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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 Science, vol. 9, pp. 635-645, 2009. http://dx.doi.org/10.5194/nhess-9-635-2009

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

  1. 101
    jgnfld says:

    @97

    Good God. It always amazes me how deniers lecture professional scientists on how the scientific method or statistical methods “actually work” using every bit of their sophomoric knowledge.

    Reminds me of the utter stupidity of arm chair generals and quarterbacks.

    Just for your info, Vic, most scientists became fully aware of the concepts you bring up as advanced undergrad students many, many years before engaging in any independent research on their own. Lecturing practicing advanced professionals just makes you look stupid.

  2. 102
    nigelj says:

    Victor @97

    You can quote some discussion on the philosophy of statistical significance all you want, but the results for CO2 are reasonably strong. We are not in the borderline area.

    And nobody is going to accept your speculative opinion on what some graph shows. I look at the same graph and see an obvious long term correlation. THAT’S why we need tests, even if they aren’t perfect so you have NO CHOICE.

    It all comes down to PROBABILITIES.

    Basically science requires good causation and a reasonable correlation. It doesn’t require perfect correlation, (as in looking at relationships in a graph) and such things rarely exist. Correlations often get masked by other factors.

    Correlations are red flags. They neither prove or disprove anything by themselves. A rough correlation just suggests something may be going on. Sometimes correlations can be spurious. The more important thing is causation.

    We have good causation with greenhouse gas theory, and a reasonable correlation between CO2 and temperatures, enough to support the theory. That’s all that’s needed. Even serious sceptics like Lindzen and Spencer admit all this.

  3. 103
    CCVHolley says:

    Victor @97

    LOL. Now that you’ve been shown that there is a correlation between temperatures and CO2 levels you have to attempt to downplay the importance of statistical significance. Statistical significance is what it is and and it doesn’t change the fact that you are wrong about the lack of correlation. No one ever claimed correlation proved anything, it is just another piece of supporting evidence.

  4. 104
    Victor says:

    71 Marco says:

    “Victor, why do you insist on showing your ignorance of the scientific literature?

    Here, I’ll be nice and point you to an easy-to-read explanation:
    https://www.skepticalscience.com/global-warming-early-20th-century.htm

    I’m very familiar with the Skeptical Science site, thank you, been there many times and learned a lot — about how easily inconvenient evidence can be “corrected” by invoking ad hoc hypotheses. (For an explanation, see: https://santitafarella.wordpress.com/2017/05/02/best-explanation-ad-hoc-explanation-and-occams-razor/)

    Skeptical Science (https://www.skepticalscience.com/global-warming-early-20th-century.htm) offers two such ad hoc hypotheses:

    “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).”

    In the “advanced” segment they provide an impressive array of references, complete with an accompanying graph illustrating solar activity. And yes, we do see an increase in solar irradiance during the period in question. However, the increase continues well beyond the target year of 1940 all the way through to the 1990’s. And as we know, global temperatures cooled from the forties through the late 70’s. So it’s hard to see much of a correlation. Clearly this ad hoc hypothesis works only if one doesn’t look too hard.

    Oh and by the way, if you take a look at the accompanying video, at 3:46, you’ll see a very different graph, in which solar activity (in green) is presented as relatively flat throughout the length of the 20th century. When invoking an ad hoc hypothesis I suppose one is free to select whatever graph suits one’s purpose.

    As far as the argument based on the lack of volcanic activity, that one is truly a doozy, a classic example of ad hoc reasoning, as should be obvious. Now if temperatures had already been at the 1940 level around 1890, and volcanic activity subsequent to that period had driven them down, then one might be in a position to argue that the lack of volcanic activity after 1910 represented some sort of rebound effect. But there is no sign of that at all. Temperatures in 1880 were significantly lower than in 1940. So how could a LACK of volcanic activity produced that steep rise?

  5. 105
    Victor says:

    101 “Lecturing practicing advanced professionals just makes you look stupid.”

    Sorry but I was not aware that I was lecturing professionals. I was lecturing a very naive amateur who assumes that statistics is some sort of oracle revealing absolute truth.

  6. 106

    V 105: I was lecturing a very naive amateur who assumes that statistics is some sort of oracle revealing absolute truth.

    BPL: Straw-man arguments are easier to address than real ones, certainly.

  7. 107
    Tim says:

    104 Victor says
    “However, the increase (in solar irradiance) continues… all the way through to the 1990’s. And as we know, global temperatures cooled from the forties through the late 70’s. So it’s hard to see much of a correlation. Clearly this ad hoc hypothesis works only if one doesn’t look too hard. ”

    If you yourself had looked a little bit harder at the Skeptical Science article you so selectively quote you’d have read:

    “Other Forcings: 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…”

  8. 108
    CCHolley says:

    Victor @104

    We know that sea surface temperatures prior to the implementation of the ARGO system are somewhat problematic due to methodology. The temperature peak seen in the 1940s is likely an illusion due to a war time change in the gathering of the sea surface temperature data. If we look only at the land surface temperature record, the warming in the first half of the 20th century was much less pronounced and there was no cooling after 1945. Solar records are also a bit problematic in that solar irradiance was not measured directly until the advent of satellites. Your interpretation of the period is wrong. Indications are that the slight warming was due to an increase in solar irradiance as indicted by sunspot activity and a diminishment in worldwide volcanic activity along with an increase in CO2 levels. Remember the effect of CO2 is logarithmic so the initial contributions, though small, would have an impact. The effect of volcanic aerosols to temperatures is also well understood and models show good correlation therefore its influence can be shown. None of this is ad hoc thinking, it is all based on our knowledge of radiative forcings. There was no unknown magical driver of the early 20th century temperatures and none of what you claim casts any doubt on our knowledge or the physics behind AGW.

  9. 109
    Marco says:

    Victor, if you’d had paid attention, you would have known there are a number of different TSI reconstructions. Skeptical Science is nice enough to take essentially the worst case scenario (Lean et al), and still you handwave your way to proclaim “doubt! doubt! doubt!”

    Your complaints about the volcanic activity argument makes no sense. An ad hoc explanation it definitely is not – that volcanoes have an impact and in what direction has been known for a long time.

  10. 110
    Ray Ladbury says:

    Weaktroll@97,
    Sigh. You really, really do not understand science or statistics, do you? First Ionannidis studies concern biomedical research. Second, they don’t really tell us all that much that we didn’t already know. That up to 5% of studies with a p-value of .05 may be wrong has been known since the studies by Obvious et al. These are not the types of studies on which the foundation of climate change rests. You are simply too dim to be able to tell the difference. Hope that helps.

  11. 111
    Mal Adapted says:

    DDS:

    CO2 is a green house gas
    Vaccines work
    Men and Woman are different
    Communism is bad

    Perhaps deliberately, perhaps not, your list is in ascending order of subjective ambiguity. That is:

    If a ‘green house gas’ is one that backscatters outgoing long-wave radiation, then CO2 is unambiguously a green house gas;

    If ‘work’ is qualified by ‘usually, for most common vaccines’, then vaccines work;

    If one is focused on reproductive anatomy, then men and women are visibly ‘different’;

    If one somehow thinks that ‘Communism’ has actually been implemented by any nominally Communist government, and if one is not a member of the political elite of those former governments, then Communism is bad.

    Come on, DDS, you can tell us: you meant to do that, didn’t you ;^D!

  12. 112
    Victor says:

    #108 CCHolley: “If we look only at the land surface temperature record, the warming in the first half of the 20th century was much less pronounced and there was no cooling after 1945.”

    Come again? According to this graph, courtesy of NOAA (http://www.ucsusa.org/sites/default/files/images/2017/04/land-ocean-combined.png), land and ocean temps increased pretty much in tandem from 1910 to 1940. And there was most certainly a pronounced drop in land temperatures from 1945 through the late fifties. Following that, land temps bounced up and down rather aimlessly until the mid seventies, when, as we know, they shot up dramatically. Thus, as previously noted: dramatic rise in BOTH sea AND land temps from 1910 through 1940; precipitous drop in both through the late fifties, followed by some aimless ups and downs until the late seventies.

    It wouldn’t surprise me to learn that you’re getting your data from some other source. And that too is part of the problem. No matter what one’s position is there always seems to be some graph or some study to support it. Settled science indeed!

  13. 113
    Victor says:

    109 Marco says:

    “Victor, if you’d had paid attention, you would have known there are a number of different TSI reconstructions. Skeptical Science is nice enough to take essentially the worst case scenario (Lean et al), and still you handwave your way to proclaim “doubt! doubt! doubt!”

    Skeptical Science selected the reconstruction (Lean et al) that supported its claim. Period.

    “Your complaints about the volcanic activity argument makes no sense. An ad hoc explanation it definitely is not – that volcanoes have an impact and in what direction has been known for a long time.”

    Yes, we’ve known for a long time that Volcanic aerosols have a cooling effect. So how does the absence of volcanic activity produce a warming effect?

  14. 114
    nigelj says:

    Victor @104

    You say quoting from skeptical science:

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

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

    The very article you quote goes on to say:

    “Other factors, including greenhouse gases, also contributed to the warming (early last century)”

    You say “however, the increase (in solar activity) continues well beyond the target year of 1940 all the way through to the 1990’s.”

    The article you quote goes on to say ” Does this mean that solar activity is also primarily responsible for late 20th century warming? In short, no. Solar activity since the 1950s has been relatively stable and therefore cannot explain recent trends.”

    So you just talk incessant misleading nonsense over and over.

  15. 115

    Mr. Know It All says:
    11 Sep 2017 at 6:40 PM

    25 – Russel
    Your “link” to 200 F temperature difference in the hurricane went to the self-admitted “Chronicle of Idiocy” vvats up with that…

    Yes, KIA–you’ve been punked. Apparently the humor was a bit too dry…

    28 – Lynn
    Harvey was not a 1000 year storm.

    According to whom? It was widely described as being precisely that.

    It isn’t even the worst storm Houston has seen since Europeans moved in. Houston has received as much rain as Harvey dumped in 3 days in a single 24 hour period – see hurricane Claudette.

    Oh, really? Sez here that:

    “Claudette produced moderate rainfall across southern Texas, peaking at 6.5 inches (170 mm) in Tilden.” Last time I checked, 6.5 is not greater than 50.

    49 – CCH
    Quote: “There is no evidence that mainstream climatologists are driven by ideology nor that ideology influences the peer review process. None. Not only that, the science is quite robust going back almost two hundred years.”

    So, why didn’t AGW become a thing until recent decades?

    Was that supposed to be a zinger? AGW didn’t become a ‘thing’ until recent decades–although that’s a matter of defintion–because, gosh golly gee, it was in recent decades that emissions of greenhouse gases skyrocketed.

    Although there *is* the reality that, in 1896 Svante Arrhenius concluded that:

    “Over the course of a millennium, however, humans could have a major influence, since [Arrhenius] estimated that burning the world’s annual production of coal, approximately 500 million tons, produced about one-thousandth of the total atmospheric concentration of carbon dioxide.”

    It wasn’t a ‘thing’ observed yet, but it was already a ‘thing’ foreseen.

  16. 116

    Victor, #113, asks:

    “Yes, we’ve known for a long time that Volcanic aerosols have a cooling effect. So how does the absence of volcanic activity produce a warming effect?”

    Let me go Talmudic here and answer that question with another:

    Yes, we’ve known for a long time that [active stove burners] have a [warming] effect. So how does [turning the burner off] produce a [cooling] effect?

  17. 117
    CCHolley says:

    Victor @112

    I would refer to IPCC 5AR WG1, Chapter 2, Observations: Atmospheric and Surface, FAQ 2.1, Figure 2, page 199.

    Not exactly the same, but here are Wikipedia links to similar charts with the NOAA references.

    Land temperature anomalies:

    https://en.wikipedia.org/wiki/Instrumental_temperature_record#/media/File:NOAA_Land.svg

    Shows a very very slight peak in 1940, but not really statistically significant. I would call the period from 1940 to 1970 as flat, not cooling.

    Sea surface anomalies:

    https://en.wikipedia.org/wiki/Instrumental_temperature_record#/media/File:NOAA_Ocean.svg

    Here you can see the huge war time spike in sea temperatures which is not at all in step with land temperatures.

    The war time sea temperature issue is well known.

  18. 118
    CCHolley says:

    Victor @113

    Yes, we’ve known for a long time that Volcanic aerosols have a cooling effect. So how does the absence of volcanic activity produce a warming effect?

    A period of less volcanic activity results in fewer aerosols in the atmosphere. This means more solar radiation is reaching the surface. The surface must warm until the system reaches a new equilibrium. Energy in must equal energy out. This is basic physics.

  19. 119
    Marco says:

    “Skeptical Science selected the reconstruction (Lean et al) that supported its claim. Period.”

    Lean et al is the one that results in the largest solar contribution to early 20th century warming! The other two would have meant much less solar influence and thus more influence of GHGs. Does that “support [Skeptical Sciences’] claim”?

    Less volcanic activity is less aerosols in the atmosphere (and in particular stratosphere). It slowly falls out.

  20. 120
    Adam Lea says:

    113: “Yes, we’ve known for a long time that Volcanic aerosols have a cooling effect. So how does the absence of volcanic activity produce a warming effect?”

    It doesn’t, it eliminates some of the natural variability which acts in the opposite direction to the long terms warming trend. Without volcanic activity, you wouldn’t see some short term cooling superimposed on the upward trend. Same as El Nino/La Nina, a cluster of La Nina’s over a decade or so will result in an (apparrent) short term plateauing of global temperatures, whereas a strong El Nino acts to enhance the warming, which is why a strong El Nino has a tendency to be followed with a glkobal high temperature record.

  21. 121

    V 105: how does the absence of volcanic activity produce a warming effect?

    BPL: If it was preceded by a period of high volcanic activity, more sunlight would get through the atmosphere in the later period, and Earth would warm.

  22. 122
    Ray Ladbury says:

    Weaktroll: “So how does the absence of volcanic activity produce a warming effect?”

    Anyone else want to take this? Anyone? Beuhler? No?

    OK. Volcanoes are Poisson events. They occur with some mean rate, resulting in some mean concentration of sulfate aerosols in upper atmosphere. If the frequency of volcanic eruptions decreases below the mean for a significant amount of time (years to a decade or so), the mean aerosol concentration decreases. More sunlight gets in. Warming ensues.

    Now a sincere question. Weaktor, given that this was beyond your ability to figure out, do you really think you are in any position to pronounce on people who have studied climate for decades?

  23. 123
    Roscoe Shaw says:

    I ran a simple plot of HADCRUT annual temps versus Atlantic ACE since 1950. Warmer years had higher ACE. The linear eq suggests an extra deg global air temp adds 35 ACE points.

    This is a simplistic analysis but I found it interesting.

    Graph here
    https://postimg.org/image/qicqezkfp/

  24. 124
    Thomas says:

    Dan DaSilva, Mr KIA, and Victor @ 55, 97, 104, 105, 112, 113 …….

    Commenter suggests: “You may want to defend that statement … “

    Neven Retorts: “I doubt he wants that, because then he will inevitably have to refer to paid climate denier sources (Crockford etc) and that will get him banned.”

  25. 125

    The weather/risk analysis company Metstat weighs in on the recurrence intervals for Harvey:

    http://metstat.com/hurricane-harvey-extraordinary-flooding-for-houston-and-surrounding-areas/

    Spoiler: yeah, this was a very unusual storm, and no, it’s not true that its rainfall *rates* were unremarkable.

  26. 126
    Hank Roberts says:

    Well, Victor sure led a lot of people on a response chase ’round Robin Hood’s Barn there.

    Expert use of distraction.

    Squirrel!

  27. 127
    Adam Lea says:

    115: He is referring to tropical storm Claudette 1979 (42 inches of rain, Alvin, Texas), not the 2003 hurricane. 42 is still less than 50 but that is largely academic, 42 inches of rainfall in one place would still result in major flooding.

    There is a list of wettest tropical cyclones in Texas here:
    https://en.wikipedia.org/wiki/List_of_wettest_tropical_cyclones_in_the_United_States#Texas

    He is trying to make the point that massive rainfall totals from tropical cyclones have happened several times in the past. This is true but rather trivial. The question is not whether or not extreme tropical cyclone rainfall has happened before but whether extreme tropical cyclone rainfall has been enhanced by a warming climate, given the optimal synoptic conditions for extreme rainfall have occurred (e.g. stalled tropical cyclone near a warm ocean, or slow moving tropical cyclone interacting with topograhy).

  28. 128
    Mal Adapted says:

    CCHolley:

    A period of less volcanic activity results in fewer aerosols in the atmosphere. This means more solar radiation is reaching the surface. The surface must warm until the system reaches a new equilibrium. Energy in must equal energy out. This is basic physics.

    It’s also the basis of certain proposals for ‘adapting’ to AGW by Solar Radiation Management. While the principle is simple, perhaps lending the idea superficial appeal, any such attempt would be insanely reckless IMO.

  29. 129
    Victor says:

    Ray Ladbury sez:

    “If the frequency of volcanic eruptions decreases below the mean for a significant amount of time (years to a decade or so), the mean aerosol concentration decreases. More sunlight gets in. Warming ensues.”

    So let me get this straight. If a so-so volcano fails to erupt, we can expect only a small amount of warming. But if a really really BIG volcano fails to erupt, then the warming could be huge. I LOVE IT! So all we need is to measure the strength of each volcanic eruption that never happened and we can calculate the statistical likelihood of warming during any given period. Now THAT’s what I call “science.”

  30. 130
    Killian says:

    I really don’t appreciate all the thread space wasted on Victor and other deniers. Please try to remember, the more their nonsense is repeated, the more it is remembered. He’s not the fool here what with all the free advertising, the rest of you are.

    Disengage.

  31. 131
    rasmus says:

    I do not follow this logic.

  32. 132

    V 129: So let me get this straight. If a so-so volcano fails to erupt, we can expect only a small amount of warming. But if a really really BIG volcano fails to erupt, then the warming could be huge. I LOVE IT! So all we need is to measure the strength of each volcanic eruption that never happened and we can calculate the statistical likelihood of warming during any given period. Now THAT’s what I call “science.”

    BPL: I’m trying to figure out what you’re saying here and how you could have gotten it from what we said, but I’m stumped. I can’t answer you because I have no idea what you’re saying.

  33. 133
    CCHolley says:

    Victor says:

    So let me get this straight. If a so-so volcano fails to erupt, we can expect only a small amount of warming. But if a really really BIG volcano fails to erupt, then the warming could be huge. I LOVE IT! So all we need is to measure the strength of each volcanic eruption that never happened and we can calculate the statistical likelihood of warming during any given period. Now THAT’s what I call “science.”

    And there ladies and gentlemen is the essence of Victor.

    Working hard at his denial or perhaps just obfuscating the science by taking a simple explanation and changing it into something it isn’t and then mocking it. Killian is right.

  34. 134

    Victor, #129–

    “Let me get this straight…”

    Followed by a really silly caricature of what Ray said.

    There is always volcanic activity, but it varies, and with it, aerosol concentrations.* These can be quantified.

    So, no, it’s not about the hypothetical size of non-existent eruptions, it’s about the level of vulcanism that *did* occur over a particular period.

    *Note that vulcanism does not account for all aerosols, or even all stratospheric aerosols.

  35. 135
    Ray Ladbury says:

    Victor, Your inability to understand the science does not mean it is not science. I would suspect that about 90% of the folks on this site understand my explanation. They therefore understand that your inability to understand it provides strong evidence that you are an imbecile.

  36. 136
    JCH says:

    How much rain did Houston get when TS Claudette dumped a gigantic amount of rain on a little town 30 miles away that is very close to the Gulf?

    According to the HCFCD, there were no floods between 1940 and 2001 that overwhelmed their flood control infrastructure on a widespread basis. They don’t talk much about TS Claudette. The overwhelming of their infrastructure, by their own admission, started with TS Allison, and continues: H Ike; Memorial Day Flood; Tax-Day Flood; H Harvey; next multiple tens of billions of dollars event.

  37. 137
    Victor says:

    #133 “Working hard at his denial or perhaps just obfuscating the science by taking a simple explanation and changing it into something it isn’t and then mocking it.”

    It’s called reductio ad absurdum, folks. It was also intended as humor, but as I expected no one posting here got it. Lighten up.

    Look, if you want to insist that some event is caused by the absence of something then you let yourselves in for this sort of ridicule. The reason you don’t understand my “joke” is because you don’t understand the absurdity of the notion that heat can be generated from the absence of cooling.

    Now it IS true that volcanic aerosols can to some extent compensate for warming produced by solar irradiance, CO2 emissions, what have you, and when those aerosols dissipate (usually within a year or so), the atmosphere can respond by heating up to the level that would have prevailed had no eruptions taken place. It’s called “rebound.” But such a rebound can never exceed the original temperature. Why? Because a lack of cooling can never actually produce heat in itself. It can only compensate for heat lost by previous cooling. And since global temperatures were soaring way beyond previous levels in the period in question (1910-1940), there is no way any rebound effect could be responsible — because a rebound can never exceed the level from which it rebounded.

    Now maybe some of you would like to argue that we have no way of knowing how much heat could have been produced if it weren’t for some very powerful volcanic eruption. I see from Wikipedia (https://en.wikipedia.org/wiki/List_of_large_volcanic_eruptions_of_the_20th_century) that the Novarupta eruption of 1912 is described as the “Largest eruption of the 20th century,” a category 6. Now aerosols from THAT eruption would certainly have had a cooling effect. But thanks to the eruption we have no way of knowing what temperatures would have prevailed had the eruption never occurred. So you MIGHT want to argue that perhaps temperatures COULD have soared to the 1940 level if not for Novarupta and that what we see from 1910 through 1940 is a rebound from that huge event. OK, fine. But I am then forced to ask: what was the source of THAT dramatic runup in temperature? Too soon for CO2 emissions to have been a factor, certainly.

    So no matter how you want to argue this, you are still left with a dramatic runup in temperature for which there is no explanation based on the current state of climate science. It really doesn’t matter whether the 1940 levels were produced by some sort of rebound due to the absence of volcanic cooling or whether those levels would have been attained had it not been for previous volcanic cooling — they still have to be explained.

  38. 138
    Thomas says:

    130 Killian says: “He’s not the fool here”

    I’m afraid you’re quite correct there Killian.

    131 rasmus says:
    17 Sep 2017 at 2:21 AM – I do not follow this logic.

    Me: Huh?

  39. 139
    Thomas says:

    122 Ray Ladbury asks: “Weaktor, given that this was beyond your ability to figure out, do you really think you are in any position to pronounce on people who have studied climate for decades?”

    Or assert he’s smarter than your average Rabbit, who is equally unable to figure it out either?

  40. 140
    jgnfld says:

    Re. “The reason you don’t understand my ‘joke’ is because you don’t understand the absurdity of the notion that heat can be generated from the absence of cooling.”

    Uh, the basis of global warming is precisely that greenhouse gases result in heat residing where it did not before from the absence of previously occurring cooling in that location.

    Reducing your notion to absurdity: There is no reason to put clothes on in the winter because heat cannot by generated from the absence of cooling.

  41. 141
    CCHolley says:

    Victor @137

    So no matter how you want to argue this, you are still left with a dramatic runup in temperature for which there is no explanation based on the current state of climate science. It really doesn’t matter whether the 1940 levels were produced by some sort of rebound due to the absence of volcanic cooling or whether those levels would have been attained had it not been for previous volcanic cooling — they still have to be explained.

    You ignored my link to “forcings:”

    No matter how you want to argue this there absolutely is an explanation for the temperatures based on the current state of climate science. You are wrong. You just choose to focus on the least important one, volcanism and ignore the greenhouse gas forcing and solar irradiance. You’ve been told this over and over again yet you continue.

    In that period, although CO2 levels were minimal over pre-industrial, they were growing and it is the initial increases that have the greatest effect due to the logarithmic nature of the phenomena.

    Once again, you are working hard on your denialism. Or is it intentional obfuscating?

  42. 142

    Victor, #137–

    “The reason you don’t understand my “joke” is because you don’t understand the absurdity of the notion that heat can be generated from the absence of cooling.”

    Victor, a suggestion: find out what cooling system your computer has and disable it.

    Do let us know how that works out for you. I’m sure you can reach Gavin via snail mail.

    (A theoretical hint: you are stumbling over “generated.” It’s the wrong conceptual framing.)

  43. 143
    Steve Case says:

    Re: Dan Miller said 5 Sep 2017 at 11:30 AM

    Jim Hansen, et al, did a great study showing that average summer temperatures that are 3 standard deviations (“3-sigma”) above the 1951-1980 baseline have increased over 100X since the baseline period.

    Dr. Hansen should re-do his study using TMax if he wants to talk about summer temperatures. Averages lose to much information. After all, the average of 49 and 51 is 50 and the average of 1 and 99 is also 50. Two very different data sets, same average. NOAA’s Climate at a Glance shows that TMax for the Contiguous U.S. May through October has a declining trend since 1930 and most of the states east of the Rockies show a declining trend since the 19th century.

  44. 144

    V 137: if you want to insist that some event is caused by the absence of something then you let yourselves in for this sort of ridicule

    BPL: Copious bleeding would follow the absence of skin. Infection would follow the absence of an immune system. Death would follow an absence of oxygen. Is it that great a leap to “an absence of sun screening makes the Earth warmer?” Are you really this out of it, or are you pretending?

  45. 145

    Steve Case, #143–

    “Dr. Hansen should re-do his study using TMax if he wants to talk about summer temperatures. Averages lose to much information.”

    So, what about Tmin? It can often be a highly relevant number for summer heat stress.

    Wouldn’t want to lose ‘to much information’! ;-)

  46. 146
    Dan H. says:

    Roscoe,

    That is not too surprising. However, your graph also shows that the variability is quite high, suggesting that other factor(s) wield greater importance.

  47. 147
    Steven Sullivan says:

    You’re an unfunny clown, Victor. Not even a scary one. Your arguments are dumb and embarrassingly ad hoc. Just go away.

  48. 148
    CCHolley says:

    Steve Case @143

    Dr. Hansen should re-do his study using TMax if he wants to talk about summer temperatures. Averages lose to much information. After all, the average of 49 and 51 is 50 and the average of 1 and 99 is also 50. Two very different data sets, same average. NOAA’s Climate at a Glance shows that TMax for the Contiguous U.S. May through October has a declining trend since 1930 and most of the states east of the Rockies show a declining trend since the 19th century.

    Averages lose too much information? Why do you say that? If the average temperature is going up, then it shows warming, which is exactly what we are interested in and predicted by AGW science. Extremes are interesting, but in themselves they tell us nothing about warming or cooling trends. For that, you need averages. And looking at only TMax as you propose ignores too much information, far more than averages–it ignores every single other day from May through October. So why do you bring up TMax? Only because you think it sheds doubt on overall warming trends, which it clearly does not. BTW, in the United States, the trend is inline with Hansen–more summer hot days AND more hot nights. It IS, in fact, WARMING.

  49. 149
    Victor says:

    My oh my oh my. It’s amazing. No one (so far) managed to get the point.

    “Reducing your notion to absurdity: There is no reason to put clothes on in the winter because heat cannot by generated from the absence of cooling.”

    The heat in this case is generated by my body, not any “absence of cooling” produced by my clothing. The clothing simply prevents heat from escaping, it doesn’t generate any heat on its own. If my body didn’t produce any heat, then no amount of clothing could warm me. Duh!

    “You are wrong. You just choose to focus on the least important one, volcanism and ignore the greenhouse gas forcing and solar irradiance.”

    No, I never ignored either issue, as should be clear from my previous comments. But in this case it’s the effects of volcanic eruptions (and their absence) that is being discussed. Your objection is a straw man, sorry.

    “Victor, a suggestion: find out what cooling system your computer has and disable it.

    Do let us know how that works out for you.”

    I really can’t believe how hard it is for people here to get it. I’m truly astonished. I expected more from this group.

    Disabling the cooling system would NOT produce any warming, because the warming is produced from the computer system itself. The cooling system functions as a control of that warming — that’s it. Disabling the cooling system could never produce any warming over and above the warming produced by the system it’s designed to cool.

    “(A theoretical hint: you are stumbling over “generated.” It’s the wrong conceptual framing.)” Well, duh! That’s my point. Absence of cooling cannot generate warming. It can only allow temperatures to rebound from a previous level.

    Let me make it easy for everyone. Consider the following perfectly standard temperature graph: https://d1o50x50snmhul.cloudfront.net/wp-content/uploads/2007/05/dn11639-2_808.jpg

    According to Wikipedia, the strongest eruption of the 20th century was Novarupta, in 1912, a category 6. So let’s check that date on our graph. And yes, we do see a dip in temperature roughly around that date — let’s suppose it’s due to aerosols from Novarupta. Immediately following that dip, we see an abrupt rise in temp peaking at roughly 1917. Could that rise be due to a rebound from Novarupta? Who knows, but it does seem possible. That’s followed by a slight dip to roughly 1918, followed by a dramatic rise in temps until roughly 1940.

    Now according to the scale at the left, the temperature at the time of the Novarupta eruption seems to have been a little less than -.4 degrees Celsius. If the volcano had a cooling effect, then any rebound from that cooling would not be able to exceed -.4 degrees, no? Anyone care to contest that?

    Even if there were no other eruptions from that date all the way to 1940 (actually there were several), it’s impossible to see how the absence of eruptions could possibly push the temperatures any higher than that. And as we know, any intervening eruptions could only produce a cooling, NOT a warming effect. Yet the record shows a 1941 peak at ca. +.1 celsius.

    So please explain to me how that steep rise in temps from after Novarupta to 1940 could be due to any lack of volcanic activity during that period.

  50. 150
    Victor says:

    Rolling up my sleeves, I decided to look into the history of volcanic eruptions during some pertinent historic eras. Beginning with the Novarupta eruption of 1912 through the warming peak of 1940 is a period of 28 years. During that time, according to the Wikipedia records (https://en.wikipedia.org/wiki/List_of_large_volcanic_eruptions_of_the_20th_century), there were 20 “large eruptions,” with a “Volcanic Explosivity Index (VEI)” ranging from 4 through 6. Adding all the VEIs during that period we get a total of 86.
    For the previous 28 years, we find a total of only 16 major eruptions, with a VEI total of 63.

    Scratching my head here. Since the volcanic activity of the previous 28 years is less intense, in both numbers and explosivity, then where does the claim of LESS volcanic activity leading up to the peak of 1940 come from? Even if less volcanic activity were somehow able to increase warming (which makes no sense as far as I’m concerned), the claim would be moot since volcanic activity during the 28 year period of extreme warming was actually more than that during the previous 28 year period.

    Curioser and curioser.

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