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[–][deleted] 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (9 children)

Anthropogenic climate change- the science that's so real that it can only be proven with opinion surveys

[–]ActuallyNot 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (8 children)

There's been scientific proof that the warming is anthropogenic for at least 23 years

[–][deleted] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (7 children)

The '99% of scientists agree' metastudy thing is not confidence inspiring.

[–]ActuallyNot 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (6 children)

I see you didn't read the paper.

It's a decomposition of 20th century warming into that due to natural and anthropogenic warming. The warming since the middle of it is anthropogenic.

[–][deleted] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (1 child)

I will read it. I see it shows non anthropogenic forcing or something, I am still curious about that part.

[–]ActuallyNot 3 insightful - 1 fun3 insightful - 0 fun4 insightful - 1 fun -  (0 children)

Natural forcing in that paper is volcanic and solar radiation.

If you're into the maths, then Meehl et al (2004), is more fun. They show that the response to the forcings are approximately additive. (That is the change in temperature due to the sum of two different forcings is about equal to the sum of the change in temperatures due to each forcing). So they work plot the temperature response to each forcing twice. Once driving the model with the forcing, and once (which the call the residual) by subtracting the temperature response of the model using all the forcings from the temperature response of the model using all the other forcings.

Which is not important for understanding climate change, but it's still very fun.

They also decompose the temperature into the response to natural and anthropogenic parts.

The model is a bit more polished. Stott et al (2000) was one of the first papers using output from the Hadley Centre's HadCM3. Meehl et al used the US department of energy model PCM.

[–][deleted] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (3 children)

More than 80% of observed multidecadal-scale global mean temperature variations and more than 60% of 10- to 50-year land temperature variations are due to changes in external forcings.

So this is saying that non-human non-atmospheric composition external forgings are mostly responsible for land temperature variations? Are the variations the same as the temperature increases that we care about?

It kinds seems like it's saying that human C02 emissions can at most only be responsible for 20-40% of variations.

Oops shit, the paper I reference is 3 comments up.

[–]ActuallyNot 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (2 children)

So this is saying that non-human non-atmospheric composition external forgings are mostly responsible for land temperature variations?

Good question. No. But they're using "external variation" differently from how it would be used today.

Those are the correlations between the average of the model runs and the observed temperature. (It talks about them in the middle column of the third page; page 2135 of the journal). So by "external forcings" they mean everything that is driving the model: natural forcing, plus anthropogenic forcing. And "internal variation" those things that affect the observed temperature that aren't due to any forcing driving the model.

Are the variations the same as the temperature increases that we care about?

Yes, including those.

It kinds seems like it's saying that human C02 emissions can at most only be responsible for 20-40% of variations.

It seems like that at first glance. But they're calling all forcing "external".

[–][deleted] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (1 child)

Well God damnit how can I parse any of this if the definitions are squirrelly and changing.

Also how does this paper prove a damn thing? All they did was fiddle with a computer model until it matches reality. They are picking and choosing what to model in the system. There's gotta be better proof for anthropogenic climate change than this.

[–]ActuallyNot 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (0 children)

Well God damnit how can I parse any of this if the definitions are squirrelly and changing.

Sometimes you have to read the paper to understand. Sometimes I read it, and still don't understand.

All they did was fiddle with a computer model until it matches reality.

I don't think they tweaked HadCM3 for this paper.

They are picking and choosing what to model in the system.

No, they're not avoiding modelling anything that they had the understanding and computing power to model.

And the results are consistent with other models, as demonstrated by Meehl et al. Completely different model. The observed warning is still anthropogenic.

Stott et al got similar results later still with HadGEM1.

HadGEM1 was capable of showing the warming on each continent was likely anthropogenic.

There's gotta be better proof for anthropogenic climate change than this.

Proof of anthropogenic climate change is clearest from first principles. The increase in CO2 will result in a warmer planet.

This kind of paper is investigating the dynamics of that: How much of the observed warning is anthropogenic?