John Hartz says: May 4, 2018 at 6:44 pm
“Back to basics: Climate Sensitvity (CS) is an index created to compare model runs. It is model output, not a model input.”
Dave_Geologist says: April 27, 2018 at 2:43 pm
” Dessler’s point AFAICS is that if you take a suite of physics-based models, where you know the ECS in advance, and try to calculate it the way LC13 and LC18 do, you get the wrong answer.”
The old chestnut, Lucia [whom I trust] used it as well, is that ECS is an emergent property of climate models. The truth is that the ECS is hardwired into all the GCM.
At around 3C.
Put 3C ECS in and 3C ECS comes out.
Compare it to the real world, the only one, where 3C rarely comes out unless you pick exact time frames of extra warming like a decade ending in a large El Nino.
Consequence is shadow boxing, dodging the real questions and answers.
Dessler is right but so is Lewis but on two different stages.
It is so easy to answer a question on the first stage show in the second show arena.dikranmarsupial says: April 24, 2018
Even angech’s own sources refute him. His original claim was:
These can give an indirect record of past temperatures, but only locally. Such records indicate that Temperature changes equivalent to the modern 150 year warming have happened a number of times in the past 3000 years. [emphasis mine]
and he supports that with:
“The NRC committee stated that “The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years. This conclusion has subsequently been supported by an array of evidence that
includes both additional large-scale surface temperature reconstructions and pronounced changes in a variety of local proxy indicators”
and says: This basically agrees and supports what I have said. There are possible higher and lower spikes in the temperatures in the past that do not show because of “the wide error bars” as one goes backwards and the “uncertainties inherent in temperature reconstructions for individual years and decades are larger than those for longer time periods’.
DM “Err, no it doesn’t, it says that the recent warming is unprecedented.”
Having been called out in the past for not fully quoting comments I guess I can do a tu quoque?
The NRC did not say “the recent warming is unprecedented.” Mann et al said that.
The part that DM leaves out says clearly plausible only with substantial uncertainties before 1600.
I will append the bit he missed by accident.
“Based on the analyses presented in the original papers by Mann et al. and this newer supporting evidence, the committee finds it plausible that the Northern Hemisphere was warmer during the last few decades of the 20th century than during any comparable period over the preceding millennium”, though there were substantial uncertainties before about 1600?”.
“Note also the goal-post shift from “have happened” to such spikes being “possible”, without acknowledging the weakening of his position. Rather shabby.”
Sorry DM I have not changed my position. No goal post shift. Read my comment again noting “have happened” refers to events ” past temperatures, but only locally” which are well known and real.
The ”spikes” being possible refers to the separate concept that such temperature spikes may have been general rather than local and would not be visible due to the large error range in time and temperature.
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