RealClimate logo


Why extremes are expected to change with a global warming

Filed under: — rasmus @ 5 September 2017

Joanna Walters links extreme weather events with climate change in a recent article in the Guardian, however, some  reservations have been expressed about such links in past discussions.

For example, we discussed the connection between single storms and global warming in the post Hurricanes and Global Warming – Is there a connection?, the World Meteorological Organization (WMO) has issued a statement, and Mike has recently explained the connection in the Guardian.

We still cannot say that single events are caused by climate change for the simple reason that climate change is not a force.

Rather, climate change is a consequence of changed physical conditions. Indeed, one type of climate change could hypothetically consist of storms just becoming more powerful.

I will explain what I mean with climate change below.

Added insight through statistics
If you want to understand the world, then statistics can provide some insights if you have a large number of observations or measurements. This is especially so if you live in a very complex universe with a lot of complicated factors and it is difficult to solve all the equations representing the physics.

To distill information about the climate, you can sort weather data according to different categories, such as magnitude. Then create a table keeping a count of the number of cases that fall into each category, and you will be able to see what magnitudes are common and what range within which you expect them to fall.

You can also plot this type of statistics as a figure known as a histogram.

The histogram is a crude way of showing how frequently you can expect the measurement to fall into each category.

The frequency is proportional to the probability, and you can fit a smooth probability density function (pdf) to the data.

Typical examples of pdfs include the bell-shaped normal distribution for temperature (left panel in the Fig. 1) and the exponential distribution for 24-hr precipitation (right panel i Fig. 1).

What I mean by climate
I usually say that climate is the same as weather statistics (or more precisely, the statistical characteristics of meteorological variables), providing information about what type of weather to expect and its probability.

This statistics, however, will not tell you what one particular outcome will be (i.e. a weather forecast) nor is it a force that influences the outcomes.

The statistics is a mere reflection of (hidden) underlying forces of physics.

Global warming is one kind of climate change caused by an increased greenhouse effect with an impact on both meteorology and the hydrological cycle. It involves physical conditions which set the stage for evaporation, convection, condensation of water vapour, formation of clouds, and precipitation.

Statistical parameters are surprisingly predictable, and weather statistics is systematically influenced by the physical conditions present.

This dependency to physical conditions is evident from how the temperature and precipitation vary from place to place: typically warmer at low latitudes and cooler at higher altitudes; more rain near the coast and less in the interior.

There is also more intense rainfall in the warm tropics than the cooler extra-tropics, and summer precipitation is often more intense than in winter due to different physical conditions.

probability density functions

Typical probability density functions (pdfs) of temperature (left) and precipitation on rainy days (right).

What I mean by climate change
One definition of a climate change is a shift in the pdf describing the temperature, precipitation, or some other variable.

Such a shift in the pdfs is illustrated in Fig. 1 where the grey shading represents the original climate and the red shading a changed climate.

Some variables are strongly affected by changes physical conditions, others are less so. One indicator for their sensitivity to a climate change can be how their character depends on the season, geography, natural variations, or if they exhibit pronounced long-term trends.

Different kinds of extremes
Extremes are often defined as the tails of the distribution (upper or lower parts of the curves in Fig. 1), which are associated with low probability but magnitudes near observed ranges. The magnitude can be either very high (e.g. heat waves, heavy precipitation, intense wind speeds) or low if the pdf has two tails (e.g. freezing temperatures).

The expression “weather extremes” is a catch-all phrase, and not very useful for describing the actual situations. There is a range of different types of extreme weather events, with different nature and different manifestations.

For instance, there are conditions which are present all the time, such as temperature or barometric pressure (there are no days without temperature or pressure). These can be described by one single pdf to indicate their magnitude at any time.

Some conditions are intermittent, such as rain (it doesn’t rain constantly all the time). There are two aspects characterizing intermittent phenomena: how often do these phenomena take place and how intense are they.

For intermittent phenomena, you need two pdfs: one describing their presence (e.g. a Poisson distribution) and one indicating the magnitude when their are present (e.g. Fig. 1).

Some meteorological phenomena are both rare and violent, such as tropical cyclones, mid-latitude cyclones, tornadoes, hail, and lightning.

The more frequent they are, the greater the chance for seeing very extreme events just because you get a larger sample of events over time.

We can use these ideas as a context for Joanna Walters’s article and Hurricane Harvey.

Tropical cyclones
One thing is that global warming may have boosted its force, but will a global warming result in more frequent tropical cyclones?

The oceans are warming, and these hurricanes represent one mechanism that moves the heat from the surface to high levels in the atmosphere where it can escape to space.

We know that the number of tropical cyclones is influenced by several factors: the seasonal cycle, the geography, ocean temperatures and the wind structure in the atmosphere.

According to the IPCC AR5, however, there are little indications of a change in the number of tropical cyclones, although they are becoming more intense (p. 107, TS.5.8.4 Cyclones):

that it is likely that the global frequency of tropical cyclones will either decrease or remain essentially unchanged, concurrent with a likely increase in both global mean tropical cyclone maximum wind speed and rain rates

I believe the jury is still out on the question of the number of tropical cyclones because the IPCC’s assessment has so far not included studies on the relationship between the number of tropical cyclones and the area of high sea surface temperature, such as the analysis shown in Fig 2 (1).

Fig. 2 shows predictions with a simple model that predicts the number of tropical cyclones (NTC and n) in the North Atlantic based on the area of warm sea surface (A) and the NINO3.4 index. It was created in R using the script tropicalcyclones.R which also retrieves the data. The model was calibrated over the period 1900-1960, and the predictions provide reasonable similar evolution of the North-Atlantic tropical cyclones outside this period. (PDF-version).

The analysis in Fig. 2 shows a crude prediction of the number of tropical cyclones (n) in the North Atlantic based on the area of warm ocean surface (A), and we see a roughly similar trend in these predictions as in the HURDAT2 tropical cyclone record.

One caveat with such empirical studies, however, is that the data record is incomplete and there is a risk that the analysis presents a false picture.

Nevertheless, the IPCC AR5 presents an outlook of increasing extreme precipitation in tropical cyclones making landfall (p. 106, Table TS.2), which is relevant for the flooding connected to Harvey.

Flooding may also become more severe from changes in the landscape, as explained by John Vidal in an article in the Guardian.

I think Joanna Walters’ article about extremes and climate change describes the current situation well, and we should not be too surprised.

A change in the pdf reflects a climate change, and in most cases its range and tails tend to follow the part of the curve that represents the more common conditions. 

We must assume that it is only the exceptional cases where the tails of the pdf are unaffected. Furthermore, an increase in the number of tropical cyclones would increase the number of more cases with extreme rainfall.

References

  1. R.E. Benestad, "On tropical cyclone frequency and the warm pool area", Natural Hazards and Earth System Sciences, vol. 9, pp. 635-645, 2009. http://dx.doi.org/10.5194/nhess-9-635-2009

277 Responses to “Why extremes are expected to change with a global warming”

  1. 201
    CCHolley says:

    Children children children. We seem to be having a bit of a reading comprehension problem.

    Yawn.

    We seem to have someone making a mountain out of a molehill. Victor’s original premise that we do not understand the warming of the first half of the last century therefore this sheds doubt on AGW is completely false. If Victor would refocus his substantial efforts to understanding the science and evidence supporting AGW rather than trying to prove his moot point about volcanism he might actually gain some insight into the actual robustness of the science. However, his online history says that won’t happen. Either Victor simply does not want to understand or more likely, he is purposeful in his obfuscation.

    The volcanism discussion is a waste of everyone’s time and just one big distraction.

  2. 202
    Victor says:

    The rather extreme runup in temperatures during the early 20th century has been explained, in part, as due to a relative lack of volcanic aerosol emissions. A handy summary of this position can be found in this Skeptical Science post (https://www.skepticalscience.com/global-warming-early-20th-century.htm):

    “Before 1940, the increase in temperature is believed to have been caused mainly by two factors:

    1. Increasing solar activity; and
    2. Low volcanic activity (as eruptions can have a cooling effect by blocking out the sun).”

    This notion that low volcanic activity can enhance global temperatures is a perfect example of what I have called an “ad hoc explanation,” i.e., an attempt to explain away evidence inconsistent with the prevailing hypothesis by introducing an “explanation” applying only to that part of the evidence that poses a problem, and ignoring all other factors. As I have demonstrated, there is no way that an absence (or relative lack) of volcanic activity can do more than produce a rebound from a previous cooling, thus the net effect of such a lack can never be more than zero.

    Some other claims made by climate scientists intent on supporting the mainstream view can also be characterized as ad hoc in a similar manner. Take, for example what has become the standard explanation for the lowering and/or leveling off of global temperatures from ca. 1940 through ca. 1975, a period of 35 years: cooling due to industrially produced aerosols, largely from the widespread burning of coal. It has been claimed that this effect was strong enough to either overcome or neutralize the effects of rising carbon emissions. Since pollution prevention laws in the US and other first world nations resulted in a lowering of such aerosols after the period in question, the steep runup in temperatures during the last 20 years of the 20th century is then explained by the unleashing of heretofore suppressed CO2 emissions, no longer inhibited by industrial aerosols. There is, of course, no way to actually prove that this relationship is anything more than coincidental, but no matter, it’s been widely accepted as sufficient to account for a cooling episode that would otherwise completely contradict the prevailing hypothesis.

    Why would anyone characterize this as an ad hoc explanation? Because it is designed only to account for what happened during a single period, and cannot be applied across the board. To see the problem, consider the claim discussed above, that a significant portion of the 1910-1940 temperature rise was due to the relative LACK of volcanic aerosols. Now if a LACK of volcanic aerosols can explain a significant amount of warming during the early 20th century, then the same logic could be applied to a very similar LACK of industrial aerosols, which, according to this same (faulty) logic, would be expected to also drive up temperatures. But since the prevailing view is that THIS runup in temperatures was due to a precipitous rise in carbon emissions, the aerosol logic applied to the earlier runup is conveniently ignored.

    We find similar attempts at ad hoc explanation in the many very different attempts to explain away the notorious “hiatus” in temperature rise during the 21st century. We’ve already been over that territory many times, so I won’t bother getting into it again. But it’s a problem that will not go away. At the heart of all these issues is the very problematic notion of “confirmation bias,” far more prevalent in all forms of scientific research than one might think.

  3. 203

    V 194: The volcanic activity is therefore irrelevant. It is certainly not the cause of the temperature rise, which you yourself attribute to background radiation.

    BPL: The volcanic activity is not irrelevant if you’re on the ground. As far as I can see, you’re just playing with definitions.

  4. 204
    nigelj says:

    Victor @194.

    “But the temperature rise you describe as due to an increase in back-radiation would have happened in any case, regardless of whether the inputs had initially been masked by volcanic aerosols.”

    Actually no. But assume you are right, only for the sake of argument. So what? It doesn’t change the fact that lack of volcanic activity contributed to warming early last century, because warming is only what a thermometer measures, and this volcanic activity thing is the thing you are denying. So you are raising a red herring of no significance.

    Watching you try to dig yourself out of holes you create is embarrassing. Do you think there is one person here who cant see that?

  5. 205
    Hank Roberts says:

    Victor comes here to polish his sciency-sounding phrasing. Note the repeated iterations of similar spun claims.
    We knock the rough edges off the claims for him, improving the way the words sound.
    Once kind of shiny he uses the words elsewhere, benefiting from the patina of credibility he picks up by using words learned here.

  6. 206
    CCHolley says:

    Victor @202

    Before 1940, the increase in temperature is believed to have been caused mainly by two factors:

    1. Increasing solar activity; and
    2. Low volcanic activity (as eruptions can have a cooling effect by blocking out the sun).

    blah, blah, blah, blah, ad hoc BS

    For the umpteenth time Victor ignores the “advanced” tab of the Skeptical Science article for which one will find the following quote which is representative of the current scientific understanding:

    CO2 and the Sun played the largest roles in the early century warming, but other factors played a part as well. For example, human aerosol emissions caused a slight cooling, ozone and other greenhouse gases caused a slight warming, low volcanic activity resulted in a slight warming, and natural cycles like the Atlantic Multidecadal Oscillation (AMO) may have contributed to the warming as well.”

    Continuing to ignore this point is a clear sign of his intellectual dishonesty and nefarious motive.

    The rest of his discussion is pure garbage. None of which shows that our understanding of climate science is in anyway lacking in its voracity.

  7. 207
    nigelj says:

    Victor @202

    “This notion that low volcanic activity can enhance global temperatures is a perfect example of what I have called an “ad hoc explanation,” i.e., an attempt to explain away evidence inconsistent with the prevailing hypothesis by introducing an “explanation” applying only to that part of the evidence that poses a problem, and ignoring all other factors. As I have demonstrated, there is no way that an absence (or relative lack) of volcanic activity can do more than produce a rebound from a previous cooling, thus the net effect of such a lack can never be more than zero.”

    No it is not an ad hoc explanation.

    Lack of volcanic activity was simply a fact. Three things correlate with warming early last century, including an unusual lack of volcanic activity, increasing CO2 emissions, and Increasing solar activity. They correlate in terms of timing. All of these three things are known causative factors in warming (as defined as an increase in temperature). Therefore all three MUST be implicated in this warming period.

    We are not totally certain about the proportions each contribute, because the solar data and volcanic data is old and not high quality etc, but there’s very good reason to conclude all three were definitely involved. I personally think solar activity volcanic activity and CO2 were all clearly very significant, and about equally significant early last century.

    An absence of volcanic activity and a rebound effect. I think you are really saying an absence doesn’t introduce new energy into the system or something. It really doesn’t matter because all that matters for the purposes of this discussion is that thermometers register increased temperatures, and part of that cause is low volcanic activity. Its a scientific observation if you like.

    “Some other claims made by climate scientists intent on supporting the mainstream view can also be characterized as ad hoc in a similar manner. Take, for example what has become the standard explanation for the lowering and/or leveling off of global temperatures from ca. 1940 through ca. 1975, a period of 35 years: cooling due to industrially produced aerosols, largely from the widespread burning of coal. It has been claimed that this effect was strong enough to either overcome or neutralize the effects of rising carbon emissions. Since pollution prevention laws in the US and other first world nations resulted in a lowering of such aerosols after the period in question,”

    No aerosols are nothing ad hoc.

    Its a simple fact there were high aerosols through the middle of last century correlating with a flat period of temperatures quite well. We know aerosols can reflect sunlight so you have very good causation as well that explains why temperatures were stable, even while underlying CO2 emissions increased and greenhouse warming increased. In effect the aerosol issue cancelled out the heating from CO2 and we ended up with flat temperatures. Once aerosols exited the atmosphere the underlying greenhouse warming became dominant..

    “the steep runup in temperatures during the last 20 years of the 20th century is then explained by the unleashing of heretofore suppressed CO2 emissions, no longer inhibited by industrial aerosols.”

    No very recent temperatures are not explained by any unleashing of CO2 emissions from this very prior period. They reflect more recent emissions. You would be right to attribute the warming late last century to an unleashing effect I suppose although the words are not ideal , its more an unleashing of the greenhouse effect. CO2 emissions increased at a close to linear rate from 1900 to 2017, so nothing was unleashed in terms of CO2.

    The thing that changed was a reduction of aerosols in the 1960s – 1970s which simply exposed that there was a strong underlying greenhouse warming going on and increasing from decade to decade. The climate response to a reduction in aerosols is by nature quite rapid. The last 50 years has had flat solar activity, and so greenhouse gases truly have dominated the trend from about 1970 – 2017.

    “There is, of course, no way to actually prove that this relationship is anything more than coincidental, but no matter, it’s been widely accepted as sufficient to account for a cooling episode that would otherwise completely contradict the prevailing hypothesis.”

    There is nothing coincidental about it. We know for a fact aerosols can affect warming so this removes any suggestion of mere coincidence.

    You are clearly well educated, but just wrong, wrong, wrong about most of these issues.

  8. 208
    Mal Adapted says:

    jgnfld, to Weaktor:

    my suggestion is you try out your ideas that “the absence of cooling cannot produce warming” on the next subzero day by walking around nude for a few hours to check out your ideas.

    Overcoming my repugnance at that image, I suggest trying it at the same subzero temperature on sunny and overcast days.

  9. 209
    CCHolley says:

    Victor @194

    You, like so many other supporters of the mainstream view, treat “the physics” as though it were some rock solid truth that could not possibly be in error. Sorry, but that’s not how science works. The “physics” on which the mainstream climate view is based is not simply a matter of the usual laws, such as thermodynamics, on which mainstream science correctly relies — it is far more complex than that, with many uncertainties. It is, therefore, a theory, not a law, a theory which can be validated only through testing on the basis of real evidence, not the manipulation of mathematical formulas, statistical or otherwise.

    Wrong wrong wrong. Don’t be so arrogant to think you can lecture me on *how science works* as you most certainly cannot. The greenhouse effect IS based on irrefutable physical laws. The radiative effect of CO2 can be determined precisely based on physical laws and the result of this radiative effect on the heat balance of the planet can also be determined based on physical laws. The uncertainty and complexity only lies in exactly how the multiple feedbacks respond and how and when the heat is distributed within climate system. However, just because there is uncertainty and complexity does not mean that they are not well within our ability to understand with a fairly high degree of confidence. Uncertainty does not mean ignorance in the least. As for your claim of validation only through testing based on real evidence, this is just pure gobbledygook. If you would ever take the time to do the research, you’d realize that there is far more than just statistics and mathematical manipulations that confirm the *theory*; there IS significant observable evidence. You just pretend it does not exist.

  10. 210
    Victor says:

    The ability on the part of so many presumably intelligent and knowledgeable people to dodge the issues I’ve raised is indeed impressive. I’d call it “denial,” only that term seems to have been all used up by now. :-)

    Let’s first clear up some issues that maybe we all can agree on. First of all, any rise in temperature due to volcanic aerosols (an effect I’ve acknowledged) is the result of the dissipation of the aerosols, NOT any subsequent “lack of volcanic activity.” Can we agree on that at least? Secondly, the dissipation of the aerosols is a temporary activity which can have no long-lasting effect and cannot, in principle, result in a rise in temperature above and beyond a level prior to the production of said aerosols. (Not sure why so many seem confused on that score.) Thirdly, I made it clear from the start of this particular thread that I was not referring to any aspect of the temperature run-up in question other than the widely asserted claim that a “lack of volcanic activity” contributed to it in some meaningful way. Thus solar radiation or greenhouse gases have NO bearing on the present discussion. I’ll be happy to get to those issues later.

    The only one to have presented anything close to a meaningful response is Kevin (#196), and I thank him for that. Here’s the gist of his argument:

    Kevin: “The problem with this is that the question as posed is unanswerable, because we don’t have all the necessary information: specifically, we don’t know what the volcanic influence was during the initial period (ie., prior to the first eruption.)”

    First of all, the issue I raised was a matter of principle, applicable in all cases, regardless of what the initial conditions might have been at any given time or place. However, if you insist on getting specific, the necessary information is, in fact, there — though I have no idea what you mean by “the first eruption” — the first in history or what? We do have reasonably good estimates of global temperature in the period prior to and after 1910 (or if you prefer 1912, when Novarupta erupted), and we do have reasonably good estimates of volcanic activity during that period and beyond, as illustrated in the paper Kevin cited, by Robock. Consulting a typical graph (see for example https://d1o50x50snmhul.cloudfront.net/wp-content/uploads/2007/05/dn11639-2_808.jpg), I see an interesting spike in global temp around the year 1879. Following that spike, we see an abrupt dive, possibly induced by the major volcano that erupted around 1882, according to Plate 6 of Robock’s paper (http://climate.envsci.rutgers.edu/pdf/ROG2000.pdf). But that was almost 30 years before 1910, by which time we can assume that most or all of those aerosols had dissipated.

    We see a more modest temp. rise around 1889, followed by a rather abrupt downturn until around 1910. We then see an upswing in temperatures around 1912, at roughly the same time as the powerful eruption of Novarupta in that same year — and here is where things get interesting, because immediately after that abrupt temp. rise, we see a significant downturn (especially if we consult the yearly graph), which might very well have been due to the aerosols spewed by that especially powerful eruption. Following that downturn, however, we see the beginnings of a steady and quite steep rise in temperatures. And the question is: to what extent could that rise be due to a rebound caused by the dissipation of the aerosols produced by Novarupta?

    As I see it, there are two aspects of this issue we need to be aware of. First, since the temp. anomaly just prior to the eruption had risen rather steeply to -.2 before descending, there is no way any dissipation of aerosols from Novarupta could cause a temperature rebound beyond that point — yet we see that, indeed, temperatures do indeed continue to soar well beyond -.2.

    The other thing we need to be aware of is the cause of the temperature peak that occurred prior to the eruption of Novarupta, because THAT is the source of the initial warm-up we see after 1910, NOT the absence of aerosols from a volcano that had not yet erupted. It is THAT warm-up that should concern us in our attempt to understand the rise from 1910 to 1940, not the temporary blip caused by a cooling and subsequent rebound due to a volcanic eruption, no matter how intense. In other words, if we are after a cause (or causes) for the temperature increase during the period in question, the presence or absence of aerosols from volcanic eruptions is beside the point, because they cannot explain any increase in temperatures that occurred prior to any cooling effect they might have had.

    I would not have thought that such a long and detailed explanation would have been necessary, but apparently it is. Not that it’s likely to make much difference in this setting, I’m sad to say.

  11. 211
    CCHolley says:

    Victor@210

    The ability on the part of so many presumably intelligent and knowledgeable people to dodge the issues I’ve raised is indeed impressive. I’d call it “denial,” only that term seems to have been all used up by now. :-)

    Volcanism played only a minor role in the temperatures of the first half of the last century.
    It is you who dodges. It is you who is in denial.

  12. 212

    V: I would not have thought that such a long and detailed explanation would have been necessary, but apparently it is. Not that it’s likely to make much difference in this setting, I’m sad to say.

    BPL: A little advice from a science fiction writer. I submit my manuscripts to my writers’ workshop so everyone can have a go at them. This helps me improve my writing.

    When one person says he had trouble understanding a passage, but he’s the only one out of, say, eight people, I check to see if the passage can be fixed further, but I don’t take it too seriously.

    On the other hand, if all nine members of the group say they didn’t get the passage, I know something is seriously wrong with the way I wrote it.

    If no one on a message board can get what you’re saying, it’s time you looked over what you were saying and how you were saying it. Blaming the audience for not getting it is characteristic of dilettantes, not professionals.

  13. 213
    MA Rodger says:

    Victor the Troll @210.
    Here is a little conundrum for you grand theory. You insist that once a negative volcanic forcing has dissipated (due to a lack of volcanic activity allowing the aerosols to reduce to insignificance) the temperatures will bounce back immediately to the level they would have been had the volcanoes not occurred.
    If so, why does UN IPCC AR5 Figure 10.1a show a final temperature significantly lower than in Figure10-01c? Note in Figure10-01b, the natural forcings absent in Figure10-01c are even positive for the final few years, so that should be boosting the warming in Figure10-01a above Fifure10-01c, according to your brave theory.

  14. 214
    Hank Roberts says:

    You can look this stuff up, there’s info from real scientists.
    Go there rather than pay attention to the “sciency” posts from you know who.
    _________________
    Climate Lab Book has posted a new item, ‘What do future eruptions mean for
    climate projections?’

    The world has not seen a major volcanic event for at least 25 years, but the
    tropical volcano Mt Agung on Bali is now threatening to erupt. Mt Agung’s last
    eruption in 1963 was one of the largest during the 20th century and had
    widespread climatic effects. Going further back in time, ice core-based volcanic
    reconstructions reveal events – such as the Samalas eruption in 1257 in
    Indonesia – that were an order of magnitude larger than the 1963 eruption of
    Mt Agung.

    Because the timing and intensity of eruptions cannot be predicted in advance,
    they are commonly excluded from projections of future climate. The imminent
    eruption of Mt Agung raises important questions: How feasible and important is
    the inclusion of potential volcanism in future climate projections? Will
    eruptions help mitigating long-term anthropogenic global warming? What is their
    effect on climate projection uncertainty? How do eruptions affect future climate
    variability and the likelihood of climate extremes?

    View the latest post at
    http://blogs.reading.ac.uk/climate-lab-book/2017/what-do-future-eruptions-mean-for-climate-projections/

  15. 215
    Victor says:

    I would now like to address the claim that both greenhouse gases due to fossil fuel emissions and an increase in solar irradiance were significant factors in the temp. run-up from 1910 to 1940.

    Let’s begin with solar irradiance. A significant problem is posed by the fact that different researchers have come up with different results. A good example can be seen in a paper by Ogurtsov et al., which, in Figure 2c, superimposes three different graphs based on three different datasets for TSI (total solar irradiance) during the 20th century (see https://file.scirp.org/pdf/ACS20120200003_24395854.pdf.) Of the three, only one, the dotted line, shows TSI increasing to any significant degree from 1910 to 1940. The other two show only a very slight increase.

    A more recent paper shows yet another set of graphs, more closely in agreement but presenting a somewhat different picture (see https://arxiv.org/ftp/arxiv/papers/1601/1601.05397.pdf, Figure 5). Here, we do indeed see a rather steep rise in TSI during the early 20th century — but when we examine the reconstruction as a whole, we do NOT see any real correlation between TSI and temperature during any earlier period. According to this same Figure 5, TSI also rose dramatically from ca. 1700 through 1780, and again from 1800 through ca. 1840. The peak achieved ca. 1780 was in fact very close to the one we see in ca. 1960. If pre-industrial temperatures were governed largely by solar irradiance, then we would expect temperatures during these earlier periods to be comparable in intensity to the peak we see ca. 1940, but as we know, that is far from being the case. If we can find no consistent correlation between TSI and temperatures during the Eighteenth and Nineteenth centuries, when CO2 emissions were clearly not yet a factor, then the “correlation” some have claimed to have found during the early 20th century is almost certainly an artifact, i.e., a fluke, with no real significance. Here again we see an example of ad hoc reasoning, based on evidence carefully selected from only one period of time, while evidence from other periods is conveniently ignored.

    Moving on to assess the influence of fossil fuel emissions during this same period, it’s important to stress that literally all investigators acknowledge that both the level of AGW and the rate of increase were far less at that time than what we see in the latter part of the century. And for this reason, most investigators are forced to acknowledge that the modest run-up in fossil fuel induced CO2 during this period would have had only a relatively small effect. In the words of Carl Mears, assessing the contribution to climate science of G.S. Callendar, “The scientists who brushed aside Callendar’s claims were reasoning well enough. (Subsequent work has shown that the temperature rise up to 1940 was, as his critics thought, mainly caused by some kind of natural cyclical effect, not by the still relatively low CO2 emissions. . .”

    And for those of you who want to insist that aerosols produced by the uncontrolled burning of coal neutralized the effects of AGW from 1940 to 1979, please explain how the same argument could not be made for the effects of coal-induced aerosols during this earlier period, when no constraints on the polluting effects of coal combustion were present at all. If these aerosols were powerful enough to produce a net cooling during the latter period, they would certainly have had the same effect in the earlier and in that case industrial CO2 emissions during this earlier period could be ignored entirely.

    Given the total irrelevance of volcanic aerosols during the period in question, the only very modest effect of fossil fuel emissions and the many inconsistencies governing the data pertaining to solar irradiance, it seems clear that climate science has no meaningful explanation for the considerable warming trend we see in the earlier part of the 20th century — and if that’s the case, then there is no reason to assume that the warming we see in the latter part of that century could not also be due to either some as yet unknown natural force, or perhaps simply random drift.

  16. 216
    Marco says:

    Victor, you ignored the 1902 Santa Maria VEI 6 eruption. Back to the drawing board you go…

  17. 217
    nigelj says:

    Victor @210

    “Can we agree on that at least? Secondly, the dissipation of the aerosols is a temporary activity which can have no long-lasting effect and cannot, in principle, result in a rise in temperature above and beyond a level prior to the production of said aerosols.”

    Yes the effect is not hugely long lasting. It will last until the volcanic cycle changes probably not that long. (except for the point made by BPL but its a smallish effect). But you are lecturing scientists in the obvious what a total bore. Volcanic activity wiggles up and down and causes temperature to wiggle up and down a little bit over time. That’s the guts of it.

    “We see a more modest temp. rise around 1889, followed by a rather abrupt downturn until around 1910.

    Ok you sifted through this material like a detective quite well, but nobody cares about this irrelevant very short term material. Anyone knows a specific volcanic eruption can effect the climate for a year or two.

    And whats all this about aerosols not being significant? One of the most basic things is aerosols reflect heat and are significant. Its 100% certain science.

    What we are interested in is the longer term less easy to explain warming period from 1920 to about 1950. Why did it happen? The causes are however reasonably well identified, a longer period than “usual” of lack of volcanic activity, so a lack of aerosols, combined with solar and CO2, although the latter two factors probably dominated.

    Why would anyone in their right mind spend pages trying to claim volcanic emissions are not implicated? It sure beats me. Maybe I’m missing something.

  18. 218
    Astringent says:

    Victor @210, I know you don’t really care, but it’s really not so hard, if you stopped trying to pretend that subtleties of phrasing matter one whit in the real, warming, world.

    So I’m on a bus, driving up a mountain, on a road that starts out by the sea. For each year of my long journey (it’s a big hill and Its a slow bus) we go up about 0.02 metre (its not a very steep hill, but its the biggest one I’ve driven up). If it’s a double decker bus, and I walk down from the top deck to the bottom deck I would be losing height faster than the bus is climbing. If I walk back up to the top it looks like the rate of climb has gone way up for a while.

    I could get really hung up on measuring the rate of climb at any one point, and relating it to whether I was going upstairs, or downstairs, or stopped halfway on the stair. In fact I might even want to study that quite carefully to tease out just how fast the bus is climbing.

    I might casually say things like ‘the rate of ascent fell in the last decade because of me being on the bottom deck’ or ‘the sharp increase in altitude was a result of climbing the stairs’. It doesn’t matter. The bus is climbing the hill. Each time I go to the top deck, I’m a little bit higher. Each time I go back down I’m not quite as far down. That’s physics. Physics doesn’t really pay much attention to linguistic pedantry. It just goes on being real.

  19. 219

    #210, Victor–

    Victor, no one is ‘dodging the issue’–except, actually, you. And you are displaying impressive yet increasingly tangled footwork in order to do so.

    Let’s look at your response to my #196. You are kind enough to characterize it “close to a meaningful response”; I hope you will be even more impressed should you come to the point of actually understanding it.

    Let’s skip over your “first” point to clarify preconditions first. You wrote:

    …though I have no idea what you mean by “the first eruption” — the first in history or what?

    No, the one in your first sentence (in the blockquote I excerpted):

    Let’s assume an average global temperature of 0 degrees Celsius and a subsequent volcanic eruption whose aerosols cool that temperature to -.1 degrees.

    You posit subesquent eruptions, starting 30 years later, though admittedly they don’t receive much focus. Hence my ‘first’. Make sense?

    I hope so, because I’m going on to your ‘first’ now.

    First of all, the issue I raised was a matter of principle, applicable in all cases, regardless of what the initial conditions might have been at any given time or place.

    Sorry, but a bare assertion that a problem has been ‘universalized’ does not automatically generate a guarantee that that problem has been adequately structured. What my response pointed out was that in order to answer the question, it is necessary to posit whether the level of aerosols during the ‘pre-eruption’ period was zero, or non-zero.

    By following the logical consequences of assuming a zero level of ‘pre-eruption’ aerosols, I showed that that led inescapably to an “uncaused” rise in temperature. This is a classic reductio ad absurdam, whether you are willing to admit it or not.

    On the other hand, the alternate scenario–a non-zero ‘pre-eruption’ aerosol burden–is both logically self-consistent, and in accord with empirical observations, as I showed by citing the Robock paper. It is, of course, also completely consistent with mainstream science.

    To put it bluntly, on the one hand there’s an impossible assumption, on the other there’s a result that poses no problems for the mainstream science. Intentionally or not, you obfuscate this reality by refusing to consider the need for a ‘background level’ aerosol burden. That’s understandable, because if you admit that reality, you recognize that you are firmly impaled upon the horns of a tactical dilemma. On the one hand, you recognize that your assumptions lead to an absurd result; on the other, you admit that your case is completely toothless as an attack on the mainstream science.

    IMO, your discussion of the Robock graph is beside the point, because you attempt to deal with real-world data in terms of an “aerosols only” case–which, however, doesn’t actually exist in the real world. Therefore, I’m not going to deal with that discussion here.

    It’s pretty ironic, because you repeatedly accuse the mainstream science of creating an “ad hoc explanation” by invoking aerosols, yet it is you who insists on a focus on one variable at a time. Real science has been concerned with trying to ascertain the roles of all relevant forcings and feedbacks on climate, including all their interactions.

    I’d also point out that the idea that aerosol research is “ad hoc” for the purpose of defending the role of CO2 is historically false. Such research goes back well before there was a thorough-going consensus on global warming–though admittedly, not before there was a pretty thorough exploration of the viability of CO2 as a forcing. For instance, a Google Scholar keyword search on “aerosols and climate” filtering for papers published between 1900 and 1980 turns up 3920 results:

    https://scholar.google.com/scholar?q=aerosols+and+climate&hl=en&as_sdt=0%2C34&as_ylo=1900&as_yhi=1980

    The most famous is probably Rasool & Schneider’s “global cooling” paper from 1971, but there were many others, obviously. And all of them more than a decade, or more, before the framework convention on climate change (UNFCCC) was even dreamed of. “Pre hoc, ergo non propter hoc.”

    Your presumption that climate research isn’t “real” curiosity-based research is, in fact, mere presumption.

  20. 220
    nigelj says:

    Victor @202

    You are wrong about most of that, and definitely your conclusions. You are forgetting the obvious thing that the warming from about 1920 – 1940 was only half a degree so not much. Its easily explained by CO2 ( even although concentrations were clearly only mildly increased over previous decades), solar cycle and volcanic activity.Its one of the easiest things in climate science to explain overall, but the proportions are very challenging because data from the period is poor. So there is debate about that and it may never be settled because theres not much you can do about poor records, but there’s enough data to know what factors were implicated.

    You are also cherry picking a few papers on the early warming period solar irradiance levels and correlations, so get a false impression on what its about. There’s far more work than that and most show some increase in solar irradiance early last century and a reasonably good correlation with those temperatures. Its not a huge increase in solar irradiance, but once again, neither was the total temperature increase over that period. Doh!

    You also completely misinterpret figure 5, because nowhere does that actually show temperatures.

    You also don’t seem to know that we know what level of solar irradiance produces what level of warming in wm2, and same for CO2 we know what warming in wm2 specific change in CO2 causes. Its not knowledge that is reliant on some correlation. The correlation is just a rough confirmation. The variance of opinion on the period is patchy quality basic data that’s all.

    The solar cycle does correlate well with temperatures going further back in history, once you strip out other factors. You fail to understand the complexity and combinations of factors and how to isolate them properly because you have no science qualifications or even some introductory university science. You also lack natural talent for this sort of thing, but may well be very talented in your own field.

    For example a low point in the solar sunspot cycle correlates approximately with the so called little ice age of the 19th century, but was only part of the cause of this. But just glancing at randomly chosen graphs on the internet can be deceptive, you have to look at a lot of stuff to get to the bottom of these sorts of things, because there are a lot of interrelated factors, and you have to know what you are looking for and what it all means and where the uncertainties are. This is why we have climate scientists who spend years figuring it out.

  21. 221
    Victor says:

    #213 MARodger: “You insist that once a negative volcanic forcing has dissipated (due to a lack of volcanic activity allowing the aerosols to reduce to insignificance) the temperatures will bounce back immediately to the level they would have been had the volcanoes not occurred.”

    Not so. First of all, the dissipation of aerosols from any given eruption is NOT caused by “a lack of volcanic activity,” where did you get that? How could a LACK of volcanic activity cause anything? (I’m starting to worry about you, MA).

    Secondly, I never claimed that “temperatures will bounce back immediately to the level they would have been had the volcanoes not occurred.” What I said was that they could not rise above that level. There are all sorts of reasons why some of that energy could be lost in the meantime. Also I didn’t assume anything about the timing, though it’s usually thought to be roughly a year or so — certainly not “immediately.”

  22. 222
    Victor says:

    #219 Kevin, I’m assuming your complaint centers on the following paragraph from an earlier post of yours:

    “On the other hand, we might assume that there has been some lower, but non-zero ‘background level’ of volcanic aerosols-let’s arbitrarily make it 2 on a scale of 10, for ease of discussion. In this case, everything makes sense (at least qualitatively speaking): you have temperature dropping when aerosol forcing increases from 2 to (let’s say) 8, then rising again as the aerosols clear. During the subsequent period, you have aerosol forcing of 0, by Victor’s assumption, and sure enough, the temperature rises higher than it had previously been, when the forcing was 2. I wouldn’t say that it’s due to “NO influence whatsoever,” though, because I consider 0 to be a number.”

    As I see it, your confusion is best revealed in the following sentence: “you have temperature dropping when aerosol forcing increases from 2 to (let’s say) 8, then rising again as the aerosols clear.”

    You neglect to mention the cause of the original temperature that dropped. Could it have been caused by a LACK of volcanic aerosols? Certainly not. Could it have been caused by the dissipation of aerosols from some earlier volcanic eruption? Possibly, yes. So if you like you can posit some sort of infinite regression (as in, “it’s turtles all the way down”). But at some point it will be necessary to acknowledge that ultimately any given temperature originates in some positive forcing, even if we have no idea what that could be. So, regardless of how many aerosols are present at any given time and regardless of how much temperature rise can be attributed to the dissipation of those aerosols, ultimately neither the eruptions nor the aerosols can be the source of the original heat. Thus, in our effort to understand that ultimate source, we can safely ignore volcanic activity — or the lack of it.

  23. 223
    Victor says:

    #220 Nigelj: “the warming from about 1920 – 1940 was only half a degree so not much.”

    The warming from 1910 – 1940 is what we’re talking about and that was ca. .6 degrees. The warming from 1979 to just before the recent El Nino was ca. .8 degrees. A difference of “only” .2 degrees. Yet one is significant and the other isn’t.

    “You fail to understand the complexity and combinations of factors and how to isolate them properly because you have no science qualifications or even some introductory university science. You also lack natural talent for this sort of thing, but may well be very talented in your own field.”

    Actually I have considerable scientific training and experience, though certainly not in the boring field of climate science. (No interest in camping out, sorry.) And that includes statistical research, by the way — though I’m not a statistician I’ve worked closely with some of the best. I have enough training and experience (as both published author and peer reviewer) to be skeptical when challenged to “understand the complexity and combinations of factors and how to isolate them properly.” I know how easy it is to fool oneself when evaluating such factors.

    When a group of people claiming superior scientific knowledge and understanding refuses to grasp the extremely simple point I’ve been making regarding the heating capacity of an absence of volcanic eruptions, then I am forced to take all their other arguments with a huge grain of salt. And it doesn’t help when I’m expected to accept that industrial aerosols balanced the effects of CO2 from 1940-1979, yet can be safely ignored when considering the years 1910-1940.

    Sure, when the data doesn’t support your hypothesis it’s all too easy to look for complicating factors that “correct” said data in your favor. It’s the oldest trick in the book. Which is why Occam developed his Razor. And why Newton’s explanations are superior to Ptolemy’s.

    And of course I am not the only one who’s noticed this problem. A great many others with far more expertise in hard science than I share my skepticism.

  24. 224
    Thomas says:

    Go on guys sock it to Victor .. you’ll show him. You’ll fix him real good.

    What a joke! Gavin hasn’t put Victor in the bore hole yet? WHY is that so? Answer that question and then maybe you’ll all get a little bit more “real” at real climate. ;-)

  25. 225
    Astringent says:

    V @221 – I am fairly sure you could find a website that would welcome detailed discussions on the finer points of grammatical style if you looked – if there are lots of aerosol producing eruptions there are lots of aerosols. If there are fewer eruptions there are less aerosols. An observer, seeing the aerosols reduce says’ oh, aerosols are dissipating, that’s probably because there aren’t many eruptions going on’. If you can’t appreciate something that simple in the use of language, what makes you think you have a hope of understanding the detail?

    In your third paragraph you seem to be positing a system with a single variable and linear effects. Firstly you don’t know what else outside the aerosol system might have happened while aerosols were present, if the other factors (CO2/sun/El Nino/etc) were rising while the aerosol even occurred of course temps can rise above ‘that level. And in the real world aerosols have complex effects, both in terms of optical physics and atmospheric chemistry. It hardly takes imagination to posit that while initial aerosol dimming might depress temperatures, the aerosols and atmosphere might react in ways that change heat balance in other directions as they disperse, through stratospheric chemistry, and the fact that, unsurprisingly, there is a difference in aerosol behaviour depending on day vs night (you can’t reduce the sunlight that reaches the south pole on June 23rd….). 30 seconds on a search engine finds plenty of papers discussing these real world complexities.

  26. 226
    MA Rodger says:

    Victor the Troll @221
    From the first encounter with you, it has been apparent that you have difficulty grasping even the simplest of concepts, but you do appear to be rather struggling with the exceedingly simple idea that a dissipation of aerosols does require an absence of volcanic activity. You clearly agree that volcanic activity results in aerosols arriving up in the stratosphere. Yet you are also clearly struggling with the idea of volcanic activity replenishing that stock of aerosols. Because such a struggle is the only reasonable explanation for why you fighting so hard against the idea that a dissipation of aerosols requires an absence of further volcanic activity.

    And your assertion that global temperatures “could not rise above that level” preceeding the eruption seems wedded to a “bounce back” mentality. The impact of volcanoes is greatly longer-lived than you appear to appreciate.

    You may feel you know all there is to know about it, that you can clatter down this comment-thread telling all and sundry how it is. But yet again, your understanding of the matter-in-hand is laughable. Perhaps some numerical studies will assist your understanding of this subject.

    I would refer you to Figure 1 of Hansen et al (2011) ‘Earth’s energy imbalance and implications,’ Atmos.Chem. Phys. 11. which clearly show the radiative forcing resulting from volcanism since 1880. Note that the period 1920-1960 is significantly less troubled by such forcings. This is true for longer periods, as illustrated (less clearly) in UN IPCC AR5 Figure 8.18 plotting forcings 1750-2010. The “lack of volcanic activity” has allowed the stratospheric aerosols responsible for such forcing to “dissipate” through the 1930s & 1940s.

    Yet you are not interested with forcings “bouncing back” but with “bouncing-back” global temperatures. That is a more complex matter as it will depend on the elusive value of climate sensitivity. The bounciness of the climate to volcanism has even been used in attempts to constrain the value of climate sensitivity. See figure 3 of Wigley et al (2005) ‘Effect of climate sensitivity on the response to volcanic forcing,’ J.Geo.Res. V10.1. which shows warming trends resulting from the cooling of early 20th century volcanism is still ongoing to a significant but diminishing extent into the 1950s. And perhaps I should also refer you to a famous denialist who holds similar views to you, Dicky Lindzen, who managed to calculate in Lindzen & Giannitsis (1998) ‘On the climatic implications of volcanic cooling, J. Geo. Res. Vol103.D6 that, unless climate sensitivity was miniscule, that early 20th century volcanism would still be trying to bounce back in the late 20th century. (The silly old fool is still repeating this nonsense into his dotage.)

    So, while the size of effect is dependent on climate sensitivity, its longevity requires both time for aerosols/negative forcings to dissipate and for the climate to reverse the cooling resulting from such forcings. This full process is thus measured in decades not years. And as the experts will tell you, a “reversal of cooling” is what is technically called “warming”.

    Thus, Victor the Troll, to contradict all that you wrote @221, “the dissipation of aerosols from any given eruption IS caused by a lack of volcanic activity,” and global temperatures CAN “rise above (the) level” “they would have been had the volcanoes not occurred” because the impact of previous volcanism would have also dissipated in the interval.

  27. 227
    Victor says:

    Regarding the influence of solar irradiance on global temperatures:

    “Despite the fact that ACRIM I, ACRIM II, ACRIM III, VIRGO and TIM all track degradation with redundant cavities, notable and unexplained differences remain in irradiance and the modeled influences of sunspots and faculae.

    Persistent inconsistencies

    Disagreement among overlapping observations indicates unresolved drifts that suggest the TSI record is not sufficiently stable to discern solar changes on decadal time scales.”

    From the very authoritative and detailed Wikipedia article on “Solar Irradiance.” https://en.wikipedia.org/wiki/Solar_irradiance

    “Today, scientists who study the links between solar activity and climate are confident that the small variations in TSI associated with the eleven-year solar cycle cannot explain the intensity and speed of warming trends seen on Earth during the last century. The 0.1 percent shift in TSI simply isn’t enough to have a strong influence, and there’s no convincing evidence that suggests TSI has trended upward enough over the last century to affect climate.”

    From a NASA report: https://www.nasa.gov/mission_pages/Glory/solar_irradiance/total_solar_irradiance.html

    “The TSI-record assessment in this section suggests that the current measurement-record does not have the needed stability to definitively detect secular trends in solar variability. Improvements to instrument stability and/or absolute accuracy are needed to detect secular variations at the <0.001 % yr-1 level required for secular solar-variability detection and climate studies (Kopp 2014)." from "Magnitudes and Timescales of Total Solar Irradiance Variability," by Greg Kopp.
    https://arxiv.org/ftp/arxiv/papers/1606/1606.05258.pdf

    So, no, I am not a climate scientist, nor am I in a position to evaluate any of the claims made by climate scientists regarding solar irradiation or any other influence on global temperatures. But, unlike some posting here, I CAN read. And what I've learned from reading the literature on this topic bears out Nigel's assertion that "there are a lot of interrelated factors, and you have to know what you are looking for and what it all means and where the uncertainties are."

    Yes, you do, Nigel. But what, exactly, is it "you are looking for"? If you look hard enough you will certainly find "what you are looking for," undoubtedly. However, from what I've been able to learn from the people who actually do this type of research, there are simply too many variables and too many uncertainties in the field of climate science to make the sort of claims being made by advocates of the so-called "consensus" view. There is certainly no consensus on the effects of solar irradiation.

  28. 228

    Victor, #219–

    You neglect to mention the cause of the original temperature that dropped. Could it have been caused by a LACK of volcanic aerosols? Certainly not.

    That’s for sure, since stratospheric aerosols cool. And *I’m* supposedly confused? At least I’m keeping track of the sign of the effect involved!

    Could it have been caused by the dissipation of aerosols from some earlier volcanic eruption? Possibly, yes.

    Again, keep track of the sign…

    So if you like you can posit some sort of infinite regression (as in, “it’s turtles all the way down”).

    Well, it does at least seem to be denial all the way down.

    But at some point it will be necessary to acknowledge that ultimately any given temperature originates in some positive forcing, even if we have no idea what that could be. So, regardless of how many aerosols are present at any given time and regardless of how much temperature rise can be attributed to the dissipation of those aerosols, ultimately neither the eruptions nor the aerosols can be the source of the original heat. Thus, in our effort to understand that ultimate source, we can safely ignore volcanic activity — or the lack of it.

    Oh, bosh. Negative numbers are numbers, too.

  29. 229

    Oops, apparently I blew a blockquote tag in my last post–if it helps, that second-last paragraph is supposed to be Victor, not me.

  30. 230
    CCHolley says:

    Re. Victor @215

    Victor once again is making a non-point. As stated earlier, attribution studies for the first half of the last century are highly uncertain due to the lack of good information. But uncertainty does not mean no knowledge.

    The references provided by Victor on solar insolation do nothing to say that solar could not have contributed to the warming. Most of the evidence says that it did and there is little debate over the fact that solar was increasing in this period. It is simply is not a significant problem as Victor asserts, that is just made up BS. The range of solar contribution is generally accepted as 0.1 to 0.15 degrees. This is not *ad hoc*, it is what the evidence shows. As for CO2 forcing, using best guess on CO2 levels for the period, the resulting level of change in radiative forcing can be calculated. Of course this has been done and shows the likely contribution of CO2 to warming during this period was about 0.15 degrees. This is relatively small as to the total warming and certainly not as large as the current level of forcing, but never the less is a contributor. Combining the two gives us an estimate of 0.25 to 0.3 degrees. Warming for the period was approximately 0.4 degrees. This would leave us with an additional 0.1 to 0.15 degrees for other causes. Since we know natural unforced variation can account for no more than a plus or minus 0.15 degrees in temperatures about the forced mean, by adding some natural variation the total temperature rise can be easily accounted for. This including a cooling effect from anthropogenic aerosols and the slight warming from low volcanic activity. There is just nothing that says the warming for the period cannot be accounted for and that there *must* be some other unknown cause. The premise is inane and baseless.

    As for Victor’s claim that there is no correlation between TSI and temperatures in the 17th and 18th century, this is just another baseless assertion. First, we know that Victor has trouble identifying correlation. He thinks he can determine this by just looking at charts, which is problematic, you can’t, you need to do a statistical test. Second, the instrument record prior to 1850 is considered unreliable for determining global temperatures due to sparse coverage and proxies for these periods also contain significant uncertainty. So making a determination as to correlation is somewhat problematic. Finally, Victor’s claim that solar levels in 1780 were at the same level as the end of the 1960s period is patently false. One annual spike does not constitute TSI for the period. Overall it was clearly lower.

    Could industrial aerosols have had the same effect in the first half of the last century as they did during the non-warming period of the 1940s thru 70s? Sure they would have had an effect, but not equal. The effect of both CO2 and aerosols by mass in the atmosphere are not linear and do not follow each other in lock step, hence to claim that aerosols would have a cancelling effect no matter what the rate of fossil fuel combustion would be a false assumption. Industrial aerosols are considered to have minor influence in this period and did not have much of a cancelling effect. In addition, the later non-warming period also was a period of high volcanic activity adding even more aerosols to the atmosphere. It was the result of a combination of both.

    So Victor thinks it is possible that there is some other yet unknown cause of the current warming. What he fails to hypothesize is what the mechanism for such warming could possibly be, he just states it could be just some unknown natural variation or natural drift. Magic, I suppose, since warming of this amount must be the result of an influx of energy and Victor cannot explain where such unknown energy could possibly be coming from. Not to mention, does he explain what is happening to the heat that the CO2 radiative imbalance causing. An imbalance that is measurable TOA. Nor does he explain how this unknown force is warming nights faster than days, or the arctic faster than the rest of the planet, or how it warms winters faster than summers. Things that a *force* or natural drift wouldn’t cause, only something that inhibits cooling. Victor is just so full of it. Full of himself and full of baloney.

  31. 231
    nigelj says:

    Victor @223

    “The warming from 1910 – 1940 is what we’re talking about and that was ca. .6 degrees. ”

    Nitpick if you want its still small and is easily explained by solar plus volcanic plus C02. If you cant see it you are being obtuse.

    “Actually I have considerable scientific training and experience, though certainly not in the boring field of climate science. ”

    Really because month ago you said you hav no scientific qualifications, and only qualifications in media studies.

    You may be trained in not fooling yourself, but you literally fool yourself constantly on these pages, over and over.

    “And it doesn’t help when I’m expected to accept that industrial aerosols balanced the effects of CO2 from 1940-1979, yet can be safely ignored when considering the years 1910-1940.”

    This completely ignores the considerable increase in industrial aerosols from the 1940s on with 1) The War and 2) The consumer and electricity generation revolutions!

    “Sure, when the data doesn’t support your hypothesis it’s all too easy to look for complicating factors that “correct” said data in your favor

    Now you are just implying corruption. Bore hole material without a shred of evidence.

    “And of course I am not the only one who’s noticed this problem. A great many others with far more expertise in hard science than I share my skepticism.”

    Yeah about 3% of climate scientists are sceptics from various studies like the John Cook study. Several paid by fossil fuel companies. Im not impressed.

    And regarding volcanoes its quite simple. A 100 or 200 year period has a certain level of aerosols as typical. It can be unusually higher or unusually lower for short periods like 20 years, as in the early part of last century, so it effects warming patterns for shortish periods like this.

  32. 232
    nigelj says:

    Victor @227

    You are confusing the 11 years sunspot (solar irradiance) cycle which does indeed have very small effect on temperature, with longer term sunspot (solar irradiance) cycles than can effect temperatures over periods more like 50 years and up to approx. 0.5 degrees maximum. This partly explains how the climate warmed early last century, but is not enough to fully explain it.

    The amazing thing is you actually posted several graphs showing increasing solar irradiance over a 50 year period but obviously you dont know what you are looking at half the time. Go back and look at them.

  33. 233
    nigelj says:

    Thomas a 244 you are obviously in one of your irritating moods today. The reason the comments are printed is presumably because they are on topic and are asking some fair questions, even if Victor has missinterpreted about 100 things.

    I know I probably wont convince Victor but I comment because 1)For the benefit of more astute and open minded readers and 2) I’m interested in climate change science and also the psychological dimensions of scepticism 3) the mental exercise 4) I live alone right now and get bored with television and 5) I enjoy a bit of argument and 7) Obviously scepticism has its place.

    But each to their own Thomas. Whatever rocks your boat.

    And if you think you have a better way of convincing Victor, don’t hold back!

    Don’t get me wrong. Im very much on your side on a number of things and you make some good points.

  34. 234
    Victor says:

    @226

    Mr. Rodger,

    Your long, convoluted “explanation” of how heat can be generated by a lack of cooling reminds me of the efforts of someone trying desperately to punch his way out of a paper bag. You can spin this every way from Sunday and the result will be the same. Yes, a kettle of water will cool down after the flame underneath it is reduced. But after that flame is extinguished, the absence of any subsequent flame will never cause it to heat up again.

    And yes, an accumulation of aerosols from previous eruptions can delay the process of aerosol dissipation from the most recent eruption, but the presence of these leftover aerosols only prolongs the cooling effect, no?

    What IS cooling but the reduction of some already prevailing temperature? No matter how many cooling events take place there is no way any subsequent absence of such events can possibly restore the environment in question to a level higher than that at which the cooling began, regardless of how many cooling events have taken place.

    And the paper by Wigley et al ( http://onlinelibrary.wiley.com/doi/10.1029/2004JD005557/full ) does NOT help your case. From the abstract:

    “After the maximum cooling for low-latitude eruptions the temperature relaxes back toward the initial state . . .” Get it? “Relaxes back toward the INITIAL state.” !!!!

    As for their Figure 3, all it shows is an estimate of the time required for the cooling aerosols to completely dissipate (and thus return the temperature to its initial state). Note that they all wind up at same reading for temperature change: 0.

  35. 235
    Brian Dodge says:

    “First of all, any rise in temperature due to volcanic aerosols (an effect I’ve acknowledged) is the result of the dissipation of the aerosols, NOT any subsequent “lack of volcanic activity.” Can we agree on that at least?”

    No. How, pray tell, would volcanic aerosols “dissipate” if there were no lack of volcanic activity continually replenishing them?
    There is periodic volcanic activity and has been for more than 2 billion years. Anything above VEI 3 will likely have some effect on stratospheric aerosols, (although the amount of sulfur emissions don’t correlate precisely with VEI index). The decay times of volcanic aerosols are approximately exponential, though there are seasonal and geographic influences*; Observations vary from ~ 5 to 95 months for 1/e; eruption durations vary from week to decades; the mean time between VEI 4 eruptions is 18 months. Positing that there have been any times with zero volcanic aerosols is almost as ludicrous as positing there is no water vapor feedback; neither compares with trying to use them as the basis for a long winded attempt at justification for a wished for “safe” climate sensitivity.

    *http://journals.ametsoc.org/doi/pdf/10.1175/1520-0469(1978)035%3C1296%3APVSADA%3E2.0.CO%3B2
    I would expect that eruptions that cause more cooling, which slow the evaporation/rainfall cycle, would lengthen the time for the aerosol concentration to drop by 1/e.

  36. 236
    MA Rodger says:

    Here is an analysis of Victor the Troll’s latest offering (@227).
    The good news is that Victor’s contribution to this thread @227 is not complete codswallop. That is, he states “I am not a climate scientist, nor am I in a position to evaluate any of the claims made by climate scientists regarding solar irradiation or any other influence on global temperatures.” This statement is of course entirely correct. Indeed, it is why it is necessary to evaluate any of the “claims” Victor the Troll does present here.

    In reverse order, Kopp (2016) tells us “…in pre-industrial times … natural influences dominated climate forcings. Sensitivities to natural forcings can be determined, for example, by correlating historical solar-irradiance variability estimates with observational surface-temperature records. Reliable knowledge of possible secular changes in TSI during these earlier eras is therefore important for establishing climate sensitivity to natural influences in the absence of larger anthropogenic effects.” Kopp goes on to demonstrate that the big climatological impact of TSI (the 17th century Maunder Minimum) is “generally-accepted (to) have been about 0.04 to 0.08% lower in irradiance for several decades” relative to “current levels.” Thus the big big waggle in TSI of recent centuries amounted to 0.14-0.28Wm^-2 which is or course tiny relative to what Koch (2016) describes as the “larger anthropogenic effects.” This historic TSI waggle differs from the also-tiny TSI waggles set out by UN IPCC AR5 Annex AII Table AII.1.2 solely in its duration.

    The troll’s second citation (an explanation of the relevance of a past NASA satellite mission) echoes Kopp (2016) in branding TSI variation over the last few decades as an irrelevance when attributing the climatic change observed over that period. “Today, scientists who study the links between solar activity and climate are confident that the small variations in TSI associated with the eleven-year solar cycle cannot explain the intensity and speed of warming trends seen on Earth during the last century.”

    The troll’s first citation is to good old Wikkithing which presently contains an unchallenged quote from Scarfetta & Wilson (2014) who are well known as being denialist sources that would warm the cockles of any cold-blooded troll. So not a primary source and not a very reliable place to go searching for juicy quotes.

  37. 237
    CCHolley says:

    Victor @223

    The warming from 1910 – 1940 is what we’re talking about and that was ca. .6 degrees. The warming from 1979 to just before the recent El Nino was ca. .8 degrees. A difference of “only” .2 degrees. Yet one is significant and the other isn’t.

    lol. Perhaps 0.6 degrees if you start with the very lowest point. Maybe. And of course we know the warming is overrated due to the wartime change in methodology. Lets keep ignoring that. As for the current period, why not pick the lowest temperature just like you did for the earlier period, not 1979? Then you would clearly have 1.0 degrees of warming. And why ignore the El Nino? The earlier warming period also ended with a large El Nino event. Difference of only 0.2 degrees. Not.

  38. 238
    Victor says:

    “How, pray tell, would volcanic aerosols “dissipate” if there were no lack of volcanic activity continually replenishing them?”

    My oh my. This statement is a perfect example of the very strange reasoning I’ve been faced with since I raised this issue. So what Mr. Dodge is saying is that the dissipation of volcanic aerosols could not have happened unless they were being replenished by a LACK of additional volcanic activity? How can something be replenished by the LACK of something else? What he really means, of course, is that additional volcanic activity, had it taken place, would have added more aerosols, thus slowing the overall dissipation, which would in turn have slowed the cooling effect of said aerosols. But slowing a cooling effect is NOT the same as generating additional heat. And it is the source of the rise in heat from 1910-1940 that is in question, surely.

    As for the rest, we could go on and on quibbling over all the various ins and outs, but as far as I’m concerned I’ve made the essential points:

    1. The commonly held notion that the rise in temp. we see from 1910-1940 could be explained, even in part, by some relative lack of volcanic activity during this period is a logical fallacy. You don’t need to be a climate scientist to understand this very simple point. But you DO need to free your mind from long-entrenched dogmas that appear to have morphed into articles of faith.

    2. The oft-cited evidence for solar irradiance as an additional cause of the same warming has never been confirmed and remains an untested hypothesis. While some graphs depict a steep rise in solar irradiance during this period, others show only a very gradual rise or none at all. Ironically, the video accompanying the Skeptical Science discussion of this issue, exhibits a very different graph, in which solar influence (green line) is essentially flat during the entire 20th century. See https://youtu.be/0n3bX_5d7vA?t=3m55s

    Also, from the NASA report cited above: “The TSI-record assessment in this section suggests that the current measurement-record does not have the needed stability to definitively detect secular trends in solar variability.”

    3. As almost all climate scientists agree, release of CO2 due to the burning of fossil fuels could have played only a relatively minor role during the early years of the 20th century, when it was only a fraction of what it is today. See the statement by Mears, quoted above.

    In view of the above, the notion that the early 20th century temp. increase is “well understood” by climate scientists is extremely difficult to swallow. Yes, there are a great many hypotheses regarding its cause, but it is far from “settled science.”

    So once again: if it is not possible to determine the cause of the earlier temp. runup then it is not possible to claim that the latter runup can ONLY be explained by fossil fuel emissions. And as I’ve argued many times in the past, there are a great many additional reasons to doubt that fossil fuel emissions are leading us on the path to some inevitably disastrous future. Which is NOT to say that they are a good thing. IMO they are far from being an unalloyed benefit to mankind and we’d all be better off if we didn’t need them so much. Unfortunately we do.

  39. 239
    MA Rodger says:

    Victor the Troll @234.
    And it seems we have almost managed to punch your denialism out of that wet paper bag of yours. A hearty round of applause for Victor! Your analogy of the kettle was set out correctly. Congratulations, Victor!! Sadly, your kettle analogy does argue against the position you still continue to occupy like the corpses of the forlorn hope prior to the burial detail’s arrival. But the kettle analogy of your was correct!!!

    You will note the words of Wigley et al (2006) that you yourself quote. They say – “the temperature relaxes back toward the initial state.” (My bold). And you will note if you re-examine the paper’s Figure 3. You say @234 “Note that they all wind up at same reading for temperature change: 0.” but that is flat wrong. Figure 3 shows that even during the rare un-volcanicy 1920s-40s, the initial state is never arrived at. It is close but “the temperature relaxes back toward the initial state” and that “initial state” is never actually ever achieved.

    So where does that leave any explanation of for the global warming 1910 to 1940? There are significant contributions from AGW. There are contributions from the unusually low volcanism. There are contributions from the increase in TSI. And reconstructions of the MEI, the PDO and even the IPO all point to a likely contribution from ENSO. Sadly for a simpleton like yourself, Victor, this particular episode of climate variation requires a little more than eye-balling a couple of traces on a graph to check the ups-&-downs meet with your approval.

  40. 240
    jgnfld says:

    @237

    Pssst. Vic. Did you know the proper way to describe a trend over time is, well, er, to use the actual trend???

    The linear trend (GISS data) during the 1910:1940 interval is .01 deg/year. The fitted trend value for 1910 is -.36 and the fitted value for 1940 is -.06. When you subtract the latter from the former you just do not get .6 at all. Your “math” is off by only a mere factor of 2. Note also that the trend then was only a bit over half the modern value which runs around .17 deg/yr.

    Fiddling with local start-end values and subtracting only the most extreme points rather than using all the available trend information to estimate the trend is a very old, much beloved denial trick. Depending on how you work it you can generate a false larger “trend” like you did here, or you can generate a false lower “trend” or even a “pause” like you try with your “just before the recent el Nino” trick. And I wonder why you didn’t start in 1976 rather than 1979?! (Actually I don’t wonder at all.)

    Interesting that you use the same trick in opposing directions! Anyway, I don’t think anyone even minimally knowledgeable is fooled by it these days. One might even label it a trick worthy of the designation “boring”.

  41. 241
    jgnfld says:

    Typo on modern trend: Should be .017 deg/yr.

  42. 242
    CCHolley says:

    Re. Victor @238

    So once again: if it is not possible to determine the cause of the earlier temp. runup then it is not possible to claim that the latter runup can ONLY be explained by fossil fuel emissions. And as I’ve argued many times in the past, there are a great many additional reasons to doubt that fossil fuel emissions are leading us on the path to some inevitably disastrous future. Which is NOT to say that they are a good thing. IMO they are far from being an unalloyed benefit to mankind and we’d all be better off if we didn’t need them so much. Unfortunately we do.

    Baloney. The earlier temperature run-up IS explainable. All Victor has done is exaggerate the trend, then attempt to show that the explanations are uncertain, which is really nothing new, the exact contributions are uncertain. Uncertainty does not equate to unexplainable.

    Furthermore, even if the earlier run-up were unexplainable, it does not follow that the current warming trend must also be unexplainable. This is just silly logic. Just BS of the highest order. The evidence that the current trend is ALL anthropogenic IS very compelling.

    A great number of other reasons to doubt fossil fuel emissions are leading us down a disastrous path? Perhaps more reasons as baseless and illogical as Victor’s current volcanism red herring rant.

    We need fossil fuels? Says who? Victor, therefore it must be true.

  43. 243
    MA Rodger says:

    Brian Dodge @235,
    I think you are cruel presenting Victor the Troll with a double negative. He is too much of a simpleton to cope with such a logical construct. Look how he flounders @238 replying to you. You’ve got him saying that “more aerosols” will have “slowed the cooling effect of said aerosols” which is plain bonkers. We have to keep it simple. The troll is not just incredibly stupid. His is also in denial. That is a heady mix to grapple with.

  44. 244
    Victor says:

    240 jgnfld:

    “The linear trend (GISS data) during the 1910:1940 interval is .01 deg/year. The fitted trend value for 1910 is -.36 and the fitted value for 1940 is -.06. When you subtract the latter from the former you just do not get .6 at all. Your “math” is off by only a mere factor of 2. Note also that the trend then was only a bit over half the modern value which runs around .17 deg/yr.”

    Not sure what your point is. The temperatures I cited were read directly off the graph I linked to. If you think you know more than the people who designed this graph, I urge you to direct your complaint to them.

    If you’re attempting to minimize the importance of this early 20th century warming trend, I invite you also to make your case to the many climate scientists who have taken it very seriously and spent considerable time, effort and grant funding in their varied attempts to account for it.

    Here is one sample out of a great many that could be cited:

    “Of the rise in global atmospheric temperature over the past century, nearly 30% occurred between 1910 and 1940 when anthropogenic forcings were relatively weak. This early warming has been attributed to internal factors, such as natural climate variability in the Atlantic region, and external factors, such as solar variability and greenhouse gas emissions. However, the warming is too large to be explained by external factors alone and it precedes Atlantic warming by over a decade.” https://www.nature.com/ngeo/journal/v8/n2/full/ngeo2321.html

  45. 245
    Mal Adapted says:

    Presumably, this thread abundantly gratifies our dogged denier’s need to be the center of attention with minimum investment. Recreational typing requires him neither to accept uncomfortable facts nor discard comforting fallacies.

  46. 246
    nigelj says:

    Victor @238 you are cherrypicking some video on solar cycles and it appears inaccurate. You fail to look at the weight of evidence. You are quoting NASA massively out of context.

    You have no intellectual rigour at all. You fool only yourself.

    There are literally hundreds of studies, reconstructions, research papers and graphs of solar cycles, and the vast majority show an increase in solar activity early last century, and a flat cycle after about 1970. (A few unreliable ones from oil companies and sceptics websites show something else). Please refer below for a few hundred examples, literally.

    https://www.google.co.nz/search?q=graph+of+solar+activity+and+temperature&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwigta_2xN_WAhVGrJQKHYzCB9wQ7AkINw&biw=1105&bih=588

  47. 247
    MartinJB says:

    Victor (@238)

    You say “But slowing a cooling effect is NOT the same as generating additional heat.” That is not the question. What’s generating the heat is energy from radiation from the sun (you know, sunlight). Aerosols reflect some of that radiation back into space, reducing the amount of energy entering the earth system. So, if lower volcanic activity during a period allows the concentrations aerosols to fall, more energy gets into the earth system, thus generating more heat. It’s that bloody simple.

    Again, with arrows: lower volcanic activity –> lower aerosol concentrations –> more sunlight gets in –> more heat

    Now, I expect you know that. So, when you say something as daft as the quote above, are you ignoring the underlying physical mechanism or are you just obfuscating and playing dumb?

  48. 248
    nigelj says:

    Victor @244 complains about people trying to allegedly minimise the warming period early last century. He then quotes a source he claims has different and better information, yet that source says warming is 30% of total for the century, so it IS actually quite minimal.

    The source he supports also says the cause was partly solar and CO2 while Victor has been desperately claiming they are not causes! Talk about confused inconsistency. Its just priceless!

  49. 249
    jgnfld says:

    The point is reading 2 individual cherrypicked points off the graph and ignoring all the rest is not how anyone with a brain and/or any scientific training defines a “trend”. You defined a trend by reading 2 individual cherrypicked points off the graph. There is an obvious conclusion to be made here.

  50. 250
    CCHolley says:

    Victor @244

    Not sure what your point is. The temperatures I cited were read directly off the graph I linked to. If you think you know more than the people who designed this graph, I urge you to direct your complaint to them.

    But then you didn’t read the graphs the same for the present warming trend, you cherry picked a starting point that wasn’t the lowest. You ignore the el Nino when the earlier warming ended in an el Nino. You ignore that the earlier warming is inflated by too high of readings during war time. You are purposely deceitful. Blame the graphs, what a joke you are.

    If you’re attempting to minimize the importance of this early 20th century warming trend, I invite you also to make your case to the many climate scientists who have taken it very seriously and spent considerable time, effort and grant funding in their varied attempts to account for it.

    No one is minimizing it. It is you who are making a mountain out of a mole hill. Attempts to account for it better does not mean there is any possibility of some unknown warming force. THERE IS ONLY UNCERTAINTY IN THE EXACT ATTRIBUTION BECAUSE THE INFORMATION IS INCOMPLETE. There is no such shortage of data for the current warming trend.

    Here is one sample out of a great many that could be cited:

    “Of the rise in global atmospheric temperature over the past century, nearly 30% occurred between 1910 and 1940 when anthropogenic forcings were relatively weak. This early warming has been attributed to internal factors, such as natural climate variability in the Atlantic region, and external factors, such as solar variability and greenhouse gas emissions. However, the warming is too large to be explained by external factors alone and it precedes Atlantic warming by over a decade.”

    30% directly contradicts YOUR claim when you stated 0.6 degrees warming versus 0.8 degrees which actually extends into the present century. 0.6 degrees is 30% of 2.0 degrees.

    No one ever said part of the earlier warming wasn’t due to unforced natural variation. Your quote does nothing to support any of your silly assertions.

    You are so full of baloney.