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Empirical evidence that humans are causing global warming

What the science says...

Select a level... Basic Intermediate

Less energy is escaping to space: Carbon dioxide (CO2) acts like a blanket; adding more CO2 makes the 'blanket' thicker, and humans are adding more CO2 all the time.

Climate Myth...

There's no empirical evidence

"There is no actual evidence that carbon dioxide emissions are causing global warming. Note that computer models are just concatenations of calculations you could do on a hand-held calculator, so they are theoretical and cannot be part of any evidence." (David Evans)

The proof that man-made CO2 is causing global warming is like the chain of evidence in a court case. CO2 keeps the Earth warmer than it would be without it. Humans are adding CO2 to the atmosphere, mainly by burning fossil fuels. And there is empirical evidence that the rising temperatures are being caused by the increased CO2.

The Earth is wrapped in an invisible blanket

It is the Earth’s atmosphere that makes most life possible. To understand this, we can look at the moon. On the surface, the moon’s temperature during daytime can reach 100°C (212°F). At night, it can plunge to minus 173°C, or -279.4°F. In comparison, the coldest temperature on Earth was recorded in Antarctica: −89.2°C (−128.6°F). According to the WMO, the hottest was 56.7°C (134°F), measured on 10 July 1913 at Greenland Ranch (Death Valley).

Man could not survive in the temperatures on the moon, even if there was air to breathe. Humans, plants and animals can’t tolerate the extremes of temperature on Earth unless they evolve special ways to deal with the heat or the cold. Nearly all life on Earth lives in areas that are more hospitable, where temperatures are far less extreme.

Yet the Earth and the moon are virtually the same distance from the sun, so why do we experience much less heat and cold than the moon? The answer is because of our atmosphere. The moon doesn’t have one, so it is exposed to the full strength of energy coming from the sun. At night, temperatures plunge because there is no atmosphere to keep the heat in, as there is on Earth.

The laws of physics tell us that without the atmosphere, the Earth would be approximately 33°C (59.4°F) cooler than it actually is.

This would make most of the surface uninhabitable for humans. Agriculture as we know it would be more or less impossible if the average temperature was −18 °C. In other words, it would be freezing cold even at the height of summer.

The reason that the Earth is warm enough to sustain life is because of greenhouse gases in the atmosphere. These gases act like a blanket, keeping the Earth warm by preventing some of the sun’s energy being re-radiated into space. The effect is exactly the same as wrapping yourself in a blanket – it reduces heat loss from your body and keeps you warm.

If we add more greenhouse gases to the atmosphere, the effect is like wrapping yourself in a thicker blanket: even less heat is lost. So how can we tell what effect CO2 is having on temperatures, and if the increase in atmospheric CO2 is really making the planet warmer?

One way of measuring the effect of CO2 is by using satellites to compare how much energy is arriving from the sun, and how much is leaving the Earth. What scientists have seen over the last few decades is a gradual decrease in the amount of energy being re-radiated back into space. In the same period, the amount of energy arriving from the sun has not changed very much at all. This is the first piece of evidence: more energy is remaining in the atmosphere.


Total Earth Heat Content from Church et al. (2011)

What can keep the energy in the atmosphere? The answer is greenhouse gases. Science has known about the effect of certain gases for over a century. They ‘capture’ energy, and then emit it in random directions. The primary greenhouse gases – carbon dioxide (CO2), methane (CH4), water vapour, nitrous oxide and ozone – comprise around 1% of the air.

This tiny amount has a very powerful effect, keeping the planet 33°C (59.4°F) warmer than it would be without them. (The main components of the atmosphere – nitrogen and oxygen – are not greenhouse gases, because they are virtually unaffected by long-wave, or infrared, radiation). This is the second piece of evidence: a provable mechanism by which energy can be trapped in the atmosphere.

For our next piece of evidence, we must look at the amount of CO2 in the air. We know from bubbles of air trapped in ice cores that before the industrial revolution, the amount of CO2 in the air was approximately 280 parts per million (ppm). In June 2013, the NOAA Earth System Research Laboratory in Hawaii announced that, for the first time in thousands of years, the amount of CO2 in the air had gone up to 400ppm. That information gives us the next piece of evidence; CO2 has increased by nearly 43% in the last 150 years.


Atmospheric CO2 levels (Green is Law Dome ice core, Blue is Mauna Loa, Hawaii) and Cumulative CO2 emissions (CDIAC). While atmospheric CO2 levels are usually expressed in parts per million, here they are displayed as the amount of CO2 residing in the atmosphere in gigatonnes. CO2 emissions includes fossil fuel emissions, cement production and emissions from gas flaring.

The Smoking Gun

The final piece of evidence is ‘the smoking gun’, the proof that CO2 is causing the increases in temperature. CO2 traps energy at very specific wavelengths, while other greenhouse gases trap different wavelengths.  In physics, these wavelengths can be measured using a technique called spectroscopy. Here’s an example:

Spectrum of the greenhouse radiation measured at the surface. Greenhouse effect from water vapor is filtered out, showing the contributions of other greenhouse gases (Evans 2006).

The graph shows different wavelengths of energy, measured at the Earth’s surface. Among the spikes you can see energy being radiated back to Earth by ozone (O3), methane (CH4), and nitrous oxide (N20). But the spike for CO2 on the left dwarfs all the other greenhouse gases, and tells us something very important: most of the energy being trapped in the atmosphere corresponds exactly to the wavelength of energy captured by CO2.

Summing Up

Like a detective story, first you need a victim, in this case the planet Earth: more energy is remaining in the atmosphere.

Then you need a method, and ask how the energy could be made to remain. For that, you need a provable mechanism by which energy can be trapped in the atmosphere, and greenhouse gases provide that mechanism.

Next, you need a ‘motive’. Why has this happened? Because CO2 has increased by nearly 50% in the last 150 years and the increase is from burning fossil fuels.

And finally, the smoking gun, the evidence that proves ‘whodunit’: energy being trapped in the atmosphere corresponds exactly to the wavelengths of energy captured by CO2.

The last point is what places CO2 at the scene of the crime. The investigation by science builds up empirical evidence that proves, step by step, that man-made carbon dioxide is causing the Earth to warm up.

Basic rebuttal written by GPWayne

Addendum: the opening paragraph was added on 24th October 2013 in response to a criticism by Graeme, a participant on the Coursera Climate Literacy course. He pointed out that the rebuttal did not make explicit that it was man-made CO2 causing the warming, which the new paragraph makes clear. The statement "...and humans are adding more CO2 all the time" was also added to the 'what the science says section. 

Update July 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial



Last updated on 12 July 2015 by MichaelK. View Archives

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Comments 201 to 250 out of 417:

  1. Razo @200:

    "...all the research in global warmimg would not be necessary if this rebutttal was indeed proof"

    First, the rebutal is an attempt at science communication, ie, to present scientific information in a readilly digestible form.  No matter how good it is at that, it can be no substitute for scientific research.

    Second, the evidence summarized in this post establishes a prima facie case that the current warming is anthropogenic.  Scientists are not happy with prima facie cases, and test them rigorously as they should.  The prima facie case was established in a fairly rigourous form by the mid 1960s, and all the testing since then has failed to falsify it.  Indeed, it continues to be tested, because that is what scientists do, but the vast majority of climate research is now focussed on expanding on less well established aspects of climate science.  This is something Raz would know if he knew anything about the scientific method, or climate science.  He is either making a case from his own ignorance, or (at best) being deliberately obtuse for rhetorical advantage.

    It is, however, very kind of him to so prominently flag that his an AGW denier intent on publishing talking points rather than a genuine enquirer or person interested in reasoned debate.

    "The question is 'what impact does man's CO2 producction have' and thus 'emperical evidence of his impact on climate change'."

    Harries (2001) (as shown in the intermediate version of the OP) directly addressed that issue, and showed the following differences in IR brightness temperature: 

    The first thing to note is that the increase in concentration of all the listed gases is anthropogenic in origin, so that even if methane had more effect it would be irrelevant.

    The second thing to note is that the area of reduced emission due to methane is slightlly larger than that of CO2.  That, however, is misleading on two counts.  First, the spectrum shown does not show the full CO2 band, showing, in fact, only one wing (see spectrum below).  With the full CO2 band shown, the impact of CO2 would be approximately double that shown.  Second, the graph shows the "brightness temperature".  The brightness temperature is the emission spectrum so scaled that black body curves are shown as straight lines parallel with the x-axis.  Because the region of the spectrum in which methane is active has much less IR activity at Earth temperatures than does the area in which CO2 is active, that greatly inflates the area in the Methane portion of the spectrum relative to the CO2 portion.  We can see from the spectrum shown below, that approximately doubles the apparent impact of methane.  Combined these factors inflate the apparent effect of methane by a factor of four.  Correcting for this it is very apparent that CO2 has an impact around 4 times that of methane over the time period covered by the chart (27 years).  That short time scale further inflates the apparent effect of methane, which is oxidized to form CO2 plus water over about a thirty year time frame in the atmosphere.  Thus while Harries (2001) shows near the full forcing effect of methane since the preindustrial, it shows only a fraction of the effect of CO2.

    "...methane is heavy, and would stay near the surface."

    Methane (CH4) has a molecular mass of 16, ie, half the molecular mass of oxygen (O2), and 36% of that of CO2.  The claim that it is heavy is the opposite of the truth.  Further it is irrelevant, in that atmospheric motion is sufficient to keep even the heavy CO2 in near constant mixing ratios (within 10-20 ppmv) up to the meso-sphere.

    "It also been all over the news now that temperatures have not risen in the last 15 years."

    The HadCRUT4 OLS for the last 15 years (Jan 1999-Dec 2013) was 0.66 +/-0.13 per decade.  That is, it was positive, but not statistically significant.  It is similar if we take it from May 1999 to April 2014.  Indeed, all major global temperature series are positive (but not stastically significant) over that period.  Clearly Razo has accidentally cherry picked the wrong interval.

    Perhaps he really meant the last 16 years.  That would have included the 2nd largest (SOI) or largest (temperature based ENSO indices) El Nino as the start year, but alas the trend remains positive but not statistically significant if you do.

    To get a negative trend, you have to reduce the trend to 13 years, starting in Jan 2001, which gives you a HadCRUT4 trend of -0.011 +/- 0.145 C per decade, though it remains stubornly positive in temperature series that actually include the entire globe such as Gistemp.  Even then, and cherry picking our temperature indice to get a negative, trend it is misleading to say "the temperature has not risen" in the last thirteen years.  The trends to Dec 2007, or Dec 2010, are both positive.  Ergo, the temperature has risen, then fallen back.  Specifically, it has fallen back in 2008 (due to a strong La Nina and a solar minimum some solar experts consider to have been as low as the Maunder Minimum), and in 2011-2012 (due to the strongest La Nina on record based on the SOI index).  It appears not to be as usefull to Razo to say that two recent short term cooling events have temporarilly wiped out a decades worth of global warming, so he chooses a less accurate form of expression. 

  2. Sorry, I mistyped the HadCRUT4 trend for the last 15 years as 0.66 C/decade rather than the correct 0.066 C per decade.

  3. Hey Tom,

    You're just putting words in my mouth. You wanna critisize me for not being exact, just Relax. FYI I do have a degree in a scientific field, I have bben published, and I didn't know what prima facie means.

    Anyway, this is the article I was reffering to

    They say they found a cooling trend. And is was in all the papers around February 10, 2014, such as

    Thank you for the information about methane.


    [JH] Pease tone down the rhetoric. 

    Please note that posting comments here at SkS is a privilege, not a right.  This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

    [PS] fixed links


  4. Razo @203:

    1)  I did not put words into your mouth.  I quoted you verbatim.

    2)  I am astonished that you do not know the meaning of "prima facie".  As you do not, you need to learn it as it is a useful concept in understanding the practise of science.  Of course, your intention was a rhetorical trick to allow you to criticize the OP without substance, so it may not help you.

    3) Your precise words were:

    "It also been all over the news now that temperatures have not risen in the last 15 years."

    The paper for which you provide a link discusses the so-called "hiatus" since 2001, ie, the last 13 years.  Thank you for indirectly confirming that you were exagerating the length of time involved.  Further, to that, it is irrelevant how frequently a paper is echoed in the press.  

  5. Razo, did you actually read the England et al papers that you quote? How come you have changed a slowing in the rate of warming into a cooling trend?

    From the first "Here we show that a pronounced strengthening in Pacific trade winds over the past two decades—unprecedented in observations/reanalysis data and not captured by climate models—is sufficient to account for the cooling of the tropical Pacific and a substantial slowdown in surface warming through increased subsurface ocean heat uptake."

    and the second...

    "A variety of mechanisms have been proposed to account for this slowdown in surface warming" and "This hiatus could persist for much of the present decade if the trade wind trends continue, however rapid warming is expected to resume once the anomalous wind trends abate."

    The papers conclusions do not appear to match your perception.

  6. scaddenp, I must confess to not reading it thouroghly enough. I seem to remember it differently, or was relying on journalists interpretations too much. For that I apologize. But nevertheless Fig 1 does describe cooling over part of the last decade

    "Observations of global average surface air temperature (SAT)
    show an unequivocal warming over the twentieth century1,
    however the overall trend has been interrupted by periods
    of weak warming or even cooling (Fig. 1)."

    I also do criticize global models for not capturing decade long cooling intervals very well, and not predicting trade winds. I am not in the climate field, but I do have experience with numerical modelling. I simply think GCM should be able to predict trade winds and ocean warming.


    [JH] Your "experience with numerical modeling" is nor a substitute for doing your homeowork on GCMs before proceeding to critique them. Please stop flying blind and look before you leap.

  7. Razo wrote "I also do criticize global models for not capturing decade long cooling intervals very well"

    Criticising models for not being good at something they are not designed to do and for which they do not claim a high degree of skill suggests that you have not put much effort into finding out what models do and how they work.  I criticise them for not being able to predict volcanic eruptions.  This is about as meaningful a criticism as Razo's ;o)

  8. I have posted this link elsewhere, but I post it here to show that others share my critism of climate modeling not predicting recent stagnation in global warming. Also he considers the stagnation to be a 15 year period from 1998 to 1012.

  9. Razo can models be reasonably expected to predict the stagnation of temperatures over a 15 year period?  The answer is essentially "no, but hey can be expected to predict that such stagnations will happen evey now and again (but not when)" and indeed they do, see Easterling and Wehner.

  10. Razo @208:

    1)  von Storch et al (unpublished*) shows a temperature increase over the 15 year interval at 40% of what they claim to be the preceding 30 year trend in the only fully global temperature series used (GISS).  They state:

    "Estimates of the observed global warming for the recent 15-year period 1998-2012 vary between 0.0037 C/year (NCDC), 0.0041 C/year (HadCRUT4) and 0.008 C/year (GISS).  These valuesare significantly lower than the average warming of 0.02 C/year observed in the previous thirty years1970-2000."

    We immediately face problems in that 1970-2000 inclusive is a 31 year period so we do not know which trend they used.  However, the Jan 1971 - Dec 2000 (Jan 1970- Dec 1999) trends are:

    GISS: 0.166 +/- 0.058 (0.164 +/- 0.58) C/decade

    NOAA: 0.167 +/- 0.054 (0.165 +/- 0.54) C/decade

    HadCRUT4: 0.174 +/- 0.056 (0.168 +/-0.057) C/decade

    Which ever trend you choose, von Storch et al have exagerated the preceding thirty year trends by 15-20%, thereby exagerating the extent of the slow down in temperature increase.

    Further, they give incorrect values for the 15 year trends as well.  The actual values are:

    GISS: 0.073 +/- 0.147 C/decade

    NOAA: 0.04 +/- 0.137 C/decade

    HadCRUT4: 0.047 +/- 0.14 C/decade

    Consequently the actual (reported by von Storch et al) ratio of trends using 1971-2000 for the 30 year trends are:

    GISS: 0.44 (0.4)

    NOAA: 0.24 (0.185)

    HadCRUT4: 0.27 (0.205)

    They therefore exagerate the slowdown by 10 or more percent.

    2)  von Storch et al avoid mentioning ENSO events to an extraordinary extent.  There only reference is a casual mention that models have difficulty modelling ENSO events.  He nowhere mentions the fact that 1998 was one of the largest El Nino events on record which, coming at the end of the thirty year trend and the start of the 15 year treand, exagerates the former while depressing the later.  Nor does he mention the strong La Nina in 2008, nor the record La Nina (SOI Index) of 2011/2012.  Nor does he mention the strong La Nina in 1974/75 (second strongest on record in the SOI).  These La Ninas exagerate the 30 year trend, and supress the 15 year trend.

    As a side note, von Storch et al's claims about the inability of models to model ENSO events are not strictly true.  They were true of about half of models used in the CMIP3 intermodel comparison and the IPCC AR4; but it is not longer true of those used in CMIP5 and AR5.  What models cannot do is generate ENSO events with the same timing as real ENSO events for the simple reason that that timing is essentially random.

    3)  von Storch et al make no allowance for the fact that 1998 was well above the temperature trend, or that 2011/12 by virtue of the La Nina were presumably well below it.

    This is extraordinary.  It means his entire argument is analogical to a person trying to prove that water does not settle to the same level because lines drawn from a point at the crest of a wave to other parts of the water surface have, on average, a negative slope.

    Of course trends drawn from a peak well above the trend do not have the same statistical distribution as trends drawn from points on the long term trend line.  For them to have the same statistical distributions, the series of data points (temperature records) must be a random walk.  That the twentieth and early twentieth temperature record constitutes a random walk is a flat contradiction of the predictions of the models and climate scientists - yet that is the implicit assumption in von Storch et al's criticism.  This flaw is made worse by both the fact that von Storch et al use a trend not only from a "peak", but to a "trough", and by the fact that they eschew any discussion of this issue.

    IMO the statistical analysis in von Storch et al falls to the level of pseudo-science.  I was greatly disappointed to see that von Storch had sunk that low.



    * The article by von Storch et al was never published in any journal, but merely distributed on the internet.  It follows, of course, that it is not peer reviewed.

  11. Razo: Here are some more facts about GCMs for you to ponder.

    Climate Models Show Potential 21st Century Temperature, Precipitation Changes
    Posted Sep. 27, 2013, NASA/GISS

    "New data visualizations from the NASA Center for Climate Simulation and NASA's Scientific Visualization Studio at Goddard Space Flight Center, Greenbelt, Md., show how climate models used in the new report from the United Nations' Intergovernmental Panel on Climate Change (IPCC) estimate possible temperature and precipitation pattern changes throughout the 21st century.

    "For the IPCC's Physical Science Basis and Summary for Policymakers reports, scientists referenced an international climate modeling effort to study how the Earth might respond to four different scenarios of carbon dioxide and other greenhouse gas emissions throughout the 21st century. The Summary for Policymakers, the first official piece of the group's Fifth Assessment Report, was released Fri., Sept. 27.

    "This modeling effort, called the Coupled Model Intercomparison Project Phase 5 (CMIP5), includes dozens of climate models from institutions around the world, including from NASA's Goddard Institute for Space Studies."

  12. Razo - WRT Von Storch and the avoidance of ENSO effects on trends, it is notable that: if you select as an endpoint an extrema value from a time series, the statistical significance of anything terminating there is much much lower. 

    There's a good discussion of this over on Tamino, under Cherry-p. Von Storch followed in the trail of many a pseudo-skeptic, and selected the 1998 El Nino (3-sigma in scale) as one of his trend endpoints. Without noting the fact that it was indeed a time series variation extrema.

    In the presence of such selection of an extrema, the required p-value for statistical signifcance can be 10x normal!! That's because in any system with noise you can find short trends up and down, meaning once you start selecting extrema endpoints, you need far more supporting data to make your claim(s). Supporting data that simply doesn't exist in the temperature record.

    1998 trend claims are the essence of cherry-picking, of selecting a subset of data that appears to support a claim while ignoring the remainder of the data that contradicts that claim. It's a "fallacy of selective attention, the most common example of which is the confirmation bias", and such claims are logical fallacies.

  13. Just to add to KR's comment, if you look at a comparison of the AR4 SRESA1B model ensemble with the observations (courtesy of RealCLimate):

    you can see that the observations were further into the upper tail of the envelope of model runs than they are into the lower tail of the distribution in recent years.

    Now, ask yourself why the skeptics were not interested in pointing out the model observation "inconsistency" in 1998.  Cherry picking indeed, the 1998 one clearly wasn't ripe. ;o)

  14. Note: I am not stating that Von Storch is a pseudo-skeptic, just that the selection of 1998 is statistically ill-considered, and that claims of trends from that time point are not supported by the data. 

    Further discussion on this topic (i.e. no warming since...) should probably move to this thread, as it is somewhat off-topic here.

  15. The Earth's tempurature is 33 degree lower than if no atomosphere and all evidence suggested that CO2 the primary element to create green house blanket. Arround the time of industrial revolution, avarage tempurature is less than 1 degree lower than now. Also the amount of CO2 was 280 ppm and it is almost 400 ppm now.  One thing I  struggle to understand is why temprature raised only less than 1 degree since industrial revolution. If the green house blanket has warmed the Earth by 33 degree in 280 ppm, would 120 ppm increases of CO2 attribute larger temprature variation ? If not what is factors to supress a large margine of warming ? 

  16. Souichi Tsujimoto @215, Schmidt et al (2010) showed that with CO2 concentrations at 339 ppmv (1980 levels), CO2 contributes 20% of the 155 W/m^2 total greenhouse effect, or 31 W/m^2.  The increase in CO2 forcing from preindustrial to 1980 levels is 1 W/m^2, resulting in a net increase in total CO2 forcing from 30 to 31 W/m^2 over that period.  The further increase to the current date is another 0.9 W/m^2, meaning the total increase from the preindustrial to the current date is from 30 to 31.9 W/m^2.  This small increase in forcing as a result of a large increase in CO2 concentration is a result of the fact that you need to double CO2 concentration to obtain a 3.7 W/m^2 forcing.  As a result of that, we know that the increase in temperature is in the right ball park to have been caused by the increase in CO2 levels.

    Of course, there are further complications.  The expected increase in temperature at equilibrium from an increase in CO2 from 280 to 400 ppmv (pre-industrial to current) is 1.55 C.  That has not occurred as yet primarilly because the ocean acts as a thermal fly wheel, slowing the changes in temperature due to changes in forcing.  Of course, that expected increase includes feedbacks, which are partly uncertain, which is another complication.  But the largest cause of the apparent disparity is a failure to allow for the fact that CO2 forcing increases by a constant amount for each doubling of CO2. 

  17. Here is what I believe you are missing. You claim: "Humans are emitting more than twice as much CO2 as what ends up staying there. Nature is reducing our impact on climate by absorbing more than half of our CO2 emissions." It's true. But we have also degraded the ecosystem services by ~1/2 as well...with modern factory farming style agriculture. The hocky stick isn't fossil fuel emissions, it's agricultural degradation of the soils, particularly carbon. Sure emissions also help somewhat, but even without a single fossil fuel drop, degrade the ecosystem services and we get global warming. It is us doing the harm, so it is AGW. But you guys are looking at the wrong source. Here is your evidence:

  18. Change in Land use is accounted for - see the IPCC report. Your thesis is not compatible drop in O2 and isotope ratio of CO2 in atmosphere. Some discussion of that here. I think you may be underestimating the role of oceans in CO2 cycling compared to land. You can get references to studies doing the maths of CO2 accounting from the IPCC WG1 chapter 6.

  19. RedBaron @217, adding to scaddenp's response, here is the graphic showing reservoirs and fluxes of CO2 from the IPCC (Fig 6.01):

    Fluxes are shown in by the arrows, reservours by the boxes.  "Natural" (ie, preindustrial) values are shown in black, changes since the preindustrial in red.  Units are in terms of Petagrams of Carbon per year for fluxes, and Petagrams of Carbon for reservoirs, with a Petagram equalling 10^15 grams, or a billion tonnes of Carbon (Gigatonnes).

    So, looking at the reservoirs, we see that the combined atmosphere/ocean reservoir has increased by 395 Gigatonnes of Carbon, while vegetation has decreased by 30 gigatonnes of carbon, and fossil fuel and cement stocks have decreased by 365 gigatonnes of carbon.  That is, the combined effect of land use changes and the CO2 fertilization effect has resulted in only 8.2% of the total increase, with fossil fuels accounting for the rest.

    The total emissions from fossil fuels and cement manufacture is well known.  For it to be even matched by emissions from LUC, you need a new, and very large reservoir to store the excess CO2.

    There is additional evidence that the primary source of the increased CO2 comes from fossil sources.  Of these the most important is the decline in C14 concentrations.  Another is that there is a very strong correlation between cumulative fossil fuel emissions and CO2 concentrations:


    Over the period of observations at Mauna Loa, that correlation is 0.9995 with an r squared of 0.999.  That correlation actually decreases slightly when emissions from LUC are included, probably because estimates of those emissions are not as accurate as those for fossil fuels.

  20. @ scaddenp & Tom Curtis,

     I am well aware of the IPCC report and the charts. I even think most of it is relatively good. There are however several flaws that change the overall picture. This for example is potentially quite flawed.

    "It is very likely, based on new experimental results {} and
    modelling, that nutrient shortage will limit the effect of rising
    atmospheric CO2 on future land carbon sinks, for the four RCP
    scenarios. There is high confidence that low nitrogen availability will
    limit carbon storage on land, even when considering anthropogenic
    nitrogen deposition. The role of phosphorus limitation is more uncertain.
    Models that combine nitrogen limitations with rising CO2 and
    changes in temperature and precipitation thus produce a systematically
    larger increase in projected future atmospheric CO2, for a given fossil
    fuel emissions trajectory."


    another flaw is the fixation with forests. The primary historical carbon fixation is not forests. It is grasslands. The fixation is not in vegetative material, but rather exudates. Forests do have a moderating effect, especially as seen now with a new balance being made as fossil fuels emissions increase. But ultimately the long term effect of forests is near neutral, as a much higher % of the products of photosynthesis are above ground. A relatively small % is sequestered, because ultimately above ground and near surface carbon compounds are released in the short term carbon cycle by way of the processes of decay. So you get a net effect of maybe 2% +/-? Depending on how long a time frame you look? Grassland sequestration is completely different. Those grasses and forbs sequesture as much as 37% directly deep in the soil by direct exudate production. The carbon is sequestered far longer than near surface and above surface carbon. In the thousands of years if undisturbed. That's why historically molisols have far deeper A horizons with much higher SOC than alfisols (even old growth forst alfisols).

    But, while only about 1/2 the land suface is under agriculture and there are still forests, the grassland/savannas of the world (primary terrestrial carbon sequetration of the Earth) are largely either extirpated like the tallgrass prairie, or under poor management and no longer functioning as a carbon pump. Pretty much all of it is gone. So the secondary buffers (forests) are helping to take away 1/2 the excess carbon from fossil fuels. But the primary terrestrial buffer to the carbon cycle is nearly completely gone or disfunctional due to poor management.

  21. Redbaron - your quote applies to potential scenarios in the future, not to current source of CO2 in the atmosphere. I am not sure why you think there is a fixation with forest in the carbon budgets given the soil carbon storage in grassland is well known. The change in grassland is explicitly calculated. While land use change is part of AGW, the evidence to date is that is small compared to fossil fuel burning. The check on the calculation is the carbon isotopic concentration in the atmosphere. You need a massive change in carbon fluxes for this to be significant compared to FF.

  22. RedBaron @220, with respect, your anonymous, non peer reviewed analysis consisted of a map showing the proportion of the land surface currently under agricultural production.  But now you want us to give a pass on that analysis, and question the expert, public and peer reviewed analysis of the IPCC based on your say so?  I think you have radically disparate standards of evidence depending on whether or not you agree with a theory.

    Further, you simply neglect the force of the case as presented by the IPCC.  The IPCC shows changes in reservoirs with 90% uncertainty intervals.  Specifically, changes are as follows:

    Atmosphere + 240 +/- 10 GtC

    Ocean  + 155 +/- 30 GtC

    Fossil Fuels - 365 +/- 10 GtC

    It follows that the change of all other reservoirs combined (ie, vegetation plus soils) is 30 +/- 33 GtC from that information alone (assuming the data is independent).  Calling into questin the partition between soils and vegetation in no way allows the sum of change in soils plus vegetation to exceed those limits.  So, until you find the evidence that the ocean is absorbing CO2 at several times its rate as reported by the IPCC, you do not have a case.  Indeed, looking at the uncertainties, it is more likely that vegetation plus soils have increased in CO2 content than that they account for even 20% of the atmospheric and ocean increase, let alone most of it.

  23. Just one more point, one of the factors showing it is the consumption of fossil fuels leading to the increase in atmospheric CO2 has been the reduction in the O2 content:

    As can be seen, given known emmissions from fossil fuels, measured delines in O2 and increases in CO2 concentration, the equations only balance if the combined effect of LUC plus natural uptake by the land (vegetation plus soils) decreases the CO2 concentration over the period of measurement.  That is consistent with total anthropogenic emissions from LUC being positive, but only if they are less than natural sequestration by vegetation and soils.  That is again inconsistent with RedBaron's thesis.

  24. Red Baron, the factor you describe is already taken into account by the IPCC (and all other carbon cycle researchers) and it is described as "land use change emissions" (as pointed out above by scaddenp).  You can get data on on this from the Carbon Dioxide Information and Analysis Centre (CDIADC).  One of the most surprising things I found out about climate change when I first looked into it just how late cumulative anthropogenic emissions from fossil fuel use finally overtook those from land use change.  The answer turns out to be about 1965. 

  25. I'll try to address you guys points one by one. First scaddencamp, you said: "Your thesis is not compatible drop in O2 and isotope ratio of CO2 in atmosphere." Actually it is compatable, even the IPCC report says as much. C12 isotope ratios are consistent vegetative sources, whether fossil, or in the biosphere. "With a very high confidence, the increase in CO2 emissions from fossil fuel burning and those arising from land use change are the dominant cause of the observed increase in atmospheric CO2 concentration." p 493

    But what is lacking in the IPCC report is the Land Use data is far too crude. There is little analysis of land use changes within agriculture. In other words IPCC says this:

    "With a very high level of confidence1, the increase in CO2 emissions from fossil fuel burning and those arising from land use change are the dominant cause of the observed increase in atmospheric CO2 concentration. About half of the emissions remained in the atmosphere (240 ± 10 PgC) since 1750. The rest was removed from the atmosphere by sinks and stored in the natural carbon cycle reservoirs. The ocean reservoir stored 155 ± 30 PgC. Vegetation biomass and soils not affected by land use change stored 160 ± 90 PgC. {6.1, 6.3,, Table 6.1, Figure 6.8}"

    But not factored was the "land use change" that was a result of the green revolution. The Green Revolution refers to a series of research, and development, and technology transfer initiatives, occurring between the 1940s and the late 1960s that radically changed how agriculture is practised world wide. That's the same flaw in the graph posted by Dikran Marsupial. Agricultural land that changed methodology but was prior agricultural land and is afterwards agricultural land is no counted as "land use change". However, there is a radical change in the carbon cycle that accompanies that change in methodolgy. Specifically the most radical change is in soil health, primarily carbon. If you change that graph to include changes within agriculture, I believe you'll find that instead of crossing in 1965 you'll see it continuing to be the primary cumulative anthropogenic emissions.

    Further confirmation of this flaw can be seen in this quote from the IPCC report. "Since 1750, anthropogenic land use change have resulted into about 50 million km2 being used for cropland and pasture, corresponding to about 38% of the total ice-free land area (Foley et al., 2007, 2011), in contrast to an estimated cropland and pasture area of 7.5 to 9 million km2 about 1750 (Ramankutty and Foley, 1999; Goldewijk, 2001). The cumulative net CO2 emissions from land use changes between 1750 and 2011 are estimated at approximately 180 ± 80 PgC (see Section 6.3 and Table 6.1)" They have the numbers right for the land use change to agriculture, but are missing the land use changes within agriculture as methodologies change.


    [JH] Formatting glitch fixed.

  26. Read a little further into the IPCC report. FF has zero C14. The continued dilution of C14 in atmospheric CO2 since nuclear testing is consistant with the calculation of relative proportions of FF v LUC.  You claim IPCC has not considered changes in agricultural management affecting soil carbon. However the IPCC source for LUC using fig 6.8 is Houghton et al 2012. This uses and compares a number of different studies all producing similar results. Your point is explicitly discussed in section 4.2. From the studies discussed, it concludes "Globally,
    the current flux from agricultural management is uncertain
    but probably not far from zero". If you have papers that can challenge those studies, then please cite. However, as Tom points out, if LUC contribution is higher than current estimates, then given known FF emissions, you then need to account for an unknown sink to get our measured concentrations (and the C14 dilution).

  27. I see scaddenp has beat to the punch on Houghton et al.  Here is the full quote:

    "4.2 Agricultural management
    The changes in soil organic carbon (SOC) that result when native lands are converted to croplands are included in most analyses, but the changes in SOC that result from cropland
    management, including cropping practices, irrigation, use of fertilizers, different types of tillage, changes in crop density, and changes in crop varieties, are not generally included
    in global LULCC model analyses. Studies have addressed the potential for management to sequester carbon, but fewer studies have tried to estimate past or current carbon
    sinks. One analysis for the US suggests a current sink of 0.015 Pg C yr−1 in croplands (Eve et al., 2002), while a recent assessment for Europe suggests a small net source
    or near-neutral conditions (Ciais et al., 2010; Kutsch et al., 2010). In Canada, the flux of carbon from cropland management is thought to be changing from a net source to a net sink, with a current flux near zero (Smith et al., 2000). Globally, the current flux from agricultural management is uncertain but probably not far from zero. Methane and nitrous oxide are the predominant greenhouse gas emissions from agriculture."

    The IPCC in turn indicated that it's estimates of emissions from LUC were:

    "Estimated from the cumulative net land use change emissions of Houghton et al. (2012) during 1850–2011 and the average of four publications (Pongratz at al., 2009; van Minnen et al., 2009; Shevliakova et al., 2009; Zaehle et al., 2011) during 1750–1850."

    (Footnote g to table 6.1)

    So, the flux that RedBaron says the IPCC ignores is explicitly taken into account by the IPCC's primary source.  Further, while he estimates that flux to dominate the flux from Fossil Fuel emissions without evidence or reading of the primary literature, Houghton et al (2012) looked at the primary literature and found that while in some cases the flux is positive, increasing atmospheric CO2, in others it is negative and that the net global effect is close to zero.

  28. Think about it Tom. You said, "Houghton et al (2012) looked at the primary literature and found that while in some cases the flux is positive, increasing atmospheric CO2, in others it is negative and that the net global effect is close to zero." And the IPCC report that I quoted said, "Since 1750, anthropogenic land use change have resulted into about 50 million km2 being used for cropland and pasture, corresponding to about 38% of the total ice-free land area (Foley et al., 2007, 2011)" Meanwhile about 1/2 fossil fuel emissions are being sequestered (although not all of that is in terrestrial sinks)

    Add up what all those independant sources mean. It means just what I said in my first post here. Agriculture has broken the natural buffering capability (ecosystem service of sequesting carbon and moderating climate) of the terrestrial biosphere roughly by about 1/2 +/- and the current biosphere is falling short of sequestering CO2 from fossil fuel emissions roughly by about 1/2. There is your primary problem confirmed in yet another way.

    The reason this is important IMHO is that it points to many potential mitigation solutions that are biology based. Agricultural land is already intensively managed. It doesn't take huge budgets of new research and development that the energy technology fixes require to simply change the management. It's simply an educational solution. Farmers only need educated in the already developed management techniques that restore the ecosystem services to the land they manage. Very small costs, and big returns in both carbon sequestration and actually instead of costing society huge sums, turns out to be a net profit!

  29. But what Houghton does is add up all those changes. That is where the numbers come from. Your original post was "Sure emissions also help somewhat," whereas the evidence from all those sources with all the maths, calculated by multiple methods, would suggest that the phrase should be "Sure human agriculture also help somewhat" - to the tune about 8% what FF does. There is strong evidence to support a number around that magnitude and so far you havent cited a source which would suggest otherwise.

  30. @Scaddenp: You said, "But what Houghton does is add up all those changes. That is where the numbers come from. Your original post was "Sure emissions also help somewhat," whereas the evidence from all those sources with all the maths, calculated by multiple methods, would suggest that the phrase should be "Sure human agriculture also help somewhat" - to the tune about 8% what FF does..." Actually I have seen figures around 10% but either way 8-10% is close enough. That's emissions. The ecosystem service of carbon sequestration is on the opposite side of the carbon cycle. So we have emissions of 8-10% but what is missing from your analysis is that we have degraded the terrestrial biosphere's capability to sequester carbon by roughly ~50%+/- by degrading the terrestrail ecosystems world wide. Even in their highly degraded state, the ecosystems manage to sequester about ~ 50% of all emissions. Restoring the ecosystems to full function with regard to carbon sequestration should potentially be able to eliminate the other 1/2. Restore them to higher functionality than wilderness ecosystems should actually potentially begin drawdown.

  31. Okay, RedBaron, it looks like we are in more agreement. What is the basis for your statement "we have degraded the terrestrial biosphere's capability to sequester carbon by roughly ~50%+/- by degrading the terrestrail ecosystems world wide." I havent seen data published on this (which is not to say that it doesnt exist). I admit to being skeptical because some sequestration mechanism are sensitive to CO2 concentration so the maths doesnt fit.

  32. RedBaron @228 and 230:

    1)  The argument that we have degraded the terrestial biosphere's ability to sequester fossil fuels is different from your initial claim that:

    "The hocky stick isn't fossil fuel emissions, it's agricultural degradation of the soils, particularly carbon", and that. Sure emissions also help somewhat, but even without a single fossil fuel drop, degrade the ecosystem services and we get global warming."

    Specifically, your current argument relies on fossil fuels providing the excess CO2, with the implication that has we equally degraded the biosphere, but not emitted the fossil fuels, there would have been a much reduced increase in CO2 emissions.

    2)  Degrading 50% of the terrestial biosphere's ability to sequester CO2 is not the same as degrading the terrestial biosphere's ability to sequester CO2 by 50%.  For them to be the same, we would need to, not degrade, but eliminate 50% of the terrestial biosphere's ability to sequester CO2, that 50% would have to account for half of natural sequestration, and there would have to be no compensating increases in the ability to sequester in the other 50% of the biosphere.  You have not shown any of these conditions to be true.  Indeed, plausibly, the degradation of the ability to sequester scales with the biomass.  That is, plausibly we have degraded the ability of the terrestial biosphere to sequester CO2 by the ratio of cumulative LUC emissions (160 GtC) to total terrestial biosphere Carbon (2500 GtC), or by 6.4%.

    3)  Whatever the degradation of the ability to sequester is, the fact is that the terrestial biosphere has sequestered 130 GtC, and that over the last few decades, total biosphere sequestration has exceded total emissions from LUC as shown by the O2 data (see my post @223).  Ergo the increase in the ability of the terrestial biosphere to sequester CO2 due to the increase in temperature, humidity and CO2 concentration exceeds the degradation of the ability to sequester consequent on LUC.

  33. I also have found very limited maths concerning this as well! It is an over looked but in my opinion highly important part of the problem! It's an oversite that in my opinion causes the IPCC analyses to be flawed! There is however some information out there. It just hasn't been rigorously applied to climate science models. At least not to my satisfaction.

    But let's start with historical ecosystems prior to the anthropocene. (the proposed epoch that began when human activities had a significant global impact on the Earth's ecosystems) 

    "the truly novel event of the Cenozoic was the evolution and expansion of grasslands, with their uniquely coevolved grasses and grazers. Neogene expansion of the climatic and geographic range of grasslands at the expense of woodlands is now revealed by recent studies of paleosols, fossils, and their stable isotopic compositions. Grasslands and their soils can be considered sinks for atmospheric CO2,CH4, and water vapor, and their Cenozoic evolution a contribution to long-term global climatic cooling. Grassland soils are richer in organic matter than are woodland and desert soils of comparable climates, and when eroded, their crumb clods form sediment unusually rich in organic matter. Grasslands also promote export of bicarbonate and nutrient cations to lakes and to the oceans where they stimulate productivity and C burial"

    So according to Retallack, the primary driver that gave us the climate we humans evolved in was the grassland/grazer biome. Admittedly taking geological time to evolve. Grasslands/graziers didn't just pop into existence and immediately take over 1/2 the worlds forests. But the biome is the biome that once established did make a major contribution to our climate. So this is the biome that historically originally pulled down our carbon to pre-industrial levels. Simply removing that biome would tend to cause climate to rebalance at pre-Cenozoic levels. (much warmer and wetter than we are now)

    Now look at agriculture. What is the primary agricultural ground? Yes some of it is cleared forests and alfisols. But they tend to loose their carbon and fertility quite rapidly. The prime agricultural land is regions like the midwest North American plains. Particularly the tall grass prairie. Why? because that's where the deep fertile mollic soils are primarily formed! But those ecosystems are largely extirpated and replaced by artificial agricultural ecosystems. Even in the dryer plains/savanna areas of the world, the grazers are largely extinct or extirpated, causing those grasslands to no longer effectively function as carbon sinks. Replaced once again with agriculture, either dryland crop production or livestock. Often many of those grasslands are burned due to there not being nearly enough animal impact to cycle the vegetation.

    Because of this we get analysis from many sources already mentioned in this thread: "Since 1750, anthropogenic land use change have resulted into about 50 million km2 being used for cropland and pasture, corresponding to about 38% of the total ice-free land area (Foley et al., 2007, 2011)"

    It's not just that 38% is in agriculture. But the prime arable land is almost completely under agriculture. It's not evenly distributed. Mountains and deserts have far less % of the land in agriculture. Agriculture rests primarily right in the middle of the best land, which also is the land responcible for mitigating carbon increases in the atmosphere! So that 38% is right in the same land that potentially would be mitigating our fossil fuel emissions. Quantifying it is hard though. Entire regions and whole trophic levels of the biomes are gone. We are not going to let loose millions and millions of bison in Iowa corn country and let them and the wolves roam freely to measure what carbon would have been sequestered if we hadn't extirpated them. Certainly can't bring back the extinct megafauna of the planet. So hard numbers on that are very difficult to get.

    But what we can and have done is develope models of agriculture with farming methods that function as carbon sinks. They have been measured compared to conventional best management practises currently being used.

    Here is an example: LINK


    These studies show that best management practises on both rangeland and planted pasture increases CO2 sequestration by 11 tons CO2/ha/yr simply by regenerating ecosystem function. You couldn't of course say all grassland does that, but it shows an INCREASE over conventional by that amount in those locations. Some areas like Iowa probably would be more as the conventional model there is corn fed instead of grass fed. Here is a white paper by the author of the first paper descibing the potential if that model were applied worldwide:


    It's not as easy to restore ecosystem function without animal impact. But relatively good results have been achieved by David Brandt on traditional row crops. Documented by USDA NRCS on Brandts demonstration farm. 


    Unlikely to reach the historic 8-10% SOC with Brandts system as it doesn't include animals. But he has achieved results as high as 4-5% SOC  sequestered in a decade even in a row crop model. (no til with multi species covers)

    There are systems out there that integrate all three of the above that have achieved the historic 11%!



    [RH] Shortened links that were breaking page format.

  34. RedBaron @233.

    Down this thread since #217, you have been presenting perhaps three separate arguments which may be why the responses haven't been quite hitting the mark for you.

    Perhaps the least controversial (relatively) of your three proposals concerns sequestartion of CO2. There are people (coming from different directions) who advocate using grassland management techniques to improve sequestration of atmospheric CO2. It is usually at the same time also argued that such management of grassland would hughly incerease pastoral livestock production. Further I have seen such argument made in a general sense to cereal production as well.

    These multiple approaches reaching similar conclusions would suggest there is merit in such arguments although the slow of progress made by such arguments suggests also that the benefits are not as straightforward as claimed (or as not so easily demonstrated as claimed).  It also suggests that a discussion here will not easily provide a clear outcome.

    However, it is the second argument that you present that is the main bone of contention within the thread. You are arguing that the rise in atmospheric CO2 results directly from changes in agricultural practice and such changes have caused CO2 emissions that remain unaccounted for by any of the studies of the likes of Houghton.

    Such an argument is strong stuff. Yet in establishing such a hypothesis, I would say that I don't think you have begun even to scratch the surface.

    But there is a third hypothesis that you are proposing. You suggest that it was the spread of grasslands during the Cenozoic that resulted in the fall in atmospheric CO2 levels over that period. Again, this is strong stuff.

    Mixing up all this into one big debate will get us nowehre. Thus I would recommend that these three areas of discussion are addressed separately.

  35. @MA Rodger,

    I am not sure I am up to the monumental task you just outlined. But what I can say is that Greg Retallack and Richard Teague both spoke at the most recent Annual Review of Earth and Planetary Sciences conference. They appear to be in support of each other completely. Ie the paleo record supports the current observations and they both point to potential near future solutions of AGW. 


    [JH] Please document what Greg Retallack and Richard Teague said at the most recent Annual Review of Earth and Planetary Sciences conference. Where and when was this conference held? Who sponsors it? Were you in attendance? 

  36. RedBaron @235.

    I assume this paper by Retallack will contain what you're advocating. And (I do hate linking to video - life is too short) this 24 minutes of somebody's life will explainwhat you mean by Teague (& this the Retallack equivalent).

  37. Correction to #236. That Teague link is here.


    [JH] Commenters like RedBaron are expected to document the source of their assertions about what others have supposedly stated. It they do not, or cannot, their comments are merely heresay hearsay. 

  38. OK I got the Name of the conference wrong, but here is a link.


    [PS] Fixed link

  39. Here is the published text that support the conference lecture. That is what is in The Annual Review of Earth and Planetary Sciences. Sorry I got the conference name wrong by swapping it with his published paper.


    [PS] FIxed link

  40. RedBaron @239.

    Fine. We are looking at the same sources. So where within this work of Rellatack or this work of Teague is there support for your assertion @225 that the IPCC AR5 Chapter 6 "have the numbers right for the land use change to agriculture, but are missing the land use changes within agriculture as methodologies change."?

  41. MA Rodger,

    You asked, "So where within this work of Rellatack or this work of Teague is there support for your assertion @225 that the IPCC AR5 Chapter 6 "have the numbers right for the land use change to agriculture, but are missing the land use changes within agriculture as methodologies change."?" 

    Retallack I used to establish a base line and context. So for example, when I speck about methodologies in agriculture that use biomimicry to restore ecosystem services function, it is important to define exactly what that means, and show evidence that indeed at one time ecosystems did function to sequester carbon and cause global cooling. So Retallack provides that evidence, context and helps one to exactly understand which ecosystem functions we are trying to restore, why. and how.

    Teague is the direct answer to the question of changes in agricultural methodology, as several types of land use change within different management types of agriculture were directly measured on a real world working ranch scale. Now that was accomplished by using biomimicry, and the concepts being mimicked are evidenced by Retallack. So they are interconnected in that way although Retallack's research has nothing to do with agriculture directly. There are other methodologies that use biomimicry to accomplish carbon sequestration. I simply used Teague because his research is well documented and pretty robust. Many other carbon farming techniques are still in what we would call development and verification stage. I am deveoloping one myself in fact. But I couldn't use that here as it is unpublished original research. Teague's work is published reviewed and pretty strong evidence.

  42. RedBaron @241.

    So what you are saying is that these two Retallick & Teague do not accuse the IPCC or anybody else of failing to account properly for CO2 emissions from land use changes. Are there any other studies or published theories that lend support to accusations of such mal-accounting of emissions by the IPCC? Or is it all some analysis of your own invention? Perhaps you would like to share your detailed reasoning with us. Or perhaps it is not that well-founded and yet unready for the rough-&-tumble of public scrutiny.

  43. @ MA Rodger,

    Actually a closer aproximation of what I am saying is that the IPCC is vastly underestimating the problem, by ignoring much of the most basic underlying causes. This has also flawed their analysis of what needs to be done to fix the problem as well. Maybe if I approach it in more general terms you'll understand better. I admit I am not a very good "rough and tumble" public debate specialist. So you'll probably need to fill in some blanks yourself. But let's look at some disturbing trends. As a result of erosion over the past 40 years, 30 percent of the world's arable land has become unproductive. Now of course this is measured in terms of agricultural food production for humans. But if you understand that unproductive also means not feeding the soil food web that is responcible for the major part of the carbon cycle, you get an idea why the biosphere can't keep up with fossil fuel emissions. Or look at it from still another angle. The least efficient natural ecosystem for long term sequestration of carbon is forests, and forests currently occupy only 20-25% of the land surface of the planet, yet nearly all the carbon sequestered in world wide terrestrial ecosystems is in forests. Why? Because mismanagement of agricultural "artificial" ecosystems. Mismanagement that has turned the largest terrestrial carbon sink into an emissions source! Depending on how IPPC calculates it, it is either 8-10% of emissions, or calculated differently near net 0 effect. See references above. post 227 "Globally, the current flux from agricultural management is uncertain but probably not far from zero." See the IPPC got that part! But what they left out was that the same ecosystems that are currently "probably not far from zero" are the same ecosystems that pre-human intervention were the primary terrestrial sequesters of carbon. I am not sure how to explain the math flaw. If you have a negative and turn it into a positive, it is wrong to use the positive as the effect. So if you start with -A and later measure +B due to anthropomorphic changes. It is improper to use +B as the anthropomorphic effect. The real anthropomorphic effect is A+B. IPPC has vastly underestimated the effect of agriculture for this reason. Admittedly that is highly oversimplified, but it addresses the principle IPCC flaw. The effect of environment degradation is underestimated because the measurements are being done on the degraded ecosystems we see now, not the functioning ecosystems prior to humans degrading them. 

    Adding to the confusion, humans can actually improve on the natural ecosystems function beyond the natural pre-historical state (with intensive management). We haven't. We have done the opposite. But there is no reason we couldn't.

  44. In response to Red Baron in general, Houghton et al (2009) itemizes total biomass/hectare for various ecosystems.  Carbon constitutes about 50% of the biomass.  Taking low values where two are given, we thus determine that the carbon content constitutes 95 Tonnes/Hectare (ie, Megagrams per Hectare) for tropical rain forest, and 28.5 Mg/Hectare for tropical savannah.  The difference is 66.5 Tonnes per Hectare.

    Figure 8 of Retallack et al (2013), shows the carbon content in Kilograms per meter squared for for various ecosystems in African and Australia by precipitation.  In Australia, forests have a greater carbon content in soil than do grasslands (Mallee scrub).  In Africa forests have less carbon in soil than do grasslands.  Taking the largest difference (4 Kg/m^2) and converting units, that represents 40 Tonnes per Hectare.  Therefore, using conservative estimates, and counting both soil carbon and biomass Tropical rainforests sequester 26.5 more tonnes/Hectare than do equivalent grasslands.  Using more reasonable estimates, forests sequester as much as 126.5 tonnes/Hectare more carbon than do grasslands, ie, about twice the carbon per hectare.

    Interestingly, Teague (in a book chapter for Geotherapy) shows a tabulation (table 17) of soil and total Carbon stored in various ecosystems from White (2000).  He points out that globally, grasslands store more carbon in soil than do forests, although forests store more tonnes per hectare.  That is true of soil carbon alone, but once biomass is included, forests store 90% more carbon as grasslands per unit area, globally averaged.  White's results, as quoted by Teague, suggest the African situation is anonalous, and that the Australian situation where forests store more soild carbon than do grasslands is more typical.  Indeed, on the White (2002) figures, forests store 50% more carbon in soil per unit area than do grasslands.  (That may partially be because grasslands are typically found in more arid conditions than are forests.)

    Of more direct interest to your vague theses, Teague also tabulates estimates of emessions from various sources, showing 136 GtC from land use conversions from 1750 onwards (compared to the 180 GtC estimated in AR5), with a further 320 GtC estimated emissions over the Holocene to 1750.  The 136 GtC estimate for industrial era emissions compares to an estimated 270 GtC emitted from fossil fuels (compared to 365 GtC estimates in AR5).  Part of the discrepancy between these estimates and those from AR5 may be due to the final date of the estimate.

    Importantly, Teague is not suggesting that soil degradation is responsible for the hockey stick in atmospheric CO2 concentrations.  He does suggest soil revitalization can eliminate excess CO2 from the atmosphere, but that is because he assumes the revitalization of soil degraded in the preindustrial era will contribute to the sequestration.  The sharp increase in CO2 concentration, however, is due primarilly to the very sharp increase in fossil fuel use as shown in his post at 224.

    Teague does, however, suggest that restoration of the grasslands could sequester sufficient CO2 to bring the atmosphere back to preindustrial levels.  He writes:

    "If, for the sake of argument, we accept Buringh's 537 Gt number for the historic
    loss of carbon from soils, it is the equivalent of 218 ppm that was once safely 
    stored in the ground instead of in the atmosphere, and is roughly twice the
    excess carbon that we've injected into the atmosphere since 1750 (half of which
    was absorbed by the ocean and other carbon sinks). We need only put 224 Gt
    (112 ppm) back into the ground, even though a percentage of the excess didn't
    come from soil, it's from our burning of fossil fuels. To emphasize, replacing
    just half of the soil carbon we have lost in the past ten thousand years has
    the realistic potential for reducing atmospheric carbon to a pre-industrial
    280 ppm, presumably a significant step in restoring a relatively stable
    climate. Note that in so doing we would also sequester all past and current
    emissions from fossil fuels."

    (Original emphasis)

    I do not, however, trust his sums.  First, 1ppmv of CO2 in the atmosphere is 2.12 GtC (AR5), not 2 as uses in his estimate.  More importantly, just as only 44% of anthropogenic emissions have stayed in the atmosphere, only 44% of any carbon sequestration will result in a reduction on atmospheric CO2, the rest being compensated for by oceanic outgassing.  Therefore, to reduce CO2 concentrations by 120 ppmv, we need to sequester 580 GtC.  That is, he underestimates the task at hand by 60%.  Put another way, we would need to sequester 27% more CO2 in the soil than he estimates to have come out of it since the start of agriculture to tackle global warming this way.

    Second, he appears to fudge his figures.  Ruddiman's estimates of preindustrial emissions include excess methane production from the spread of rice paddies, and emissions from deforestation.  That is, they are not an estimate emissions of soil carbon.  Indeed, even the industrial era emissions from LUC only include 78 Gigatonnes from soil itself.  Assuming a similar proportion of preindustrial emissions are from soil, that means only 260 GtC have been emitted from soils due to human activities over the last 10 thousand years.

    Given this, the idea that we can solve AGW simply by changing our pastoral practises is fanciful.  (We may be able to help solve the problem by such changes, but it will only be a small contribution to the problem, most of which must be solved by reducing industrial emissions.) 

  45. RedBaron @243.

    I fear you are straddling all three of your different arguments you have brought here with your comment. As I explained @234, this is a great impediment to getting anywhere in this discussion.

    As I interpret it, your -A+B illustrates this situation of mixing these different arguments. The +B is the carbon sequestration from future improved agricultural practice that you contend is a way of reversing CO2 levels. The -A is (it seems) is not the carbon loss from present agricultural practice that you contend the IPCC is underestimating. Rather -A is some natural sink that has ceased due to human intervention, a third issue that you argue here.

    Sticking with the IPCC underestimation before we address anything else (which makes things much less complicated), you again quote Houghton et al (2012) as referenced by IPCC AR5 which states "Globally, the current flux from agricultural management is uncertain but probably not far from zero." And for all the world, you are agreeing with this statement @243 - "See the IPPC got that part!"

    So, as we both seem to agree with the IPCC, can we agree? The on-going management of agrcultural lands (as opposed to changing land use) is as the IPCC say roughly carbon neutral.

    And if we can do that, do you then accept that the sources of carbon emissions set out by the IPCC are not in gross error?

  46. Tom Curtis @244.

    The error by Teague in suggesting that sequestering 2GtC from the atmosphere would reduce atmospheric CO2 by 1ppm(v) is identical to that made by Savory.

  47. Continuing from #247 in the absence of a RedBaron reply.

    I see no evidence that Houghton and others are in error over CO2 emissions from land use.

    Concerning the issue of the role of soils in the reduction of atmospheric CO2 levels over the last 19 million years, this contention is based solely on the work of Retallack (eg Retallack 2013) which attempts to argue that there are three competing theories that could be responsible for this reduction, rock weathering, ocean up-take and soil creation and Retallack argues that soil creation is the most likely. Such argument is badly flawed as Retallack makes the same basic  mistake as Teague & Savory described @244. From Retallack (2013):-

    "If grassland soils sequester approximately 1 kgC per sq m more than do preexisting woodland soils (Retallack 2001), 40% of the current world’s land surface of 148,940,000 sqw km could have sequestered an additional 596 PgC,  comparable with 750 PgC as CO2 currently found in the atmosphere (Sanderman et al. 2010) and compatible with the observed halving of atmospheric CO2 over the past 19  million years ."

    However, to draw down atmospheric CO2 to half the level, say by 700 PgC, there will also be a need to sequester the resulting emissions from the biosphere (350 PgC) and the oceans (2,450 PgC) as the atmospheric level is in balance with boisphere and ocean. This totals at 3,500 PgC. (These figures very roughly based on the work of David Archer.)

    The colder oceans would have taken perhaps 1,400 PgC leaving 2,100 PgC but the oceans can be considered as a feedback mechanism due to global cooling. The appearance of deeper soils may have reduced the amount of rock weathering required to handle the 2,100 PgC, but if this was something like 600PgC, the largest contribution to CO2 draw-down remains rock weathering.


    The final line of argument fron RedBaron was the use of agriculture to sequestrate CO2 from the atmosphere and reduce the atmospheric levels despite continuing emissions from fossil fuel use. Because of the basic error described above, this could only hold CO2 levels static. It could not reduce them with the present CO2 emission levels. That in itself would be a wonderful thing to achieve if it were possible but it would require a change in agricultural practices worldwide to get such a result, a task almost as difficult as weaning mankind off the fossil fuels which is the primary cause of our problem.

  48.  I find it rather odd that nobody ever brings up the fact that our Magnetosphere has been steadily weakening during all of this "climate change" nonsense.
      It has been weakening by 5% per decade, this could very easily account for elevated temperatures and erradic weather patterns. Just food for thought.


    [PS] Please substantiate your claim of 5% per decade and that this has only started happening over period of global warming, and how a weakening magnetosphere can warm the earth. Unsupported claims are sloganeering and violate comments policy.

     Further - if you are linking to Svensmark cosmic ray hypothesis, then please see here for what the science has to say about this

  49. Talvar is almost certainly referring to data from the Swarm satellites which recently showed that magentic field strength was changing ~10 times more rapidly than expected over a six month period. The expected rate, based on research suggesting that a magnetic pole reversal is underway, was approximately 5% per century... multiplied by ten yields his 5% per decade. However, as noted, that is based on six months worth of data from a new system. There is no evidence whatsoever that this has been going on for a long time as he implies.

    Further, it just isn't relevant because this cannot "very easily account for elevated temperatures". To my knowledge no one has even suggested a mechanism to explain how variations in the Earth's magnetic field would cause massive planetary warning. If anyone ever tries they will have a fun time explaining why there seems to be no connection between the pattern of magnetic variation and the pattern of warming... e.g. during that six month period the magnetic field over the entire North America continent actually strengthed greatly (that change being offset by declines elsewhere around the globe), yet the western part of the continent was warmer than normal and the eastern portion colder.

  50. @MA Rodger,

     Sorry for the delay in replies. I realise I have probably poorly stated my argument. So I found a presentation explaining it online. I realise the presentation is not the same weight as a scientific study or even a synthesis. But I hope this will explain my position with more clarity. Please explain to me where you believe this guy is wrong. That will give you context and me a place to start digging.

    PS. You said, "That in itself would be a wonderful thing to achieve if it were possible but it would require a change in agricultural practices worldwide to get such a result, a task almost as difficult as weaning mankind off the fossil fuels which is the primary cause of our problem." I would counter with the fact the green revolution happened almost overnight. A similar change to a carbon farming revolution could be equally rapid in my opinion.

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