2010-09-02 00:29:43New ADVANCED rebuttal 'positive feedback implies runaway warming' - feedback required...
John Cook

john@skepticalscience...
124.186.162.78

UPDATE: have created new thread in the Advanced Rebuttal forum on Neal's 'positive feedback' rebuttal. Feedback and comments would be appreciated...


The problem with climate discussions is skeptics continually bring up the same old zombie arguments. The beauty of Skeptical Science is over time, we gradually build up rebuttals to more and more skeptic arguments. So when someone posts a zombie argument, we point them in the right direction and the discussion can stay on-topic. This is partly why the discussion at SkS is of a high quality (the other reason being the excellent work of the moderators).

A skeptic argument that pop ups regularly in the comments whenever positive feedback is mentioned is the misunderstanding that net positive feedback should lead to runaway warming. The argument goes, "as we haven't experienced runaway warming in the past, this proves net feedback cannot be positive". The answer to this is relatively simple - whether we have runaway warming or not depends on the degree of net positive feedback. If it's not too great, then instead the warming stabilises at a higher level. This was simply presented by Ned Flounders in a comment:

To illustrate the point about positive feedbacks, here are graphs of two cases, one where f > 1 (resulting in a runaway increase) and one, like the real-world positive water vapor feedback, where 0 < f < 1, so that the temperature increase is bounded (2C in this case):

I asked Ned if he'd be interested in fleshing this out in a short blog post which we could then use as a rebuttal. Then whenever someone posts a 'runaway warming' comment, we can simply link to the rebuttal. Ned said he'd like to do it is but very busy. So he said anyone else is welcome to have a go at it. So hopefully someone will be interested in taking this one on...

Anyone...? Bueller...?

2010-09-02 09:55:29I'll think about it...
nealjking

nealjking@gmail...
91.33.105.199

but you'll have to explain to me how to incorporate graphs. They'll probably be useful in explaining the range of behaviors.

 

Neal

2010-09-02 11:48:24Instructions on how to upload images
John Cook

john@skepticalscience...
124.186.162.78

Instructions taken from the Welcome thread. If you do decide to go for it (which would be great, thanks!), I suggest clicking the 'Add New Rebuttal' link in the left margin so you can claim this argument - lowers the chance of duplication of work.

There are several ways you can insert a figure into your posts:

  1. If the figure is already on another webpage, just highlight it, copy (Ctrl + C), insert the cursor in the form box here, paste (Ctrl + V) and bob's your uncle!
  2. If the image is uploaded to the web somewhere and you know the URL, click on the picture icon (found in the WYSIWYG icons in the forum form box - it's a tiny tree) then enter the URL
  3. If the image is on your computer, you need to upload the image to the web. As a Skeptical Science author, you can upload images to my pics folder. Just go to the Upload Image feature in Author Admin. This will upload a pic into the www.skepticalscience.com/pics folder then give you the URL of the image. So copy that URL then paste it using the steps in option #2 above.

Apologies that these are fairly clunky options - I will work on a better option soon.

2010-09-02 20:08:01Can't find anything about "positive feedback"
nealjking

nealjking@gmail...
91.33.99.186
So I can't claim it, within the system.
2010-09-02 20:51:12Missing argument
John Cook

john@skepticalscience...
121.222.93.62
Good point, the argument didn't exist. Just added it, it's #125 down the bottom of the rebuttal list
2010-09-03 08:13:58I've written some text
nealjking

nealjking@gmail...
91.33.99.186

but I'm not sure how to generate an image from the graph I get out of MS Excel.

I can generate some useful numbers in Excel, and use the chart tool to get a box with graph, floating over the spreadsheet - but how do I separate the graph from the background so that it can be printed on something? 

In  your graphs above, how did you get them away from the background?

(In the meantime, you can preview the text; but it's got a lot of mathematical argument that I would rather replace by the graphs.)

 

Neal

 

2010-09-03 09:31:47excel graphics
John Cook

john@skepticalscience...
121.222.93.62

Okay, I have my method but I'm sure there probably is a much more sophisticated manner. I just hit Print Screen which screen captures the graphic. Then I paste it into Photoshop (or any photo editing software) and crop out the background, leaving just the graph.

If anyone has a better method, please post here.

Neal, if you want to email me (john@skepticalscience.com) the spreadsheet, I'd be happy to generate the graphics for you and upload them to the website.

2010-09-04 00:01:22First draft of text
nealjking

nealjking@gmail...
84.151.34.163
is ready in Preview; if you get the graphs ready, we can stick them in and post it.
2010-09-04 22:24:36Added to advanced rebuttal
John Cook

john@skepticalscience...
121.222.93.62

Neal, thanks heaps, great job! Have created your graphs and added to your rebuttal. It's such a great post, it's way above Basic level - I mulled over intermediate or advanced but opted for advanced. The general rule of thumb for me is if it has equations, go to Advanced :-)

Anyway, I've raised a few discussion points in the new thread in the Advanced forum...