2011-12-02 12:06:53Farenheit Celsius ppm 451


Well, I finally got tired of feeling guilty about spending my time just making long, tiresome comments and decided perhaps I should invest some time into making a long, tiresome blog post for SkS.

I need to go through and tighten up the too-wordy language (my, but I do love words, the more, the better) and I have to make sure that all the science is right (what little there is in the post), and mostly I need to spruce it up with an appropriate graphic or two, but...

Farenheit ppm 451

Comments are greatly appreciated.

[Edit -- title changed]

2011-12-02 19:01:17
Tom Curtis


Sphaerica, I enjoy the narrative and the writting style.  Unfortunately you are neglecting the change in forcing due to change in albedo between the LGM and the present.  That forcing represents 54% of the total forcing from LGM to Holocene.  Despite Hansen's argument about slow-feedback climate sensitivity, there is now less ice at higher latitudes so that slow feedbacks are highly unlikely to match, let alone exceed an initial forcing from CO2.  Hence 451 ppmv is not unusualy significant except as the concentration of CO2 at which we can expect a 2 degree rise in temperature from the pre-industrial by best estimate.


Sorry to be such a downer.

2011-12-02 22:27:54
Daniel Bailey
Daniel Bailey

The Arctic is poised to enter a new energy state (see comments made in this Response).  To further add ammunition to Sphaerica's post, see this recent Comments post.  Thus I find it completely credible that a possible reorganization of the NH weather systems could take place due to the achievement of 451ppm (no, I don't know what that will look like; Hansen is fairly non-specific in his Storms book as well). 

But we all know it won't stop at 451...

2011-12-03 01:52:53



I had considered that and had (and axed) a section explaining it -- not arguing it one way or the other, but just admitting that there are differences .

At the same time, this certainly is part of the climate sensitivity debate, that while we would like to cast things as degrees-per-doubling, the reality is that the change between one pair of regimes and another is apples and oranges -- different starting conditions, different net feedbacks, etc.

But while the ice sheet feedback is seemingly less (ignoring Dan's points to the contrary), who is to say that other feedbacks may not be greater?  For example, it is possible (does anyone know?) that the cloud feedback between a glacial and interglacial period is net negative, given that the overall influence of clouds in the pre-industrial climate state was net negative... although I suppose it could have been "more" negatie if the only clouds over a glaciated world are low lying equatorial clouds.

At the same time, while the transition in ice sheets does, scientifically, suggest that the overall temperature change will not be the same, that's sort of missing the point of the entire article, which is that we are applying an equivalent force in an abstract sense, and so should expect a similar result in a purely abstract sense.

Without getting lost in the science, or going overboard trying to prove by looking at the details what will happen one way or the other, the fact is that we are applying teh same push now that nature did then (although perhaps to a system with more "friction").

I think I'd stand by this argument, especially for those people -- exacty for those people, they are who it was written for -- who cannot get into the science in any detail and need things put into simpler terms and a more easily managed analogy.

2011-12-03 02:23:33
Tom Curtis


Sphaerica, with regards to feedbacks, I know that the water vapour feedback (positive) becomes stronger with increasing temperature, but so also does the lapse rate feedback (negative).  I believe the combination of the two also becomes stronger with increased temperature (ie, more positive) but at what rate I could not tell you.  


As for clouds, in general they would have been a more positive feedback in glacial than in non-glacial times.  That is both because they are strongly positive over ice, and because much equatorial or near equatorial land in the LGM was savannah rather than forest, with  a consequent higher albedo.  Hence the shortwave energy balance of clouds would have been less over land in general, not just over ice.  Of course, the amounts, locations and altitudes of clouds is critical to this equation, and are complete unknowns to me at least.  Further, although the positive contribution of clouds to the energy balance may have been stronger in the LGM (as per above), the cloud feedback could still have been either positive or negative.  Just as the net negative contribution of clouds now does not determine the sign of the feedback, so a net positive contribution (if it was) would not have determined the sign of the cloud feedback in the LGM. 


Finally, the point of my post was not just about the temperature change, although it is relevant.  It is that the change of forcing itself is not equivalent, even if the change of CO2 forcing is.  The push is not equivalent.  This does not preclude using your hook.  But to do so I think you would need to be more explicit that the change in CO2 forcing since the LGM is not the total change in forcing to avoid charges of misrepresentation.  And given that, I think you would need to be explicit about a few possible tipping points that could carry us into a new regime, ie, into the fire age.


2011-12-03 04:33:26Title of the post?


Not sure how you actually intend to have the title look like eventually, but using formatted texts like you have at the moment doesn't work properly:

It does at least two things:

  1. the title in the (Firefox)tab looks odd: <strike>Fahrenheit</strike> ppm 451
  2. it seems to "lose" the Celsius completely
2011-12-03 04:44:25



I think I should probably add a section ("Safety Net" or something such) that at least direclty addresses the fact that it's apples to oranges, and there are reasons to hope for the best -- but it's hope, not science or any reason to continue BAU.

I'll work on that tonight and see what people think.

2011-12-03 04:46:32



Yeah, I noticed that.  I actually changed the title to remove Celsius, deciding it was too much, so that's what's going on there.

The page title comes from how John's software creates the page, and could be corrected manually, I assume, but I was wondering myself whether or not is was too cute to use the strikeout, and whether I should just go with Dan Bailey's original suggestion of just plain Farenheit 451 as the title (or maybe Farenheit 451 ppm or Farenheit 451 - 2039).

Thoughts on these titles are welcomed.

2011-12-03 05:44:07
Dana Nuccitelli

Tom raises an important point that there were other large forcings in the LGM.  For example, see my Schmittner post Figure 4, where we won't achieve the LGM temp change (which is more important than the CO2 change) until next century at the earliest, in all likelihood.  The post as-is almost suggests we'll get there in the next few decades.  I'd suggest differentiating between comparing CO2 and comparing temp/climate changes somewhere towards the end.

As a general point, I think the post could be trimmed down a bit.  I'm a get-to-the-point kind of guy :-)  The CO2 lag section in particular is lengthier than it needs to be, IMO.  Generally the less you write, the more likely people are to read the whole thing.

There's also this after Figure 2:

"Man will be able to undo in 150 years what took nature hundreds of millions of years to accomplish, and in so doing, in that same time frame, we are duplicating a feat that normally takes nature 10,000 years to accomplish (i.e. increasing atmospheric CO2 levels by two thirds)."

Not sure if you're talking current or future levels, but right now the increase is just 40%.  In general the post alternates between talking current and future levels.  You say 150 years a lot, but by the time we reach 450 ppm, it will be closer to 200 years.

2011-12-03 08:15:46



Good points.  I will clarify that 451 ppm will be reached by 2039, although I think my 395 number is wrong (I thought I'd seen it, but the current level I'm seeing for annual data for 2010 is 389.8, or basically 390).  That would put the actual date at 2041.

I will clarify that my 150 is counting from when we really got going with fossil fuels around 1900, when we really started to generate emissions at a notable rate.  Or I'll switch it to 200.  I want to work with numbers that are easy for people to handle in their heads.

I'll shorted the CO2 lag section.  I agree, and I tend to repeat myself (which is important when teaching, but can become tedious in blog posts).

I will clarify that while 451 ppm will be reached by 2041, the actual changes will take longer to take effect.  We'll simply have been committed to them by that point.

As I said to Tom, I'll add a section to discuss the fact that the two situations aren't exactly the same, and maybe the difference in ice sheets and such will help because the forcings won't be the same... although, too, we're talking about a planet that is already sustaining just about the maximum number of humans possible.  Any retreat from that level of livibility is going to be very bad.

And, again, I'm not talking about equivalent temperature changes at all, I'm talking about a more generally equivalent "regime" change.  My point is rather (I believe) a common-man's version of the fact that if Schmittner is right and climate sensitivity is lower than expected because the temp change since the last LGM is lower than previously proposed, that's a bad thing, because it implies that for a lower temp change you get the same big real-world effect, so a lower temp change for us, now, ain't so good.  It's just like changing from Farenheit to Celsius.  Just because you were told the water is at 212˚F, and you are now told it's at 100˚C, it's still going to scald you.


2011-12-03 10:10:11
Dana Nuccitelli

Just remember that CO2 isn't the only factor driving those climate regime changes (i.e. Tom's point about the LGM ice albedo forcing).  It's a big one - the main control knob - but just matching the CO2 increase doesn't necessarily mean we'll match the climate shift.  It's an important caveat to note so you're not being "alarmist".

2011-12-03 19:06:44
Ari Jokimäki


Talking about alarmism, I would get rid of all those "chillings" and "frightenings". Or, putting it differently, I think this article would make a fine factual piece but now it's a little bit in the opinion piece side.

2011-12-06 01:07:46


I need final input, in particular corrections to any wrong (or misleading) science.  [That said, there was a ton more I wanted to explain, but cut or left out... I can't say everything I want or it would be a whole book.]

I made all of the proposed changes (much text that will be removed is struck out, but left in place to show what was ditched).  Unfortunately, while I made every effort to avoid my habit of redunantly saying the same thing over and over redundantly, again and again...

... it's gotten even longer due to the sections I added.  It strikes me as too long now, even though each section is short.

I also still need to add just a simple pretty picture or two, possibly this which I patched together from an NOAA graphic:


Target CO2 Levels

2011-12-06 05:49:55My two cents
John Hartz
John Hartz

Suggest that you change the title to: "Climate Regime Change" (Very few people under the age of 60 have any recollection of the book/movie Farenheit 451.

If the text is too long, break it up into a serial post.


2011-12-06 06:15:57


Actually, my daughter had to read Farenheit 451 as a freshman in high school two years ago.  American public schools use it a lot, along with the staples like Scarlet Letter and The Crucible.

Yes, something that we read for fun as a paperback is now being taught as "classic" American literature.

Tell me that doesn't make you feel old.

As an interesting side note, I've found references that the ignitiion temperature of paper is actually 450 C, not 451 F, although there are as many references (some seemingly credible) to it being 451 F, and many others that give it a broad range based on the quality of the paper.  So... did Bradbury get the temperature wrong and begin a science myth that now pervades the earth?  Or was Bradbury right, and it's just a confusing issue because not that many people spend time running experiments to determine the ignition temperature of paper?

[And yes, I considered opening the discussion with a reference to all this, as a preface about how confusing numbers can get, until I realized that I couldn't track down a final resolution with all of the conflicting info out there, so barring running my own experiment, I dropped it.]

2011-12-06 18:04:46
Glenn Tamblyn


Sphaerica. I come from the same prolix school of writing as you do so I didn't mind the length. And I liked the writing style. However you do need to sharpen the opening so that you will hold people through the entire length. The old adage in public speaking is 'Tell them what you are going to tell them. Then Tell them. Then tell them you have told them' Length is OK if you grab them at the start.

And I really like that your math leads to 451. Not just the Fahrenheit 451 reference but also the 450 ppm target reference. It does read a bit like an opinion piece. Which also makes it a sumary piece which is useful to leaven the detail posts with.

Also agree with Tom's comments about the details of the glacial cycle being to simplistic. Skeptics will pick up on this and you will be in a comments war with the pdeants. My basic understanding of Glacial cycles are that there are 4 main drivers and some secondary ones.

Main: Orbital, CO2, Methane, Ice Sheet expansion/contraction

Secondary: Vegetation changes, ocean current changes, Dust...

2011-12-06 23:54:26



My problem with the methane release is that I haven't found any real consensus in the literature on what the cause of the methane release was.  I was afraid to go there when I couldn't find anything definitive to point to to justify anything I'd said.  I've seen papers (as far as I recall) on methane release from exposed/thawing peat bogs, CO2 release from burning methane from huge peat bog fires, marine clathrates, gradual methane release due to tropical precipitation changes, etc.

I added a fly-by line stating that it happens, just so that it's in there, without going into any details.

I expanded the intro, but this of course expands the whole piece.

[And yes, it actually is as much an opinion -- or sales -- piece as anything, since I'm not a scientist... I just play one on the Internet.]

2011-12-07 00:08:11Open-access article on the PETM
Daniel Bailey
Daniel Bailey


Down the Rabbit Hole: toward appropriate discussion of methane
release from gas hydrate systems during the Paleocene-Eocene
thermal maximum and other past hyperthermal events

G. R. Dickens1,2

1 Department of Geological Sciences, Stockholm University, Stockholm, Sweden
2 Department of Earth Sciences, Rice University, Houston, USA

Received: 21 March 2011 – Published in Clim. Past Discuss.: 6 April 2011
Revised: 30 June 2011 – Accepted: 1 July 2011 – Published: 5 August 2011


Abstract. Enormous amounts of 13C-depleted carbon
rapidly entered the exogenic carbon cycle during the onset
of the Paleocene-Eocene thermal maximum (PETM), as attested
to by a prominent negative carbon isotope (13C) excursion
and deep-sea carbonate dissolution. A widely cited
explanation for this carbon input has been thermal dissociation
of gas hydrate on continental slopes, followed by release
of CH4 from the seafloor and its subsequent oxidation to CO2
in the ocean or atmosphere. Increasingly, papers have argued
against this mechanism, but without fully considering existing
ideas and available data. Moreover, other explanations
have been presented as plausible alternatives, even though
they conflict with geological observations, they raise major
conceptual problems, or both. Methane release from gas hydrates
remains a congruous explanation for the 13C excursion
across the PETM, although it requires an unconventional
framework for global carbon and sulfur cycling, and it lacks
proof. These issues are addressed here in the hope that they
will prompt appropriate discussions regarding the extraordinary
carbon injection at the start of the PETM and during
other events in Earth’s history.

2011-12-07 01:55:18


Thanks, Dan.  Link added.  Post now wildly out of control in length.

Perhaps it should be split.  I'm open to suggestions, although... it's not really the sort of piece that you tune into a "part 2" for.  It doesn't have any cliff hangers, and it's just not as seam-able as things like the OA series.

2011-12-07 02:09:02
Daniel Bailey
Daniel Bailey

Just ~2900 words.  One of Trenberth's and one of Maury Pelto's each went over 4,000.

2011-12-07 02:12:29


Oh, well, that makes me a 3/4 Trenberth (or is that a 0.75 climate blogger on the Trenberth scale)!  I should feel honored.  I do feel honored!

2011-12-07 20:10:25
Rob Painting

I know it's way too long, but I really enjoy your 'flavour' of writing.

A couple of other major bummers: 450ppm will probably signal the end of coral reefs, and will also usher in the death-knell of the Southern Ocean foodweb.  But don't let it get you down! (That's an old Aussie comedian's joke). 

2011-12-08 11:45:32


Sphaerica – Congratulations on an insightful and informative article written in language which Mr and Mrs Average can understand – and I love Figs 2 and 5.  A few points are as follows:

Schmittner argues for climate sensitivity of 2.3C, while Hansen claims on the basis of paleo evidence that it is ~3C.  Can they both be right?  I’ve found no recent comment from Hansen – have you?  I note that you use a climate sensitivity value of 3C.

temperature incrase of 2˚C    increase, not incrase

temperatures in Europe north of the Alps were roughly 1-2˚C higher than today.  Sea levels were 4 to 6 meters higher.   Hansen and Sato 2011 state that paleoclimatic evidence shows average global temperature are now within a few tenths of a degree of the Eemian maximum when sea level was ~5 metres higher than at present.

These seasonal changes in turn cause the ice sheets covering the northern hemisphere land masses to begin to melt.   I argue that present loss of polar ice is initiated by warming ocean water penetrating polar regions, rather than increased exposure to sunlight which could not be occurring given present orbital characteristics.  This results in  increasing emission of methane (particularly as a result of permafrost loss on which Shakhova and Semeliitov have written extensively), enhancing Arctic amplification, further increasing loss of land based ice.  Failure to take into account the effects of these slow feedbacks is what I argue (as does Hansen without specifying methane and albedo slow feedbacks) makes 450 ppm an unsafe, indeed a very dangerous target to aim for.

bandied about in recent days — 450 ppm.

Might it be more accurate to say --- bandied around in recent decades.

Sorry if this is just nitpicking.

2011-12-08 12:31:58



Climate sensitivity -- I saw that (2.3), but I'll stick with the standard estimated sensitivity of 3 for the post (which is also the basis for 450 ppm, etc.).

Incrase -- Fixed, thanks.

Eemian -- I took my temps and sea levels from multiple other sources which all seemed to agree.  I meant to reference Hansen and Sato, but then decided it made things too complicated.  I may still go back and add a link.

Polar ice sheets -- Polar, yes, but not the ice sheets that extended down to cover the continents at the start of the glacial termination.  They're two different animals.  I do discuss methane and such very briefly later in the post, in the section titled "Decades, Centuries or Millenia" but the post is already too long so I had to just touch on things... either that, or turn the entire thing into a climate science primer.

450, days or decades -- Yeah... but I couldn't find any clear reference to when 450 ppm first appeared, so I figured I'd leave it as "recent days" because SkS just had a post on it.  If you or anyone else knows when the number was first floated, so I could nail that down, that would be great.

2011-12-08 13:59:46
Dana Nuccitelli

"CO2 is termed the Earth's biggest control knob.  But it never has been, not really, because a knob implies something that someone can turn to control things."

I get your point, but we can (and are) turning that control knob (as you later note).  Plus you know the denialists will quote mine this and say "SkS contradicts Alley's control knob analogy!"  Maybe revise this just to say that in the past, temp and CO2 were intertwined, with one changing the other.

"CO2 does not "lag" temperature." => link

"We do not yet know if it was not terribly easy to turn the knob in one direction, with no capacity whatsoever to turn it in the other."

Bit of awkward wording here.  Maybe 'Right now we can turn the knob in one direction, but not the other', or something like that.

1.583 - kind of high precision there.  I'd just call it 1.6.

2011-12-08 15:11:36



Good points, all.

1) It urks me to lose emphasis (fun writing) to avoid quote mining, but you're right.  Rephrased as:

It hadn't been until now, because a knob implies something that someone can turn to control things.

2) I already had that link, earlier in the post, but there's no harm in repeating it, and you're right, it belongs there of all places.

3) Yeah... double negatives, followed by another negative.  Now:

We have far too easily turned the knob in one direction, but with no capacity whatsoever to turn it in the other.

4) 1.583... yes, you're right, especially since the post is trying to put things in layman's terms.  1.6 used.


2011-12-08 15:22:19
Daniel Bailey
Daniel Bailey

"We have far too easily turned the knob in one direction, but with no capacity whatsoever to turn it in the other."

Like over-winding your analog (showing my age) watch...

2011-12-08 16:14:39
Dana Nuccitelli

I think we can post this tomorrow if you feel ready.

2011-12-09 01:26:25



I tweak it from time to time, but yes, it's ready.  If I were ever a published author I think I'd visit people's houses periodically to update their purchased copies with corrections.

Question: Is the Notes section at the bottom the part that shows up on the page below the comments?  If so, I may go in and add footnotes and clear links to all of the supplemental/supporting material.

Also... note that as BaerbelW pointed out, the HTML <title> tag is going to need to have the <strike> tag removed from the title, as formatting is not supported in browser titles.  This change should not be applied to the <h2> title actually displayed on the page.

If this can't be done because of the way the site builds pages (i.e. if pages are loaded dynamically from a database without the option to vary the head title from the body title) then the title of the article will need to be changed (maybe to Farenheit, no, ppm 451 or (Farenheit) 451 ppm or just ppm 451 or 451 ppm, which isn't nearly as clever and entertaining).


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
   <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
   <title>Farenheit ppm 451</title>
<div id="mainbody">
		<h2><strike>Farenheit</strike> ppm 451</h2>
		<h4>Posted on 2 December 2011 by Sphaerica</h4><h1>A Chilling Thought</h1>
<p>The recent <a href="http://www.skepticalscience.com/Schmittner-climate-sensitivity-goood-bad-ugly.html" target="_blank">Schmittner paper
2011-12-09 01:55:34
Daniel Bailey
Daniel Bailey

I like

(Farenheit) 451 ppm

2011-12-09 02:52:03



Agreed, (Farenheit) 451 ppm was my preference, too, after the strikethrough version.

Who ever posts it... if there's any trouble with the strikethrough, the new, workable title should become (Farenheit) 451 ppm.

2011-12-09 03:02:47
Tom Curtis


I think PPM 451 would be a better title as it has the same syllable count as Farenheit 451.

2011-12-09 03:10:41
Daniel Bailey
Daniel Bailey

Title updated to

(Fahrenheit) 451 ppm

note the spelling correction.

2011-12-09 03:11:38
Daniel Bailey
Daniel Bailey

But I like Tom's suggestion, too...

2011-12-09 03:19:21
Dana Nuccitelli

I think John is going to post Plimer vs. Plimer today, and I might post Huber and Knutti tomorrow, so we might hold off on this one until Saturday.

2011-12-09 03:34:27


My fear with PPM 451 was that people wouldn't recognize the connection to Farenheit 451.  It works as long as people recognize it, otherwise it's just an obtuse scientific measurement.

It would have worked if I'd included the paragraph explaining how Bradbury got the temperature wrong in his title, but it's qusetionable whether he did or not.  But without that tie, I'm not sure the connection will be made.

I could instead open or close with a paragraph about how Bradbury's classic Farenheit 451 presented a dark future where books are burned, when reality — PPM 451 — may turn out to be darker than fiction.  But that's a bit heavy handed, I think, when I've worked so hard to tone down the post, rather than to too "alarmist."

2011-12-09 03:34:59



Whatever you choose is fine.  I'm just happy to have finally taken the time to have written something.