[jmcqk6]

I think in order to make the claim that climate change isn't happening, you need to be able to explain how a massive change in CO2 and other greenhouse gasses in the atmosphere will not result in warming.

There is fundamental data that does not depend on climate models that tells us we're in danger. Atmosphere composition in one of them. Ocean ph is another.

If you have specific criticisms against how climate models are being run, then the place for that debate is within the scientific community, with scientific arguments. Apparently you have decided that is not for you, though.

[huffpopo]

I make no claim that climate change isn't happening. Being between the modeler and the results meant it was my job to explain the result to the modeler. So criticizing climate change models within the scientific community was my job for over a year and a half.

[Florin_Andrei]

> criticizing climate change models within the scientific community was my job for over a year and a half

So you had a long and glorious career spanning more than 18 months, that makes you feel entitled to criticize those who studied the field for decades and are actually making a living therein.

[huffpopo]

Yes; but it seems your answer to my question is that I must also have several decades of experience.

[Florin_Andrei]

My answer is - you need to actually understand the thing you're criticizing, not just feel like you do. Another prerequisite is a lack of agenda or bias.

[gus_massa]

> you need to be able to explain how a massive change in CO2 and other greenhouse gasses in the atmosphere will not result in warming.

It's not so easy to be sure about the warning produced by the CO2 because a very big part is the "Climate Sensibility". And there is no straightforward way to calculate the climate sensibility, you must use climate models. From https://en.wikipedia.org/wiki/Climate_sensitivity#Radiative_...

> CO2 climate sensitivity has a component directly due to radiative forcing by CO2, and a further contribution arising from climate feedbacks, both positive and negative. "Without any feedbacks, a doubling of CO2 (which amounts to a forcing of 3.7 W/m2) would result in 1 °C global warming, which is easy to calculate and is undisputed. The remaining uncertainty is due entirely to feedbacks in the system, namely, the water vapor feedback, the ice-albedo feedback, the cloud feedback, and the lapse rate feedback";[14] addition of these feedbacks leads to a value of the sensitivity to CO2 doubling of approximately 3 °C ± 1.5 °C, which corresponds to a value of λ of 0.8 K/(W/m2).

[jmcqk6]

> "Without any feedbacks, a doubling of CO2 (which amounts to a forcing of 3.7 W/m2) would result in 1 °C global warming, which is easy to calculate and is undisputed.

We're going to get warmer, to find out how much warmer, you need more complex models.

[gwright]

No one is making the claim that "change isn't happening". The skeptical view point isn't even "warming isn't happening". The skeptical view is that catastrophic warming isn't an accurate prediction of future temperature trends.

I believe the primary difference between the "consensus crowd" and the "skeptic crowd" is that the consensus crowd is confident in the predictive value of models that have a net positive feedback sensitivity to temperature increase while the skeptics argue that we don't actually know what the feedback mechanisms well enough to be confident in the models and in fact basic physical principles argue for a negative net feedback to temperature increases (to avoid runaway warming).

As for possibile negative feedback loops, increased CO2 might increase clouds, which increases the earth's albedo resulting in less energy input from the sun, which reduces temperature.

[Oletros]

> The skeptical view point isn't even "warming isn't happening".

What the heck?

[gwright]

Let me clarify. There is a difference between warming and catastrophic warming. Serious skeptics are arguing against catastrophic warming as predicted by the models.

There is another level of debate, less foundational, regarding the quality of our temperature observations and the amount of warming (not catastrophic warming) that is a result of natural variation, human activity, measurement errors, data adjustments and the like.

Observational warming has in general been less than that predicted by the models suggesting that the extrapolation into the future by the models may not be accurate.

[Oletros]

> Serious skeptics are arguing against catastrophic warming as predicted by the models.

What catastrophic warming? Or better, define catastrophic warming

And by the way, 90% of skeptics still say that there is no warming.

> Observational warming has in general been less than that predicted by the models suggesting that the extrapolation into the future by the models may not be accurate.

Source for that?

[gwright]

I'm using the phrase 'catastrophic warming' to refer to the warming predicted by climate models as opposed to the warming directly observed today and in the historical record.

Anthropomorphic global warming theory is roughly two connected claims. 1) rising CO2 levels caused by human activity results in a rise in the average global temperature and 2) the climate system has a feedback mechanism (sensitivity) that magnifies this CO2 induced warming.

Basic physics can be used to determine the warming caused by increased CO2. There are no serious skeptics in regards to these physical properties of CO2. My understanding is that the IPCC reports have consistently reported this warming as 1-1.5 degrees for every doubling of CO2 concentration in the atmosphere.

But that temperature rise isn't enough to create the catastrophic side effects that you see reported. That rise has to be magnified by the climate system through a variety of feedback mechanisms. This magnification/sensitivity can't be measured. It is the output of the climate models not one of the input parameters. Credible skeptics argue that a positive sensitivity is incorrect and that the climate system (as with most natural systems) has a negative sensitivity.

Here is what seems to be a reasonable review of predictions vs observations using a variety of methodologies most showing observations trending towards the lower half of the predicted ranges of the models (as opposed to trending toward the center line of the predictions): https://judithcurry.com/2017/09/26/are-climate-models-overst...