Dyson doesn't NEED to "be quantitative". His simple statement to the effect that the models DO NOT INCLUDE biological systems is sufficient on its face to discredit them.
When the underlying premise is completely flawed, what need for calculations?? Bad science is bad science.
I apologize for not being able to reply to this date due to other commitments. I will try to do so soon. Old Prof, I did look at the link you provided and several other on that site, but it’s too dense for me to evaluate properly. What he’s doing there definitely doesn’t overlap much into my skill zone. I can’t figure out if his latest comment concerns a return to “normal” or not. I’ll keep trying.
His simple statement to the effect that the models DO NOT INCLUDE biological systems is sufficient on its face to discredit them.
How up-to-date is Dyson? Computers get bigger and faster; coupled AOGCMs with biology are computationally intensive and having complex ones wasn't feasible for pretty much most of the 20th century.
But it might be now. Found this:
How does ocean biology affect atmospheric pCO2? Theory and models
A STRATEGY FOR CLIMATE CHANGE STABILIZATION EXPERIMENTS WITH AOGCMs AND ESMs (PDF)
Read page 6. This doesn't indicate that there have been a lot of models with biological systems yet. But there are some, and there are going to be more.
So what else does Dyson say?
"My objections to the global warming propaganda are not so much over the technical facts, about which I do not know much, but it’s rather against the way those people behave and the kind of intolerance to criticism that a lot of them have. I think that’s what upsets me."
We know that plants do react very strongly to enhanced carbon dioxide. At Oak Ridge, they did lots of experiments with enhanced carbon dioxide and it has a drastic effect on plants because it is the main food source for the plants... So if you change the carbon dioxide drastically by a factor of two, the whole behavior of the plant is different. Anyway, that’s so typical of the things they ignore. They are totally missing the biological side, which is probably more than half of the real system."
[If he doesn't know the technical details, how can he make any even rough quantitative estimate of "the biological side"?
And this is an active area of study:
Forest response to elevated CO2 is conserved across a broad range of productivity
Continuing...
"Of course. No doubt that warming is happening. I don’t think it is correct to say “global,” but certainly warming is happening. I have been to Greenland a year ago and saw it for myself. And that’s where the warming is most extreme. And it’s spectacular, no doubt about it. And glaciers are shrinking and so on."
"And the most serious of almost all the problems is the rising sea level. But there again, we have no evidence that this is due to climate change. A good deal of evidence says it’s not. I mean, we know that that’s been going on for 12,000 years, and there’s very doubtful arguments as to what’s been happening in the last 50 years and (whether) human activities have been important."
Not exactly "doubtful". Of course, you have to accept that some of the warming causing the melting and thermal expansion is human-caused, but that's not in the scope of my effort here.
"And, secondly, I am not an expert, and that’s not going to change. I am not going to make myself an expert."
"e360: Do you mind being thrust in the limelight of talking about this when it is not your main interest. You’ve suddenly become the poster child for global warming skepticism.
Dyson: Yes, it is definitely a tactical mistake to use somebody like me for that job, because I am so easily shot down. I’d much rather the job would be done by somebody who is young and a real expert. But unfortunately, those people don’t come forward."
So ultimately, Dyson doesn't think the models are doing a good job with biology -- which has already been done and is increasing being done -- and also thinks that there is uncertainty about the causes and rate of sea level rise, which is demonstrably a lot less uncertain than he thinks it is. And he keeps saying he's not an expert.
I take him at his word.