I get a lot of questions about the connection between heatwaves and climate change these days. Particularly about the heatwave that has affected northern Europe this summer. If you live in Japan, South Korea, California, Spain, or Canada, you may have asked the same question.
The raindrop analogy
However, the question is inaccurate and I will try to explain this through an analogy. Let’s say I go for a walk with a friend and my friend feels a few drops of water that fall on her. She asks me if it’s raining. But as long as there was only few drops of water, it could also be something else.
I tell her that we can get some more relevant information in order to get a more reliable answer. Look at the sky. Are there dark clouds on the sky above? And what does the weather forecast say?
If there are dark clouds above and the weather forecast suggests showers, it’s a safe bet to say it is the start of the rain. The rain always start with a few drops, just the way a climate change starts with a few events.
In the same way as with the observation of the first drops of of water, you could not be sure whether the heatwave is a freak event or the emerging pattern of climate change, if you don’t include other relevant information.
There is a range of different pieces of information which are relevant when it comes to the question about weather events and climate change: (a) statistical evidence, (b) physical processes connecting different aspects, and (c) attribution work.
(a) Statistical evidence
Heatwaves are becoming more widespread, last longer, and are getting more extreme (e.g. Keellings and Waylen, 2014). This trend has been predicted and reported in multiple reports, such as the IPCC SREX (2013), the Proceedings of National Academy of Sciences (e.g. Palmer, 2009), and European Academy Science Advisory Council (EASAC, 2013).
Climate change is equivalent to changing weather statistics, and one line of evidence includes the nature of record-breaking events. We can find evidence in both the number[a] and the magnitude of new record-breaking values.
Coumou et al., (2013) observed an increase in the global number of monthly heat records that corresponded to what one should expect if the temperatures increased everywhere by the same rate as the global mean. They also found that local monthly records are on average five times as frequent as they would be in a stationary climate. In other words, four out of five new heat records would not have occurred without global warming.
Other types of evidence includes how often the events (e.g hurricanes) take place, their duration and intensity. Standard statistical tests can also indicate whether a particular event fits in with the expected range of outcomes.
(b) Physical processes
Physical conditions and processes play a role both for the emerging pattern of precipitation, the evolution of weather, and their statistical characteristics. Indeed, we expect the statistics of rainfall and temperature to respond to an altered physical situation.
Earth’s climate has always changed, and there have always been physical causes for the changes. This means that the climate is sensitive to altered conditions, such as greenhouse gases.
It would be difficult to explain why increased concentrations of greenhouse gases had no effect on the global mean temperature or on the statistics of extreme weather conditions while other types of forcing clearly have an effect.
There is no shortage on explanations for why changes in the physical environment should cause more extreme events. Some of these are:
I have also reviewed the greenhouse effect and described how convection can be altered by higher concentration of greenhouse gases. This link with the hydrological cycle may explain why the rains seem to be concentrated over small area of Earth’s surface (Benestad, 2018).
Diminished area of precipitation explains both more frequent flooding and more droughts, and dry conditions exacerbate the heat, as moisture restrain temperatures during evaporation.
We also expect more extreme rainfall in some locations, as higher surface temperatures boost the evaporation and increase the turn-around rate of the hydrological cycle. There are also indications of higher cloud tops (Witze, 2016) which allow the rain drops to grow further than before.
(c) Attribution
It is possible to reproduce extreme weather episodes in computer models, such as those used for weather forecasting. We can conduct experiments to see which effects greenhouse gases have for the outcome. In other words, the models can be used to simulate the same event with and without the present levels (Schiermeier ,2018).
The World Weather Attribution (WWA) has carried out such experiments, and their efforts suggest that recent extreme events have become more likely with an increased greenhouse effect.
Individual cases and emergent behaviour of many events
The planetary system is extremely complex, with interactions between atmosphere, oceans, ice and land, and taking place over a vast range of temporal and spatial scales.
It is hard to say that one aspect is directly connected to another, when there are so many interacting parts and such rich level of complexity. Understanding the difference between individual versus collective events is key to making sense of the situation.
Nevertheless, complex systems tend to give rise to emergent behaviour (explained in Gavin’s TED-talk). And the statistical characteristics of a large number of outcomes is often predictable. In fact, statistics is remarkably predictable, and we can often attribute some probability to the causes of some event through standard statistical tests.
What is causing what?
On another level, there is also the more philosophical question of whether rain drops are caused by the rain or the rain is a result of many rain drops. Rain is a phenomenon that includes many collective events in the clouds.
The same way that extra information such as cloud observation and weather forecast give confidence in our interpretation of the first drops being the start of the rain, the statistical evidence and our understanding of the atmospheric physics provide relevant information for judging the connection between heatwaves and climate change.
A more relevant question
I think it makes sense to rephrase the usual question of whether climate change causes a particular event, since climate and weather are different aspects of the same earth system.
The bottom line is whether we now are observing the first glimpse of a new normal, or if the world will return to its old state. In other words, the question should be whether the recent heatwave is a signs of a new type of weather patterns we can expect for the future. I think the answer to this question is “yes”, based on current information and knowledge.
Footnotes
[a] If data is independent and identically distributed (iid), then the probability of a new record-breaking event diminishes with the number of measurements (
) ![P(X > [x_1, x_2, ... x_{n-1}]) = 1/n](https://www.realclimate.org/wp-content/ql-cache/quicklatex.com-63def0dac8a5a1b1f89ce7ff0f456cd9_l3.png "Rendered by QuickLaTeX.com")
. In this case, the expected number of records is 
. On the other hand, if you count many more records than 
, then that is a sign that upper tail of the statistical distribution is stretching towards higher levels. In other words, it indicates that extremes are becoming more frequent.
Update
Both the World Meteorological Organisation (WMO) and Copernicus have posted some comments and analysis of the recent heatwaves.
References
- D. Keellings, and P. Waylen, "Increased risk of heat waves in Florida: Characterizing changes in bivariate heat wave risk using extreme value analysis", Applied Geography, vol. 46, pp. 90-97, 2014. http://dx.doi.org/10.1016/j.apgeog.2013.11.008
- T.N. Palmer, "Climate extremes and the role of dynamics", Proceedings of the National Academy of Sciences, vol. 110, pp. 5281-5282, 2013. http://dx.doi.org/10.1073/pnas.1303295110
- J.A. Francis, and S.J. Vavrus, "Evidence linking Arctic amplification to extreme weather in mid‐latitudes", Geophysical Research Letters, vol. 39, 2012. http://dx.doi.org/10.1029/2012GL051000
- V. Petoukhov, S. Rahmstorf, S. Petri, and H.J. Schellnhuber, "Quasiresonant amplification of planetary waves and recent Northern Hemisphere weather extremes", Proceedings of the National Academy of Sciences, vol. 110, pp. 5336-5341, 2013. http://dx.doi.org/10.1073/pnas.1222000110
- M.E. Mann, S. Rahmstorf, K. Kornhuber, B.A. Steinman, S.K. Miller, and D. Coumou, "Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events", Scientific Reports, vol. 7, 2017. http://dx.doi.org/10.1038/srep45242
- R.E. Benestad, "Implications of a decrease in the precipitation area for the past and the future", Environmental Research Letters, vol. 13, pp. 044022, 2018. http://dx.doi.org/10.1088/1748-9326/aab375
- A. Witze, "Clouds get high on climate change", Nature, 2016. http://dx.doi.org/10.1038/nature.2016.20230
- Q. Schiermeier, "Droughts, heatwaves and floods: How to tell when climate change is to blame", Nature, vol. 560, pp. 20-22, 2018. http://dx.doi.org/10.1038/d41586-018-05849-9
Further to my blather @160 on the significance (or otherwise) of feedbacks that fall outside the CIMP5 modelling and thus IPCC AR5 projections for AGW, I thought to examine the impact of IPCC Arctic Sea Ice projections which are famously under-projecting the levels of sea ice loss. To this can be added projections of Northern Hemisphere snowcover. Is this under-projection and resulting under-estimation of changed Arctic albedo significant for the IPCC AR5 AGW projections?
There are some who seem to be arguing that the albedo feedback is something we have to get right. If we underestimate it, our AGW projections will be badly wrong. Consider this Peter Wadhams comment from 2012 concerning an ice-free summer Arctic:-
Such comment could be considered as poor reporting on an obscure climate blog. It is plainly wrong to suggest that reduced albedo from an ice/snow-free summer Arctic will create a greater global climate forcing than AGW-to-date. Yet in his book of 2016, Wadhams (2016) ‘A Farewell To Ice’ we read that the Arctic albedo effect is apparently half the force of positive AGW forcing – full stop.
Now that sounds very significant and given GCMs famously underestimate Arctic sea ice loss (and less famously Spring snow cover loss) it could be construded as a major underestimation of AGW by IPCC AR5.
And elsewhere we read a 2018 blog:-
And unlike Wadhams, Francis is truly on the more conservative side of Arctic Sea Ice loss predictions as this 2016 Independent article demonstrates:-
This will all be music to the we-told-you-so doom-sayers but hold on to you hats. All is not what it seems. The above accounts greatly misrepresent the Arctic albedo feedbacks and the level of underestimation of any feedbacks within CIMP5 models.
To be continued….
43 jgnfld says:
“NEITHER study has ANY relation at all to a double blind randomized clinical trial which would show whether smoking causes cancer.”
Didn’t take me long to find this one, that does, dating from 1982:
“Double-blind study on the effect of cigarette smoking on the chromosomes of human peripheral blood lymphocytes in vivo” –https://www.sciencedirect.com/science/article/pii/0027510782902330
I feel sure there are many others of a similar nature. Perhaps you’ve never heard of them. In any case, neither you nor I has the time to wade through all the various studies, but that does not change the fact that double-blind research is preferred due to the well-known tendency of researchers to come up with the results they want to see. And as I see it, we have good reason to suspect many instances of confirmation bias in the research supporting the climate change meme. Unfortunately it’s difficult to imagine how double blind methods could be applied in this field. But that is no reason to set aside skepticism when so many studies, using different methods to promote very different explanations of the data, claim to support the so-called “consensus” view.
https://www.nytimes.com/interactive/2018/07/11/climate/summer-nights-warming-faster-than-days-dangerous.html
https://static01.nyt.com/newsgraphics/2018/07/10/heat-records/9d201d932ecb9ae8a63b9d3262c2444d14e9a43a/charts_ext-Artboard-945.
#42 Dan Miller,
Wrong. This is another example of saying that climate change is caused by climate change.
What those statistics tell us is that the climate has changed. They tell us nothing, without the underlying physics and modeling, about the cause.
This is such a basic concept, and it really is puzzling why people can’t get it straight– I can’t imagine what kind of science education would lead to this level of misunderstanding. One expects it from the Denialists, but the science side needs to do better.
Victor@41 I asked for references to peer-reviewed, scientific literature that showed bias in the peer-reviewed, scientific literature.
You replied with your opinions, which aren’t peer-reviewed, scientific literature.
Try again.
Rather than “the new normal”, perhaps “the end of normal” is more accurate.
#43 After doing some more digging into the history of the smoking research I realize that I was wrong and apologize. Because of the importance accorded double-blind trials in the medical literature I assumed they were used in the research on tobacco and cancer. But you’re right — clinical trials on smoking would not have been ethical so they had no choice but to base their findings on observational research. So yes, one can draw a meaningful parallel between research on the effects of smoking and research on climate change, as both rely so heavily on observational studies.
That’s just an analogy however, with no bearing on the validity of the climate research. Nor does it invalidate the principal point I’ve been making for some time: in the absence of double-blind research, there is always a risk that any result could be tainted by investigator bias.
Rasmus
Why not?
Victor: MY point is that double-blind studies are considered important as a means of eliminating the sort of unconscious bias that can too easily lead to faulty conclusions.
AB: I’m a little late to the conversation, but I’m pretty sure that climate data is double-blind by definition. Either that or the Gaia hypothesis is an understatement and the Earth is a sentient being whose temperature is rising via the placebo effect because humans are discussing global warming.
Sure, models and conclusions vary because of human nature, but historical data is what it is.
#54 Zebra: I agree that Hansen’s graphs do not prove that the changes are caused by manmade emissions of GHG. The graphs only prove that the climate has changed (and, as Hansen pointed out, the global version of the graph is proof, by definition, that the climate has changed). But as the OP points out, like the rain drop example, you need to take other information into account. We know how much GHG we have put in the atmosphere and we know how much that should warm the atmosphere. In addition, we have explored and eliminated “natural” causes such as increased output from the sun, volcanos, etc.
So we know by (many) other means that the warming is caused primarily by manmade emissions of GHG and therefore the attribution that a 3-sigma event is almost certainly (98%+) caused by manmade climate change stands.
AS THE STARTING OF CONVECTION STILL HAS OBSCURE POINTS, THE RAIN EXAMPLE.. YOU PERHAPS WOULD CHOSE SOMETHING BETTER.. BUT COMPLIMENTS FOR THE PEDAGOGY
YES the heatwaves are caused by climate change
WORST, THE SYSTEM EARTH ENTERED IN A THERMAL POSITIVE FEEDBACK. AND SO, REMEMBER NYQUIST IN THE ELEMENT, IT OSCILLATES WITH A CONSTANT RISING OF THERMAL OSCILLATIONS. TO AN EXTINCTION OF THE HUMANITY.
TILL THEN WE WILL OSCILLATE FROM TOO HOT, FOLLOWED BY TOO COLD TOWARD A MORE HOT AND COLD
SINCE KYOTO’98 NOTHING HAS BEEN DONE **TO LOWER** the rates of greenhouse gases. Kyoto asked storage wells, burial. NOTHING BUT A DOUBLEMENT OF THOSE RATES HAS BEEN DONE.IF YOU REMEBER, BETWEEN AR4 AND AR5 THE RISE WAS OF 20%. IN 4 YEARS, DURING 20 YEARS = 200% OF RISE. HAVE A NICE DIE FELLOWS..
ONLY BLABLA IN NICE “CONFERENCES” AND COCTAILS.
I’ll say it in french because is too Horrible : FAMILLE DE SCIENTIFIQUES,
NOUS NOUS DIRIGEONS À GRAND PAS VERS UNE EXTINCTION DE L’HUMANITÉ
S’IL VOUS PLAÎT, NE CACHEZ PLUS VOTRE LÂCHETÉ DERRIÈRE VOTRE PETIT DOIGT. À MOINS QUE VOUS VOUS SOYEZ DONNÉS BATTUS. REPRENEZ-VOUS. SINON, NOS ENFANTS VONT SOUFFRIR MAIS NOS PETITS ENFANTS VONT **MOURIR** DE CELA.
AS THE STARTING OF CONVECTION STILL HAS OBSCURE POINTS, THE RAIN EXAMPLE.. YOU COULD CHOSE SOMETHING BETTER.. BUT COMPLIMENTS FOR THE PEDAGOGY
YES the heatwaves are caused by climate change
WORST, THE SYSTEM EARTH ENTERED IN A THERMAL POSITIVE FEEDBACK. AND SO, REMEMBER NYQUIST IN THE ELEMENTARY SCHOOL, IT OSCILLATES WITH A CONSTANT RISING OF THERMAL OSCILLATIONS. TOWARD TO AN EXTINCTION OF THE HUMANITY. AS SIMPLE AS THAT
TILL THEN WE WILL OSCILLATE FROM TOO HOT, TO TOO COLD .. TOWARD A MORE HOT AND MORE COLD AT THE NEXT OSCILLATION
SINCE KYOTO’98 NOTHING HAS BEEN DONE **TO LOWER** the rates of greenhouse gases. Kyoto asked storage wells, burial. THOSE RATES DOUBLED !! NOTHING HAS BEEN DONE. IF YOU REMEMBER, BETWEEN AR4 AND AR5 THE RISE WAS OF 20%, IN 4 YEARS.. 200% OF RISE IN 20 YEARS.
I ASK A NOBEL PRICE FOR JEAN-JOUSEL. WHO DISCOVERED THE PHENOMENON. AND FOR 20 AND MORE YEARS TODAY, NO ONE DID ANYTHING AGAINS IT.
SO, AFTER PLETHORA OF BLABLAS IN NICE “CONFERENCES” AND COCKTAILS AND PAC’s and AGU’s, JpGU’s, EGU’s, etc. etc. :
HAVE A NICE DIE FELLOWS..
MORE SERIOUSLY, I THINK THERE IS AN **EXTINCTION OF HUMANITY** in front of us
IF WE DO NOTHING, OUR CHILDREN WILL SUFFER, BUT OUR GRANDCHILDREN WILL **DIE** THERE.
51 MA Rodger;
1) You’re in the wrong thread. Please some accuracy, please! :-)
2) Waddhams was but one minor ref used as example. Jem’s paper and discussion topics do not rely upon the efficacy of Waddhams blog claims, youtube vids nor his published papers. Hurry before you run out of cherries.
3) Jem lists a number of refs. and discusses a number of issues that could be read holistically and in context. Replace Waddhams with Francis refs if it makes you happier. It doesn’t change the points he is making.
4) Add in a Gavin Ref that says all Models are wrong as well if you like. You may as well given where your heading and your narrow cast motivations.
5) The ASI loss driven Albedo Feedback is not the only ASI Positive Feedback mechanism worth including in these complex interrelated issues.
6) Are IPCC Arctic Sea Ice projections famously under-projecting the levels of sea ice loss or not? Yes.
7) Do the CIMP5 modelling and thus IPCC AR5 projections for AGW include all current best practice Positive feedbacks into the future and are they still in line with the present 2018 knowledge base or not? No.
8) Does it significantly matter to the topics of discussion and conclusions / warnings of inaction to rapidly drive down GHG emissions by humans and natural sinks in the Deep Adaption paper by Jem? No.
9) Is this true and reasonably accurate? “”The albedo effect due to vanishing sea ice is already responsible for about 25 percent of global warming, according to Jennifer Francis, a research professor at Rutgers University’s School of Environment and Biological Sciences.”” Yes.
10) That’s great, now what? Remove Waddhams from the face of the earth as if he never said or wrote a single thing in this life – now what’s your point exactly? :-)
11) Is this true and reasonably accurate? “These three tropical regions released 2.5 gigatons more carbon into the atmosphere than they did in 2011″ and ” In 2015 and 2016, OCO-2 recorded atmospheric carbon dioxide increases that were 50 percent larger than the average increase seen in recent years preceding these observations.” and “That increase was about 3 parts per million of carbon dioxide per year — or 6.3 gigatons of carbon.” – Yes.
12) Please show me where these land based vegetative mass emissions of CO2 are included in prior CIMP5 modelling and thus IPCC AR5 projections for AGW circa by 2015-2016.
13) Please show me in the AR5 where such feedbacks to AGW are included out to 2030 and then to 2050 which also are following accurate projections the net GHG real world emissions scenario data of 2010 to 2020, then 2020-2030.
Now was there a useful definitive point you wanted to make? Don’t forget to shift back to the right thread and post #s.
Thanks, there’s a good sport. Maybe go write your own Future Scenarios Paper that Analyses Deep Adaption issues inclusive of the required Mitigation needed 2020-2040 to avoid destabilizing the Climate system and forestalling Societal Collapse. It’s easy isn’t it?
Must be time for YOU to sell a positive realistic story to the public and policy makers MA Rodger that’s grounded in credible referenced Climate Science Data Modelling. Yes?
The greenhouse effect on Earth is as old as the planet itself and is one of the causes of life in it. If the Earth were not able to retain certain gases around it, life as we know it would be impossible. Moreover, the very existence of the Earth’s atmosphere is linked to the greenhouse effect. So talking about the greenhouse effect or global warming is as old a subject as the planet we inhabit. The fundamental question is whether only the action of men will be able to modify the temperature in such a high amount that the hecatomb that some predict or if there are other factors outside the intervention of man will be caused. https://planckito.blogspot.com/2018/08/el-efecto-invernadero-y-el-cambio.html
vic..
—
Didn’t take me long to find this one, that does, dating from 1982:
“Double-blind study on the effect of cigarette smoking on the chromosomes of human peripheral blood lymphocytes in vivo” –https://www.sciencedirect.com/science/article/pii/0027510782902330
—
Didn’t take you too long to show your ignorance yet again, you mean.
There is simply no “double-blind, randomized clinical trial” to research “the relation between smoking and cancer” (all your words) when the subjects are assigned to treatment versus control groups on the basis of history (smokers versus nonsmokers) rather than randomly. I assume “double blind” here means they basically farmed out the analyses which is a much different thing than a “double blind randomized clinical trial”.
Again, you are just googling for two terms being contiguous without a trace of understanding what you are googling about. Kinda’ like your googling of climate issues. It is simply a way to display ignorance, not understanding. Kinda’ like doing regressions and correlations “by eye”.
Give it up. You are simply wrong unless you can find something in the Mengele papers.
@59
There have been studies where statisticians have been given climate data to analyze without being informed that the data were from climate series. Oddly enough, even when unaware of the hypotheses the statistcians routinely found that there was a significant effect in the data.
I’m on my boat at the moment and don’t have time/interest in finding the cite. Maybe someone knows it off the top of their head.
This would correspond to vic’s “double blind, randomized clinical trial” notion.
57 Victor; hey kudos! well done.
Victor is getting pretty desperate.
Re: Victor, above ad nauseum:
A necessary condition to double blinding is a sentient experimental unit. I know that we call her Mother Earth, but nobody seriously thinks that her response is contingent on her perception of the treatments we apply. Do they?
Simply put, double blinding is completely inapplicable to climate issues. Victor was either obfuscating (knavery) or applying stupid to the problem (foolishness).
He was right about one thing. Bias is possible. Just look at this example we’ve all seen: https://tamino.wordpress.com/2018/08/08/usa-temperature-can-i-sucker-you/. Statistical methods must be applied properly, but the fact that they can be misused does not justify disregarding them.
Start with a selection of identical Planet Earths. Instrument them all identically. Don’t let the scientists see which ones have coal-fired industrial eras, then assess whether there’s any change to any of those planets as CO2 in the atmosphere increases.
Yep, that’s workable.
Of course you want identical to mean identical — one Victor on each planet.
Hm.
#60 Dan Miller,
OK, good– think about the raindrop analogy. The question is whether we are talking about those initial few drops or a downpour.
Once you have sufficient data over a sufficient period (e.g. 30 years), it doesn’t even make sense to talk about “attribution” for a single event. Because, in fact, it is the frequency of those events that defines the new climate. Which is why I say you are really making a circular statement. If we’re in a downpour, we don’t distinguish individual drops, and ask what “causes” each one, in order to decide that it is raining.
So, we need to focus on the “few drops” situation, where there isn’t sufficient data to define a “new normal” climate for that variable. In that case, we have only two things to consider:
1. The physics.
The physics tells us that increasing CO2 causes an increase in the energy in the climate system. (This is validated directly by measurements like GMST and OHC, for example.) Then, we can infer, qualitatively, that a change in things like heatwaves will occur, and in what direction.
2. The models.
The models can quantify, to some degree, those changes in specific events like heatwaves. So we can have statements about a specific event: “Heatwaves like that at this location would occur twice as often with increased CO2 than without.”
But– this is all we can say, and all we should say. It is sufficient to say that an extreme event is consistent with theoretical predictions resulting from anthropogenic increase in climate system energy. If you are trying to convince people of the validity of the Theory as a whole, give them a list of all the different phenomena that meet that criterion, instead of overstating about individual events.
“Once you have sufficient data over a sufficient period (e.g. 30 years), it doesn’t even make sense to talk about “attribution” for a single event. Because, in fact, it is the frequency of those events that defines the new climate.”
This is not technically correct. You can say that a single event was made xyz times more likely to occur due to climate change (or strictly speaking agw global warming).
And climate change can potentially alter the frequency, intensity and duration of an event. This combination defines the new climate, although I think you will be proven right to highlight the importance of frequency.
#71 Zebra: The temperature “bell curves” have shifted to the right… this is global warming (by definition). Now the question is what caused the shift? We have a plethora of information from models, observations, and physics that tell us the likely explanation is manmade GHG emissions. Among the observations, we know that high levels of the atmosphere have cooled while lower levels have warmed (so it’s not the Sun, and is consistent with manmade emissions), and we can measure that the extra CO2 in the atmosphere comes from underground (by carbon dating). We can also see that O2 levels have dropped consistent with fossil fuel combustion. There are many, many other data points that all point to manmade emissions being the cause of the shift… and no credible alternative theories. If you have another theory why the curves shifted right, please let us know.
Once the cause of the shift is established (and it has been established), then we can say that a certain 3-sigma event was 98%+ sure caused by manmade climate change. While you can argue that this is not scientifically useful, it certainly is useful in explaining the impacts of climate change to the public and policymakers.
73 Dan Miller says:
“Among the observations, we know that high levels of the atmosphere have cooled while lower levels have warmed (so it’s not the Sun, and is consistent with manmade emissions)”
V: Not really. See
https://www.climate.gov/sites/default/files/Stratospherictemp_1958-2012_radiosondes.png
Stratospheric temperature has leveled off since the late 1990’s.
“and we can measure that the extra CO2 in the atmosphere comes from underground (by carbon dating).”
Come again? That’s the first I’ve heard of that one. Can you supply a reference? In any case, it stands to reason that the steep rise in CO2 since mid-century has been produced by fossil fuel emissions, hardly anyone would contest that point.
“There are many, many other data points that all point to manmade emissions being the cause of the shift… and no credible alternative theories. If you have another theory why the curves shifted right, please let us know.”
Alternative theories are not necessary, since natural variation is the null case.
#73 Dan Miller,
Your first paragraph is a longer version of exactly what I said:
“The physics tells us that increasing CO2 causes an increase in the energy in the climate system. (This is validated directly by measurements like GMST and OHC, for example.)”
So your last sentence in that paragraph doesn’t make sense.
In the second paragraph you say: “you can argue that this is not scientifically useful”.
No, I’m saying that the words/language being used are neither scientifically correct nor helpful in communicating to the public.
“change in climate” does not equal “increasing CO2”
“the predictions of a model” does not equal “data”
I will try to organize the concepts for you again but please try to read carefully.
1. “climate change” means we see a change in some climate variable between statistically significant time periods (again, something like 30 years). It’s data, measurements, not a “cause”.
Increasing CO2 is a cause, it causes increasing energy, which causes changes in climate variables.
2. Models are based on the physics and make predictions, and we trust them because we have confidence in the physics. Then, we accumulate data– in the near term, we say “these results are consistent with the model”. That means we don’t see contradictory evidence. In the long term, if the predictions are verified, we say the model and the underlying physics have been validated.
3. If you have sufficient years worth of data that has validated the model and the physics, then what is the point of telling the public that some individual datum is “caused” by increasing CO2? That appears to be what you are saying, and it just doesn’t make sense to me.
Can you can explain your reasoning (using language consistently as I have illustrated)?
Dan Miller @73,
That is not entirely accurate. The physics state that the average energy will increase. The physics suggests and the data shows that this is not evenly distributed as increases are most evident on the cold side; high latitude, winter, and nighttime. The entire bell curve has not shifted. Rather, the midpoint has shifted upwards, and the width of the curve has contracted, such that the extremes are closer to the midpoint. The low end has increased much more than the midpoint, and the high end has actually decreased slightly. This is borne out in the data.
@74
vic: “natural” variation is not the null hypothesis in any experimental design (though of course we cannot do experiments, so experimental design concepts are not really correct in any case). If we actually WERE doing experiments, the null hypothesis would be RANDOM variation. This is a different thing entirely.
Victor @74
What exactly is this *natural variation* spoken of? What makes this *natural variation* any less of a theory than AGW and what exactly makes *natural variation* the null case? You are just a tiresome troll.
Dan H., #76–
No. That’s only true in US data, and over a cherry-picked interval at that. I’ve showed the evidence for that several times now. While it is true that highs are increasing more slowly in the US data than lows, it isn’t true that they are declining. Since the start of the modern warming era (ca. 1970-75), when the warming signal is generally agreed to have emerged from the noise of variability, highs show a robust rising trend. While it is true that they are only now closing in on the highs of the 1930 IN US DATA, 1) the 30s are an extreme anomaly in the data, and 2) there is no reason to expect that the current (ie., post ’60s) warming trend in high temps will fail to continue. And if it does, those 30s high temp records that still stand will start to fall rapidly.
Victor @73 The reason the stratospheric temperatures have leveled off since the 1990s is to do with the depletion and recovery of the ozone hole as in the research below. This leveling off in the stratosphere temperature is a temporary thing, like the so called pause after 1998.
https://core.ac.uk/download/pdf/43095024.pdf
Did it not occur to you to do a simple google search asking why the temperatures had stalled?
Kevin @79,
Actually, cherry-picking would be using only that data since the start of the warming era (ca. 1970-75), rather than the entirety of the temperature record. The curve has not changed in just the U.S. The Arctic has shown the same trend, but to a larger degree.
http://ocean.dmi.dk/arctic/meant80n.uk.php
#75 Zebra and others…
Here is the link to Hansen’s latest temperature report:
http://www.columbia.edu/~mhs119/Temperature/Emails/July2018.pdf
Note the curves he shows are DATA, not model results. The warming he describes already happened (and is relative to a 1951-1980 baseline).
As for what caused the warming, this is a site by and for climate scientists, so I do not need to demonstrate to the folks here that the warming is primarily caused by manmade burning of fossil fuels!! Go look at IPCC reports if you are in doubt.
In the Hansen report, check out the Summer graph for Mediterranean and Middle East (Figure 4). The 3-sigma-plus summers that (just 50 years ago) used to happen every 500 years or so now happen about every 3 years! Now that’s climate change!
80 nigelj says:
“Victor @73 The reason the stratospheric temperatures have leveled off since the 1990s is to do with the depletion and recovery of the ozone hole . . .”
Yes. Of course. Now why didn’t I think of that? There is AlWAYS a reason, isn’t there? For every case in which the evidence fails to support the favored theory, a reason has been found. In some cases, a great many different reasons. That’s how “the science” of climate change works, no? That’s what makes it impervious to falsification. And, by the way: how do you know this? How could anyone know it? It’s nothing more than an assumption that might (or might not) be the cause of the observed effects, no different in principle from the attempts by the followers of the Ptolemaic model of planetary orbits to “explain” them on the basis of the so-called “epicycles.”
In the context of Occam’s Razor, your “explanation” can be categorized as a typical “saving hypothesis,” the introduction of a complicating factor that “saves” the original theory by explaining away any evidence that would appear to contradict it. Once we go down that road, then it’s impossible to meaningfully evaluate any theory:
“Though the principle may seem rather trivial, it is essential for model building because of what is known as the “underdetermination of theories by data”. For a given set of observations or data, there is always an infinite number of possible models explaining those same data.” (http://pespmc1.vub.ac.be/OCCAMRAZ.html)
In any case, and regardless of what you might think of Occam’s Razor or how you might prefer to interpret it, the fact remains that one cannot point to a given dataset as “evidence” if the presumed evidence isn’t actually there. Whatever the reason might be for its absence, if the evidence isn’t there then there is in fact NO evidence (duh!). So citing the purported cooling of the stratosphere as evidence consistent with AGW orthodoxy, when the evidence isn’t actually there strikes me as a very odd way of doing science.
77 jgnfld says:
@74
“vic: “natural” variation is not the null hypothesis in any experimental design (though of course we cannot do experiments, so experimental design concepts are not really correct in any case). If we actually WERE doing experiments, the null hypothesis would be RANDOM variation. This is a different thing entirely.”
78 CCHolley says:
“Victor @74
Alternative theories are not necessary, since natural variation is the null case.”
CC: What exactly is this *natural variation* spoken of? What makes this *natural variation* any less of a theory than AGW and what exactly makes *natural variation* the null case?
V: Natural variation is the variation in climate caused by natural conditions as opposed to variation caused by human activities (such as the burning of fossil fuels). Until the industrial revolution, all the many climate changes, including various rises and falls in temperature and sea level, could uncontroversially be attributed to natural variation. Since nv could be considered the obvious default explanation for all manner of climate change, there was never any need to formulate it as a theory.
The notion that since the industrial revolution the situation has changed drastically, and that changes in global temperature are now controlled primarily by human activities (AGW) is a hypothesis that challenges the notion that climate is controlled largely by natural variation. Thus natural variation, as the generally accepted default, can be regarded as “null case” (or null hypothesis) and AGW the “alternative hypothesis” that challenges it.
In certain types of experiment a random result is considered to be the null case but this by no means applies to all scientific research. For example, prior to the investigations conducted by Copernicus, Kepler, Newton, etc., the notion of an Earth-centered universe was widely accepted, making that the null hypothesis. Since this was the generally accepted view, the burden of proof fell on advocates of the alternative hypothesis, i.e., that the Earth was not the center of the universe and that it, along with all the other planets, revolved around the sun. This was, of course, ultimately demonstrated, as we know, and as a result the null hypothesis was falsified.
Similarly, when Einstein was developing his general theory of relativity, Newton’s laws of gravity constituted the null hypothesis, which Einstein was able to falsify, as we know.
The notion that any consideration of “randomness” played a role in either situation seems ludicrous to say the least.
Victor @83, the ozone hole theory in relation to the stratosphere is much more than an “assumption”. The research paper is compelling, and is based on simple mainstream physics and chemistry. You have not been able to refute it on the science, and all your blather about occams razor and convenient explanations is unable to hide this from me, and I dare say anyone else.
Occams razor doesn’t change the laws of physics and make the research paper wrong.
If the greenhouse effect is real (and it is), you would expect there to be logical explanations for pauses within longer term trends, and other issues, and there are plenty of sensible explanations.
Occams razor says the simplest explanation is usually the right one. The simplest explanation for the current warming period is greenhouse gases, because only this can explain all the observed phenomena, so how the atmosphere is warming, nights warming faster than days, etcetera, and including any temporary pauses. None of the climate denialist alternative theories (solar forcing, cosmic rays etc) even come close to explaining everything, and they thus require immense levels of convoluted complexity to try to make them viable, and so they collapse in a heap of rubble.
@83
Barely merits comment it’s so stupid: Let’s just say that Mt. Pinatubo and subsequent nonwarming didn’t “disprove” global warming. Nor did it provide a “saving hypothesis”. It simply showed climate is multicausal.
I will say again that lecturing professionals about their profession is pretty stupid as well be the professionals all-star wrestlers or physicists. Insiders can tell other insiders pretty fast, you know. And you’re no insider.
V: There is AlWAYS a reason, isn’t there? For every case in which the evidence fails to support the favored theory, a reason has been found. In some cases, a great many different reasons. That’s how “the science” of climate change works, no? That’s what makes it impervious to falsification.
BPL: No, you still have the idea that a theory has to account for everything or it fails. Not true. There can be multiple causes for things. Smoking can kill people, but that doesn’t mean other things can’t kill people. If someone is found to have died from a heart attack, it doesn’t mean smoking is cleared of causing lung cancer.
Oh my, Victor once again doesn’t know something from the 101 level college classes in Biology and Physics, and asks help searching out an explanation. Well, there are no doubt other gradeschool-level students writing papers who could use the help.
ESRL Global Monitoring Division – Global Greenhouse Gas Reference …
https://www.esrl.noaa.gov/gmd/ccgg/isotopes/c14tracer.html
For Victor:
.wiley.com/doi/full/10.1002/2016GL068511
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL068511
Victor et al,
Victor, to have a useful discussion, it is necessary that everyone speak the same language. Unless you and your interlocutors are using the same definitions, it is all a waste of bandwidth.
Victor, “Hypothesis” has a meaning, “Theory” has a meaning. “Null” has a meaning. If you just make up your own definitions, and the others in the discussion allow it, again– waste of bandwidth.
Hypothesis: “If I change x, holding all other variables constant, then y will change.”
Null Hypothesis: As a formality, for various reasons, we say “If I change x, holding all other variables constant, then y will not change.” Has nothing to do with Theories
Theories, like Newton and Einstein: Complex expositions on phenomena, which usually consist of three parts:
1. Mathematical models.
2. Physical descriptions or cause-and-effect narratives, perhaps some metaphysical differences.
3. The body of techniques and equipment employed and empirical evidence produced.
Ockham’s Razor: Applies to #2 only– nothing to do with hypotheses. It says that, given two Theories, we continue working with the Theory that has the fewest entities that themselves require further exploration, as long as both Theories predict results equally well.
That’s the way people discussing science interpret those terms. If you want to accept those definitions, and argue using them, fine. If you want to give your own definitions, then you have to state them independently of the current discussion, so they are not circular… I guess that’s fine too, but kind of silly.
From Scientific American, Feb. 2018, “Wait—the Ozone Layer Is Still Declining?”:
“Ball’s team found the ozone in the lower stratosphere has slowly, continuously dropped since 1998. “We see a small but persistent and continuous decline—not as fast as before 1998 but a continued [trend] down,” he says. “This is surprising, because we would have expected to also see this [region’s ozone] stop decreasing.” The finding is important because the lower stratosphere contains the largest fraction of the ozone layer.
Overall, Ball says, global ozone has declined 5 percent between 1970 and 1998—prior to the protocol’s effect. Since then “our analysis suggests that the [ozone in the] stratosphere has declined…another 0.5 percent, most of which has occurred in the lower stratosphere,” he says. “It doesn’t sound like much, and it’s slower, but it’s contradictory to the trajectory expected in models.”” https://www.scientificamerican.com/article/wait-the-ozone-layer-is-still-declining1/
So yes, the attempt to explain away the “hiatus” in stratospheric cooling by invoking the effects of ozone recovery IS based on an assumption. Which has been proven wrong. There is a difference between an explanation based on one’s notion of what “the physics” ought to be telling us and what the data actually IS telling us. I see this discrepancy over and over again when examining the actual evidence as opposed to the many assumptions based on “the physics”. We must never forget that there is no such thing as “the physics” per se, but only various interpretations of physical principles, offered in many cases by individuals with an agenda.
Re #85-87
While it’s true that any long-term trend might temporarily be obscured by certain transient natural events, it is also true that explanations of this sort cannot constitute evidence for the actual existence of the long-term trend. So when we see NO evidence whatsoever of a correlation between CO2 emissions and global temperatures over an 80 year period, the possibility that some hypothetical “long-term” correlation might have been obscured by this or that transient event, while certainly worth considering, can hardly count as evidence for its existence.
Victor @84
Utter nonsense (as usual). If we are to understand climate and what causes it to change, then we need to understand what *natural variation* is as well as what actually drives climate. Any of these explanations of climate drivers could be said to be theoretical. To say there is no need to formulate theories for *natural variation* is ludicrous. All physical phenomena require theories to explain them. So I will ask it once again in another way, which of the theoretical processes that drive climate are the default explanation and why? *Natural* is NOT a physical process and in itself, is not an explanation. Also, while you are at it, please explain how the *natural* physical processes of your null hypothesis can account for the warming. i.e. what is the physics and evidence?
Science is about explanations. A theory is a comprehensive, coherent and consistent explanation about a phenomenon often based on several lines of evidence (consilience) that may be accepted eventually by the global community of scientists (consensus).
It seems to me rejection of AGW is due to a misunderstanding science and how it works. This can occur at several levels, from simple ignorance and incredulity to scientists hidebound by familiarity with bench-top experiments.
Some deniers pontificate about the scientific method, as though there is some definition inscribed on an altar somewhere, whereas the scientific method is whatever the scientific community — as represented by the Royal Society, National Academy of Sciences, American Association for the Advancement of Science, American Physical Society, American Chemical Society etc etc etc — accepts is producing valid science.
When asked what other explanation there might be for global warming if it’s not more greenhouse gases, some deniers say there is no proof it’s CO2 (for example) it could be something else. If you say other causes have been investigated and it’s not they say it could be something unknown. Well it could be, but that’s not science.
If you are dealing with someone who doesn’t believe science offers us our best view of reality, believes (s)he knows more science than the global community of scientists or there is some vast conspiracy within it, then there is no answer to your problem.
If, in the end, democracy does not allow us to deal with global warming in a rational and civilised way, then no doubt we’ll try something else.
V: There is AlWAYS a reason, isn’t there?
BPL: No, you still have the idea that a theory has to account for everything or it fails. Not true.
AB: And theories are always evolving. Now, when there isn’t a reason, when there isn’t an explanation, then the theory has a hole that needs to be filled. If said filling proves impossible (such as when Einstein hit Newton over the head with an apple) then the theory does not become bunk. Instead, the theory has reached its level of accuracy and as long as that level is good enough the theory is still useful. We still use Newton. It’s not like it matters that the apple’s time went ever so slightly slower than Newton’s during its fall.
Hey Vic! When playing darts and you get a double-bull, do you whine that the dart is .02964319mm from the exact center?
Victor @91, no the assumption would only be wrong if the ozone levels were not behaving as predicted in a substantial way. Levels are behaving mostly as predicted, with only some small decline still occurring. So the explanation in the article I posted for stalling temperatures in the stratosphere still holds true.
90 Zebra you are both blowing smoke and nit picking. There are many different definitions of a hypothesis. The formal one you offer is very much your own. I’ve never seen the term defined so narrowly, so YOU are the one offering “your own definitions,” not me. Here’s a more general definition of the term that’s consistent with just about every other definition I’ve come across: “In science, a hypothesis is an idea or explanation that you then test through study and experimentation.” (https://www.vocabulary.com/dictionary/hypothesis) Here’s another: “A supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.” https://en.oxforddictionaries.com/definition/hypothesis
As for the “null hypothesis,” it too need not be defined in strictly formal terms. For example:
“. . . the “null hypothesis”, is the reference or baseline hypothesis. If the null hypothesis is supported, nothing unusual is going on; the factor under investigation has no explanatory power; the drug being tested has no effect; the advertising campaign doesn’t work. . .
The other side of the coin is the alternative hypothesis: the interesting and challenging contender, the hypothesis that may lead to new discoveries, decisions and advances. The drug that’s been tested does work; the advertising campaign is a smash hit.” https://theconversation.com/explainer-what-is-a-null-hypothesis-10757
Note that it is the drug that’s being tested, NOT the null hypothesis, which is the baseline.
And here’s a simple example from the same source:
“Null Hypothesis: eating apples does not improve sleep quality
Alternative Hypothesis: eating apples does improve sleep quality”
In the present context, we can modify the above as follows:
Null Hypothesis: global warming is the product of natural climatic variations of the sort that have been in play throughout the entirety of Earth’s history.
Alternative Hypothesis: global warming over the last 120 years or so is largely the product of CO2 emissions due to the burning of fossil fuels.
Or, if you prefer:
Null Hypothesis: CO2 emissions do not affect global warming to any significant extent.
Alternative Hypothesis: CO2 emissions have a significant affect on global warming.
NB: If CO2 emissions do not affect global warming, then the only alternative is natural variation, so there is no reason to deny that natural variation is equivalent to the null hypothesis as set forth above.
Also your attempt to question the parallels I’ve offered by distinguishing between a hypothesis and a theory is beside the point. The Ptolemaic system is hardly a theory — it’s a hypothetical attempt to explain the planetary orbits in terms of epicycles and was, for many years, the equivalent of a null hypothesis, as it was generally accepted as the default explanation. The contributions of Copernicus, Kepler and Newton refuted the null hypothesis of Ptolemy by offering an alternative hypothesis with far greater explanatory power, as PART of a much broader theory.
93 CCHolley once again jumps to indefensible conclusions: “To say there is no need to formulate theories for *natural variation* is ludicrous. All physical phenomena require theories to explain them.”
So, if someone were to contend that flying saucers, or poltergeists or ghosts were real, then, according to your way of seeing things, it would be possible to contend that such entities must in fact exist, as no one has yet been able to come up with a completely convincing alternative explanation for things like UFOs, alien abductions, unusual domestic noises, spectral sightings, etc.
To put it another way, if I’ve been appointed to peer review a scientific paper offering a particular hypothesis which I cannot accept, is it incumbent on ME to develop a superior alternate hypothesis before I can justify a recommendation to reject that paper? If you reply in the affirmative then you know very little about how the peer review process works.
Dennis Hiorne: “Science is about explanations.”
Not quite. Science is about understanding. The explanations come as a by-product of that understanding. And for it to really be science, every explanation has to lead to new questions. Science satisfies, but does not satiate curiosity.
In contrast, anti-science is about Just-So Stories that explain without increasing understanding. The goal is to satiate curiosity so one can go back to being a passive, ignorant food tube.
Victor: “For example, prior to the investigations conducted by Copernicus, Kepler, Newton, etc., the notion of an Earth-centered universe was widely accepted, making that the null hypothesis.”
And Jesus fricking wept! Dude. Please. Just stop. You’re embarrassing not only yourself, but our entire species!
The null hypothesis is NOT the alternate theory. It is a mathematical construct made necessary by the fact that the goodness of a probabilistic model cannot be measured in an absolute sense, but only relative to other alternatives. The difference in goodness of fit, etc. between the proposed and null hypotheses is meant to be a measure of the information in the proposed hypothesis. You NEVER, EVER, UNDER ANY CIRCUMSTANCES accept the null hypothesis.
One thing your null hypothesis cannot be is unphysical–and positing that an entire planet can just heat up all by itself with no external source of energy is unphysical. You denialist imbeciles remind me of a teenager explaining how they got into an accident, “It just happened, OK!”