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“No-one is claiming that these are the types of questions that we could answer, or even why we’d want to.”
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The question of the response time to a certain level of CO2 in the atmosphere is paramount or germane to a lot of the discussion on CO2 effect.
The result of not addressing it, other than “You keep on asserting things as fact that are simply and obviously incorrect. ” is to make one wonder whether the matter is too difficult.
Or taboo.
To put it simply I note from RNS that CO2 2018 is 410.79.
There is a world global temperature that fits this CO2 level, what is it?
CO2 controls temperature.
‘What temperature should it be, now, 2018?
“Even if we cannot definitively attribute a climate change link to a specific event does not mean that we can’t discuss how climate change is likely to impact such events and whether or not we’re seeing changes that are consistent with what is expected.”
Leads to a degree of confirmation bias.
If every extreme event is expected to occur with greater frequency then the mere occurrence of any said extreme event becomes automatic proof of your position, making it a definite attribution.
Seems wrong on some level even if right.
Nothing wrong with talking about the expectation
“Climate change is clearly happening and it is mainly driven by our emission of greenhouse gases (mostly CO2) into the atmosphere. Doing so causes atmospheric CO2 to increase, reducing the outgoing energy flux and causing energy to accumulate in the climate system. This will lead to warming of the surface and troposphere, increasing ocean heat content (and increasing sea surface temperatues), an increase in evaporation, an increase in the frequency and intensity of extreme precipitation events, and a change in the latitudonal temperature gradient that has the potential to influence the jet stream and, hence, weather patterns. This means that in regions that are susceptible to extreme weather events, the conditions will increasingly tend to favour these events becoming more extreme.”
But extreme events have to be rare and rare events are difficult to pin causation on and even a 5% increase is perfectly acceptable within a normal range. As well as fitting an expectation.
It is an argument that can lead to calls of crying wolf.
Wolves are out there but no-one appreciates calls that are not definitely attributable.
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Thanks Izen for mentioning a sensible time scale environment.
Andrew, I don’t understand or do not want to believe or do not get it.
Your change in temperature for a x4 inst. forcing only goes up very slowly, years in fact to perhaps get to 2 C, then much longer to get higher [ATTP’s centuries+ to get to an equilibrium].
I want to believe that an atmosphere with a x4 increase in CO2 [and maintained there thereafter] must have a new temperature very close to the maximum achievable and fairly instantly. like within 36 hours.
I am prepared reluctantly to accept some lapse as the change in heating permeates to its final level. Perhaps a different simpler picture of a non rotating earth would help the imagery. Here the retained incoming heat would rapidly build up and then spread to the dark side over time, hours days until the outgoing again balances the incoming. Obviously some heat would be transferred/ building in the oceans. But this again could balance fairly soon. The oceans being hotter on the surface keep the air warmer and decrease rapidly the amount of heat needed to be put in to achieve that balance as well.
My point, dense though it is, is that a volume of gas of known composition, on a known backdrop of water/land on one side, space on the other, heated by a known income source [np clouds] has a known expected scientific temperature.
Earth at 500 ppm CO2 , Earth at 2000 ppm, each has a set expected temp [specifiable in a range if not exact]
I realise that ocean temperatures can take months to vary but atmospheres are much thinner and reactive. 0 at night to 30C in the day at Alice Springs. Why should not the temperature reaction of a known composition adjust to that expected temperature, or close to. more quickly? -
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Steven, “attack the pattern argument”
I read AD An Estimate of Equilibrium Climate Sensitivity From Interannual Variability
“It is also worth stepping back and asking what could cause our calculation to be seriously in error.
It seems unlikely that forcing from doubled CO2 is wrong given our good understanding of the physics of CO2 forcing (e.g.,Feldman et al., 2015).Estimates of ? iv,obs and ?iv,obs are derived from observations we view to be reliable,
so our judgment is that they are also unlikely to be significantly wrong.The ?TS/?TA factor comes from climate model simulations, but models have long been able to accurately reproduce the observed pattern of surface warming (e.g., Stouffer & Manabe, 2017), and we have simple physical arguments explaining how the atmospheric and surface temperature should be connected (Xu & Emanuel, 1989).
Finally, we can compare the models to data (Compo et al., 2011; Poli et al., 2016) to validate their simulation of this ratio.Thus, the transfer function seems the most probable place for a significant error to occur. We also argue that while errors may exist in a model (i.e., in the cloud feedback), this will affect both the numerator and denominator and such errors will tend to cancel out.
While one must be careful about conclusions based on a single model, this nevertheless provides some support for the hypothesis that errors in ? 4xCO2
will cancel errors in ? iv when the ratio is taken.As a preliminary test of this, we have analyzed three different versions of the MPI-ESM 1.2 model that have had their cloud feedbacks modified to produce different ECS (Thorsten Mauritsen and Diego Jimenez, personal communication, 2018). The three versions are the standard model (ECS calculated from an abrupt 4xCO2 run using the Gregory method = 3.0 K), an iris version (described in Mauritsen & Stevens, 2015; ECS = 2.6 K), and a high ECS version, in which the convective parameterization has been tweaked to generate a large, positive cloud feedback (ECS = 5.2 K). ”
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I have cut, pasted and tweaked this somewhat, apologies for those bits left out. It contains numerous items relevant to past discussions on this and other blogs supportive of some of my past statements.
I have trouble understanding “if the argument turns on which version of ice is used,”
So I am probably cross discussing..
Here, with Andy, He has outlined his procedures well. He believes ” models have long been able to accurately reproduce the observed pattern of surface warming ”
I would argue that reproduction is different to predication, I would hope the models do accurately reproduce. any argument that observations could be put aside when they disagree with the reality of models is fraught. though not untenable. -
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I have trouble understanding “if the argument turns on which version of ice is used,”
Time scales as we both know are very relevant to the accuracy of prediction and expectation. When I argue from a very few years of ice increase from one data set you are more than entitled to laugh at me, and others. When the ice sets [satellites] are of short duration 40 years themselves then the laughter should be stifled though the message is still with the long term trend.
I have no beef with people having beliefs or predictions. Only sticking to legitimate scientific methods. PIOMAS is currently creating some issues for people wanting warming. They believe it is not accurate now though they were happy to accept it while it was falling precipitously. Skeptics did not believe it when it was falling. Both cut from the same cloth.
