Climate: What we know and what we don’t
Professor Salby giving his presentation on 7th November 2013
to the Scottish Climate & Energy Forum.
produced by Mike Haseler BSc. MBA
Summary
In order to understand the importance of the evidence presented by Salby it is necessary to understand the case for attributing the recent rise in CO2 to human emissions. This starts with the assertion that man-made, rather than natural, emissions of CO2 can be shown to be the cause of the recent rise in atmospheric CO2 because:
- The recorded rise in CO2 from 1958 of about 100ppm is larger than anything apparent in the proxy record. This “unprecedented” rise is seen as a fingerprint of recent human activity
- The ratio of carbon 13 to carbon 12 in the atmosphere has decreased since 1830. This was thought to be due to the burning of fossil fuels which have a lower ratio of carbon 13. As such the reduction in the ratio was thought to be the “fingerprint” of man-made emissions.
And then it is argued that this rise in CO2 is causing global warming because:
- CO2 and temperature move together in an apparent relationship in the proxy records
In his lecture Salby showed:
- Whilst there is a good fit in the ancient record from proxy ice-cores, the measurements of recent global temperature is poorly correlated with the measured level of CO2.
- Instead, net emissions of CO2 (not the level) is more closely related to temperature.
- If we model surface conditions with temperature & humidity in the atmosphere:
- net emissions of CO2 can be predicted from surface conditions
- net emissions of Methane can be predicted from surface conditions
- net emissions of Carbon 13 can be predicted from surface conditions
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Evidence shows that the sources of atmospheric CO2 (as shown by areas with highest concentration) are not related to man-made emissions from burning fossil fuels.
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The evidence shows Carbon 13 is not a fingerprint of human emissions.
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The IPCC are wrong to say: “all … increases [in CO2] are caused by human activity.” or “the increased atmospheric CO2 concentration is known to be caused by human activities”.
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In significant part, changes in the level of CO2 are controlled by global temperature.
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Furthermore he proposed a mechanism to explain the anomaly between the behaviour of CO2 in the actual atmosphere and that seen in the proxy record from the ice core. This was that there was a non-conservative damping mechanism such as diffusion or loss in removal of the ice core.
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Non-conservative influences would cause past atmospheric CO2 to be significantly underestimated, so it is likely that the recent rise in CO2 is not unprecedented.
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All the recent history of CO2 can be explained from surface conditions alone.
Introduction
On 7th November 2013, Professor Salby gave two presentations in Edinburgh. The first was hosted by Murdo Fraser MSP in the Scottish Parliament, the second by the Scottish Climate & Energy Forum at the Links Hotel.
This report summarises & explains the arguments & evidence presented at the lecture. Its purpose is to inform members of the Scottish Climate & Energy Forum & other invited guests who could not attend with an aim of highlighting the significant implication on public policy.
Please note:
Whilst every care has been taken compiling this report, it is not intended to be a reproduction of the lecture which was largely scientific in nature. Any omissions or mistakes are likely the responsibility of the author.
In line with the convention for scientific work we will refer to Professor Salby in this work as Salby.
Terminology
ppm: Parts per million. 100ppm = 0.01%
Correlation & coherence: When we measure two things and their measured values increase and decrease together they are said to be correlated. An example is children’s age and height. The better they are correlated, the more a change in one is proportional to a change in the other.
Lag (when referring to correlation): Often, although two things are related, they do not occur at the same time. For example, freezing conditions cause burst water pipes – but usually after the pipes thaw. So, the weather has to warm before the effect of the severe cold shows. There is a time delay between the cause and the measured effect. So, if we plotted burst pipes with temperature, we would find a poor correlation between the number of call outs to plumbers and the current temperature, but perhaps a much better one between the number of call outs and the temperature the day before. This is the lag.
Proxy: We do not have reliable direct measurements of temperature or CO2 before 1958. However we can infer the level of these in the past by measuring other things. A proxy is something that isn’t a direct measurement but something from which we estimate the value of something else.
Two proxies are commonly used. It has been found that there are bubbles trapped within ice-cores in areas like Greenland where it has been continually cold, long enough for ice to accumulate over long periods. It is possible to measure the amount of CO2 in the air in these bubbles and this is believed to tell us the amount of CO2 present when the snow that formed the ice fell.
The other proxy is the ratio of Oxygen 16 and Oxygen 18 in the water. Since the ratio of these varies with temperature, this ratio can be used to estimate temperature when the snow formed.
The Case for human emissions causing the recent rise in CO2 & global warming.
Since 1958 when good records of CO2 begin, both CO2 and global temperatures have risen. Two questions arise:
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Did the rise in CO2 cause the rise in global temperatures.
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Is the CO2 rise caused by humans.
If both are true then it is reasonable to conclude that that humans are causing global warming through man-made emissions of CO2. If not, then this conclusion is false.
The evidence CO2 causes warming: the proxy ice cores.
The main evidence for CO2 causing global warming lies in the proxy measurements of CO2 & temperature derived from polar ice cores.
Fig 1: Graph of temperature (blue), CO2 (green) & CH4 (purple) from 450,000BC to present
This plot shows the proxy values of CO2, methane (CH4) and temperature over time derived from measurements from ice-cores. But note, these proxy values are not the actual value of CO2, temperature or methane, instead they are indirect measurements of the original value. These indirect measurements appear to show that global temperature is high when CO2 & methane are high, and that global temperature is low when CO2 & methane is low. If the CO2 in the ice cores were the same as the atmosphere, it would show that global temperature is related to the level of methane and CO2 in some way.
Therefore it was assumed that there is a direct relationship: that CO2 level causes the temperature to respond. However, more detailed analysis showed that temperature causes the response in the level of CO2.
Moreover if true, this proxy record shows that CO2 levels change from a low of 180 parts per million
in the depths of ice ages to about 280 during the warm periods. This 100ppm change would make the recent change from around 300ppm before industrialisation to 400ppm “unprecedented”. So small range of CO2 in the ice core samples is seen as evidence that the recent change in CO2 is highly unusual. This is taken as proof that the change must be due to human activity.
Carbon 13 – the “fingerprint” of Mankind on CO2
One of the key pieces of evidence for human causation for the CO2 rise is that there have been changes to the carbon isotopes in the atmosphere. Isotopes are different forms of atoms with the same chemical behaviour but with different masses. Carbon has three main isotopes: carbon 12, carbon 13 & carbon 14 (For shorthand these are often written: 12C, 13C and 14C). Carbon 12 is the most common.
Fig 2: Recent evolution of CO2 (green) & the ratio of Carbon 13 to carbon 12 (δ13C in red).
This shows CO2 has risen whilst the ratio of Carbon 13 to carbon 12 has dropped
Figure 2 (above) shows that whilst the level of CO2 has risen in the atmosphere, the ratio of carbon 13 to carbon 12 (δ13C) has dropped.
About 1% of carbon in atmospheric CO2 is carbon 13. But, the level in CO2 produced in fossil fuels, burning forests or rotting vegetation, has less carbon 13 than the atmosphere. This is because plants have a preference for the lighter isotope of carbon 12. So things like wood or fossil fuels which are formed from plant material have a lower level of carbon 13. If CO2 from these materials is released into the atmosphere, the the ratio of Carbon 13 to Carbon 12 in the atmosphere would decrease. So figure 2 is thought to show the “fingerprint” of humans: that as we burn fossil fuel, with lower levels of carbon 13, the proportion of Carbon 13 in the atmosphere drops.
Summary of the case
Taken together, the dropping carbon 13 levels, the unprecedented rise in CO2 & the correlation of CO2 and temperature are all believed to be conclusive proof that humans have caused man-made warming. The carbon 13 & apparently unprecedented rise appear to show the CO2 is man-made. The correlation is believed to show that the CO2 rise in turn caused global temperatures to rise; the so called smoking gun.
Are humans responsible for the rise in CO2 and does CO2 drive temperature change?
Are recent increase in temperature driven by CO2?
There were two key graphs in the presentation. The first was this:
Fig 3: Observed record (atmospheric measurements) Absolute value of CO2 in green
and global temperature in blue. This shows poor correlation.
It shows a plot of the level of CO2 in the atmosphere (green) and global temperature (blue). This is usually interpreted as the rise in CO2 driving temperature. If true, we would expect the temperature plot to follow the plot of CO2. In contrast, except for the general upward trend, the two have no features in common. The CO2 plot curves upward, in contrast, with no general general warming after 1998, the temperature plot curves downward. The CO2 plot has a yearly cycle which hides other features. The temperature curve is full of sharp variations which cannot be seen in the plot of CO2.
Finding 1: Global temperature is poorly correlated with CO2.
However, the large yearly cycle of CO2 may be hiding fine detail. We can see if there is any detail in the CO2 curve by by averaging over a year to remove yearly changes and then plotting the rate of change. This removes the overall trend and magnifies any small rapid changes. This produces the blue plot in figure 4 below. In contrast to the level of CO2 shown in figure 3, the plot showing the rate of change of CO2 is a very close match to the global temperature curve in green (which has been similarly smoothed).
Fig 4: Plot of CO2 inter-yearly CO2 net emission rate against global temperature
This time, the two show a remarkable high level of correlation: they both share the same constant upward trend which is consistent over the whole period from 1964 to 2008, and almost every peak and trough in CO2 emissions has a corresponding peak or trough in global temperature. So is this the fingerprint showing that changes in CO2 drive global temperature?
No! The reason is that this time we have not shown the level of CO2 ,but net emissions of CO2 . When temperature is higher, there are more net emissions of CO2. When temperature is lower, there is less net emissions of CO2. This is very strong evidence that the rate of emissions is linked to global temperature. This is not what we would expect if CO2 were driving global temperatures.
Finding 2: Measurements of the atmosphere show that it is the rate of change of CO2 , not the level, which is closely related to global temperature.
Finding 3: Measurements of the atmosphere show a very different relationship between CO2 and temperature than indirect estimates of ancient CO2 and temperature from ice-core proxies.
Could human activity changing in response to temperature explain the relationship between net CO2 emissions & temperature?
It is possible that there is some kind of indirect relationship between net global emissions of CO2 and temperature. For example, when the weather is cold we turn on fires. So we would expect emissions to increase when the weather is cold. However the relationship is that emissions increase in warmer periods, so perhaps warmer conditions allow more building or other economic activity that produces more CO2 ? Could human emissions be responding to changes in global temperature and could this be responsible for the increase in emissions when temperatures rise?
Fig 5: World production of CO2.
As figure 5 above shows, the plot of human emissions does not look anything like (the) net change of atmospheric CO2 in figure 4. So human emissions cannot explain the change in atmospheric CO2. The plot is remarkably smooth with nothing to suggest any link to the changes in emission we see in figure 2. Indeed natural fluxes should be more important because as figure 6 (below) shows the human emission of 29 gigatons is a minor flux of only 4% of total emissions. So, even a small imbalance in natural fluxes will dwarf the small human emissions, so one would look at these first for the cause of any change in net CO2 emissions.
Fig 6: Global carbon fluxes of carbon dioxide in gigatons
Source: (Figure 7.3, IPCC AR4).
Finding 4: Net emissions of CO2 to the atmosphere do not show a relationship to global consumption of fossil fuels because natural fluxes are more important.
Is human produced CO2 increasing atmospheric CO2 levels?
As human we burn large amounts of fossil fuel which produces CO2 it would be reasonable to assume that as we burn more or less that these changes would lead to a corresponding change in the level of CO2 , but apparently not. Although Salby did not say so himself, the following two maps more or less demolish this assumption. Figure 7 shows calculated human emissions of CO2 (in red). Figure 8 shows the actual concentration of CO2 as observed by satellite, with likely sources (in red) and likely sinks (in blue). It is clear that the two maps are very different.
Fig 7: Map showing production of CO2 with highest areas in blue and then red.(source EDGAR)
Fig 8: Map showing concentration of CO2 (highest in red)
Man-made CO2 emissions are highest in the mid-northern latitudes, in a band going from the East USA through Europe down to India and up to China. In contrast, the satellite image shows almost no high concentrations of CO2 in these areas. Instead the high concentrations of CO2 are in a band at the equator. Indeed, the only area of high emissions near the equator in Africa is Nigeria which has conspicuously low levels of CO2. One could even suggest that these maps show that rather than humans increasing CO2, the data would better suit a hypothesis that humans are decreasing CO2! There is clearly no fingerprint of human emissions from fossil fuels in its distribution.
Finding 5: The sources of atmospheric CO2 (as shown by areas with highest concentration) are not related to emissions from burning fossil fuels.
If changes in CO2 levels are not related to human activity what can explain the changes in CO2?
When two things happen together, it is not always easy to work out which is causing which. For example, does the dog wag its tail because it gets a treat, or does the mistress give the dog a treat because it wags its tail?
Common sense can often help, but not always. One possible explanation for rising CO2 is that human emissions are the cause, but this does not fit the evidence of figure 4 & 5 which show that net global emissions of CO2 into the atmosphere are related to temperature and not to human emissions.
So, we need to look for some way to explain the change in CO2. Salby proposes that soil conditions must play a part in the same way that field measurements show that natural CO2 emissions increase when temperatures rise. This is fairly simple to understand. Fungi & plants, like all living things, prefer warmer conditions. So when it is warm, there is not only more growth but faster breakdown of organic material which releases CO2.
Because decomposition in anaerobic conditions tend to produce methane with CO2 , then if decomposition is responsible for the production of CO2 then we would expect to see that the level of methane (CH4.) is also affected by surface conditions.
To validate this hypothesis Salby shows that he can reconstruct the emissions of: CO2 (figure 9); Methane (figure 10), and Carbon 13 (figure 11), very accurately using only two features of surface condition, namely temperature and humidity.
Table 1 (below) shows that proxy CO2 (from ice cores) correlates well with proxy temperature with a figure of about 0.85. But when the actual recent measurements of CO2 are compared with measured temperature the correlation is poor (about 0.5). The correlation improves when we compare net CO2 emissions and temperature (0.63) and very good when we include soil moisture to model surface conditions with correlations between modelled surface conditions and CO2 of 0.93, methane/CH4. of 0.94 and the ratio of carbon 13 to carbon 12 of 0.88.
So this is very strong evidence that it is soil conditions that are causing the changes in net global emissions of CO2 , methane and the change in the ratio of Carbon 13.
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Comparison
with
Correlation
Notes
Proxy CO2 level
Proxy Temperature
~0.85
at <1000 years lag
CO2 level
Temperature
>0.5
at 10 month lag
CO2 change
Temperature
0.63
CO2 change
Temperature & soil moisture
0.93
Methane change
Temperature & soil moisture
0.94
Carbon 13
Temperature & soil moisture
0.88
Negatively correlated.
Table 1: Correlation of proxy CO2, measured CO2 & change of CO2 with temperature.
Correlation of methane and Carbon 13 with temperature.
Fig 9: CO2 emissions compared to global model for surface conditions
(i.e. surface temperature and soil moisture). Correlation is 0.93
Figure 9 (above) shows that the emission of CO2 is closely related to surface conditions (surface temperature & soil humidity) achieving a much better correlation than that between actual CO2 & temperature or even proxy CO2 and proxy temperature.
Fig 10: Methane (CH4) emissions compared to global model for surface conditions
(i.e. surface temperature and soil moisture). Correlation is 0.94
The correlation of methane with soil conditions shows that variation in the soil conditions are the main cause of the observable change in methane. Because methane is not produced by burning fossil fuels but by decomposition this shows that soil conditions cause these emissions.
Finding 6: There is compelling evidence that the change in CO2 is driven (in whole or part) by temperature & surface conditions.
Fig 11: Carbon 13 emissions compared to global model for surface conditions
(surface conditions based on surface temperature and soil moisture are shown inverted).
Finally the correlation of carbon 13 with soil conditions (shown inverted) shows that changes in carbon 13 are a result of native sources affected by soil properties.
Figure 11 is particularly important because it shows that changes in the proportion of carbon 13 in the atmosphere are strongly related to surface conditions. This contradicts the assertion that the change in carbon 13 is caused by man-made CO2 emissions. As the decrease in carbon 13 in the atmosphere in figure 2 was taken as proof of human emissions, this graph shows that this assertion is wrong.
Finding 7: Carbon 13 is not a fingerprint of human emissions. Instead its production (at least in part) relates to surface conditions.
Is there other evidence the change in CO2 is caused by global temperature?
If one thing causes another, then it follows that if there is a time delay between the two, then the cause will occur before the effect. Figure 12 below shows how well the temperature measurements match the increase in CO2 if the two are compared for various time differences.
Fig 12: Correlation between CO2 and temperature in the observed record
showing maximum correlation where temperature leads CO2 level by 10months.
This shows that the closest match occurs when the CO2 lags the temperature by about 10months. Taken together with the graphs showing a correlation between net emissions and temperature this is very strong evidence that global temperature causes the change in CO2 emissions.
Finding 8: A significant part of the change in the level of CO2 is controlled by global temperature.
Finding 9: The IPCC are wrong to say:
“All these increases [in CO2 from pre-industrial times] are caused by human activity”
or: “The increase in atmospheric CO2 concentration is known to be caused by human activities because the character of CO2 in the atmosphere, in particular the ratio of its heavy to light carbon atoms, has changed in a way that can be attributed to addition of fossil fuel carbon.” (IPCC AR4)
In fact this is impossible as Salby put it.
How can we explain the anomalous relationship between proxy CO2 and temperature and actual CO2 and temperature.
Having shown that the rate of actual net CO2 emissions into the atmosphere correlates with surface conditions, we still have left the anomaly that the level (not net emissions) of CO2 in the proxy record from ice-cores correlates with proxy temperature. There is strong evidence from recent direct measurements that temperature causes the emission of CO2 readings. But, so long as we have the unexplained anomaly, it is possible that the anomalous position is that seen today rather than that seen in the proxy record of CO2 from ice cores.
What Salby proposes is in principle very simple: that ice-cores do not correspond to actual levels of CO2 at the time the snow was formed.
To understand this it is worth recapping how CO2 is trapped in and then obtained from ice. Although snow is frozen water, it is “fluffy” and has lots of air spaces. As more and more snow settles, this air gradually becomes trapped as the snow compacts to form ice. Eventually the air is enclosed by ice and bubbles form in the ice. The assumption is that this air remains completely unchanged for thousands of years in the ice, so that when the ice is drilled to remove a core, the ice can be melted and the air collected. If this air is completely unchanged it will tell us the amount of CO2 in the air at the time the snow fell. In addition the ice can be sampled for the ratio of Oxygen 16 and Oxygen 18 which indicates temperature when the ice was formed.
However, by showing that the relationship between CO2 and temperature is different in the ice core compared to current measurements, Salby shows that this simple assumption may be wrong. That the air in the ice-core may not be a true sample of the air at the time the snow fell.
The hypothesis Salby proposes is that CO2 is lost from these bubbles in some way. Either this is some mechanism that reduces CO2 entering the ice; or that CO2 diffuses slowly through the ice column so that it is slowly lost, or that it is lost at the time of extraction (see below).
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Potential Mechanisms that may mean the level of CO2 from ice cores does not represent the level in the atmosphere when the snow fell are given below. They are illustrative & were not in the lecture.
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Although Salby did not suggest a specific mechanism, he suggested that the evidence shows that a non-conservative process was causing damping of the proxy CO2 readings. This would explain the anomaly between actual measured CO2 and CO2 in the proxy record. The evidence for this is in the form of the correlation curve as we compare the proxy temperature against the proxy CO2.
Fig 13: Correlation between CO2 and temperature in the proxy record (blue)
and theoretical model with damping (red)
What we would expect in the above graph if the proxy CO2 level were only related to the temperature at the time the ice in the ice-core formed, is that the graph would be very narrow (too narrow to show). This is because the curves would only match when we are comparing the temperature at a particular date to the CO2 at that same date. In contrast, the measured curve (blue) in figure 13 is very broad with correlation of tens of thousands of years. This shows that the proxy CO2 and temperature match over a very broad range of offsets. It is as if we are comparing a blurred image with the original scene. The blurring means we are not quite sure where it fits so there is a range of positions where they could match.
A non-conservative “damping” process like diffusion would cause this to happen. We can model this, and a match in their behaviour is strong evidence for such a damping process (although we do not know exactly what it is). To test this, Salby created a theoretical model and used this to calculate what the correlation would look like if a non-conservative damped mechanism were present. (red curve). The two curves are a very close match showing that some form of non-conservative process is a very good explanation for the anomaly. The reason for the anomaly is because the proxy record of CO2 is not an accurate record of past CO2. Also note how the actual curve is lopsided toward a positive lag. This is further proof that temperature leads CO2 in the proxy record.
Finding 10: The anomaly between proxy CO2 and actual CO2 can be explained by a non-conservative damping mechanism such as diffusion within the ice core.
If there is a non-conservative process causing damping in the signal, this process would cause the level of ancient CO2 to appear much lower in the ice core than that in the atmosphere when the ice formed. So, the evidence for this damping process is evidence the ancient CO2 levels have been underestimated. As such it is not possible to say whether the present rise in CO2 is unprecedented.
Finding 11: Because there is evidence the CO2 in the ice core does not represent actual CO2 , it is not possible to say whether the recent 100ppm rise in CO2 is unprecedented.
Can the temperature induced CO2 emissions explain all recent changes?
Whilst the presentation more than ably demonstrated that temperature induced emissions of CO2 must be responsible for part of the increase in CO2 seen in recent times, there remains the question of how much could still be due to human emission. Salby did not address this question directly but instead showed that all the recent rise in CO2 could be explained by emissions due to surface conditions.
Fig 14: Modelled CO2 net emissions (blue) from surface conditions compared to actual CO2 (green).
Figure 14 compares the net CO2 emissions (blue) calculated by integrating the sum of net emissions derived only from surface conditions (surface temperature and soil moisture). This tracks actual CO2 closely showing that this model can explain the entire recent history of CO2 (except the yearly swings which were not modelled).
Fig 15: Modelled (blue) versus actual (mauve) net emissions of methane. Modelled from surface properties
And as figure 15 shows, surface conditions also closely predict the net methane (CH4.) emissions. As methane is not produced during combustion of fossil fuel, this is further strong evidence that surface conditions are responsible for these emissions. However, the above reconstructions only use satellite temperature data which is not available much before the 1980s. To show that this model could explain all the recent history of CO2 since records began in the mid 1800s, Salby used the less reliable surface thermometer network to produce the following plot, this time without including soil moisture.
Fig 16: Plot of modelled CO2 in the atmosphere using satellite (mauve) and surface thermometers (red)
against CO2 from direct measurements (light green) and ice-core proxies (red). Due to the uncertainty
in surface temperature measurements there is a corresponding predicted range of modelled CO2 (pink shading)
Figure 16 (above) shows that the modelled level of CO2 from temperature alone using satellite (mauve) and surface thermometers (red) closely matches the measured CO2 (light green) as well as the less robust level of CO2 from the ice core proxies. It is all well within the range of uncertainty due to the uncertainty in surface temperature data.
Finding 12: All the recent history of CO2 can be explained entirely from surface conditions alone.
Finding 13: Man-made CO2 emissions are not necessary to explain recent changes to CO2 levels in the atmosphere.
References
Anon Carbon dioxide clathrate – Wikipedia, the free encyclopedia [Internet]. Available from: <http://en.wikipedia.org/wiki/Carbon_dioxide_clathrate> [Accessed 12 November 2013a].11
Anon Ice algae – Simple English Wikipedia, the free encyclopedia [Internet]. Available from: <http://simple.wikipedia.org/wiki/Ice_algae> [Accessed 12 November 2013b].
EDGAR EUROPA – EDGAR – Carbon dioxide (CO2) [Internet]. Available from: <http://edgar.jrc.ec.europa.eu/part_CO2.php> [Accessed 12 November 2013].
IPCCFAQ 7.1 – AR4 WGI Chapter 7: Couplings Between Changes in the Climate System and Biogeochemistry. Available from: <http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-7-1.html> [Accessed 12 November 2013a].
IPCC Figure 7.3 – AR4 WGI Chapter 7: Couplings Between Changes in the Climate System and Biogeochemistry [Internet]. Available from: <http://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-7-3.html> [Accessed 13 November 2013b].
> The main evidence for CO2 causing global warming lies in the proxy measurements of CO2 & temperature derived from polar ice cores.
This is certainly wrong. Notice that no source is given for this assertion. Compare, for example, https://en.wikipedia.org/wiki/Attribution_of_recent_climate_change which says:
Attribution of recent climate change to human activities is based on multiple lines of evidence:
* A basic physical understanding of the climate system: greenhouse gas concentrations have increased and their warming properties are well-established.
* Historical estimates of past climate changes suggest that the recent changes in global surface temperature are unusual.
* Computer-based climate models are unable to replicate the observed warming unless human greenhouse gas emissions are included.
* Natural forces alone (such as solar and volcanic activity) cannot explain the observed warming.
Notice that what you are reporting as “the main evidence” isn’t used at all.
1. the so called physical “understanding” is derived from modelling the proxy & actual records. The historical estimates are from the proxy record. The computer models are the same as their “understanding. So everything is in some way tied to this proxy record (why do I keep on wanting to say poxy?)
And your last point is ridiculous because you have got the cart before the horse as the report clearly shows that warming is not a consequence but a cause of changing CO2.
I don’t think you’ve understood. I’m not asking you to believe the evidence at this point – I know full well that you agree. What I’m pointing out is that your/Salby’s description of the “pro-IPCC” position is wrong. You don’t even know what the IPCC *is*. You’re inventing arguments, in order to knock them down. This is called creating strawmen.
The key words are:
“evidence” NOT ARGUMENT, THEORY, “understanding” and certainly not models as they don’t count as evidence
And “causing” … as in what causes what.
What you are trying to say is “the main evidence for CO2 causing … is because we understand it” … in which case you are saying there is no evidence.
No. You still haven’t understood what I’m saying, and I’m unsure how to make it simpler.
What I’m trying to tell you is what the IPCC puts forward as its arguments for why-its-anthro. I’m not trying to explain them in detail, and for the moment I’m not even trying to tell you they are correct. All I’m giving you is a broad outline, or rather simply the overall heading, of what those arguments actually are. And they are the things I’ve listed under the 4 bullet points.
And you’ll notice that what you/Salby claim is the main IPCC argument is not one of those arguments. You are not allowed to say “ah, but what I *think* you should be arguing is such-and-such”. You need to engage with what the IPCC are actually arguing.
So you/Salby have erected a strawman.
So whether you demolish that strawman or not is irrelevant to the IPCC’s arguments.
William, the point of those statements is to explain the evidential base which is addressed in the discussion which is the inference that the rise in CO2 is man-made and that CO2 causes warming.
If you had read the report you would have found that Salby does not disagree with either of these points So, to suggest this is a “strawman” argument is absurd. And to suggest I should have put in a lot of irrelevant details about the IPCC “understanding” when Salby didn’t even address this issue is not at all helpful.
What Salby’s actually concludes is that “at least in part it must be natural”. This is not the opposite of “CO2 causes warming” or “mankind is increasing CO2”.
I appreciate that you are unfamiliar with any paper that doesn’t start with the statement “there is overwhelming evidence blah blah”, however, when I look at what is real evidence and what is just assertions I find the main evidence is as I stated.
Yes, there are a lot of other points that I could have added to the introduction, but as they would have done nothing whatsoever to help explain the point being made by Salby and I’m not setting them up to knock them down, but instead explaining that they are important, you are yet again attacking the wrong thing.
Where you might have a point is on the CO2 greenhouse effect. I swithered about including this, but as Salby did not cover this in his lecture, as it is not relevant to the discussion and as you yourself dispute the direct evidence of the greenhouse effect from Hermann Harde …. (30% less using the 2008 HITRAN database), I don’t think I should count this as the “main evidence” … particularly in relation to the specific topic being covered.
> I appreciate that you are unfamiliar with any paper that doesn’t start with the statement “there is overwhelming evidence blah blah”
Are you being deliberately impolite? That’s certainly how that comment comes over.
You’re also wrong: firstly, we’re not talking about a paper – Salby refuses to write his stuff down – we’re talking about a talk. And As I’ve proved – http://scienceblogs.com/stoat/2013/11/09/thrust/ – I have listened to some of Salby’s stuff. Indeed, I’ve understood it in more detail than you have.
> And to suggest I should have put in a lot of irrelevant details about the IPCC
You still haven’t understood what I’m saying. I have not suggested adding the IPCC views. I’ve pointed out that your/Salby’s “The main evidence for CO2 causing global warming lies in the proxy measurements of CO2 & temperature derived from polar ice cores.” is incorrect. The ice cores do *not* form the main evidence for “CO2 causing global warming”.
I don’t know why you keep insisting otherwise.
If you mean to say “one possible argument in favour of CO2-causes-GW is from the ice core CO2/T” then I would say fair enough: its one small part of one of the less important arguements. But its not a major argument, and its certainly not “the main evidence”.
You don’t seem to be very interested in precision in language.
Pingback: Salby comment 1 | Wotts Up With That Blog
As you can see from the pingback above, I’ve written a post commenting on some of the evidence you present here. Apologies for not simply commenting here, but it was a little too long for a comment and it seemed easier to just write a post of my own.
Pingback: Carlin Economics and Science » Professor Murry Salby Delivers Devastating Critique of IPCC AGW Climate Science
The correlations between net-emissions and temperature that Salby discusses is well known, and was first pointed out by Bacastow back in the mid 1970s and is essentially the result of changes in the terrestrial biota in the americas due to ENSO.
However, Salby’s analysis is fundamentally flawed as statistical correllations are not sensitive to the average value of the signals over which they are computed (i.e. they measure only the similarity of the wiggles in the two signals around their average values). Sadly it is the average value of net emissions that gives rise to the long term trend, not the wiggles. This means the correllation tells you nothing about the cause of the long term rise in atmospheric CO2, it just explains the very small wiggles of atmospheric CO2 concentrations around its long term trend.
I wrote an article on this for Skeptical Science, which you can find here: http://www.skepticalscience.com/salby_correlation_conundrum.html I emailed Prof. Salby a copy of this article prior to publication for his comment, but he failed to reply.
I can’t agree with the dogmatic way you’ve stated this, but if I am allowed the appropriate level of scientific caution to us “coulds” rather than “is”, then I wouldn’t dispute that ENSO could be a cause of at least part of what Salby shows, however it does not explain the better correlation with surface humidity which strongly suggests a link to soil conditions.
Also your statement about the correlation – I know what you mean and as such what you mean is a valid criticism, but unfortunately you would have to couch it in suitably cautious scientific language before I could say I agree.
I’m sorry you haven’t heard from Murry. I understand having spoken to him that he has not had an easy time in Australia since he started looking properly at climate from a critical perspective.
Scottish “Sceptic”, did you bother reading what Dikran wrote? He pointed out that the fluctuation in short term CO2 levels is due to the effects of ENSO on terrestial biota in the americas, and you come back saying it doesn’t explain the correlation to surface humidity with a purported strong link to soil moisture. So, effects on terrestial biota have no connection to soil conditions, by your implicit argument.
Even worse is when you insist that he couch his main criticism in “suitably cautious scientific language” where his main criticism was to state a mathematical fact, and the consequences for analysis. Should Dikran also be duly cautious in stating that “one plus one equals two”?
Further, the hypocrisy in insisting on “due caution” from Dikran when no such caution is to be found in Salby’s lectures. Your comments indicating this flaw seem to be entirely lacking, but it is rushed out as a quick (and only) rebutal to Dikran’s comments.
Tom, is there really the need to use such aggressive language? Salby says that world CO2 emissions are related to temperature. You cite an example where they are. In a reasonable science that would not be cause for a disagreement because once we have one example we are likely to find others.
Regarding the “suitable scientific language” … he said ” This means the correlation tells you nothing about the cause of the long term rise”. This is factually incorrect. What is correct is that the analysis tells us more about short term influence than about the long term … and I think he may be able to argue (but didn’t) that the scale of this correlation effect becomes too small (but he didn’t say when). However, it is also true that if the temperature is driving the CO2 in the short-term, then unless we have very good evidence to the contrary, then we would expect it to drive CO2 in the long term.
However, praise where it is due. He is the only person on the none-sceptic side who seems to have any idea what Salby was saying. He does appear to have read, understood and thought about it, rather than what everyone else has done which is to attack the messenger rather than listen to the message.
No, because we know how temperature influences CO2 concentrations. We also know what the anthropogenic emissions are, so we have a perfectly good explanation for the rise in atmospheric CO2 concentrations. Furthermore, as others have pointed out to you, the CO2 concentrations in all parts of the system are rising, so there is no natural source for the rise in atmospheric CO2. If there was we would expect to see a decline in the concentration in at least part of the system. In other words, if you want to explain the rise in atmospheric CO2 as partially anthropogenic and partly natural, you’d need to find a source for the natural emission. There isn’t one.
I take some offense at your statement
However, given the normal tone of discussions about climate change, I’ll let this one pass.
ScottishSceptic There are plenty of people who have taken the time to understand what Salby is saying, Tom Curtis is certainly one of them, he has made a couple of posts on SkepticalScience that reveal the errors in Salby’s reasoning, and also one of them that sets out all the lines of reasoning that show that the rise in CO2 is anthropogenic, that anybody listening to Prof. Salby’s talk ought to read, you can find it here:
http://www.skepticalscience.com/anthrocarbon-brief.html
Now as to tone, in this case we do *know* that the rise in atmospheric CO2 is not a natural phenomenon. There are many lines of evidence that show this to be the case, as Tom points out. Thus to call my post “dogmatic” is incorrect, it is nothing to do with dogma, it is to do with evidence and reason. I would apply more cautious language if it were warranted, but the simple fact is that the evidence is overwhelming on this particular issue.
On the correllation, you write “This is factually incorrect. What is correct is that the analysis tells us more about short term influence than about the long term …”. This is fundamentally incorrect. It is a mathematical fact that correllations tell you precisely nothing about the average value of the signals, nothing, zero, zip, nada. As my SkS article shows the part of the signal that the correllation actually explains integrates over time to equal *exactly* zero. If you think that the analysis tells you anything about the long term trend, then you have fundamentally misunderstood the flaw in the analysis.
The simple fact that atmospheric CO2 levels are rising faster than anthropogenic emissions means that the natural environment is a net carbon sink, and has been taking up more CO2 than it emits every year since the start of the Mauna Loa record. As the observations tell us that the natural environment is a net carbon sink, it is *opposing* the rise in atmospheric CO2, not causing it.
I have always wondered what the following amounts to over the years.
The population is increasing a100,000 a day, each breath we take expels around 40,000 ppm of co2.
So after every ten years an extra 360,000,000 people times 40,000ppm of co2 expelled every so many seconds.
I am sure in the global scale of co2 insignificant, just seems like it should be a lot.
William, fortunately breathing is essentially carbon neutral (neglecting the fossil fuel used in producing and transporting our food) because the carbon we exhale comes from the food we eat, which directly or indirectly comes from carbon taken out of the atmosphere by photosynthesis. This means we are just helping to move carbon around the carbon cycle from one reservoir to another. Fossil fuel emissions are different as there we are taking carbon that has been locked out of the carbon cycle underground for millions of years and putting it into the atmosphere. So unlike our exhalations, fossil fuel use is adding to the amount of carbon cycling through the environment.
“Computer-based climate models are unable to replicate the observed warming unless human greenhouse gas emissions are included.” This is certainly wrong as well you know. Professor Jones pointed out to you over two years ago that computer-based models replicate the observed warming even if greenhouse gas emissions are completely excluded but the falsification of the surface temperature record is included instead. The surface temperature record was indeed fraudulently tampered with to include (i) an extra one degree per century warming over the entire twentieth century, (ii) an extra five degrees per century warming over the last two decades of that century. Once the fraudulent adjustments are removed, the surface temperature shows a fall over the last decade and, over the last fifteen years, a hiatus (neither warming nor cooling). When the existing computer models are re-run over the genuine data, the least poor match is achieved when”greenhouse gases” are excluded from the models altogether.
wottsupwiththatblog:
However, it is also true that if the temperature is driving the CO2 in the short-term, then unless we have very good evidence to the contrary, then we would expect it to drive CO2 in the long term.
No, because we know how temperature influences CO2 concentrations.
I am really finding your arrogance very tedious. There is a simple test as to what you know. That is called a climate model. These I hope you will admit encapsulate all the very best of what you know about the climate. That test proves that all you know was not enough to predict the climate one year let alone ten years into the future.
So a lot of humility is in order on your part and the part of other climate researchers.
You don’t know. You clearly think you know. But the evidence tells me otherwise.
We do gave good evidence. The mechanism that gives rise to the short term variability is not actually to do temperature as much as precipitation, which are both influenced by ENSO. ENSO causes changes in precipitation in the Americas, which causes changes in CO2 via changes in soil respiration and primary production. The mechanism that causes long term changes (e.g. during ice ages) is largely due to the solubility of CO2 in the oceans being temperature dependent. These are different mechanisms, and for the temperature driven solubility to be causing the current rise you would also need to explain (i) why the solubility of CO2 in the oceans is ten times more sensitive now than it was in the iceages (ii) why the CO2 content of the oceans has been rising rather than falling and (iii) how can nature be the cause of the increase when we know it is emmtting less CO2 than it takes up. While Wotts was being rather direct he wasn’t being arrogant, he was just pointing out that a lot of very good scientists have put a lot of work into trying to address these questions and published the results in journal papers. I’d say that asserting the worlds scientists in a particular field are all wrong on a very basic issue is not exactly an exercise in humility.
Well, I apologise for appearing arrogant. What I was referring to was partly Henry’s Law which tells us how CO2 concentrations in a liquid depend on the partial pressure of the gas in the atmosphere above the liquid and on the temperature. It’s well tested. I suspect it plays quite an important role in Coca Cola’s business model. Additionally we have paleo-climatological evidence for the relationship between atmospheric CO2 concentrations and temperature. So, maybe “know” is too strong but we’re “virtually certain” (i.e., given our current scientific foundations, we “know”). Furthermore, the evidence that I think you’re referring to is entirely consistent with this picture. Also, there’s all the other reasons why we are “virtually certain” that the rise in atmospheric CO2 concentrations is anthropogenic that people have mentioned on numerous occasions, that I won’t repeat again.
An entertaining side note – I’ve been criticised for using “could”, “I believe”, and “as far as I understand” – amongst other terms – on the basis that it shows too much uncertainty and hence how can I be taken seriously. Now you’re criticising me for being too certain. Oh well, it seems I just can’t “win”.
dikranmarsupial, yes evidence … now I’m listening.
However, as a physicist, you will have to forgive me, but I was taught only to assert things as being true in science which are beyond doubt. That requires laboratory testing in controlled conditions, instead you are dealing with a single complex situation where causation is very difficult to prove, controlled experiments are all but impossible and the state of knowledge is very primitive and all I hear is “this is so”, “that is so”, when I know you can’t possibly have the evidence to show anything more than a correlation.
For example: “ENSO causes changes in precipitation in the Americas,”.
I can easily change this around:
“the precipitation in the Americas causes ENSO” … and it would be as meaningless.
What I think you mean (and please do tell me if I am wrong) is that there is a correlation between ENSO & precipitation in the Americas.
A correlation is a fact, “ENSO causes” requires many steps:
1. You have to demonstrate that there is a well defined object called ENSO which definite properties which can be characterised without ambiguity.
2. That there is a correlation
3. That the is causation
4. That this is an identified & testable measurement which is being caused.
So, taking the last “causes changes” … is entirely untestable because you do not define what is the “normal” from which to be changed, or what it is that is being changed or the timescale or …
That is why scientists use phrases like “there is a correlation between this measurement and that measurement”. This is because it is very clear what it is that is being compared.
Then, assuming it is a correlation, this does not exclude there being other correlations between similar measurements worldwide.
This is why I called Woots arrogant. Someone dealing with science must accept the possibility they are wrong because that is the fundamental nature of science. New evidence always trumps opinions. And no scientist just dismisses evidence by asserting their own opinion about a causal link which they cannot possibly prove and certainly do not know. Yes, a scientist may offer an interpretation … yes they may think it a better interpretation of the evidence but no interpretation rules out another unless the evidence proves it. And yes, they may offer more evidence (but that doesn’t negate the evidence unless the evidence can be proven false).
So, all this nonsense talk of “we know this” and “we know that”, is just arrogant non-science.
> In line with the convention for scientific work we will refer to Professor Salby in this work as Salby.
Salby isn’t a professor. You know that. Why are you still pretending that he is one?
scottishscience There is a physical process which explains how ENSO causes changes in precipitation in the Americas, namely that warmer air supports greater humidity, which means that warm moist air from the Pacific can supply more precipitation to the Americas than cooler dryer air during the other half of the ENSO cycle. This is based on solid, well understood physics (the Clausius–Clapeyron relation).
There is no such plausible physical mechansim that could explain how precipitation in the Americas can cause changes in ocean temperature in the mid Pacific. The only contact that the precipitation has after it has fallen is in the outflow of the rivers, which are a very long way from the mid Pacific and are very small in magnitude compared to other ocean currents such as the Humbolt current. If you want to assert that there is a plausible causal link from precipitation to ENSO, you need a physical process that could explain the magnitude of the effect, which you did not do.
So, no I am not saying that there is merely a correlation between ENSO and precipitation, as there are good physical reasons to show the direction of the causal relationship. Now I didn’t explain that because if I were to explain every single detail to you one by one I would have to write a textbook, just to explain to you a basic fact about the carbon cycle. Ultimately, there is some onus on you to go and find out, rather than make non-sensical objections, such that precipitation causes ENSO. There have been hundreds of journal papers written about ENSO, the reason I know something about it is because I have read some of them.
I enjoy discussing science, I have little interest in rhetoric (for instance raising objections without first determining whether they have any validity – such as the idea that precipitation causes ENSO). Life is just too short, so I will leave it at that.
Scottish, The premise of what you’re saying is – I think – that I (for example) should consider the possibility that I’m wrong (I guess more than just me, a major area of scientific research). Fair enough – I actually think I do quite a lot of that (both considering that I’m wrong and actually being wrong). Consequently, I should then be willing to consider that Salby, for example, might be right. Okay, fair enough, let’s consider that Salby might be right.
If Salby is correct, there are a number of obvious conclusions. Henry’s Law would need to be wrong. Much of paleoclimatological research would need to be wrong. Here’s my issue number one. If Salby is going to present some kind of evidence that some fairly fundamental law is wrong, then really he should be presenting an alternative law for testing. Not only has Henry’s Law been tested, but all of what Salby presents is consistent with Henry’s Law. So, we don’t need another law. We have Henry’s Law which is consistent with all the known evidence (including that presented by Salby).
Furthermore, if Salby is right (as many have pointed out) there must have been eras in the past when our atmosphere had no CO2. How did our biosphere survive that? Wouldn’t everything would have died?
So, I have considered that Salby could be right and I can see no way that he can. Maybe I can turn the tables. What about considering that you’re/Salby is wrong and see what happens?
“Scottish” “Sceptic”, I asked you two questions on Wotts’ blog. I have still not received an answer. Here are the two questions:
Firstly, you and Salby claim that increasing temperature is causing an increase in CO2 concentration. What exactly is causing this increase in temperature?
Secondly, where is this extra CO2 coming from if not from human emissions caused by burning fossil fuels?
I hear what you are saying, that was just an example. However, it will do for my point. When we are dealing with a subject as fundamental as causation of CO2 production, then we have to be very careful not to start jumping to conclusions and saying “we know”.
The answer to Salby who shows a correlation between global temperature and net CO2 emissions isn’t “we know [it is not true]”.
Evidence trumps opinion.
On the specific issue of ENSO, a mere correlation between two measurements doesn’t mean that an object exists. ENSO is a complex series of features & measurements. I am sure if I looked I would find ambiguity about which features are, and are not, considered part of ENSO.
So when you say “ENSO causes”, you are in fact not saying anything much at all as I have no idea which of those many things that are considered part of ENSO is the part you believe has a correlation.
To turn it around, you can’t possibly disprove me if I say “ENSO doesn’t cause….”, because I too can just pick and choose what I consider to be “ENSO” … and then I can pick and choose what I consider to be “changes” and then I can pick and choose what is “precipitation”, and given the nature of natural variation, I bet I could “prove” any relationship I liked.
That is not how science works.
In contrast if I state the two measurements (one seen as part of ENSO and the other a measurement of precipitation) and I say there is a correlation, we can both know what we are referring to, we can have an intelligent discussion and we can then move on to more important subjects such as how to interpret this information.
At the very least, John Nielsen-Gammon (Texas A&M) and Alan Plumb (M.I.T.) heard Salby’s reputation-killer bait-and-switch talk @ Melbourne IUGG and the former commented in 2011, in comment thread at RC., as did Gavin Schmidt and Eric Steig. It was deemed so silly as to not be worth a blog post, just comments in an open thread. I liked Eric’s words:
‘’86. “…So far many people in this thread have written off this research without even having seen it!
[Response: Yup. Just as I have written off research demonstrating the non-existence of gravity, the validity of astrology, evidence that consuming plutonium is good for you, or the discovery of the fabled ‘counterEarth’ on the other side of the sun, I have not bothered to look any farther than Salby’s podcast, which provided enough information to tell me not to look further. Being a scientist means, among other things, not wasting one’s time reading every random bit of ‘research’ that pops up in the blogosphere making claims to have overturned well established facts. I could be wrong of course, but until I hear something at least vaguely believable, I’ll not be paying much attention to this one. –eric
Carbon cycle expert Colin Prentice @ Macquarie wrote a rebuttal in 2011. Ice-core expert Eric Wolff attended Salby’s talk @ Cambridge in April and refuted him. Tom and Dikran have certainly looked at his talks, and so I have I (all 3 videos, several times). They know the science pretty well, I know it well enough.
The problem here is Dunning-Kruger: people who actually know the science don’t need very long to know how absurd Salby’s claims are, but the less competent do not recognize that anyone else actually knows more than they do.
Have you read and understood Ruddiman,etal(2011), which makes absolutely clear the fact that:
a) Humans caused CH4 and CO2 patterns totally different from every past interglacial for which we have ice-core records, and those changes started millennia ago.
b) The post-I.R. rise is completely off the graphs of the last ~million years.
You’ll have to excuse me as I’ve missed ” there must have been eras in the past when our atmosphere had no CO2.” … could you tell me where to find this written up.
What Salby says is that net gas emissions appear to be driven by surface conditions. I don’t see any conflict with Henry’s law.
There is a conflict with ice-core data – I can’t vouch for the rest of palaeoclimatological research. He has proposed a model to account for the ice core data. That model has some testable implications and if there were a more enlightened debate, I would feel confident to discuss short-comings in his approach. But at the moment all I would be doing is handing ammunition to people who seem intent on just dismissing him out of hand.
Scottish, I give up. Good luck with your search for truth, or whatever it is that you’re trying to do here.
OK, apology for getting stroppy – but you used up all my good will criticising a graph comparing two curves – for having two curves on the same graph – and then talking about greenhouse warming which wasn’t at all relevant to what Salby had talked about.
I’ve checked and anyone can make anyone a professor,. so we’ve decided to make him and honorary professor of the Scottish Climate and Energy Forum.
Sorry, I can’t spend all my life being interrogated.
What Salby says is that there is a correlation between surface conditions (temperature mostly but adding in moisture improves correlation) and the net-emission of CO2 (or rate of change of atmospheric CO2). There is also a correlation with methane and Carbon 13 (ratio reducing).
The “fingerprint” of natural (Salby used the word native) emissions is the methane. The apparent link between surface conditions and net-methane tends to suggest that some kind of soil process is causing the release of methane … and presumably this is the same as is releasing the CO2.
Beyond that we are going into the realms of pure speculation. An obvious candidate is soil humus … but without doing even basic calculations to check whether this is anywhere near large enough I’m just guessing.
I suppose given my other persona protecting peat bogs I ought to speak up for the importance of fragile organic soils like peat and the consequence of drainage. The evidence around this bog from core samples suggests that there has been no peat growth in the last 300 years (or it grew and then oxidised), there is also evidence of about 1m loss of surface material since 1945.
If the process of land drainage we saw in Scotland after the agricultural revolution were repeated in Africa in fragile organic rich soils like mango swamps, then there could well be something like the same mass as fossil fuel.
And I am reminded of the damage done by trawling which disturbs the sea bed.
There’s plenty there that it would be sensible to investigate. So it is very unfortunate that far from being supported to find out what is really going on Salby has found himself being attacked for daring to be a proper scientist and go where the evidence takes him.
No … but when I read the first line I realised it seemed rather pointless: “Atmospheric concentrations of CO2 and CH4 increased during the last several thousand years.”
Did you read the bit in the report which said that the ice-core record of CO2 may not represent actual values?
However continuing reading the abstract I find: “ Neither the anthropogenic nor the natural explanations for the CO2 increase can at this point be falsified.”
That seems to be supporting Salby who is saying that “at least in part it must be natural” and it is in sharp contradiction to the IPCC who are coming across as saying it must all be man-made.
I’ve now read enough to be confused because I can’t see what point you are trying to make … so, before I spend an hour reading this, can I just check you’ve sent me a link to the right paper?
Thanks for your contribution. All I want is a fair and open debate about the climate based on the evidence and not preconceived ideas or prejudice. I will know I have succeeded when I see those who are paid by the public arguing between themselves in a civilised way based on the evidence with fair funding for people like Salby.
Salby may not be right, but he more than justifies being listened to and being funded to carry on his work. Likewise, if it came to the crunch and the pendulum swung to the other extreme, I would say the same for those who proposed man-made causation
Scottish Sceptic, yes, the aggressive tone is more than warranted. That is because Salby is spreading falsehoods by deliberate deceit. There may be some other parts of his material which are interesting – but that seems unlikely. You have demonstrated repeatedly that you are not amenable to changing your mind based on contrary evidence. Rather, you seize upon Salby’s work, and without any background study assume he has refuted the large number of scientists who have been studying this issue from the 1950s onward. You don’t even notice that Salby maintains that CO2 concentration varies with the integral of temperature, not with temperature itself – a claim that directly contradicts Henry’s law.
His precise words from the Hamburg lecture are:
However, that is not the issue I am going to raise with you. The fact is that Salby used different scale factors in the graphs he uses to “prove” that:
He has no more strenuous proof of this point than his visual comparison of the slopes of the temperature and CO2 concentration plots on his two graphs. And while the graph showing observations do in fact show a large difference in slope, this is only the case because he used a different scale for CO2 concentration relative to temperature to that which he used in comparing models. This is discussed in detail here.
Since that discussion, a year ago, Salby has added another claim to his discussion, purportedly justifying his selection of scale. That claim also appears to be a straight out lie.
So, why have you not advised your readers of these lies? Why will you not investigate them and confirm them prior to putting Salby on a pedestal as a modern day Galileo? Why, in fact, are you, by silence, consenting to Salby’s deception.
Until you show the minimum of intellectual integrity necessary to check my claims about Salby, and publicly state they are accurate, and that Salby is, therefore, not to be relied on as a source of factual information – there is nothing do discuss with you. There is no point discussing why Salby does not draw attention to the fact that the integral of anthropogenic emissions is better correlated with CO2 concentrations than is the integral of global temperature. Or why, when discussing the reliability of the ice core record he does not distinguish between the ability of firn and of ice to retain information.
His claim is that net-Carbon emissions is correlated with temperature.
That is a simple fact.
Can you clarify, did these people prove this to be false, if so that seems a bit incredible because I was able to reproduce it in half an hour with a spreadsheet.
Ruddiman et al (2011) deals with anthropogenic increases in CH4 and CO2 prior to 1750. It therefore does not discuss CO2 concentrations in the twentieth century. The key point, however, is that it shows rising CO2 levels with declining temperatures (the opposite of what Salby would predict). The data in the paper, however, show Salby’s hypothesis to be wrong.
Salby’s argument that the ice core records are unreliable is simply mistaken. It depends on extrapolating diffusion rates in firn over millenia, without acknowledging that ice is far less permiable to gases than is firn. That Salby is wrong regarding ice is proven by the fact that icecores retain large fluctuations of CO2 concentration over small distances in the ice core back to 800,000 years ago; by the fact that the ice core CO2 record retains the correlation with temperature proxies over the entire period of their existence; and by the fact that the ice core CO2 record correlates well with the CO2 record obtained by other means.
“Scottish” “Sceptic” said:
So you consider “guessing” to be good scientific practice?
How does your “guessing” account for the fact that there was no increase in CO2 concentration during the MWP or any other warm period during the Holocene?
And you still haven’t answered my first question:
“Firstly, you and Salby claim that increasing temperature is causing an increase in CO2 concentration. What exactly is causing this increase in temperature?”
Are you really sure you’ve got the paper. I did a search of the text for temperature and not one bit of the text talked about a link between temperature and CO2.
So, I checked the figures. None explicitly mentioned a link, however figure 4 showed a rising CO2 “after Start of Deglaciation”.
So when it got warmer CO2 rose … which is precisely the correlation which Salby found in the modern record.
This is a review of other work. Is it possible that it mentions another work which I’ve missed? Or perhaps you saw this in one of the studies referred to in this paper?
“And you still haven’t answered my first question:”
I did … I said what my guess is. You may not like that answer but it is the only one I can give you.
And yes giving a guess is quite proper in science … the formal name is a “hypothesis”.
If however you want a more detailed answer and data, then I’m sure we could put together a project plan and you could pay for me to spend time researching it.
Stop insulting science and scientists with your ridiculous comments. “Guessing” is not the same as “hypothesis”. Hypotheses are based on scientific principals.
And you haven’t answered my question about what you think is causing a rise in temperature. You answered my second question. Why are all deniers so lacking in simple English syntax?
Why should anyone pay for the rubbish you are providing via this and other sites?
I was not going to comment again as this does appear to be rather pointless, but I’ll try one more time. What he showed was a correlation between the rate at which the atmospheric CO2 concentration is changing and temperature. Firstly, as Dikran has pointed out, this relates only to the short-term variations. It says absolutely nothing about the relationship between temperature and the long-term trend. I believe that that is a mathematically robust statement. Secondly, this does not immediately imply a correlation between emissions and temperature. It only implies a correlation between the rate at which the atmospheric concentration is changing and temperature. One could infer that this suggests that temperature is influencing emissions, but there is an alternative. Henry’s Law (and maybe you’re sick of me mentioning this) tells us that there is a relationship between the concentration in the oceans and temperature and that it also depends on the partial pressure in the gas. Hence, Henry’s Law alone would suggest exactly the kind of correlation that Salby sees (i.e., as temperature changes the fraction going into the oceans changes and hence the rate at which the atmospheric concentration varies also changes). Furthermore, as others have pointed out, there are other relationships due to ENSO and the terrestrial biota in the Americas.
So, as many have already said, Salby has illustrated a relationship that is perfectly well explained by known phenomena and that is entirely consistent with the rise in atmospheric CO2 being entirely anthropogenic. Why would we possibly then consider an alternative when well known and well tested Laws and observations explain what Salby is presenting? He doesn’t even present anything that could possibly be falsified.
May I suggest you need a little bit more education on the nature of science before hurling insults.
The definition of a hypothesis is a proposed explanation for a phenomenon.
To make it clear that I was answering your question without doing a lot of research I properly highlighted this by flagging it as a “guess”. A guess is another way of saying a “proposed explanation for a phenomenon”
Moreover, for a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. One can test the guess/hypothesis I proposed.
I was entirely scientific, entirely proper and your behaviour and attitude toward someone who honestly answered your question as best as they were able is quite appalling.
I’m finding it very difficult to see what is making you so angry. How can you get upset when someone states a bland fact that there is a correlation between two things and then suggests that if the correlation is to the differential, then by integrating the rate of change of CO2 one should get the total sum of CO2.
No one has shown these statements to be incorrect. Indeed most of what has been said has supported this finding that net-CO2 emissions is correlated to temperature.
I read this: http://www.skepticalscience.com/salbyratio.html … but I gave up reading when they showed they didn’t know which ratio to use, likewise with the other.
I can (not could but can) do a better job at critiquing Salby than that
wottsupwiththatblog says: “I was not going to comment again as this does appear to be rather pointless, but I’ll try one more time.”
If we agree on the following, then
1. A correlation between the rate at which the atmospheric CO2 concentration is changing and temperature. This relates to short-term variations
2. this does not immediately imply a correlation between emissions and temperature. It only implies a correlation between the rate at which the atmospheric concentration is changing and temperature.
3. Henry’s Law could explain this if the temperature of the oceans were warming as we expected outgassing if the oceans warm.
4. There is a correlation between ENSO and emission of CO2 from terrestrial biota in the Americas which fits Salby’s hypothesis of ground conditions.
Then the issues we have not discussed and/or agreed on are these:
1. The correlation between CO2 is better when soil moisture is included. changing from 0.63 to 0.93. This supports a hypothesis that it is soil conditions and makes it less likely that it is ocean out-gassing.
2. The 10 month lag of CO2 to surface temperature would indicate that CO2 is evolved as a result of surface temperature. … however that doesn’t mean that e.g. ocean temperature would not lag and that … and so if we could show a correlation between CO2 and ocean temperature then that would support the hypothesis of out-gassing.
3. There is also a good correlation between net methane and surface properties (soil moisture and surface temperature). Again this appears to support ground conditions.
4. There is a good correlations between carbon 13/12 ratio and surface properties. This makes it much less likely that carbon 13 is a “fingerprint” of fossil fuel burning.
5. There is a phase change in the correlation between actual and proxy. What this means is that Salby found temperature to be related to net-emissions in the short term and to actual levels in the long term. His analysis shows that there is some kind of “damping process” characteristic of non-conservative process. He suggested a possible mechanism as diffusion in the ice-core. He shows evidence for this in the correlation curve (fig 13).
I can do a more detailed job of critiquing Salby than that as well. What is very clear from that particular critique is that Salby has been dishonest. Blatantly so. If you are such a great “sceptic” but cannot recognize that, you are no sceptic at all, but merely an apologist for anti-science.
Your final claim is an indictment of yourself. If true, the question is, why haven’t you? Why the sycophantic report of what he has done that doesn’t pick up on even the simplest of errors?
In any event, you have now shown you do not have the minimum intellectual integrity required to recognize blatant lies and deception, and to call them. Instead, you gloss over them with a frankly incoherent critique of those deceptions. Clearly further conversation with you is pointless.
You have not answered my questions. What caused the rise in temperature? And wild ass guesses are not science. Hypotheses are based on science. I’m sure people have looked at peat bogs as a source for the recent increase in CO2 and found it wanting. Real scientists study all aspects of a problem before producing a hypothesis, something you have failed to do and openly make “guesses” which suit your distorted view of reality in terms of AGW.
Why not just grant yourself a Ph.D. while you’re at it? Or a position in the House of Lords….
But, more seriously, the point here is simple: either you believe credentials in general (and Salby’s in particular) are important, or you don’t. Believing they matter means that you should treat them with respect. The problem is that you don’t want to treat them with respect (see the comment that I’m responding to) but you also want to act as if they matter (or else why would you repeatedly use a professional title to refer to a person who does not hold a job entitling him to it?). I don’t particularly care how you resolve this inconsistency, but if consistency matters at all to you you’ll have to do it one way or the other. Otherwise, you’ll go on promoting the credentials of people you like and diminishing those of people you don’t, and this will make you look like a hack or a fool.
Sincerely,
Professor Dr. Her Ladyship JBL
Serious discussion of the paper is over at WOTTS, starting here with several more.
The point is that humans were altering CO2/CH4 millennia ago, thus slowing the usual slow jiggly descent of CO2/CH4 and thus temperatures, our interglacial was by 1750 already totally unlike any past interglacial, and since then, it is literally off the charts.
I won’t repeat everything here, again.
I’d very much appreciate it if you could do a proper critique as I’m a bit pressed for time.
Can I help in any way?
But “wild ass guesses” is where all science starts. Then people discuss them. We look at the evidence. We see whether they have any merit … if we can we do extra research and get new readings. And that is how science progresses … by “wild ass guesses” and a general willingness to discuss things and not condemn things out of hand.
And I did answer your question … you just didn’t like me admitting that it was a guess.
“Scottish” “Sceptic”, I will ask you one last time. The question you have refused to answer is “What caused the rise in temperature?” You have answered my second question which was
What is the source for the increase in CO2 in the atmosphere? You replied with your wild ass guess of “peat bogs” with no support beyond the fact that it supports your AGW denier fantasy. So what caused the rise in temperature?
JBL – Why not just grant yourself a Ph.D
Legally anyone can call themselves “Dr …” and the only way they could fall foul of the law is if they pretend to be a medic. So, yes, I can just give myself a Ph.D. – but what would be the point?
What actually matters is whether someone warrants a title. I am more than happy that Prof Salby warrants the title so I will use the title. If you don’t agree then I can’t force you to do so.
As far as the undiscussed issues are concerned, the relevant point is that the correlation only refers to short term variations. As Dikran has already pointed out, these short-term variations average to zero. Hence, whether or not these short terms variations are ocean, soil or some combination of the two, doesn’t really tell us anything about the long-term trend. I’m certainly not suggesting that these short-term variations are related, in any way, to variations in our own emissions. Do we agree on that at least?
(I hope I am right that you meant 1750).
That’s a seems a sensible point. What Salby is suggesting is that there has been a “non-conservative” damping process which means the CO2 is very likely to be under-estimated in the ice core. That argument would also suggest that CH4 is under estimated.
The argument is quite technical, but as far as I can see his model does fit the evidence and it would, as he says, mean that CO2 and CH4 were higher in the past. Unfortunately, as a sceptic I don’t like arguments based only on models. I would want to see some hard evidence before deciding.
However lack of evidence for diffusion is not evidence it is lacking. And I just know how even the idea that the ice-core is unreliable is going to be taken. So, I doubt in this politicised climate that anyone is going to seriously look for such a process any time soon. Which means we are not going to know any time soon.
See Eric Wolff, who met Salby and wrote this., or you could attend seminars at U Edinburgh.
I’m done, I’ve got enough data for my next report. Thank you.
You will have to forgive me as I’ve lost the context for that question. So I will assume the question is this: “if temperature is driving CO2 (at least in part) then what is causing the temperature change”.
I hope you will agree this is a similar to the question “If CO2 is driving temperature change (at least in part) then what is causing the CO2 change”.
Whichever way we propose causality we have the problem of what is causing the change in the driver which is being expressed through the relationship. And then, even if we can identify what is causing the initial change, we can probably ask a further “what causes that to change”.
E.g. if I were to suggest, and I’m not proposing it, but using it as an example, but if I were to suggest the sun … then we are left with what is causing solar variation. And if I said “surface fluctuations”, then we have the question of what causes the surface to fluctuate and if I were to suggest internal currents …. we would still not really have an idea of where the variation is coming from.
So, bearing in mind that the aim of climate models is to predict the climate, then we need to find some way to encapsulate the information to hand without chasing causality back to the limit of what we can know.
So, engineers who are very used to problems and systems like this: where we need to predict behaviour because they are either so chaotic, noisy or ill-defined that we cannot properly characterise them, engineers solve this problem by creating a “noise model”.
This is a semi-random model which e.g. has the scale of variation seen in the natural world, but because the system is not fully characterised, the exact value is random.
So e.g. one expects to see so much variation year-to-year. We cannot predict exactly what the value will be, but given past history we know the scale of that variation. Likewise, we know the scale of the decade-to-decade variation but not its exact value and so on for century-to-century, millennium-to-millennium, & even over millions of years. etc.
This doesn’t explain why there is variation, but it does allow us to examine how the variation affects the system and what kind of changes we would expect to see in a “normal” climate.
Obviously, if we learn more about the climate, and learn how to predict part of that variation, we would naturally use that prediction and reducing the scale of the noise model so that the overall variation matched the climate.
The reason I’ve gone into this in detail is that I wanted to explain so that you might understand that when I say the cause is “natural variation”, it is more than saying “I don’t know” but instead it is a very useful tool used by many people to work on problems like this without the need to know ultimate causality.
So you don’t understand the basis of radiative physics? Why not just say so instead of wasting your valuable time by writing such a load of wiffle waffle? It is obvious to anyone who actually understands the physics that the radiative effect of CO2 causes warming. And you call yourself a “sceptic”, no wonder most sensible people are laughing at you and your non-scientific nonsense.
We are trying to characterise the climate in order to predict its behaviour. There is a lot we can do without every detail of how the climate works. I am trying to explain how we can do that without needing to know what is causing the variability.
Good grief, ignorance is bliss among you “sceptics”. The radiative forcing caused by the increased CO2 concentrations is THE most important factor in the recent, post IR, increase in global temperature. Surely someone who claims to have a degree in physics understands that? You do know that CO2 absorbs certain photons and which increases the energy of the molecule which then causes a rise in temperature? This has been known for at least 150 years, long before I assume you got your degree in physics. So how come you missed out on that rather simple and well known science?
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Many sceptics deal with complex real world systems often where any mistake can kill.
Ignorance is not bliss, but sometimes we still have to make the best decisions when we are unfortunately ignorant of all the facts.
We know how to make the best decisions in less than perfect conditions.
“You do know that CO2 absorbs certain photons …”
I think we agree there.
“You do know that CO2 absorbs certain photons and causes a rise in temperature of approximately 3K for a doubling of CO2 concentration”? Agreed. Welcome to the real world.
Thanks. An interesting conversation. And I’ve found it useful. This morning I was lying in bed thinking about climate dynamics and why the feedbacks aren’t enough for us to enter and exit ice-ages and suddenly a thought came to me as to how we might go into and out of ice ages.
I’ve now worked into a whole “guess” (aka hypothesis).
Well, I suppose if your position is that you have a personal definition of the word “professor” that just happens to disagree with what everyone else means by the word, that’s okay then. This explanation certainly protects you from looking like a fool, at least.
Depending on context, you can have all kinds of professors
Now Eli is but an ‘umble Rabett, innocent as the bunnies of the field, a little bunny foo foo as it were, (fair warning) and it occurs to him that there is a significant indicator of CO2 emission by combustion and not warming, contained in the Keeling curve but not much remarked upon and certainly not mentioned by the Good Dr. Salby, Ph.D. Perhaps the Scottish Skeptic would like to play? Here is a giant hint, what happens during combustion.
Oh yeah, for what it is worth Fig. 3 is the usual double dealing. If you want to plot CO2 concentrations and temperature anomalies on the same graph you use temperature anomalies and the CO2 forcings, like this. Anybunny who puts up that Fig. 3 is either a scoundrel or ignorant. Pick one.
Eli, yes that’s been pointed out to ScSc a number of times. A warning, though. It does appear to make him a little stroppy.
If you had read the the report you would know that above, Salby is able to reproduce the keeling curve in full using the relationship between CO2 emissions and temperature.
As such one could say the, the keeling curve validates Salby, but I would prefer to say that it the two are not incompatible.
Hold on, surely what Salby is doing is plotting temperature anomalies and the rate at which atmospheric CO2 concentrations are changing and is then claiming that there is a correlation. You then seem to be claiming that he can then use this correlation to reproduce the Keeling curve. However, the correlation comes from actual observations anyway so this is just a circular argument. I could have plotted CO2 concentrations against virtually anything and reproduced the Keeling curve.
Are you trying to wind me up? That is not a plot of greenhouse gas forcing. The greenhouse gas forcing is about 30% of the value shown. It is instead a graph of greenhouse gas forcing + feedbacks, of which the overwhelming majority of the value plotted is to the unproven feedbacks.
It also stops just before the pause. Is there any legitimate reason for that?
No, he’s not trying to wind you up. He’s making an entirely reasonable point that maybe you should think about a little more.
Oh, and I don’t think that figure includes feedbacks. It’s anthropogenic forcings only.
Here is another thing for you to think about. What month is Figure 8 from.
Well, here is another giant hint, which Keeling?
It’s a little bit more complicated than that. Salby first shows the differential of the1958 to present CO2 matches to temperature. Then he uses that relationship to shows that the CO2 & its likely value before 1958 can be constructed from the temperature curve.
So the 1958-present fit – is rather like the climate models just happening to be a good fit in the past.
The problem is that the error bars before 1958 are so large and there is such a lack of features, that it doesn’t prove much – except that there is not a mismatch.
You are right, there’s a second scale.
Whether that graph was misleading would depend on the context.
If they clearly do not match – then whether or not the scales match doesn’t matter because they don’t match any way and it would have to be unusual circumstances where anyone would be falsely led to believe a relationship that did not exist.
However, if one is saying that they are the “same”, then using different scales would clearly be misleading as it would not be obvious that the two don’t match unless they are drawn on the same scale.
It was the “entire record” but that appeared to be only a few years, however if it were say 2.5 years, then I think you have a point.
Linky??
Those two scales are like apples and pears to each other, vaguely related but not very usefully
Well, I think this is all getting a little silly. So Salby shows a correlation between the rate of increase of atmospheric CO2 and temperature and then uses that to reconstruct the Keeling curve. However, we’ve already agreed that the correlation only applies to the short-term variations and not to the long-term trend. You noticing anything inconsistent here?
Let’s try another tack. Of course, what is legal to do has nothing to do with what we’re discussing here. But since you say “what would be the point” let me make your rhetorical question a real one: what, precisely, is your point in referring to a person who does not hold academic employment as a “professor”?
Anyone who has looked at the SCIAMACHY data would be very doubtful about that for simple agricultural reasons. As Eli said, how about a link.
Image gallery: SCIAMACHY Carbon Dioxide, University of Bremen
Yes, but that is not Figure 8:)
Want to buy another hint?
You really are not interested in the answer are you?
FWIW, since our northern sceptic has retreated, Figure 8 clearly shows evidence of agricultural burning (slash and burn) in the Amazonas State of Brazil and Central Africa, some thing that happens in the May-August time frame. The lower emissions in the Northern Hemisphere also show that this figure comes from the May-August summer period when the Northern hemisphere blooms. Murry Salby is either ignorant or deceitful. Our Scottish friend probably the former and proudly so. More here
Sorry, missed that … always interested. Although if the answer is 42 … I’ve already got that one.
That’s what I thought as well.
Just for interest there’s an image (plate 5) in Salby’s book. The title is temperature trend during the satellite era. The boundaries match well but the cooling areas in the tropics are net emitters and the cooing areas in siberia are the net absorbers. Not sure what that means.
In terms of land use, there have been some papers that talked about local warming due to change of land use to farming (I assume its a change in evaporation rate leading to less cooling in the area). This seems to be a real effect but for obvious reasons it gets ignored by both sides (the cooling is one-off not continuous – sceptics have grown suspicious of all environmental claims)
But sure, please do highlight more information in this area
That ain’t what you said
Nope, take a guess, Here is another guess, what type of reaction produces CO2?
Ah yes, well, you win. Eli has done your work for you, with a simple explanation of why Salby Tunes are off key. Mind you this ain’t everything, but it is a simple point that does considerable damage to Salby’s model.
Yes bunnies, what Salby is talking about is a model, a broken model, but a model none the less. Of course there is more that is cockeyed with his model, the Weasel has hit a few of them, with links to more, but Eli’s is much more basic and does damage in passing to a bunch of other [snip]
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