Commentary from Nature Climate Change, by John C. Fyfe, Nathan P. Gillett, & Francis W. Zwiers
Recent observed global warming is significantly less than that simulated by climate models. This difference might be explained by some combination of errors in external forcing, model response and internal climate variability.
Global mean surface temperature over the past 20 years (1993–2012) rose at a rate of 0.14 ± 0.06 °C per decade (95% confidence interval)1. This rate of warming is significantly slower than that simulated by the climate models participating in Phase 5 of the Coupled Model Intercomparison Project (CMIP5). To illustrate this, we considered trends in global mean surface temperature computed from 117 simulations of the climate by 37 CMIP5
models (see Supplementary Information).
These models generally simulate natural variability — including that associated
with the El Niño–Southern Oscillation and explosive volcanic eruptions — as
well as estimate the combined response of climate to changes in greenhouse gas
concentrations, aerosol abundance (of sulphate, black carbon and organic carbon,
for example), ozone concentrations (tropospheric and stratospheric), land
use (for example, deforestation) and solar variability. By averaging simulated
temperatures only at locations where corresponding observations exist, we find
an average simulated rise in global mean surface temperature of 0.30 ± 0.02 °C
per decade (using 95% confidence intervals on the model average). The
observed rate of warming given above is less than half of this simulated rate, and
only a few simulations provide warming trends within the range of observational
uncertainty (Fig. 1a).
Figure 1 | Trends in global mean surface temperature. a, 1993–2012. b, 1998–2012. Histograms of observed trends (red hatching) are from 100 reconstructions of the HadCRUT4 dataset1. Histograms of model trends (grey bars) are based on 117 simulations of the models, and black curves are smoothed versions of the model trends. The ranges of observed trends reflect observational uncertainty, whereas the ranges of model trends reflect forcing uncertainty, as well as differences in individual model responses to external forcings and uncertainty arising from internal climate variability.
The inconsistency between observed and simulated global warming is even more
striking for temperature trends computed over the past fifteen years (1998–2012).
For this period, the observed trend of 0.05 ± 0.08 °C per decade is more than four
times smaller than the average simulated trend of 0.21 ± 0.03 °C per decade (Fig. 1b).
It is worth noting that the observed trend over this period — not significantly
different from zero — suggests a temporary ‘hiatus’ in global warming. The
divergence between observed and CMIP5-simulated global warming begins in the
early 1990s, as can be seen when comparing observed and simulated running trends
from 1970–2012 (Fig. 2a and 2b for 20-year and 15-year running trends, respectively).
The evidence, therefore, indicates that the current generation of climate models
(when run as a group, with the CMIP5 prescribed forcings) do not reproduce
the observed global warming over the past 20 years, or the slowdown in global
warming over the past fifteen years.
This interpretation is supported by statistical tests of the null hypothesis that the
observed and model mean trends are equal, assuming that either: (1) the models are
exchangeable with each other (that is, the ‘truth plus error’ view); or (2) the models
are exchangeable with each other and with the observations (see Supplementary
Information).
Brief: http://www.pacificclimate.org/sites/default/files/publications/pcic_science_brief_FGZ.pdf
Paper at NCC: http://www.nature.com/nclimate/journal/v3/n9/full/nclimate1972.html?WT.ec_id=NCLIMATE-201309
- Supplementary Information (241 KB) CMIP5 Models
@milodon, yes. It helps to know the entomology of a word.
Bruce Cobb says:
September 5, 2013 at 10:53 am
Ouch!
I feel that these types of analyses aren’t appropriate because the mean temperature does not follow a linear process over time. It’s some combination of orbital movements, weather patterns, ocean circulation, perhaps volcanic activity, and a bit due to mankind’s activities of one sort of another. That said, the author is using the alarmists’ own methods against them and I guess it’s fine for that.
David Ball says: September 5, 2013 at 9:35 am
……………….
An excellent experiment.
Heat absorbed by the world oceans is moved around by the major currents, most notably by the Gulf Stream and its extension in the North Atlantic, Kuroshio-Oyashio currents system in the North Pacific and yhe equatorial currents in the Central Pacific.
In order to influence global climate these major currents (assuming relatively steady solar input) heat transport (current’s velocity, volume or both) has to change.
One could speculate about causes of such changes, either of the global or local proportions.
It is somewhat odd to think that a local cause is the primary factor, but from data I have looked at, that appear to be the case as listed here:
AMO – Far North Atlantic Tectonics
PDO – Kamchatka – Aleutian Archipelago Tectonics
ENSO (SOI) – Central Pacific Tectonics
http://www.vukcevic.talktalk.net/TDs.htm
@Jonnya99: “I am pleasantly astounded at how quickly discussion of the ‘pause’ has passed from heresy to mainstream. Now all someone has to do is publish the ultimate taboo: natural variability can push temperatures up as well as down.”
Good observation, although there are still a few who claim that there is no actual pause. The AGW faithful will cling to the idea for as along as they can without addressing the obvious questions:
(1) Was natural variability addressed in the models? If not, why not?
(2) If the models cannot accurately address natural variability are they reliable at all?
(3) If the pause is caused by natural variability then (as you note) can they “push temperatures up as well as down?”
My guess is that the MSM will quietly let this issue die by simply publishing less and less about it in the coming months. Funding for continued “research” and for anti-fossil fuel, environmental “advocacy” will dry up. Both of these things are happening now.
@TheoGoodwin Thank you for your description.
Question: Do the models essentially assume that all temperature variability is caused by CO2 levels plus noise?
If so and the correct model is that there are a multitude of factors (sun, oceans, clouds, volcanos…..) affecting temperatures, then we could observe the results we have observed.
When the alarmists say “the models are based on the laws of physics”, how can they make that claim and leave out the “forcings” from the sun, the oceans, clouds, etc.?
Richardscourtney: The Bayesian Treatment of
Auxiliary Hypotheses – This paper examines the standard Bayesian solution to the Quine-Duhem
problem, the problem of distributing blame between a theory and its auxiliary
hypotheses in the aftermath of a failed prediction.
http://joelvelasco.net/teaching/3865/strevens%20auxhyp.pdf
This is a bit over my head and I may have missed the mark and it is not relevant, but it may be why the models have not been falsified.
Nits or Knits will tie you in knots or not… if you remember the purpose of words.
That is, they communicate.
And they carry several forms of knowledge;
-The literal meaning (we all know what words mean)
-The emotional content (for which remembrances of things past are important)
-The tone (for which a confrontational change of rhythm may be important)
-The beat (for which word and sound length matter and it helps readability)
-Probably more…
So nits or knots or gnats are nuts.
What matters is the ease of conveying your message as persuasively, or as entertainingly, as possible.
@kellyhaughton at 11:14 am
When the alarmists say “the models are based on the laws of physics”, how can they make that claim
They are based upon laws of physics. Just not ALL known Laws of physics.
Isaac Newton modeled the flight of cannonballs using his laws of motion….. neglecting air resistance. Cannoneers weren’t impressed.
M Courtney says:
September 5, 2013 at 11:53 am
I have to agree that in context “knit” is more entertaining than “nit” at communicating the same message, although Mann does like to compare skeptics to pine bark beetle larvae.
PS: I eschewed inserting the term nit-wit into the above copy.
milodonharlani says at September 5, 2013 at 12:02 pm… Prudent call. My father does like a fight if any is offered. Or even if it just seems to be.
You know, it’s fun – in a way.
Dr Darko Butina says:
September 5, 2013 at 1:24 am
The Vukcevic’s histogram is also based on the annual average and therefore not on ‘actual’ temperatures.
Hi Darko
Only actual temperature I take seriously is my own when goes to 38C or above.
Prije 3-4 mjeseca vido sam tvoj prilog na ovaj blog, ali veci dio je dalek iznad moje expertise, koja je blago budi receno, najcesce manje nego povrsna, bes obzira na predmet discusije.
Sve najbolje.
kadaka: repeat your IR experiment with an unwaxed paper cup with water. You can boil water in a paper cup on hot coals without burning the cup. Every Boy Scout knows that trick. I leave it to the experts whether the heat transfer to water is by convection through the container, transfer from the heated air, radiative transfer or a combination of the three. In any event enough heat is transferred from the paper to the water to prevent the paper from burning.
M Courtney says:
September 5, 2013 at 12:05 pm
milodonharlani says at September 5, 2013 at 12:02 pm… Prudent call. My father does like a fight if any is offered. Or even if it just seems to be.
You know, it’s fun – in a way.
—————————–
I was thinking of Little Mikey Mann, not the distinguished Senior Courtney.
@ur momisugly Bruce Cobb says: September 5, 2013 at 10:53 am
*GROAN* – Bad pun! 😉
kellyhaughton says:
September 5, 2013 at 11:14 am
In practical terms, they are looking for forcing from CO2 and treating everything else as noise. They would dispute my claim. They would say that they are aware of the “forcings and feedbacks calculation” that must be done. However, they will get nowhere on that calculation. As explained in my first post above, cloud behavior is a natural regularity and their handling of cloud variation in their models will be subject to the same circularity as their handling of ENSO. They will treat cloud variation as summing to zero over the long run. The proof is in the pudding. How many models are trumpeting their skill at reproducing cloud behavior and, among them, how many are trumpeting their novel conclusions showing that cloud behavior is an important negative feedback (that cloud behavior seriously lowers the effects of CO2)?
M Courtney says:
September 5, 2013 at 12:05 pm
Please suggest to him that his time is better spent explaining the failings of models and other parts of CAGW.
kellyhaughton says:
September 5, 2013 at 11:14 am
“When the alarmists say “the models are based on the laws of physics”, how can they make that claim and leave out the “forcings” from the sun, the oceans, clouds, etc.?”
The only physics that they consider is the physics of radiation among Sun, Earth, and GHGs. They have no place for an experimental physics of natural regularities. They do not cover the physics of ENSO, AMO, you name it except to treat them as numerical indexes that will sum to zero. Several Alarmists have published articles arguing that the AMO and ENSO must sum to zero and cannot influence climate.
Theo Goodwin says at September 5, 2013 at 12:27 pm…
I agree entirely and my work email records my conversation with my father on much the same theme (well, in the particular) even though I am paid to have other priorities at that time.
But I am not my father’s minder. He is his own man – don’t ask me to be responsible for focussing him, please (pretty please).
milodonharlani says:
September 5, 2013 at 10:38 am
I was there when ‘knit’ became ‘nit’. The invention of the nit was a very Sixties thing.
BBould:
Thankyou for your post addressed to me at September 5, 2013 at 11:29 am which says in total.
Firstly, for some reason my computer locks up when I try to download that link. So, at the moment I cannot answer your specific question.
Do you have another link or a reference so I can access the paper another way?
For the moment, I draw your attention to a recent excellent post from Robert Brown on another thread. It starts by (rightly) chastising me for failing to caveat the ‘all other things being equal fallacy’ but if you get past that he deals with the oversimplification of models. It is here
http://wattsupwiththat.com/2013/09/03/another-paper-blames-enso-for-global-warming-pause-calling-it-a-major-control-knob-governing-earths-temperature/#comment-1406638
Richard
Friends:
It seems that some want to address me through my son.
That is not reasonable. Does any of you have a son who agrees with you, and would you want one?
Please talk to him about his views and to me about mine. Otherwise he and me may lose the fun of our arguments with each other 🙂
Richard
richardscourtney says at September 5, 2013 at 12:47 pm…
Obviously, I disagree.
richardscourtney says:
September 5, 2013 at 12:47 pm
How could I have forgotten that most fundamental point? My bad. Never again will I address you through your son.