 / 4,480,000 = 522p.p.m.
So yes it could more than double CO2 levels.
Except that only 40% of that will stay in the atmosphere for any meaningful length of time. A constant unchanging 40% by the way. Knorr, W. (2009), Is the airborne fraction of anthropogenic CO2 emissions increasing?, Geophys. Res. Lett., 36, L21710, doi:10.1029 / 2009GL040613.
(http://wattsupwiththat.files.wordpress.com/2009/11/knorr2009_co2_sequestration.pdf)
This reduces the potential CO2 from burning all known reserves of fossil fuel to just 208 p.p.m. beyond where we are now.
Given what Willis Eschenbach tells us here about natural out gassing, that is about another 45 p.p.m. to come. 253 p.p.m. in all?
Even if the IPCC are right about 3degC per doubling that means we would struggle to find 2degC of warming left in fossil fuels and “feedback” out gassing combined.
And…relax
Here is a Null Hypothesis:
When air is trapped in snow which over decades becomes trapped by more snow and buried in ice below the firn, the CO2 in the trapped air diffuses initially into the snow layer then into the ice below the firn such that a steady state concentration balance of CO2 in the ‘bubbles’ is reached after several centuries of diffusion in both directions.
Until this hypothesis is disproved all ice core proxies should be treated with extreme caution. Especially as the results from ice cores run so counter to the results from stomata counts after all fossilized plants are used for temperature proxies.
(some studies of diffusion have been done see: CO2 diffusion in polar ice: observations from naturally formed CO2 spikes in the Siple Dome (Antarctica) ice core
Jinho AHN, Melissa HEADLY, Martin WAHLEN, Edward J. BROOK,
Paul A. MAYEWSKI, Kendrick C. TAYLOR).. Shows diffusion in the firn as well as in the ice.
My issue is with figure one ice core data. I am very skeptical that all the core data readings gave exactly the same CO2 measurement (plus or minus a few ppm). I feel assumptions have been made leading to the result shown in the figure. That is, the ice core data as interpreted by current science may not be an accurate representation of ancient CO2.
1. I imagine the readings were averaged, and I imagine that the estimated dates ascribed to each reading were off by decades — centuries for more ancient data. This could lead to a seeming constant CO2 — when actually there was considerable variability.
2. CO2 trapped in ice may not be entirely trapped. It could diffuse in ice over the centuries — again averaging out large gains and losses with the same effect as item 1.
3. I imagine the ice core CO2 “measurement” was not precisely 270ppm (or whatever) in all 8 cores — possibly in no core. Rather, the readings were quite different. Then, “Kentucky windage” was applied by adding or subtracting an amount from the “level” CO2 ppm to make ice core readings coincide with recent historical atmospheric measurements. This is circular reasoning — “we can adjust old values to today’s values because CO2 has not changed until recently”. Thus, the “perfect hockey stick shape” — is based on assumption and circular reasoning.
4. I have never seen proof that actual CO2 levels in ice cores are literally invariant over centuries or on a millennial scale. That is, the amount initially trapped may not be the amount currently in the ice. This not the same concern as item 2 (but may seem similar). So, a measurement taken today from 1000 or 10000 year old ice may not be representative of the CO2 amount originally trapped in the ice. No, there is just an amount of CO2 present today — its correlation to the amount initially present a thousand years ago is not a proven fact — it is an assumption.
Hence, if we do not really know the past history of CO2 (some folks make assumptions about it, but do not really know), then we can’t be confident about what processes are raising CO2 now.
If we are being asked to change our lifestyles and pay out trillions in new taxes to prevent CO2, we need much stronger evidence.
A number of published studies suggest that between about one fifth and one third of a pulse of CO2 would remain in the atmosphere for long periods, only being eventually removed over millennia as the slow weathering of rocks delivers more CO3– to the oceans.
Those studies completely discount the rest of the biosphere.
” Joe Lalonde says:
June 7, 2010 at 4:23 am
Willis,
I enjoy these mind manipulation response games so, here goes.[…]”
Somehow this turned me off from reading the rest of whatever Joe Lalonde had to say…
Lastly, regarding the abstract of the Nature article,
http://www.nature.com/nature/journal/v279/n5710/abs/279229a0.html
Farmer 1979.
(Think we may have learned a bit more since then?)
The mismatch of the amounts predicted by a simple calculation of the anthro sources and the amounts observed would be consistent with idea that CO2 tends to be released by the biosphere when the temperature increases. This would fit the historical records where CO2 appears to be a positive feedback on Milankovitch cycles. This fits with the swings in climate being larger than the forcings of the cycles. So, in the present day, CO2 could be it’s own positive feedback. (No, there is no run-away, but that’s too long to explain here.)
1) To be thorough, Beck’s research and data have to included here. Geocarb’s 600 million year graph should also be included. The impression given is that only man can change CO2.
2) It is highly unlikely that CO2 would be so consistent over time, volcanoes and warm/cold spells would definitely have an influence – man might, too. As with climate, CO2 would be constantly varying with the conditions.
3) Why is it ignored totally that the Mauna Loa data and ice core only “agree” because the ice core data was time shifted (artificially/fraudulently?) 84 years into the future? In my book, this horrendously poisons the resulting graph which melds two vastly different data sets.
4) As mentioned by others, Jaworowski has pointed out that ice core CO2 measurements CANNOT be interpreted as absolute—there is just too much trauma involved in taking cores. Although I usually agree with most articles presented here, I think that taking ice cores as sources of absolute CO2 data is a major failing of the discussion in this article.
@ur momisugly Doug Proctor
“1850 is used as one reference point, though 1945 and 1975 are also used.”
Yep! I use this as a “tell”! It’s bad enough the referenced time periods are arbitrary and have no real reasoning behind the picking of the time periods, but they’re entirely different time periods! The 1850 is for CO2 or industrialization even though man started to industrialize well before 1850 and made greater CO2 emissions well after 1850. The ’45-’75 seems to be somebodies idea of an ideal climate. I’ve never been allowed to vote for which time period I preferred. Even if CO2 and temps had a direct correlation, it wouldn’t be appropriate to include them in the same references unless the posit is CO2 emissions lag to effect temps is about 100 years. Which, the lag thing never made much sense to me. CO2 emissions are immediate. So, too, is the re-radiative properties of CO2, unless some can tell me how it takes x amount of time to train CO2 to become a greenhouse gas. Or perhaps it takes so long for the CO2 to bounce the energy back to earth from the enormous altitude of 10 km.
Pop quiz!! Does anyone know how much of the energy absorbed by tropospheric CO2 is radiated back down to the earth by percent? I’ve always assumed 50%, but I don’t know that either.
Friends:
I write to dispute an assertion made by several people here that determiation of the cause of the recent rise in atmospheric CO2 is a trivial matter not worthy of investigation. Perhaps this assertion was best stated by Ernesto Araujo (June 7, 2010 at 7:15 am) who wrote:
“The debate about what causes CO2 concentration in the atmosphere is pointless. What matters is: does the increase in CO2 concentration cause warming? The whole thing is about Global Warming, not about CO2 concentration. To indicate that CO2 increase causes warming, you would need to present a curve where temperature oscillations match CO2 concentration, and that curve clearly does not exist for the last 1000 years, nor for the last 150 years.”
This assertion is wrong on two counts; viz. theoretical and practical.
Michael Faraday gave a clear answer to the theoretical point when the then UK Prime Minister asked him what use Farady had for his work on electical induction. Farday replied that he knew of no use for his work but he was confident that somebody would find a use for it someday. Well, “somebody” did, and nobody could be reading this if “somebody” had not.
And the practical point is directly pertinent to the argument put by Ernesto Araujo and others. The hypothesis of anthropogenic global warming (AGW) is being used as justification for amending energy, industrial and economic policies world-wide. But that hypothesis is founded on three assumptions: viz
(1) It is assumed that the anthropogenic CO2 emission is the major cause of the increasing atmospheric CO2 concentration
and
(2) It is assumed that the increasing atmospheric CO2 concentration is significantly increasing radiative forcing
and
(3) It is assumed that the increasing radiative forcing will significantly increase mean global temperature.
There are reasons to doubt each of these assumptions. But if any one of them were known to be false then the entire AGW hypothesis would be known to be false.
Perhaps the recent rise in atmospheric CO2 concentration is anthropogenic, but it would seem injudicious to disrupt energy, industrial and economic policies on the basis of an assumption that the rise is anthropogenic.
Richard
An interesting article Willis unfortunately it is full of errors and contradictions, these may have already been pointed out but I have not had time to read all the posts.
First the history of CO2 concentration in the atmosphere. The ice core samples are not the only proxy but all other proxies are noticeably ignored. Regarding the ice core data I recommend J J Drake’s paper “A Simple Method to in ice core data.” A few of the key points, below a certain level all the gasses are dissolved in the ice due to the pressure there are no gas bubbles. The solubility of the gasses are very different thus CO2 is absorbed quicker than the other gasses even in the firn. The CO2 migrates in the ice and some gets locked into calthrates, this CO2 does not get released during the crushing process. From the isotopic analysis of the O18 the H2O and the CO2 can have a difference in age of up to 7000 years and there is a correlation between the age difference and the measured concentration of CO2.
I would also like to recommend Dr. Tim Ball’s paper “Measurement of Pre Industrial CO2 Levels”. This shows the 500 million year history of CO2 and global temperatures which clearly indicates zero correlation between CO2 and temperature.
Most ice cores will cover from 100 years to 1000 years in a single core so they are at best a general average thus they can not be compared to daily samples taken with state of the art analytical equipment. The leaf stomata proxy however is a much more precise indicator of the CO2 content in the atmosphere in the year the leaf grew, carbon dating is quite accurate since the half life is around 5300 years for C14. The leaf stomata evidence shows how erroneous and misleading the ice cores are.
Now we turn to the carbon cycle reference IPCC AR4 section 7.3.1. In engineering there is a basic calculation called a mass balance, now try to apply some of these basic principles to Fig 7.3, If the air contains 597 GT of natural and 165 GT of anthropogenic CO2 then the ratio dissolving in the oceans and being absorbed by the biota should be in this ratio. What do we have, a ratio of 70 t0 22.2 by the ocean ( close) and 120 to 2.6 by the biota ????? Now when the water in the surface of the oceans evaporate we have 900 to 18 in the liquid water but 70.6 to 20 when it evaporates, now this is really getting strange.
Then we have 244 GT of fossil fuel carbon released all time by human activity but 100 GT is already sequestered in the deep ocean leaving 144 between the air ocean and biota, but look there is 169 GT in the air alone, this is what I would term political math. The make up is the minus 140 anthropogenic in the land which I assume is CO2 released by land use, if this is the case it must be shown as a flux since this carbon is not anthropogenic created but it is released by human activity there is a 1.6 GT flux shown but how can this account for 140 GT?? Now there is a 119.6 flux caused by respiration but where is the anthropogenic component.
I created a simple mass balance program using the figure values for carbon content where possible and the iteration with all ratios balanced in both directions leads to a 2.4 year residence time for all CO2 in the atmosphere and the total CO2 content was adjusted to 860 GT to bring the figure up to data of which 79.9 G which gives 34.3 ppm as the human impact even taking the generous number of .004 deg C per ppm this yields an impact of 0.14 deg C on the global climate.
Let us now consider your evaluation of residence time and half life here I am afraid you get very confused “The strength of the exponential decay is usually measured as the amount of time it takes for the pulse to decay to half its original value (half-life) or to 1/e (0.37) of its original value (e-folding time).” How on earth can half its value be 0.37 of the same value? more political math?
There is only one half life or residence time and if you cut something in half enough times it becomes insignificant but it never reaches zero and that is where the IPCC nonsense comes from. The estimate of 6 to 8 years for the half life is high and does not agree with the most recent research. I think the average is about 5 years but by mass balance calculation it is 2.4. Your number of 211 GT per year of carbon flux yields a half life of aproximately 4 years for an atmospheric content of 860 GT. I believe the cycle is much higher than 211 GT per year, check the seasonal variation in the NH levels of CO2 due to just the annual vegitation and you start to get a picture of how large the biota uptake is.
Are you crazy? Only a fool would believe these deniers and warmists and econazis with their base motives.
Seriously though, great post, really elucidated the topic nicely for me.
J. Bob @9:34 a.m.,
Interestingly, your charts look like this one. They generally seem to begin rising around 1900.
Willis
are you saying that there is 2,460.15 billion tons of co2 in the atmosphere?
I have not been able to find a figure above 750 billion tons for co2.
Ian H:
At (June 7, 2010 at 9:08 am) you ask:
“Anyone who doesn’t think the CO_2 rise is due to human beings should explain where all that CO_2 we have emitted actually went if not into the atmosphere.”
But your question has been answered in two different ways above.
I answered it at (June 7, 2010 at 2:43 am) where I explained that the anthropogenic emission enters the carbon cycle.
And at (June 7, 2010 at 6:18 am) Steve Keohane explained that the anthropogenic emission gets lost in the error terms of the estimates of natural emissions.
These two different answers amount to alternative views of the same effect.
Until somebody can provide a sufficiently accurate measure of all the sources and sinks for the anthropogenic emission then those who “think” the CO2 rise has an anthropogenic cause need to answer the question as to why they “think” that.
I want to know if the cause of the recent rise is anthropogenic in part or in whole. The anthropogenic emission could be the cause of the rise, but consideration of the carbon cycle suggests that the anthropognic emission is irrelevant to the cause of the recent rise (please see my post at June 7, 2010 at 2:43 am for an explanation of this).
Richard
The problem with this chart is that you are arbitrarily assuming one type of exponential decay for the anthropogenic component of CO2, and implicitly an entirely other, and faster, one for natural CO2. Aside from extremely minor isotopic distribution differences, nature essentially cannot tell the two molecules apart.
If you apply the same time constant to the much larger portion of naturally generated CO2, you will quickly find the atmosphere almost entirely composed of CO2. The only way to square this would be to hypothesize that the CO2 reservoir is saturating, and becoming less able to absorb the new, anthropogenically generated CO2. But, if that were the case, the yearly variations in CO2 you see in the MLO and other records would be progressively increasing in amplitude and warped. Instead, they are very regular for the past 50 years.
The isotopic ratio question is entirely speculative and, as others have noted and as has been dramatically demonstrated in the Mann-made temperature hockey stick, the grafting of proxy data onto measured data is highly questionable. So, overall, you have questionable evidence supporting an implausible hypothesis. There can be no doubt that the CO2 rise is mostly natural, it will eventually falter, and then researchers will actually start to look for what really caused it.
@ur momisugly Steven mosher
Well, he did splice……:-)
As far as germane, if the question was simply do we have more CO2 today than 150 yrs ago, then no, they aren’t very germane. However, today, any mention of CO2 has an implicit connection to a myriad of topics while I’m left to wonder how a discussion on CO2 is germane to anything other than photosynthesis.
One other thing that I feel a need to vent on: the question of whether to call AGW advocates “warmists”. “Warmist” is awfully tame compared to “denier”. “Denier” is clearly an intentional reference to Holocaust deniers, and should be offensive to every thinking man and woman on Earth.
The History channel and other cable channels have been showcasing retrospectives on WWII for the past couple of weeks, what with Memorial Day and D-Day remembrances. My wife and I watched the episode of “The World at War” focusing on the concentration camps just the other night. I can barely see straight when I contemplate these jerks popping off about “deniers” and recall the unimaginable barbarity of the Nazis which we were reminded of again that night. I would urge you to delete any posts snarking off about “deniers” immediately and without qualification.
Not quite answering Willis’s question but James’s comment to Roy Spencers blog entry sums up extremly well the relative control on volumes of CO2 that AGW believers want to implement.
Blog here – http://www.drroyspencer.com/2010/06/warming-in-last-50-years-predicted-by-natural-climate-cycles
James Davidson says:
June 6, 2010 at 11:01 AM
CO2 levels in 1890 were 290 ppmv. ( Siple ice core.) Current levels ( Mauna Loa ) are 388 ppmv ( round it up to 390 ppmv ) for an increase of 100 ppmv over the last 120 years. The mistake a lot of people seem to make is to treat these as whole numbers, instead of what they are- the numerators of fractions. In 1890 CO2 constituted 290 millionths of the atmosphere, and this has now risen to 390 millionths of the atmosphere – an increase of 100 millionths. To express this as a fraction, multiply by 100, for an answer of 0.01%. If someone in 1890 had decided that CO2 levels should be kept constant and had succeeded 120 years later to within one hundredth of one percent, they would think they had done pretty darn well. I really cannot believe that such a small increase can have had ANY effect on global warming, and as Dr Spencer has shown, natural variation is a more likely candidate.
Willis calculations assume that with the exception of sequestration the effect from the natural world is largely static or at least much smaller. With man’s fossil fuel contribution being only1/24 of the volume produced by nature (Ian Plimer P180 man nearly 4%, Oceans nearly 60% and animal nearly 40%) it would only take a small change there to swamp and invalidate Willis’s calculations. And we know that in the past from ice core data that CO2 has generally changed with a 800 year time lag on temperature so it is extremely unlikely to have been static during this period.
So to propose controlling CO2 levels “to within one hundredth of one percent” with natures vastly larger variable input – how reasonable is that.
My understanding is that most CO2 is produced from the decay of organic matter. Would increasing temperatures accelerate this process? Would the millions of miles of roads, often concrete or gravel, create local heating effects to do the same? These local heating effects, producers of CO2 (my assumption), would have a greater effect from locations that are rather cold like cities in Russia and such land use changes may produce isotopic signatures similar to fossil fuel use due to old/frozen plant matter finally having a chance to decay and release their ancient CO2.
Just some thoughts. Cheers.
” Steinar Midtskogen says:
June 7, 2010 at 6:59 am
Humans are most certainly the cause of the recent CO2 increase. A simple graph comparing CO2 with the population should offer an important hint:
http://voksenlia.net/met/co2/pop.jpg
”
Why should the number of humans be proportional to the CO2 concentration? If anything, the number of humans would have to be proportional to the differential of the CO2 concentration. Or do you posit a magical amount of CO2 in the air per living human individual? How should that work?
“Given all of the issues discussed above, I say humans are responsible for the change in atmospheric CO2 … but… please be aware that I don’t think that the change in CO2 will make any meaningful difference to the temperature.”
OK. I would say it slightly differently: Given all of the issues discussed above, I say humans are responsible for some of the change in atmospheric CO2 … but… please be aware that I don’t think that the change in CO2 will make any meaningful difference to the temperature.
Love your rules Willis!
” barry moore says:
[…]
Let us now consider your evaluation of residence time and half life here I am afraid you get very confused “The strength of the exponential decay is usually measured as the amount of time it takes for the pulse to decay to half its original value (half-life) or to 1/e (0.37) of its original value (e-folding time).” How on earth can half its value be 0.37 of the same value? more political math?”
http://en.wikipedia.org/wiki/E-folding
Bart says:
June 7, 2010 at 11:34 am
… Aside from extremely minor isotopic distribution differences, nature essentially cannot tell the two molecules apart.
Are you sure – where are your figures? As the Iranian nuclear industry is learning, isotopes of different mass do behave differently on the basis of that difference – it is not impossible for heavier C13 to settle faster than C12. This would put a spanner in the works. (“Extremely minor” – 8.3% mass difference, not quite insignificant.)
Is there any ocean floor core samples that show CO2? I ask this because there are 50+ sites for those and only 8 for ice cores. It would be nice to see a larger group if we are talking about world wide levels as opposed to localized ones. The recently online CO2 satellite does show that CO2 is not evenly distributed.
Thank you Willis for a balanced and informative article.
I agree that the balance of evidence suggests that mankind is responsible for most of the measured rise in CO2 since 1850, although I also agree with other posters that the proxy measurements prior to 1850 are not necessarily accurate for comparison with modern measurements.
But I do have a problem with the connection with increased CO2 and increased warming (particularly of the catastrophic kind). Can someone help me out here problem because my scientific knowledge is seemingly lacking on the following reasoning:
CO2 exists at less than 400ppmbv in the atmosphere (in fact, I believe ALL the GGs which have a ‘radiative forcing’ factor as described by the IPCC) exist at less than 400ppmbv. To my logic, therefore, each GG molecule capable of radiating is surrounded by approximately 2500 molecules of ‘greenhouse-inert’ N2, O2 molecules or Ar atoms. The fact that CO2 can re-radiate having absorbed LW radiation is well-known, but – and here is the main point of my confusion – simply re-radiating does not directly infer significant warming. The radiation has to be absorbed by another molecule capable of absorbing radiation and then that molecule must transfer heat by conduction to its neighbouring molecules. Given that air is a poor conductor, how is it possible that one GG molecule can conduct enough heat to enough neighbouring molecules to create a catastrophic warming? I agree a very small amount of warming is likely, but the mechanism surely has to be conduction, not radiation, and the number of neighbouring molecules which can warm by conduction must be small.
I am probably missing something important here, so could someone please advise?
Obviously I have ignored water vapour but then it is not included as a GG when it comes to radiative forcing, and I still find it hard to believe that a GG concentration of 400ppm will have that much effect even with the wv feedback.