"The Entire Planet!"

By Sean Carroll | June 4, 2006 1:33 pm

I had the great pleasure last night of meeting Melissa of Shakespeare’s Sister fame and some of the great cast of characters she has assembled over at her blog, including Mr. Shakes, Litbrit, Paul the Spud, and others. The occasion was a visit to our northern suburb of Evanston to catch Al Gore’s movie An Inconvenient Truth. In fact I had already seen the movie, but was more than willing to see it twice. I am quick to admit that I am not a Gore fan, and the thought of paying hard cash to see a movie that consists mostly of him giving a Keynote presentation (there was plenty of Apple product placement) falls somewhat below “drinks at Clooney’s villa in Tuscany with the gang” on my list of exciting ways to spend an evening.

But it turns out to be a great film, oddly compelling, with at least one priceless joke about gold bars. It’s not a science documentary — many graphs have no labels on their axes (much less error bars), and much of the evidence adduced is anecdotal and aimed at the gut rather than the brain. But what anecdotes they are. It’s hard to see pictures of Russian fishing boats stranded in a barren sandy landscape that once was a major lake bed without thinking that something needs to be done.

There isn’t any scientific controversy over whether or not climate change is happening, or whether or not human beings are a major cause of it. That argument is over; the only ones left on the other side are hired guns and crackpots. But the guns are hired by people with an awful lot of money, and they’re extremely successful at sowing doubt where there shouldn’t be any.

Their task is made easier by the fact that the atmosphere is a complicated place, and the inherent difficulties in modeling something as messy as our climate. But climate models are not the point. The point is not even the dramatic upward trend in atmospheric temperature in recent years. The actual point is made clear by the plot of atmospheric CO2 concentration as a function of time, which I just posted a couple of days ago but will happily keep posting until I save the planet.

CO2 concentration

Here is the point: We are taking an enormously complex, highly nonlinear, intricately interconnected system that we don’t fully understand and on which everything about our lives depends — the environment — and repeatedly whacking it with sledgehammers, in the form of atmospheric gasses of various sorts. Statements of the form “well, we don’t really know what that particular piece of the system does, so we can’t be rigorously certain that smashing it with a sledgehammer would necessarily be a bad thing” are, in some limited sense, perfectly true. They are also reckless and stupid. The fact that there are things we don’t understand about the environment isn’t a license to do whatever we like to it, it’s the best possible reason why we should be careful. And being careful won’t spell the doom of our economic system, bringing global capitalism crashing to the floor and returning us all to hunter-gatherer societies. We just have to take some straightforward steps to mimimize the damage we are doing, just as we very successfully did with atmospheric chloro-fluorocarbons to save the ozone layer. And the best way to ensure that those steps are taken is to elect leaders who are smart and determined enough to take them.

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  • http://iso42.blogspot.com wolfgang

    Sean,

    your chart looks really scary. Fortunatley, the climate forcing due to CO2 increases proportional to ln(C) only, with C being the concentration of CO2 in the atmosphere.

  • gringo

    Anecdotal?

    Bullshit. What you see is what you get. Nothing anecdotal about it.

  • adrian

    I’ve not seen the film yet – it doesn’t seem to be showing much in GA – but
    I’m looking forward to it. RealClimate.org is a good place to go to learn about
    what is happening in climate science and they give it a thumbs up. As for Sean’s
    quip about non-scientific graphics, I can’t help but notice the scale on Sean’s CO2 plot.

  • Say Lee

    Yeap, that’s called the Precautionary Principle.

    Detractors have tried to discredit the IPCC conclusions, ranging from the Gaia Principle to the uncertain and yet potentially ameliorating role of water vapur and aerosols. However, the key word is the balance of evidence.

    There is nothing inconvenient about the truth, only vested interests that serve as blinders.

  • s.y.

    Sean, and everyone,
    what is your take on Steve McIntyre’s skeptical stance on the Anthropogenic Global Warming hypothesis, discussed at length at his blog (http://www.climateaudit.org/)? He doesn’t sound like a crackpot, and I believe he’s not being paid by the bad guys (in fact by anyone). I can’t claim to understand everything he’s saying, but I’ve been impressed by this article, and nothing I can find on the RealClimate site has convinced me that he’s wrong. I’m interested in learning what you think is wrong about his work. I look forward to being educated. Thank you.

  • http://sourav.net/ Sourav

    […]The fact that there are things we don’t understand about the environment isn’t a license to do whatever we like to it, it’s the best possible reason why we should be careful. And being careful won’t spell the doom of our economic system, bringing global capitalism crashing to the floor and returning us all to hunter-gatherer societies.[…]

    Right, and the economy is a intricate, complex and robust system that we can whack at with carbon restrictions?

    The precautionary principle is paralyzing. It’s better to understand risks rather than assume them, for any cost-benefit analysis to be accurate.

  • Chris W.

    You know what, Sourav? Over the next century, if not sooner, we will be whacking at the economy with carbon restrictions anyway, because we are running out of fossil fuels that we can afford to exploit. We’re better off whacking at something that we created and are tinkering with on a daily basis, than an immense and ancient natural system that has been a precondition for our existence. After all, as the free market advocates would have it, the economy is a system for effectively allocating resources and managing limitations on those resources. More generally, it’s a system for solving problems. Running the risk of making the planet unlivable for much of its human population—not to mention many other species—is a big problem.

  • Chris W.

    Right, and the economy is a intricate, complex and robust system that we can whack at with [a massive and growing federal deficit, or a hugely expensive war in the mideast, or the gross mismanagement of multiple Fortune 100 companies, etc, etc, etc…]?

  • Hiranya

    I just saw this brilliant, terrifying film. Hopefully it will do more than preach to the choir, and reach a wide audience. I am sorry to hear that you think Al Gore is not one of those leaders who would satisfy your last sentence “And the best way to ensure that those steps are taken is to elect leaders who are smart and determined enough to take them.” He seemed anything but wooden, very sincere, and driven by a genuine concern for the future of the planet. Not that I have any influence on US politics, but I am not aware of anyone in the current crop of politicians who shows a similar concern about this vital issue.

  • http://name99.org/blog99 Maynard Handley

    The single most useful thing people could do for this issue is rename “greenhouse effect”. Most people have no experience with greenhouses, and the very word greenhouse has a positive connotation.

    What do I suggest?
    When you park your car in summer with the windows closed, then come back two hours later, the car interior is *scorching*, easily 10 or 15 degrees hotter than outside. THAT is the greenhouse effect — light comes in easily through the windows, but IR does not go out easily. What we need is a name along the lines of the “summer parked car effect”, but something quite a bit catchier and less dorky. I am serious about this — words matter, and we need a good phrase here.

  • http://sourav.net/ Sourav

    Chris W.:

    The world is a much varied place, by geography and over time. The human species has succeeded not because we live close to the land, but because we can adapt technologically through our industry. As such, our technology and the economic preconditions to it are more valuable to our survival than small climate variations.

    Indeed, research afforded by (or done by) the capitalist economy will allow us to adapt to a climate crisis. But I don’t see much sense in cabon caps, emissions restrictions, etc. without an assessment of the attendant costs and benefits.

    As for the other stuff, e.g. unnecessary wars and budget deficits, no argument here.

  • http://www.pieterkok.com/index.html PK

    Sourav, what do you call a small climate variation? If it is small enough that it is not a problem, then it is not a problem. But it is not small. A global temperature rise of few degrees Kelvin has a devastating effect on gulf streams, sea levels, etc.

    Also, economic forces won’t work very effectively, because poor regions will be affected first (droughts in Africa, etc.), and poor regions do not have a strong economic impact, by definition.

  • http://arunsmusings.blogspot.com Arun

    Wolfgang,
    Proportion to ln(C) if there is no feedback (which there is).

    Sourav,
    The Tibetan glaciers are retreating fast (says the Chinese Academy of Sciences) – threatened are the major Chinese rivers as well as the Indus, Ganga, Yamuna, Brahmaputra. What the around-billion people who depend on these rivers will do if their volumes diminish is a big unknown.

    Hiranya,
    Though I voted for Gore and was very sad at the results of the 2000 election, I must say Gore then was wooden, and often uninspiring. Even so, he would have been better than the current Preznit; unfortunately I do not decide elections.

  • Hiranya

    Sourav: In the movie there is a graph of the *natural* CO2 variation over the past 650,000 years, with the temperature tracking it faithfully in a sawtooth pattern (it corresponds to ice ages and interglacial periods). This natural temperature variation (what you call a “small” climate change) is the difference between a nice summer day in New England and a mile of ice over your head (good luck to the capitalist system dealing with that). The CO2 has never naturally been over 300 ppm. You can see in Sean’s graph where it is now. The attendant temperature variation could be much greater than the mile of ice, but in the other direction. Please please watch this movie – its meant to educate people who think the way you seem to – and you will see that there are measures you can take with *current* technology, that won’t bankrupt the economy and go a long way to dealing with this problem.

  • Torbjörn Larsson

    Maynard,
    If “greenhouse effect” is too positive, try calling it the “Venus effect” instead. it sounds sufficiently scary to me, at least.

    Hiranya,
    There has been several natural occurences with higher carbon dioxide content. During the Paleocene-Eocene Thermal Maximum “Atmospheric carbon levels then are thought to have been about 2-3,000 parts per million (ppm)” ( http://en.wikipedia.org/wiki/Paleocene-Eocene_Thermal_Maximum ).

  • Hiranya

    Tobjorn: I was referring to the last 650,000 years in my comment (i.e. the era of the modern humans). The conditions during the PETM does not instill me with a great deal of confidence that the capitalist system will take it in its stride :(

  • Cynthia

    adrian-

    While this film is sparsely being shown in the lesser-red-state of GA, I can vouch that this film is more sparsely being shown in the greater-red-state of AL. Furthermore, if Michael Crichton’s “State of Fear” was ever made into a film, then the movie houses within the nation’s red states would unquestionably make certain that this counterpart to Al Gore’s “An Inconvenient Truth” was readily available for mass showings.

    Sean-

    I have a slightly better opinion of Al Gore. Even if Al Gore is not a cousin of the highly celebrated author and renowned social critic- Gore Vidal, I still consider Al Gore to be one of the finest orators in present-day politics.

  • http://yourdailyllama.blogspot.com wolfgang

    Arun,

    > Proportion to ln(C) if there is no feedback (which there is).

    the CO2 forcing is proportional to ln(C) since Arrhenius and in all GCMs.
    The question about the feedback is what the climate change discussion
    is all about of course. I just thought it is a bit strange that Sean shows a
    chart with linear scale, showing a linear increase of CO2 without further comment other than “be scared”…
    This blog is about science or so I thought.

  • http://blogs.discovermagazine.com/cosmicvariance/sean/ Sean

    Perhaps this blog is not about science, but we do know enough to say that (1) log plots and linear plots convey precisely the same information, and (2) it would be hard to come up with a curve that was less linear than the one shown on that plot.

  • http://yourdailyllama.blogspot.com wolfgang

    Sean,

    > a curve that was less linear

    yes, a nice hockey stick. But as I wrote it is “showing a linear increase of CO2″
    for the relevant periode (the red line).
    Of course, I guess I agree with you that climate change is more about politics and scary charts than science 8-)

  • Hiranya

    Um – Wolfgang – if the climate forcing was proportional to ln C, and C was increasing exponentially, or at best a powerlaw, as the chart shows (I do agree that the rate of change is better apparent with a logarithmic y axis) – maybe you really should be concerned about what the “scary graph” tells you, rather than criticising the messenger…

  • http://yourdailyllama.blogspot.com wolfgang

    > and C was increasing exponentially

    ahhh, finally somebody gets my point. The whole story hangs on the assumption that C grows exponentially. But so far this is an assumption only and Sean’s chart does not adress this question at all (the only relevant question about CO2 in the context of climate change).

  • Hiranya

    I am not sure which web page you are looking at, Wolfgang, but the one I see in this post precisely addresses your question – i.e., it shows C as a function of time, and shows what looks like a near-exponential increase of C from the “baseline”.

  • http://yourdailyllama.blogspot.com wolfgang

    I am not sure how I would fit this line.

  • Hiranya

    Looks like you handily decided to ignore data before 1955.

  • http://blogs.discovermagazine.com/cosmicvariance/sean/ Sean

    Hiranya, you can’t win. They don’t care that the data are obviously not linear, even if you only look at the last century or so; through the miracle of Taylor expansions, they will always look linear if you cherry-pick a short enough interval.

    http://planetebleue.canalblog.com/images/Image1.jpg

    What they care about is distracting people into minutiae of log vs. linear plots and curve-fitting, when the point is that we have been dumping obscene amounts of CO2 into the atmosphere, raising the concentrations way way outside their natural range, which is reckless and stupid.

  • http://yourdailyllama.blogspot.com wolfgang

    Hiranya,

    I did not ignore anything; this is the Mauna Loa data.
    The relevant hypothesis is that economic growth will lead to exponential growth of CO2 concentration. The data does not support this, as far as I can see. (This indicates a negative feedback by the way, e.g. oceans absorbing more CO2 than expected …)

  • http://yourdailyllama.blogspot.com wolfgang

    Sean,

    > raising the concentrations way way outside their natural range, which is reckless and stupid.

    can you tell us what the natural range is and why?

  • Hiranya

    Sean, you’ve expressed my thoughts perfectly. Has anyone thought of the idea of making a part of income tax proportional to one’s “carbon footprint” (especially for businesses) as an incentive to adopt more climate-friendly practices?

  • Hiranya

    Wolfgang, I will continue this argument with you when you’ve had a refresher course on hypothesis testing and modelling data.

  • http://yourdailyllama.blogspot.com wolfgang

    Sean,

    in order to answer my own question:
    This chart shows that abrupt changes in CO2 (and temperature) are not uncommon during the long history of the atmosphere.
    Now we add CO2 on top of it due to human activity. This additional amount follows a linear trend as is pretty clear from the Mauna Loa data.

    Hiranya,

    you have no reason to discuss with me since you (liek many others) have already made up your mind. Also, it is pretty clear that this is not the place to discuss climate science.

    Be scared everybody! Actually, be very scared …

  • http://blogs.discovermagazine.com/cosmicvariance/sean/ Sean

    The idea of a carbon tax is a very serious one, that Gore has been pushing for a while. Brad DeLong (who served in the Clinton administration) gives some of the background:

    http://delong.typepad.com/sdj/2006/05/why_oh_why_cant_13.html
    http://delong.typepad.com/sdj/2006/06/greg_mankiw_ask.html
    http://delong.typepad.com/sdj/2006/06/those_who_forge.html

  • http://blogs.discovermagazine.com/cosmicvariance/sean/ Sean

    Thanks, Wolfgang. The chart you point to:

    http://carto.eu.org/article2481.html

    makes it completely obvious that increasing CO2 by about 100 ppm is correlated with an increase in atmospheric temperature of about 10 degrees Celsius. And also that it has never gone above 300 ppm in the last 400,000 years. Today we’ve pushed it up to 375. Which side are you on, again?

  • http://yourdailyllama.blogspot.com wolfgang

    Sean,

    > makes it completely obvious that increasing CO2 by about 100 ppm leads to an increase in atmospheric temperature of about 10 degrees Celsius.

    non-linear laws such as ln(C) are not easy to understand.

    Increasing CO2 from 200ppm to 300ppm does not have the same effect as increasing it from 300ppm to 400ppm.
    The additional CO2 can only absorb radiation that is not already absorbed…

    By the way, the variation of temperatures in the past is much larger than the increase due to human activity (about 0.6C).

    > Which side are you on, again?
    I am on no side; I just try to understand something.

  • http://yourdailyllama.blogspot.com wolfgang

    … and for Hiranya and others.
    Looking at the long-term chart makes it pretty obvious that the data before 1950 fall very well within the natural behavior. Thus you can only use the more recent data to estimate the (future) human contribution to CO2 concentration.
    (We simply did not produce enough before 1950 to have a clear signal.)
    And this trend is linear, when the assumption is that is is exponential.

  • Hiranya

    Wolfgang, check out this article and others on that site. And do you actually understand what Sean meant by his comment “through the miracle of Taylor expansions, they will always look linear if you cherry-pick a short enough interval.”? I would actually be happy to talk with you if I actually believed you were genuinely interested in understanding something, I am also, and I would be overjoyed if it turned out all the climate scientists were wrong and we weren’t facing a scary and uncertain future. But so far you have acted just like a troll.

  • http://yourdailyllama.blogspot.com wolfgang

    > And do you actually understand what Sean meant by his comment “through the miracle of Taylor expansions, they will always look linear if you cherry-pick a short enough interval.”?

    Thank you for asking.
    If you want to know what exponential growth looks like, take the (global) stock market and look at a chart *with linear scale* from 1950 to now.
    Compare this chart with the Mauna Loa data in the same time frame and tell me what difference you see.
    Both charts are supposedly proportional to economic growth.

  • http://yourdailyllama.blogspot.com wolfgang

    > check out this article and others on that site.

    I did. Thank you. I read realclimate.org on a regular basis, as well as climateaudit.org (after all I live on an island.)
    It is obvious that the increase from 300ppm to 350ppm is due to human activity. But it is also clear (to me) that the increase is less than exponential (lets put it this way). Combined with the fact that the CO2 forcing is proportinal to ln(C) this means IMHO that one does not have to be as scared as Sean suggests. Thats all.

    Have a nice day and feel free to be as scared as you want.

  • http://www.chinalawblog.com China Law Blog

    I have heard Gore holds up China as having better emission standards than the United States. This is a joke.

    China is an environmental disaster and it is not because of its laws. It is because of the lack of enforcement of the laws. China’s car emission laws may be better than the United States’, but that is basically irrelevant because there are a huge number of cars there whose emissions would probably not meet anyone’s standards.

  • Hiranya

    Wolfgang, thanks – I wasn’t awaiting your permission to be scared. And you don’t need mine to go back to your comforting echo chamber.

  • http://yourdailyllama.blogspot.com wolfgang

    Hiranya and Sean,

    it is really encouraging to see that discussions with scientists are so much more informative. Always about the facts and without personal attacks or strawman arguments. This really is a great blog!

  • http://arunsmusings.blogspot.com Arun
  • http://sourav.net/ Sourav

    Arun, PK:

    What you’ve pointed out is all part of the cost assessment. I simply disagree in principle with halting programs/technologies which are clearly beneficial, l but whose environmental costs are not yet known because the effect is intricate.

    In particular, I don’t agree with Sean that it was “reckless” to dump CO2 in the atmosphere. Most large scale human activities have a significant impact (heat in water and water vapor from industrial and residential cooling, methane from agriculture, etc. etc.). We’ve learned that CFCs and CO2 are problematic, so we curb those, but overall if we’ve had to ask permission for everything we wouldn’t be anywhere. This would affect 3rd world countries as well, who are particularly reliant on “dirty” technologies.

    Research is good, and we will learn how to optimize our activities as the knowledge is accumulated.

  • http://arunsmusings.blogspot.com Arun

    Sourav,

    Who is calling for a halt to production or anything? After all, e.g., India will be able to afford to mitigate its greenhouse gas emissions if and only if it is growing economically.

    To raise a trivial point, India could recap the US telecom history and lay millions of miles of copper wire, or India could (and is) leap-frogging into a wireless + fiber optic age. After stagnating at one phone per 100 people for decades, India will reach a teledensity of 50 (mobile) phones per hundred within the next few years. This was because technology was developed. We can hope that similar trajectories are possible with energy consumption. But it requires technology to be developed.

    -Arun

  • http://www.pieterkok.com/index.html PK

    Soarav says: We’ve learned that CFCs and CO2 are problematic, so we curb those

    We’re not curbing anything! We set up a CO2 market to buy credit from poor countries that meet the Kyoto criteria trivially, and in the mean time the CO2 levels are still rising.

    I do agree that, with a bit of direction and foresight, current and near future technology can stop this trend. In fact, it will most likely create a whole new industry and will be good for the economy. Unfortunately, the energy industry at large wants to race the same horse until it drops dead from exhaustion.

  • http://sourav.net/ Sourav

    Arun:

    Again, it is Sean who suggests that it was ‘reckless’ to have dumped so much CO2 in the atmosphere, and I think it’s not a reasonable judgment even in hindsight. At the price of CO2 there was tremendous economic growth throughout the world, and it was the right decision at the time.

    ***

    PK:

    Yes, well, there will be political problems ;)

    For example: indeed, the private sector is interested in alternative energy sources and media for storage apart from gasoline, but it’s a research horizon for them as long as crude is dirt cheap and the external costs of carbon are not fed back in.

  • http://capitalistimperialistpig.blogspot.com/ CapitalistImperialistPig

    Sean – I believe that global warming is a serious threat, but your statement that: increasing CO2 by about 100 ppm is correlated with an increase in atmospheric temperature of about 10 degrees Celsius. is quite silly. Climate sensitivity is hotly debated in the scientific community bu no one believes an increase of less than 50% in CO2 could make it warmer by 10 C. The IPCC TAR estimates 1.5 to 4.5 C for each doubling.

  • http://capitalistimperialistpig.blogspot.com/ CapitalistImperialistPig

    Hiryana and Sean – Wolfgang may not agree with any of us on global warming, but I assure you that he knows more statistics than any of us.

  • http://www.netbsd.org era

    CapitalistImperialistPig,

    Wolfgang may not agree with any of us on global warming, but I assure you that he knows more statistics than any of us.

    Do enlighten us about Wolfgang’s ‘expertise’ in statistics(not how to lie with statistics)…

  • http://iso42.blogspot.com wolfgang

    era,

    what I know or do not know about statistics is none of your business.
    If you suggest that I lie then I suggest that you i) indicate who you are instead of hiding behind a generic address and ii) perhaps point out what exactly I am lying about.

  • http://iso42.blogspot.com wolfgang

    Perhaps I should help you make your point. My main statements are/were:
    i) the climate forcing due to CO2 behaves like ln(C)
    ii) there is no good evidence that CO2 increases exponentially.
    The CO2 produced by human activity should give the strongest signal for recent
    years, i.e. after WW2, but the most reliable data (Mauna Loa) does not show this.
    By the way a proponent of global warming seems to agree with me
    http://mustelid.blogspot.com/2006/01/co2-and-sres.html

    Again, I am eager to hear where exactly I am wrong.
    And neither the words “troll”, “crank”, “liar” count as strong argument in my book.

  • http://iso42.blogspot.com wolfgang

    This picture shows the recent trend in 5 major greenhouse gases
    http://en.wikipedia.org/wiki/Image:Major_greenhouse_gas_trends.png
    CO2 can at least keep the linear trend up …

  • Hiranya

    Wolfgang, it should be clear to you if you read the responses you got that we disagree on (ii). There is a lot of evidence that humans are responsible for the CO2 increase in the atmosphere from *1800-present* – and you can find links and detailed references starting here. I didn’t call you a liar, but to cherry pick data to fit your conclusion (as you did when you threw out everything before 1955) is dishonest and misleading. We only have your *assertion* that human impact on atmospheric CO2 is only visible in the Mauna Loa data and invisible in any previous data. This does not count as an argument in *anyone’s* book, and if you post again without references to back up this claim, you will confirm yourself as a troll.

  • http://yourdailyllama.blogspot.com wolfgang

    But do you not find it a little bit odd that the data fits your assumption of exponential growth only when you include data before 1955; i.e. when the impact of human activity was the smallest?
    The mixing of CO2 in the atmosphere occurs on a timescale of a few years only.

    No you did not call me a “liar”, just a “troll” and it was ‘era’ who suggested that I was lying. Now you suggest that I am dishonest.

    We cannot agree on the statistics of CO2, but perhaps we can at least agree on the statistics of personal attacks.

  • http://yourdailyllama.blogspot.com wolfgang

    > We only have your *assertion* that human impact on atmospheric CO2 is only visible in the Mauna Loa data and invisible in any previous data.

    Re-reading your text it is clear to me that you do not understand my argument;
    It is exactly the other way around. If you want to see exponential increase (due to human activity, there is no exponential increase due to natural cause) you have to look at old data.

    I really think I am wasting my time here; Thanks anyway.

  • nano

    Wolfgang,

    The undisputed contribution from humans so far (50, according to you in #40), out of ‘natural maximum’ of 300 is HUGE considering the time scale involved (i.e., relative to geological time scales). The Taylor series explanation is apt: the above data looks even more benign if plotted against seconds instead of years, decades or centuries… Which is the proper time scale for this problem?

    If it continues ‘linearly'(as you put it) so it is 600 in a couple of centuries, is it still no big deal? Well that is your own biased opinion (to say the least).

  • http://www.pieterkok.com/index.html PK

    It is not just the Taylor expansion that hides the exponential growth of the CO2 concentration on short time scales, but mainly the error in the data, and consequently the fitted curve. That is why you need to look at this over a reasonably long time scale.

    The CO2 concentration growth can suddenly have gone linear with time, but that would require a mechanism for why this sudden change has come about.

  • Hiranya

    I actually just tried to fit just the Mauna Loa data that Wolfgang linked to, just for a check. You can already see the non-linearity in this small timescale. A linear fit is a poor fit.

  • http://yourdailyllama.blogspot.com wolfgang

    Hiranya,

    I really appreciate that we are back to science.
    I did the exercise some time ago. A direct fit (linear vs. exponential) does not show anything significant, both fits give you about the same confidence.
    If you want to test the hypothesis that the ML data shows exponential growth you should examine the first differences and check for exponential growth of those differences.
    A simple stationarity test rejects this hypothesis as you can see in
    this chart.
    The black line includes a 2nd order term in t and curves the wrong way; the growth rate flattens instead of accellerating as it should.

    You can *assume* exponential growth and fit the growth rate from the data, but the data itself does not indicate exponential growth.

  • Hiranya

    Wolfgang, I didn’t make any exponential assumptions. I tested the hypothesis whether the data was described a *linear* function. Since we are being scientific, kindly provide the scientific reasons why you abandon data before 1955, and reasoned refutations for the human impact on the atmosphere pre-1955 that I cited before.

  • Hiranya

    PS: And since you are ignoring the basic point which nano expressed very well (that at best you are postponing the inevitable a couple of generations) I won’t waste my time on this debate anymore.

  • http://yourdailyllama.blogspot.com wolfgang

    > kindly provide the scientific reasons why you abandon data before 1955

    because economic activity was lower by a factor of about 10 and thus the signal is less by the same factor and in addition you have to merge data of different quality and the merging itself introduces all kinds of artifacts.

    If I want to estimate the growth rate of the internet I would mainly use data from the 90s until now and leave out the data from before 1950 as well 8-)

    > I won’t waste my time on this debate anymore.

    This was my conlclusion yesterday and I think I will stick to it from now on.

  • Torbjörn Larsson

    Unfortunately I had no time to make a timely response.

    Hiranya says:
    “I was referring to the last 650,000 years in my comment (i.e. the era of the modern humans).”

    And I was discussing natural occurences. Otherwise we are cherry-picking data.

    “The conditions during the PETM does not instill me with a great deal of confidence that the capitalist system will take it in its stride :(”

    You don’t know that, since a) the natural system recovered from much larger disturbances b) there was no capitalist system during PETM. :-) But see my comment about the “Venus effect”. :-(

  • Hiranya

    Torbjorn: the whole “scary” part of climate change is the rapidity of the “change”. Its not that the capitalist system has to adjust to the PETM conditions while the human race evolves over a stable period of order a million years. Its the chaos caused by a sudden transition from one stable climate configuration to another that I don’t think the capitalist system can handle very well. Note that sudden is in geological terms. I don’t think a 650,000-yr baseline is cherry picking data since (a) these are the conditions during which the human race evolved, and (b) going from memory it includes 5-6 periods of glaciation to get an idea of the natural cycle of climate change.

    BTW since this is a science blog I thought I would say what I did to check the hypothesis that the ML data was fit well by a linear curve. Note that I am a theoretical cosmologist, so I don’t make any claims about how good the data are – the climate scientists who accept it are far more qualified to make that judgement than I am.

    The data appear to show a pretty monotonic upward trend modulated by yearly oscillations. There don’t appear to be statistical errors given for the data points (at least I couldn’t find any). One can assume that the statistical errors are constant from measurement to measurement, and do a least-squares fit to the data of a linear function modulated by a sinusoid. Once you get the best fit parameters, you subtract the “best fit” model from the data. If your hypothesis is right, the residuals should look like white noise. In practice, this is not quite the case, since the oscillations are not completely described by the simple sinusoid so they leave a residual too. However this effect is very easy to identify and filter, as it has a particular frequency. Now you check the power spectrum of the residuals (e.g. by taking a fourier transform of it). You can see that the power spectrum does not resemble white noise. Therefore either the data are not described by a linear function, or else the statistical errors were not random. Since the data are accepted in the field, I conclude that the former is the case.

    Of course if I could find the statistical errors there are other, more sophisticated tests I can perform, but this one works well to show the non-linearity of the data.

  • Hiranya

    Tobjorn: Let me also add that I have very little concern about the natural system recovering from what we do to it. It has taken far worse blows in the past and recovered with new types of biodiversity after massive extinction events. Its just that I have some small concern about our own survival from the consequences of what we do to the natural system ;)

  • http://yourdailyllama.blogspot.com wolfgang

    > the whole “scary” part of climate change is the rapidity of the “change”.

    Torbjorn,

    as I wrote above, the data suggests that the increase in CO2 is less than exponential (and flat to down for other greenhouse gases). The average increase from one year to the next grows less than linear (when it should grow exponentially for the really scary scenarios). This makes a huge difference, because it is important whether we have 10 years (as Al Gore suggests) or 100 years to change technology.
    And there are indications that we will have to move away from oil over the next 100 years anyway.

  • Hiranya

    #7 s.y.: I have been reading extensively on the relevant issues since watching this movie, and I found these criticisms addressed in detail at a non-technical level here and many other places on the same site, including the links to the refereed publications criticising the claims of Steve McIntyre, which discredit his methodology. Hope this is helpful!

  • Hiranya

    Wolfgang, there is no evidence in the only dataset you find admissible that there is a “less than linear” trend. There is a “more than linear” trend. The beauty of science and having public data is that such claims are very easily checked.

  • http://yourdailyllama.blogspot.com wolfgang

    I think you misinterpret what I wrote:
    “The average increase from one year to the next grows less than linear.”

  • http://yourdailyllama.blogspot.com wolfgang

    Just to make myself clear. In an exercise like this you do not fit C(t) but
    d(t) = C(t) – C(t-1) as a function of t.
    The first derivative of an exponential is still an exponential, but d(t) grows slower than a + bt.

  • Hiranya

    Wolfgang, your other statement about the trends of other greenhouse gases does not seem to be correct either. I apologise for calling you a troll, I do now think you sincerely believe what you are saying. But anytime I think you post something misleading here and it’s within my ability to verify it, I am going to correct you, because I believe it is my duty as a scientist to the people who stop by to read this and have not made up their minds.

    I agree with you that the precise rate of climate change has some uncertainty (as far as I can determine the behavior is within a power-law to an exponential). However this gives us only a time-frame between 10-100 years (as you seem to agree), and given the non-linear nature of the problem and its complexity, it is not at all clear when the “point of no return” is passed and one cannot prevent drastic climate change. I am not at all worried about the future of the planet, but I *am* worried about the future of the human race. For my part, I prefer to do something about it now, rather than have the blood and suffering of future generations on my hands.

  • Hiranya

    PS: I understand perfectly well how to fit a time series :)

  • http://yourdailyllama.blogspot.com wolfgang

    > the trends of other greenhouse gases does not seem to be correct

    I refer to the picture in #54. The one who pointed the flattening out was James Annan who is a proponent of global warming.

    I would like to clarify a few things by the way:

    i) I am certainly not an expert on climate change, all I did was to take the available data, load it into R and play around with it. I think my exercise was correct, but the beauty is that everybody can do it for herself and does not need my judgement or yours.
    I would really appreciate to see how a professional approaches this and in particular what models are used (e.g. about the feedback of the biosphere which seems to take advantage of the increased CO2 supply and thus slow its growth).
    So far I have mostly seen papers which simply *assume* that the growth is exponential.

    ii) I think it would be a big step forward if this debate would not be about global warming: yes vs. no or global warming: Gore vs. Bush
    but if it would be possible to discuss more subtle issues, like how much and how fast, without running the risk of being insulted.

  • Hiranya

    The CFCs must be dropping because of the regulations that were enacted to deal with the ozone hole problem (these regulations are an example of how we *can* take a positive step to control our own future! The ozone hole seems to be repairing itself). I would love to have some references to why methane is dropping – is it a natural effect, or is it also due to regulations on methane emissions due to human activity. The point at least in the case of the CFCs is that we *did* something to solve the problem, rather than denying either that it exists, or claiming that we couldn’t do anything about it without harming the economy.

    I think the consensus is that the increase in CO2 is due to human activity. The increase is an observation, not a model. Are you saying that biosphere feedback will take in more CO2 only in the future, and whatever mechanism you propose is not active now?

    Not sure whether you are in Chicago but we’ll try to see if we can organize a Cafe Scientifique with a real climate scientist so these questions can be asked. They also seem to respond in detail to well-posed questions on the realclimate.org site. I am not a climate expert (just trying to educate myself too) so I suggest you try asking there.

  • http://yourdailyllama.blogspot.com wolfgang

    > Are you saying that biosphere feedback will take in more CO2 only in the future

    I would assume it will take in more as the CO2 rises. As Freeman Dyson has pointed out, simple changes in agriculture etc. could make a huge difference. Of course methane depends on farming …

    No I am not from Chicago.

  • Hiranya

    Yes, there have been significant recent regulations on methane emissions and the US has been able to cut its anthropogenic emissions.

  • Hiranya

    re: feedback. The increase we measure is what is left *after* all natural processes that counteract the anthropogenic emissions have had their effect. So the present biofeedback is already taken into account. So you have to postulate some new mechanism which will only kick in when the CO2 levels have increased even further. I have no knowledge of this so I suggest asking at the realclimate site.

  • http://yourdailyllama.blogspot.com wolfgang

    > Yes, there have been significant recent regulation
    So I guess we can agree that my statement was correct and your response #73 was not. Thank you.

  • http://primaryprinciple.blogspot.com/ Thales

    Just to change the pace a bit with “ole arguments of glaciers” which resurface under new experimental data?


    “This is the first study to indicate the total mass balance of the Antarctic ice sheet is in significant decline,” said Isabella Velicogna of CU-Boulder’s Cooperative Institute for Research in Environmental Sciences, chief author of the new study that appears in the March 2 online issue of Science Express. The study was co-authored by CU-Boulder physics Professor John Wahr of CIRES, a joint campus institute of CU-Boulder and the National Oceanic and Atmospheric Administration.

    How would this change your conversation?

    There is evidence of bug infestations in the north, that winters have not taken care of, killing Pine trees in vast tracts of forest lands, all now a very colorful red.

    IN concert then with temperature values and location? Is this a cyclical condition?

  • http://yourdailyllama.blogspot.com wolfgang

    Thales,

    according to Lubos Alaska had record low temperatures this year. This might take care of the bug problem. I do not know anything beyond that about it and will really tune out of this thread now.

  • http://arunsmusings.blogspot.com Arun

    Indian livestock emitted an estimated 10 Teragrams of methane in 1994.
    http://www.ias.ac.in/currsci/jan102005/119.pdf

    Indian rice cultivation emitted an estimated 3 Teragrams of methane in 1994.
    http://www.ias.ac.in/currsci/dec102005/1904.pdf
    The US estimate for this quantity was 38 Teragrams, more than 10 times the Indian estimate.

    US emissions in 2000 as per Hiranya’s link was 28 Teragrams.

  • http://arunsmusings.blogspot.com Arun

    Here is the news source of the claim of the 7% per year shrinkage of the Tibetan glaciers:

    http://www.chinadaily.com.cn/china/2006-05/02/content_582103.htm

  • http://primaryprinciple.blogspot.com/ Thales

    Wolfgang,

    The bugs leave a ring around the outside of the wood that protect it from the cold weather. A dead tree after infestation, has no bark left.


    The second factor is climate change. Historically, beetle populations have been limited by cold winters; however, the absence of cold temperatures in the interior has allowed large populations of beetles to successfully survive the winter under the bark of the pine trees. Furthermore, the warming trend in the interior has produced ideal conditions for the mountain pine beetle. Hot, dry summers have allowed the beetle infestation to spread to higher elevations and more northern latitudes while producing drought-stressed trees which are more susceptible to attack.

    If it is warm, they will survive. If the temperatures do not drop to -30 celcius or below, for a three week period or longer, they will live because of ths anti-freeze they inject, which gives it this “blue coloring” when you cut the dead tree down.

  • Hiranya

    #80: Um – the whole point is that the greenhouse gases that have gone down have done so because we have reduced emissions. You seem to assert that they are going down on their own due to some natural process. Make up your mind what you are arguing for. There is a logical fallacy in saying we should not cut CO2 emissions because other greenhouse gases have decreased because of steps/regulations humans have taken to reduce them. Your statement was misleading.

  • s.y.

    #69 Hiranya,
    Thanks for the pointer, but I was aware of that webpage. On that page, the RealClimate team defends the result of their own research by maintaining that their result can be obtained even if they use principal component analysis in a slightly different way and even if they don’t use principal component analysis at all. But this is not a convincing rebuttal of McIntyre’s criticism. McIntyre’s main points, as I understand them, are the following:

    (i) Mann et al. (=the RealClimate team) applied a nonstandard way of normalization to their data (i.e. subtraction of the 20th century mean rather than the overall mean), with the result that their principal component analysis gave undue emphasis on the North American bristlecone pine data. (This is the point explained at length in the article I linked to at #7.)

    (ii) The North American bristlecone pine data cannot sensibly be regarded as reflecting temperature. (This point is also touched on in the article I just mentioned, and McIntyre has a new blog entry on this point at http://www.climateaudit.org/?p=697 )

    So, when the RealClimate team says “Only if you remove significant portions of the data do you get a different (and worse) answer.”, they are ignoring point (ii), rather than answering it. Also, the fact that their result can be obtained even without the use of principal component analysis is irrelevant, as long as the new method also allows the bristlecone pine data to dominate. (I actually don’t know if the RealClimate team’s new method really allows the bristlecone pine data to dominate just as their original method does. But according to McIntyre, it does, and I don’t think the RealClimate team has responded to this criticism.)

  • Hiranya

    I also wanted to correct another misleading statement made in #56. According to sources in Wikipedia, “CO2 has a variable atmospheric lifetime (approximately 200-450 years for small perturbations). Recent work indicates that recovery from a large input of atmospheric CO2 from burning fossil fuels will result in an effective lifetime of tens of thousands of years.”

  • Hiranya

    s.y., I have no knowledge at all about anything to do with the bristlecone pine data, sorry :( What I took away from the realclimate page was that McIntyre was misusing PCA techniques in a very obvious way.

  • Denis Barkats

    Hey Hiranya ,
    just wondering if your last name was Peiris ?
    Denis

  • Hiranya

    Hey Denis, yes its me, guilty as charged! Are you writing from the South Pole?? I recently had great fun looking at some Aurora Australis pictures of yours and reading your blog! You are so lucky to get the chance to have that experience!

  • Denis Barkats

    Hey Hiranya,

    yes, indeed writing from the South Pole. I try to read as much of this eminently interesting blog during the short hours that we have an internet connection to teh outside world. I really enjoy your responses and your enthousiasm for responding. I have to say I would not be as pastient as you are. Where are you now ?
    We have a NOAA station here at South Pole making the same measurements as those from the Mona Loa plot so there are a couple scientists with whom to discuss some of these issues. I wonder if “the Inconvenient thuth” is going to make it to the internet. Otherwise, I’ll have to wait anotehr 6 month to see it.
    cheers,

    Denis

  • Hiranya

    Hi Denis, I am at Chicago now and its really great being here! I feel compelled to respond because maybe it will galvanize someone somewhere to do something about this problem :( But my patience has its limits and my cosmology is being mildly neglected :) It is amazing what sort of disinformation is out there (and very depressing too, the short-termism and the denial). I hope you get to see the movie one day :)

  • Hiranya

    PS: Would be great to hear the points of view of your NOAA scientists. Can you get them to post here?

  • http://iso42.blogspot.com wolfgang

    > You seem to assert that they are going down on their own due to some natural process.
    I did not make such an assertion.

    > There is a logical fallacy in saying we should not cut CO2 emissions
    I did not suggest we should not cut CO2 emissions.

    And I do not need to ‘make up my mind’ what I am arguing, since my opinion is pretty simple to understand: CO2 is growing slower than exponential, which is
    significant because CO2 forcing is proportional to ln(C) and other greenhouse gases are ‘flattening’ even more. Thats all.
    And since I explained my opinion more than enough already, I really think there is no need to discuss this further.

  • Hiranya

    Wolfgang, ok, bye bye ;)

  • http://primaryprinciple.blogspot.com/ Thales
  • http://primaryprinciple.blogspot.com/ Thales

    Nice picture here from “page 2″ of Weighing Water.

  • s.y.

    #89 Hiranya, thanks for the response. It’s not obvious to me, though, that McIntyre is misusing principal component analysis in any way. I appreciate your effort to educate me, and I respect the professional climate scientists’ effort to advance our empirical knowledge, but I’m still not convinced that Sean’s statement that “the only ones left on the other side are hired guns and crackpots” is justified.

  • Hiranya

    s.y.: The alleged PCA misuse was in not using enough eigenmodes to make the reconstruction insensitive to the number of eigenmodes used. I am afraid I have managed to enlighten you at all :( I can’t find any references to the pine data misuse other than sites which appear to be linked to McIntyre. I don’t (yet) know how to search the professional climate science literature directly, but if I find something, I will post it!

  • Torbjörn Larsson

    Hiranya says:

    “Tobjorn: Let me also add that I have very little concern about the natural system recovering from what we do to it. It has taken far worse blows in the past and recovered with new types of biodiversity after massive extinction events. Its just that I have some small concern about our own survival from the consequences of what we do to the natural system ;)”

    Apparently we are discussing different things. When I said you were cherrypicking data it was for natural occurences since these are the events that we can test biological recovery against. I agree that if you are concerned that our survival as a species are important and could be a dramatically different process than recovery of a biosphere, a different timeline may make more sense.

    However, our economy and technology is a late invention so then you would have practically no baseline left. I guess if I were interested I could perhaps pick up the reason to the 650 000 year restriction, which isn’t obvious to me. But I’m not, really. I was originally merely reacting to your first statement on natural carbon dioxide levels.

    wolfgang says:

    “> the whole “scary” part of climate change is the rapidity of the “change”.

    Torbjorn,”

    I didn’t say that, Hiranya did. You should direct your commentary accordingly.

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Cosmic Variance

Random samplings from a universe of ideas.

About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] cosmicvariance.com .

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