Oh Say, What Is Inconvenient Truth?

Kristine N is a graduate student in the Earth and Atmospheric sciences department at Purdue University . She recieved a B.S. in Geology from Caltech and an M.S. in Geology from Penn State. Her master’s research, conducted with Kate Freeman and Chuck Fisher, focused on the sulfur stable isotope geochemistry and lipid geochemistry of sediments associated with vestimentiferan tubeworms in the Gulf of Mexico (which sounds far more pretentious than it really is). She is currently growing Sea monkeys for her PhD in an effort to reconstruct drought freqency and intensity in the Great Basin.

Ben Santer works on identifying human influences on global climate. He and Tom Wigley co-authored the eighth chapter of the second IPCC assessment, which included the controversial statement, “The balance of evidence suggests a discernible human influence on global climate.” Having survived the maligning of climate skeptics, the third IPCC assessment, and the most recent CCSP report, which was released in May of this year, he spoke to a group of us at Purdue University. Today I am presenting, for your edification and entertainment, my notes from his talk.

Climate varies naturally, and would change over time whether humans were present or not. Solar input is the most important climate forcing (a forcing is a mechanism that influences climate). The energy balance, or radiative forcing of the climate system depend on solar output and on the amount of energy absorbed or reflected by the earth’s atmosphere and surface. Orbital cycles, or Milankovitch cycles produce the pattern of long ice ages punctuated by short interglacial periods that characterizes the Quaternary period by changing the radiative forcing of the earth. On a shorter time scale, solar output varies due to the sunspot cycle, which also impacts global temperatures. Volcanic eruptions are another significant climate forcing. Increases in volcanic dust and in the concentration of sulfates in the stratosphere increase the albedo (reflectivity) of the earth. If the earth reflects more solar radiation, temperatures decrease, as was observed in the year without a summer after the explosion of Krakatoa. Solar output and volcanic dust are considered natural external forcings. Variability inherent to the system is also produced by internal forcings, such as the interactions between the atmosphere and ocean that produce El Nino and La Nina cycles.

Human activities produce climate forcings. We have demonstrably altered the concentrations of carbon dioxide, a gas that absorbs infrared radiation, in the atmosphere. The Keeling curve is considered the most famous figure in all of geophysics and shows the impact of burning fossil fuels on atmospheric CO2 concentrations. Biomass burning, ore smelting, and other combustion-type activities produce aerosols that increase the albedo of the atmosphere. As we alter ground cover by cutting down forests, growing crops. and building cities and roads we change the albedo of the ground, again impacting the energy balance of the planet.

We know we produce forcings, but do not know the magnitude of these forcings. Unfortunately, we don’t have another parallel earth sans people acting as a control that would allow us to quantify the magnitude of human-induced forcings. To get around this limitation, we use models. Models are a tool we have to predict climate change signals. They are simplifications of a complex and chaotic system, and every model posesses sytematic errors that must be taken into account. Even if it were possible to create a model with perfect physics, because climate is a chaotic system and we don’t know exactly the initial state of the earth’s climate we would see a mismatch between the modeled and observed climate. Modelers thus perform multiple realizations, starting with slightly different initial conditions, and then average the results, producing a model with surprisingly high skill and an “envelope” of the variability around the model. Models are tested against data over many time scales–from recent, daily or even hourly instrumental records, to longer paleoclimate records produced by proxy reconstruction.

Agreement between modeled and observed climate is considered evidence the model is “good;” however, mismatch between a model and observations can be just as informative. For example, in 1982 the eruption of Mt. Chichon in Mexico produced copious amounts of sulfur dioxide, which should cool climate. At the same time, the strongest recorded El Nino was occurring. The conflucence of the two events resulted in less cooling than expected based on known climate sensitivity to volcanic eruptions. The mismatch between the modeled response and observation provides information on the relative importance of each of these forcings on the climate system. Any forcing can be left out of a model intentionally and compared to observations or to other models to test the relative contribution of the forcing on the climate system. Estimates from such comparative studies suggest the contribution of human forcings is responsible for much of the warming observed over the past 50 years.

Different forcing produce unique warming and cooling patterns, or “fingerprints.” For example, increases in solar radiation warm the entire atmosphere, while increased greenhouse gases warm the troposphere and cool the stratosphere. These fingerprints provide testable hypotheses–we can test predicted patterns based on physics against observations and say which of the forcings gives the most likely explanation. According to Santer, increased height of the troposphere predicted by models matches observations, supporting the theory that increased greenhouse gas concentrations are responsible for the observed 0.6C to 0.8C increase in average global temperature.

Climate skeptics freqently point out that not all observations are consistent with a warmer troposphere. Atmospheric temperature profiles collected by radiosonde and satellite do not show the same warming trend observed in surface temperature records. In the last year, papers by Mears and Wentz, Sherwood, Lanzante, and Meyer, and by Santer and colleagues suggest corrections applied to the original data, daytime solar heating of the instrument, and uncertainties in the data explain the observed lack of warming.

We know human activities have changed the composition of the atmosphere. Concentrations of carbon dioxide have increased about 30% since 1850 and are today higher than they have been in the past 650,000 years (sorry, graph is only 400,000 years) , and we know the 20th century is the warmest century of the past 2,000 years. We have seen surface temperatures increase 0.6C to 0.8C since the mid 1800’s. We see the fingerprints of human activities in multiple aspects of the climate system. Together, we are presented with a consistent story–human activities are influencing global climate.

What we don’t know is what our future climate will look like. We don’t know how warm we will be in 2100, in part because we don’t understand every possible climate feedback, and in part because we as a people haven’t decided what to do about CO2 emissions. We aren’t sure how the carbon cycle will respond to increased CO2, or what temperature changes will do to thermohaline circulation in the ocean. Climate does not always respond linearly to forcings; there are “tipping points” where the climate will shift from one equilibrium state to another over a very short time period. We don’t know how the frequency and intensity of extreme climate events, like hurricanes and tornadoes, will change in a warmer world, and we are only now starting to investigate regional features of climate change (see here for a recent Purdue publication on a region near and dear to my own heart).

Thanks to Dr. Santer for letting me post these notes.


  1. Goodness! I will have to print this and read all the links. I will be back in three days.

    Thank you for educating us.

  2. Jargonerific post, Kristine. Like Hellmut, I’m gonna need some time to figure out what you said. Thermohalines! I love it.

    Let me see if I get the gist: humans have SOME impact, but we can’t quite tell what that impact is or what the future may hold, or quite what to do about it.


  3. Go Boilermakers!

    …and very well done :)

  4. Yep, we have some impact, and probably are responsible for the recent, half to three-quarters of a degree rise in temp, and while there are consequences we can predict, there are some we probably can’t.

    as for figuring out what to do…isn’t that what all of you lawyers are supposed to figure out?

  5. Kristine,
    Is there any hope on the horizon of actually predicting what these climate changes will mean? You said right now there is no way to know, but how could that change in the future?

  6. Oh…. I really wanted to learn more about the Sea Monkeys…

    Interesting, glad to see the Global Warming issue without either the Bush or Gore Hyperbole. After all, Only Dennis Quaid or a Dancing Penguin can save us now!

  7. Jared,
    Really, the best tool we have is modeling. The limitations on modeling are basically computing power, which is constantly increasing, allowing for more complicated, realistic models. We can start including more subrutines that describe the responses of more and more components of the climate system. We can model smaller areas–early GCM’s (Global Climate Models) divided the globe into boxes that were a couple of degrees on a side; with more powerful computers we can essentially make the boxes smaller, producing a higher resolution model.

    People are also modeling regional effects, looking at specific regions of interest. The last paper I linked to is examining moisture balance changes in just the western US.
    We also look for potential “tipping points” using paleoclimate reconstructions. Some climate responses are non-linear, so little may change for a long time, and then some threshold is breached and the state of the whole climate changes. Thermohaline circulation is one that’s recieved quite a bit of attention (that part of The Day After Tomorrow is realistic; the rest isn’t). Some people think peat bogs could have a tipping point where they go from absorbing CO2 to emitting CO2; the same is true for methane clathrates (methane-water ice–it exists at specific temperatures and pressures on continental shelves, and it’s possible increased ocean temperatures could melt the ice, releasing immense amounts of methane). We look for evidence of these events in the geologic record, and then try to figure out what caused them.

  8. Christopher Smith says:

    Excellent post. I agree 100%.

  9. MikeInWeHo says:

    Thanks for this interesting post.

    What do you, personally, think about CO2 emissions as a political issue ? Do you support global efforts such as Kyoto that attempt to reduce them ?

    I know that this is not the point of your post, but I’m curious and suspect many others are as well.

  10. I would argue that we do know the magnitude of some of the forcings, and that the forcings can have different magnitudes in different regions, ex. latitudinally

    We know the sign of almost all the forcings except perhaps dust, but that we are a little uncertain to the exact magnitudes. we know very well and to little uncertainty the effect of greenhouse gases many of the forcings that we currently have the least understanding of are the smaller ones… not entirely, but mostly

    no scientist believes any one model. it is only after we have run hundreds or thousands that we have a better idea of how the world works and where it is heading

    the more models we can run, the better we can also capture the variability, i.e. what the likelyhood that any one model might be right. the greater the number that agree, the more we believe it…. just because a single model shows the planet will cool or not warm very much, no one should believe it, which is often what politicians and industry does with their numbers… they will play up one result in there favor and try and make the public believe that it is just as valid as a hundred models that say the planet is warming

  11. kristine N says:

    Mike–I’m planning another post on that very subject.

    I think we need to do SOMETHING about greenhouse gases. The potential for a really bad outcome is too great for us to just say, we’ll deal with the consequences when they show up, in my opinion. What we should do is a matter of much debate, and I’d love to hear what you guys think about the myriad possibilities that have been proposed, from carbon taxes or limits, to geoengineering/sequestration. I’ll be posting in the next couple of days, I hope with some scholarly articles attached, and I’m really looking forward to hearing what you all think.

  12. i should also thank you for your post… i very much enjoyed it. i think it is very important for people to understand both how the science is done and what it means.

    i like the discussion of sensitivities… and testing of various strengths of forcing… right on

    one thing that the public often does not appreciate, especially given the shroud of misinformation that is often spouted, is that regardless of whether we stop emitting greenhouse gases today or not, the planet will continue to warm. stoping today, the climate will continue to warm for another two centuries, how much and what that will mean for society ARE the only questions.

  13. We know human activities have changed the composition of the atmosphere. Concentrations of carbon dioxide have increased about 30% since 1850 and are today higher than they have been in the past 650,000 years (sorry, graph is only 400,000 years) , and we know the 20th century is the warmest century of the past 2,000 years. We have seen surface temperatures increase 0.6C to 0.8C since the mid 1800’s. We see the fingerprints of human activities in multiple aspects of the climate system. Together, we are presented with a consistent story–human activities are influencing global climate.

    So, KN, what caused the CO2 concentrations to be as high as they were 650,000 years ago? Automobiles?

    Do we or can we in any way know what long-term cycles this earth goes through that could be affecting climate change? In other words, what caused the last ice age (pretty recent, after all) and what caused it to end? That seems like a pretty huge climate cycle. Did human CO2 output have anything to do with that? Do climatologists take into account that there might be climate cycles that are so long-term that they don’t even know they exist? After all, do they or can they realistically even say how old the earth is?

    In your view, and based on your education in this field, is it really possible to take a weather phenomenon and blame it on “Global Warming”? I.e., can the coincidence of numerous category 4 and 5 hurricanes in 2005 really be attributed with any conceivable accuracy to CO2 emissions from human activity? Do we know how many hurricanes occured in 1256 B.C.?

    Wasn’t there a mini-ice-age in the thirteenth century or thereabouts that caused widespread famine and extreme weather in northern Europe and America? And again in the sixteenth century? What cycles of the earth caused those? Which factories were putting loads of CO2 into the atmosphere in the 1400s?

    In your opinion, is it possible for us to focus on observing the polluting and unhealthy effects of CO2 emmissions without making outlandish claims that global warming, even if it exists, is caused by human activity? I mean, can’t CO2 be an inconvenient truth that we need to address and reduce for the sake of cleaning up the environment without claiming that Katrina is Bush’s and big oil’s fault? The latter is where those pushing theories of global warming lose the skeptics among us. I would prefer a policy direction of eliminating pollution and CO2 emissions for the sake of a cleaner environment, not because of claims that cannot be substantiated that humans are having an appreciable effect on long-term and global climate cycles that we don’t even know about and that seem to be completely indifferent to the inhabitants of the planet, i.e. all previous ice-ages.

  14. Also, you write we know the 20th century is the warmest century of the past 2,000 years.

    Okay, assuming that we can actually know such a thing (and not just that it is someone’s best guess) that sentence implied there was a century that was at least as hot, maybe hotter, more than 2,000 years ago. But there weren’t any CO2 spouting factories at all more than 2,000 years ago. What to do with this dilemma?

  15. John, I’m a bit surprised at your tone. Kristine described how there are a lot of things that effect weather. She simply outlined how humans are one of those things. She states explicitly that:

    What we don’t know is what our future climate will look like…We don’t know how the frequency and intensity of extreme climate events, like hurricanes and tornadoes, will change in a warmer world, and we are only now starting to investigate regional features of climate change

  16. J., I think my questions are valid and I’d love to hear someone who knows what they’re talking about answer them!

  17. Steve Evans says:

    John, J.’s right. You’re coming off as petulant. Questions like “So, KN, what caused the CO2 concentrations to be as high as they were 650,000 years ago? Automobiles?” do not cement your reputation as cool and level-headed.

  18. Steve, that was shot years ago.

    KN, Steve and J. have pointed out to me offline that I sounded like a jerk in # 13, so go ahead and ignore if it you want. I am seriously interested in the view of someone who is somewhat of an authority on this issue about these questions, if you care to engage them. I am certainly not such an authority. But I will state that I’ve never heard people who theorize about global warming being caused by humans and that it will soon have drastic effects, or people who try to connect specific weather phenomena to global warming by saying they are a result of global warming, like the 2005 hurricanes or floods along the Elbe and in Switzerland etc., explain how weather and climate cycles as dramatic as all previous ice-ages occurred without the presence of cars or factories.

    Also, I should point out that my pointed questions actually do not deny that people have been able to measure an increase in global temperature since the 1800s. I am not saying that and therefore I am not denying “global warming”. What I am interested in knowing is how we can know anything about the larger and deeper cycles of the earth and how we can attribute any real consequence in terms of climate cycles to human influenced global warming. What about global warming that occurred during periods where humans made no CO2 emmissions at all? We know those periods existed, right?

    I am in favor of reducing pollution and cleaning up the environment. On the other hand, the questions I posed are real questions that I have had and that truly puzzle me.

  19. ed johnson says:

    John, didn’t you read the original post? Kristine already told you about orbital cycles and sunspot cycles that produce large variations in climate without human input. Why don’t you read about those first before turning on the sarcasm.

  20. Nah, I did read them. I just wonder what implications that has for the consequences for global climate cycles that people claim can and will flow from human-influenced global warming. I guess my position is one of relative agnosticism about whether we can know much at all about the more long-term and global climate cycles that this planet experiences and about what effect human beings can actually have on those. Again, it is not a denial that human-origin CO2 has caused measurable temperature increase since the 1800s but rather what effect that will have, and, to be fair, KN basically said we don’t and can’t know that in her last paragraph.

    The questions, although some admittedly ironic, were not meant as an attack on KN even though a couple of people have pointed out to me that this is how they will come across. They are acerbic but actually are meant to pose real questions.

  21. ed johnson says:

    By the way Kristine, thanks very much for this excellent post.

    You mention the possibility of tipping points. That is what worries me. In fact, it’s really the only thing that worries me, since I think we’ll probably be able to deal with gradual change pretty well. (Or at least as well as we could deal with attempting to drastically cut carbon emissions.) But I’m concerned that these models are probably very unreliable guides to tipping points. It’s easy to make a model with such features, but hard to validate it. What do you think?

    Also, do you know anything about possibilities for using engineering solutions to counteract warming, for example by somehow incresing albedo?

  22. Steve (#2):

    Let me see if I get the gist

    Steve, it’s spelled gst; no i. As in, “I think I got the gst of it.”

  23. Steve Evans says:

    nyuk! And here I was, thinking that I was bandying words with the Canadian goods & services tax.

  24. kristine N says:


    Where do I start? Oh yes, I start by suggesting you follow the links included in the post. I’m going to direct you specifically to the link on Milankovitch cycles, which will answer your question about long-term cycles, and will tell you why we had an ice age, and why we have come out of it. In short, the earth’s orbit isn’t constant–the shape (ellipticity), axial tilt, and axial orientation all vary over thousands of years. Wikipedia has some nice pictures that will explain. As these orbital parameters change, the amount of solar radiation reaching the earth also changes, and surface temperature increases or decreases accordingly.

    To answer your first question, the concentration of CO2 in the atmosphere wasn’t any higher 650,000 years ago than it is today; 650,000 years is the extent of the ice core record. We have an excellent record of atmospheric gas concentrations going back 650,000 years because small bubbles of gas get trapped in the snow that eventually becomes glacial ice. Scientists have taken ice cores from greenland and antarctica, sectioned them (in some situations to one-year resolution), and collected the gases that are released when the ice is melted. From this, we know with great certainty, past atmospheric composition. The oldest ice we have is 650,000 years old–ice older than that gets deformed by the pressure of the ice above it and we can’t say how old it is any more with any certainty. We have estimates of CO2 concentrations from proxy studies that extend further back, but the errors the reconstructions are large so we can’t say with the same certainty that CO2 was lower then than it is today. However, this proxy study suggests CO2 concentrations have not been higher than today in the past 15 million years, and not above 500 ppm in 20 million years.

    The earth is 4.567 billion years old.

    As for the hurricane-global warming connection, that is currently a contentious issue. We have a mechanism to explain why there shoulde be more, higher intensity hurricanes. Hurricane intensity is a function of the difference between sea surface temperature (SST) in hurricane-spawning regions and temperature at the base of the stratosphere. A warm troposphere translates into a warmer ocean (which we see), and we do observe higher SST in the equatorial atlantic and pacific. Combining the warmer ocean with the cooler stratosphere produced by increased greenhouse gases gives us a higher temperature gradient, which should translate into more, higher intensity hurricanes. You are right that we don’t have long records of hurricanes, but that doesn’t mean this isn’t happening. May I just point out the irony of a person of faith using a lack of evidence or a record as a reason for disbelief?

    As an aside, Claudia Mora, who is one of my heroes, studies “paleotempestology.” We don’t have written records for hurricanes really before this century. People occasionally wrote about big, frightening storms (the chinese called them something like storms with winds from all directions) but those records tend to be inconclusive (how do you tell between a hurricane and some other big storm that knocks down trees without satellite imagery?) and sparse. Hurricanes produce water that is very depleted in heavy isotopes (deuterium and oxygen-18), which leaves a signature in tree rings. She and her group are reconstructing hurricane frequency in the southwest US using tree rings.

    Science is so cool.

    Anyway, back to your questions. There was a little ice age in the mid 1300’s, and another cool period from somewhere around 1600 to 1850. Volcanic forcing is one idea for why climate cooled then; another is decreased solar activity. By the way, both these explanations are proffered in the page you cited, as well as the supporting evidence for the speculations.

    We can substantiate the discernible influcence of human activities on global climate; that is the point of my post. We understand the climate system sufficiently to quantify the influence of greenhouse gases we emit on average global temperature and we can guess at many of the consequences of higher global temperature, including weather changes. The magnitude of human-induced warming is much lower than many natural forcings. That said, what we are doing is not insignificant, and will become more significant with time, not less, particularly if we follow a business as usual strategy. We are committed to a certain amount of warming, and we will have to deal with the consequences of that warming. The question is, do we want to deal with even more?

  25. btw, gst, drop me a line. steve -dot- evans at gmail dot com.

  26. kristine N says:

    goodness, I am behind.

    We can’t do a whole lot about the long-term climate cycle. People have pointed out to discredit the global warming people that about 30 years ago everyone was convinced we were heading into another ice age. The fact is, we are heading into another ice age, eventually. Climate in the Holocene (past 20,000 years-ish) has been amazingly stable. What we’re doing to the atmosphere could destabalize the system, and we could land in some other climate equilibrium that wouldn’t necessarily be as favorable.

  27. kristine N says:


    Tipping points are pretty impossible to predict; they’re a consequence of non-linear behaviour of the climate system and the only time we really know about them is when we see something sudden and drastic happen in the geologic record. The Younger Dryas was one such tipping point, when the Gulf Stream was shut down by a sudden, massive influx of fresh water to the north Atlantic. There are certainly other tipping points, and we don’t know what will cause us to tip. some of the “stuff we don’t know we don’t know.”

    re: geoengineering–people have proposed increasing the planet’s albedo by shooting sulfates into the stratosphere. I’ll dig up the reference, but the guy’s name is Crutzen. Anyway, the solution would be mimicking the effect of a volcanic eruption, but also has some nasty side effects, like destroying ozone and increasing acid rain.

  28. So how many trillion dollars should we spend to fix man’s effect on the climate?

  29. kristine N says:

    good question–the Stern report suggests we spend 1% of world GDP, and gives reasons for that number.

  30. “can the coincidence of numerous category 4 and 5 hurricanes in 2005 really be attributed with any conceivable accuracy to CO2 emissions from human activity?”

    absolutely not. however, work out of NCAR attributes an 8% increase in precipitation from hurricanes to increased sea surface temperatures that are a result of global warming. That 8% is an estimate based on modeling hurricanes.

    We know what the carbon isotopic composition of pre-industrial atmospheric CO2 was, and know that value has changed since we started burning fossil fuels that have a different isotopic composition. Mass balance calculations with known CO2 sources (natural and human) agree quite well with estimated human CO2 outputs.

  31. There is also the cosmic umbrella, which at first blush seems rather fatuous, but I am a chemist.

  32. unlike past paleo reconstructions, where CO2 lags behind temperature increase, current CO2 increases lead the temperature increase, indicating CO2 is causing temperature rise instead of resulting from temperature rise. there is a positive feedback between temperature and CO2, where increased temperature leads to increased atmospheric CO2, leading to increased temperature again; however in the past it has always been temperature leading, not CO2. that suggests today’s temperature rise is a result of human greenhouse gas emissions.

  33. awesome. Let’s spend several trillion dollars on umbrellas. Yeah!

  34. Kristine N,

    Wow . . . does Al Gore know about you? Interesting stuff–though way out of my league. Perhaps I’ll take it in smaller doses over the next week or so. Thanks for all the links and notes.

  35. Kristine, it is a great idea to post this on a non-science blog. Congratulations and thank you.

    Is there any chance that you and your colleagues can build on this effort? For example, turning Santer’s lecture into a quick time movie would be really useful. That way we could enjoy graphs etc, which would help us to follow some of the relationships, which confuse readers.

    Of course, it’s a big thing to ask and I am not really asking for us. Given that political economists, philosophers, and lawyers will have to act on this information, it might be worthwhile to consider rhetorical approaches.

    Most of the visual material should already exist in conference papers and posters. If one supplements them with texts for social science and humanities audiences then you have the movie script.

    Anyways, I don’t mean to burden you and thank you for everything that you have done.

  36. ed johnson says:

    It sounds like some people are mocking ideas about using engineering solutions to reduce warming. I’m not sure why. Such schemes would likely be expensive and might not even work at all. On the other hand, achieving meaningful reductions in C02 emissions in the next few decades is probably even more difficult, or impossible. Even if we in the developed countries redouble our puny efforts, it’s hard to see how we can keep the developing world from taking up the slack, and then some.

  37. herodotus says:

    OK, I’ll bite.

    I have some problems with the global warming debate. This isn’t so much a critique of what Kristine wrote as it is my objections to what is happening in the media.

    I am not a climatologist. On the other hand, I have a pretty strong base in the sciences. I know the limits of my knowledge, but I don’t get intimidated by scientific jargon.

    First of all, I don’t think many serious people dispute that humans have had a major impact on the environment. As near as I can tell, they disagree in terms of the magnitude, what it means, and what the future holds for us.

    My first problem with the debate is the degree to which it’s gotten personal. People with opposing views are dismissed as being liars on the industry payroll. Now maybe they are industry shills (I have no idea), but it’s still not a response to their ideas. And in my field when you accuse someone of falsifying data for cash you’re not just trying to discredit them, you’re trying to destroy them. I dismiss these personal attacks the way I disregard the idea that Al Gore’s habit of consuming enormous amounts of fossil fuels is evidence for his insincerity. Tell me why the ideas are bad, not why I shouldn’t listen to someone.

    Secondly, even the most ardent climate change advocates concede just how limited the current models are. The surface of the earth does appear to be warming, but the troposphere has shown very little change. Given that the bulk of the atmospheric mass doesn’t appear to be warming, is our surface data just skewed by the influence of “urban islands?” I also noted the way that debate shifted from “global warming” to “extreme weather events” until 2005 when the unusually quiet tornado season apparently failed to provide grist for the mill. My sense is that most people do believe that the earth is warming, but the degree to which models change to fit specific ends or current events makes the whole thing feel a bit slippery.

    Remember the recent story about how the world’s fisheries are about to expire? There was a subsequent story that got almost no press. It was an email that surfaced from the study’s lead author in which he essentially conceded that he’d engaged in hyperbole to grab attention. This is how the climate change debate feels to me. I have the sense there’s something happening, but I also feel like I’m not hearing the whole story.

    And here (in my mind) is the major problem:

    I think most climatologists would concede that we don’t have the knowledge or the models to accurately predict what the future holds. On the other hand, we’ll have to make a decision soon or our indecision will become its own response. Part of the problem is that we can’t even agree on what the goals are. Are we really going to try to stop climate change or just accommodate it? But given that the costs of intervention are so high (1% of the world’s GDP may not seem like much, but it is huge), how does a reasonable person decide what to do?

  38. Even if we in the developed countries redouble our puny efforts, it’s hard to see how we can keep the developing world from taking up the slack, and then some.

    It’s interesting that someone* from the country that consumes a quarter of the world’s energy resources (and is consequently responsible for a quarter of the carbon emissions) would consider the utility of preventing developing countries from increasing their current share and worry about the consequences. If the larger point is that we can’t sustain a world of Americans, I absolutely agree.

    *my apologies if you’re not an American.

  39. herodotus, Don’t worry. A huge part of the climate lobby doesn’t give a rat’s pitoot for climate change. They want their hands on the trillions of dollars people say we need to spend on what seems to me (based on what Kristine N has posted above) an experiment. The outcome will be the “smarts” who don’t have the initiative to lead economic development having control over the “capable”, who do.

    I can predict the outcome: stagnating development, slower growth, more poverty and no or negative impact on climate.

    The quest for societal domination by intellectuals is a recurring theme of history that mudworm researchers have been too wrapped up in their labs to study. The job of an intellectual is to “yak-yak-yak” but heaven help us when they get control.

  40. Wonderful tutorial on a complex topic where many people’s opinions outstrip their knowledge.

  41. Is anyone who disagrees with you a selfish SOB, GeorgeD?

    A huge part of the climate lobby doesn’t give a rat’s pitoot for climate change. They want their hands on the trillions of dollars people say we need to spend on what seems to me (based on what Kristine N has posted above) an experiment.

  42. kristine N says:


    The links regarding satellite data answer your question about tropospheric warming. The claim that the troposphere hasn’t warmed is based on a data with large uncertainties. For a long time that data set (produced by a group at the University of Alabama at Huntsville) was the only one available; a second data set, produced by Remote Sensing Systems in Santa Rosa, CA, is now available. This second data set has lower uncertainties associated with it, and does show tropospheric warming.

    I don’t know what the goals should be any more than the next guy. You’re right, though, that indecision is a decision in its own right, and almost certainly is a sub-optimal route to take. We’re going to have to accomodate some amount of climate change no matter what. That’s going to make life difficult for some people, and I would argue it’s a better idea to think about ALL the possible outcomes, especially the bad ones, and have some idea of what we want to do so we aren’t standing around talking about how to look like we care for the cameras (brownie, anyone?)

  43. kristine N says:

    “The job of an intellectual is to “yak-yak-yak” but heaven help us when they get control.”

    Yeah, like that Jonas Salk guy, or Joseph Lister.

  44. Hellmut draw me a path from my statements to your conclusion. Am I selfish because I begrudge my $75k (probably more) in taxes every year? Almost none of it comes from income on capital gains and absolutely none of it came from a financial inheritance. I go to work everyday and I produce. I am a full tithe payer and I pay fast offerings. (I would pay a lot more of those if the government were not taking so much out of my hide.) I guess I am selfish but I am excited to know that you’ll be able to tell me just why.

    Kristine N No fair giving examples of real and conclusive science to bolster a case for an experiment. Besides when did Lister or Salk ever take “control”? Best I recall they pretty well stayed close to their labs. Salk may have gotten a little pissy in the end but that was probably when he started to take himself too seriously. (As I recall he was pretty close minded about competing research.)

  45. herodotus says:


    I’ll have a look at your link. Thank you for providing it. I’m aware that I’m out of my league to debate this with you in detail, so I’ll instead just thank you for a well-written and informative post.

  46. Steve, check your junk mail folder.

  47. In the movie “Erik the Viking” the island Hy-Brasil’s King Arnulf convinces his people that when the island starts to sink destroying their city that it is not happening. In fact, they all end up on the top of tallest building, with the king hanging on to the flag pole, chanting in high voices, “This is not happening, This is not happening”. They all drown.

  48. Larry, I used to love that movie. Wonder if it is “Molly Mormon” appropriate..

  49. kristine N says:

    “No fair giving examples of real and conclusive science to bolster a case for an experiment.”

    Uh, why not?

    When I say “we are running an experiment,” I mean we as humans, especially those of us in the heavily industrialized western world, are performing an experiment by pumping CO2 into the atmosphere without knowing all of the consequences of that action.

    I don’t know of any scientists who are “taking control” in the sense you seem to be suggesting. We do say what we find, and then make recommendations as to what we think, based on available evidence, should be done.

  50. kristine N says:

    herodotus–thanks for bringing up the question. I think you clarified what I was referring to with the satellite debate.

    Everyone else, thanks for the good feedback and great discussion. this is fun!

  51. GeorgeD, my apologies.

    I am not saying that you are selfish. And if you were, it would be none of my business. More importantly, pursuing one’s self-interest need not be a bad thing.

    I am, however, troubled that you are accusing people of selfishness.

    You are saying that a “huge part of the climate lobby” is only after money. That’s an accusation of corruption for personal gain, i.e. selfishness. Rather than accusing people personally, it would be more productive to engage their argument on the merits.

    In the end, the merits will determine whether we need to dedicate resources to reduce global warming.

  52. Steve Evans says:

    Hellmut, Kristine, everyone, no need to apologize to GeorgeD. He’s a notorious troll that we are trying to ban, but which task is proving frustrating as he continually rotates his IP address. But please don’t let his bile disturb us.

  53. cew-smoke says:

    I know that there are probably no paleoclimatologists reading this, but I thought I remember being taught that CO2 was substantially higher during the Jurassic period that it is now. Is that not the case? If it is, don’t we have some estimates of how much the oceans rose, and how far back the glaciers receded, how many places were desert and how much was green?

    I was recently in the Denver Museum of Nature and Science and they have a section on Ancient Denver. They showed from the pre-dinosaur eras up until now exactly what the state of Colorado looked like. Can we not go back to those time periods (virtually speaking) for pointers at where things might go?

    Being one of those totally annoying question everything and argue with everyone kind of people, it seems to me that when we say we have no idea of what things will be like if the CO2 levels were some percentage higher than they are now, aren’t we forgetting we do have at least a little bit of historical data?

    If the CO2 levels were higher in the Jurassic time period, then don’t we have that time period as a kind of litmus for the possibilities? Feel free to jump in and correct my ignorance, as I am merely philosophising a bit here. Also, if CO2 levels were so much higher back then, who is to say that with or without our presence that kind of repeat of history could not happen again. So, perhaps in our arrogance we are simply panicking over something that was bound to happen sooner or later anyway (give or take a few million years). LOL!

  54. kristine N says:

    cew-smoke, you’re in luck–I AM a paleoclimatologist (or studying to be on at least :) ). CO2 was substantially higher in the Jurassic, and temperatures were higher, too. In fact, if you look at this paper by J. Zachos, et al, you’ll see that global temperatures were 8 to as much as 12 deg. C warmer from 65 million years ago (ma) to maybe 40 ma, cooling to around today’s temperatures from 33 ma to 28 ma, about 4C warmer from about 25 ma to 15 ma, and then steadily declined into the more recent ice age/interglacial state that characterized the Quaternary. Ice sheets existed in Antarctica, at least ephemerally betinning about 38 ma, but northern hemisphere ice sheets are much more recent–they were ephemeral beginning maybe 8 ma, and more permanent from 2.6 ma to present. atmospheric CO2 is harder to reconstruct, but we have estimates of that too, and those estimates suggest CO2 was high (like, above 1000 ppm high) until about 33 ma (see here for the article). The major control over the long term on atmospheric CO2 is actaully weathering–the creation of the Himalayas is thought to be why CO2 declined so much starting about 35 ma.

    We have reconstructions of sea level for most of the history of the earth, but reconstructing sea level is difficult. We use sedimentology to reconstruct sea level, but tectonics (plate motions) can be a confounding influence. that said, it’s suggested here that melting the greenland ice sheet would cause a 6-7m rise in sea level. Antarctica would be much more than that. I unfortunately don’t know the numbers off the top of my head and haven’t found them in my looking, but it seems like melting the antarctic glacier owould create on the order of a hundred meters of sea level rise. All suggestions of what it would take to do that are pretty extreme–several more degrees and a bunch of time.

    we DO produce paleoclimate reconstructions in part to examine possible outcomes. The problem is often finding a good match between what we expect to see and what has happened in the past, and then proving it’s a good analog.

  55. cew-smoke says:

    Well thank you for taking the time to answer my questions. I truly appreciate that.

    On a more somber note, it seems to me that most of the planet’s systems have (to some degree) some self-correcting behaviors. For hundreds of millions of years, in spite of the major disasters and climate fluctuations life has found a way to continue on; in one form or another anyway.

    Having said that, I was wondering if you would share some of your spiritual thoughts (if you have formed any) on the possibilities that could arise from the major changes (disasters?) that may or may not be in our future. Do you think there is a possibility that some of the disasters told about in Revelations might somehow tie into any of the possible scenarios? Do you think the Lord is testing us to see how we might handle the gift of this beatiful earth that was bestowed upon us? Or do you think this has nothing to do with our relationship with God and it simply is what it is?

    I don’t mean to put you on the spot, but I often wonder how LDS scientists apply the things they learn to their faith or if they tend to keep their faith and their studies seperate. If that is not a comfortable thing to talk about, then please disregard.

    I look forward to your next article.

  56. Using models myself for other purposes, I appreciate the limitations of modeling. My models are actually pretty good estimates of subsequent behavior. (I model fairly large linear micro-circuitry.)

    Earth modeling is very tricky. If you look out of an airplane window and see the chaotic order of clouds on a relatively micro level, a few thousand feet, no machine can possible model that complexity over the whole earth. But it can model large things. What I trust is that when the models test the high CO2 levels, the temperature goes up. What I presume is that it ALWAYS goes up.

    What we can not tell is how this will affect albedo, ocean circulation, etc. These are the details, and fairly large details. In some places the temperature may actually fall, but on avarage, it goes up. A tipping point might plunge Europe into an ice age if the Gulf Stream stops due to melting of the ice cap and Greenland. But the avarage temperature will go up.

    Oh, well. If it is not this, it is a large meteorite. Could be that 90% of the population, the wicked, will be removed.

  57. Kristine–I haven’t read the post yet (and I will!) but just wanted to give a shout-out to my fellow 1st Warder!

  58. herodotus says:

    Reading the BBC this morning I ran into some interesting facts:
    A recent poll carried out by the Pew Research Center in Washington suggested that only two out of five Americans think global warming is caused by human activity and only one in five were personally worried by climate change.
    People in 15 countries, rich and poor, were asked that question. Concern in the US was the lowest of them all.
    There is also an interesting article in today’s Washington Post on how the insurance industry is responding to the specter of climate change.

  59. kristine N says:

    cew-smoke, yes, there are self-correcting mechanisms (feedback loops) inherent in most systems. Feedback loops may be either negative (self-correcting or damping) or positive (amplifying) and we see both types in climate. The relationship between CO2 and temperature is a positive one–increased temperatures naturally lead to increasing atmospheric CO2 concentrations until some other feedback kicks in and starts removing CO2.

    Life will survive whatever we do–the question is will people survive (I suspect the answer is still yes), and how will we cope? I think it’s unlikely all of civilization will collapse under the effects of global warming. That said, I think parts of civilization could collapse, and life will at the very least be more difficult for significant portions of the world population until we’ve adapted. Western civilization is “at the top” right now, but it won’t necessarily be 100 years from now if major parts of the infrastructure we depend on stop functioning. We enjoy plenty of clean water and nutritiuos food, and it’s probable we in the US will continue to enjoy these things. There are parts of the world that are projected to be more arid under global warming, and most of them are already poor, like sub-saharan Africa. If climate changes very quickly, which it does when you reach a tippint point, species can have a hard time adapting. One of the scarier possibilities is that a major food crop could fail–like, the whole thing–because the climate system quickly moves out of the optimal range for that species. Not to be doom and gloomy–I’m not even sure what the potential is for that to happen–but I do think it’s a worthwhile exercise to think about and plan around. We are going to have to adapt to whatever state we land in, and that cost of that is likely to be high. It’s likely to be much lower if we plan ahead and are prepared for the most likely outcomes.

    I tend to keep my religion separate from my science, so I’m probably not the best equipped to deal with the possible relationship between revelations and global warming. I’m not sure our handling is a test either–the system is pretty robust overall, we could just screw things up for ourselves. That said, I don’t think God is going to come sweeping down and clean up any messes we make. I am reminded of the people of Alma, who still had to suffer the consequences of rejecting Abinidi’s prophesy. After they repented, the Lord did make their burdens lighter (Mosiah 24:15), but he didn’t remove the consequence of their captivity. I do think it’s likely our actions with regard to other people in response to global climate change are significant to our relationship with God. That’s more of a social justice issue, which is something I sometimes think about, but I’d bet there are other people out there in the bloggernackle who could tackle those sorts of questions better than I can. What do you think?

  60. kristine N says:

    we’re also one of the worst ranked our climate change performance according to this group.

    hey mary! good to see you!

  61. Kristine N,

    Thanks for the post. I recently had a discussion with a man in my ward who had just retired from a career in NOAA. He pointed out some things to me that I had not known or thought of before.

    1. Increasing CO2 acidifies the ocean, which is detrimental to sea-life, particularly shelled organisms.

    2. Warming on its own (independent of ice melting) increases sea levels due to expansion of the water. (Duh. I should have thought of that.)

    I see parallels between climate change and the bird flu. In both cases there is the potential for disaster, though it is hard to predict. Dealing with the potential disaster requires getting the attention of politicians, which means getting the attention of the public. It’s hard to do that using measured language, and if the threat fails to materialize (either through preventive action, or due to natural causes), it makes it harder to get people’s attention the next time.

  62. kristine N says:

    one of my friends works on coral reef systems, specifically looking at the impact of hurricanes on bleaching. Coral reefs have a much harder time precipitating their carbonate exoskeletons under more acidic conditions. Historically (like millions of years ago historically) corals have been mor limited in their extent, to as little as 20% of their current range, under higher atmospheric CO2.

  63. Neat post kristine. I’ll have to check the links when I have some time.

    I’ve always been a bit back-and-forth about global warming, so I’m willing to be convinced.

    I’ve always been extremely concerned about fossil fuel consumption, but my reasons actually have little to do with global warming. My concern is more the fact that we will gradually exhaust our supplies and will have no infrastructure or technology in place to step in. Here’s where the real human disaster is going to be. Furthermore, the US position of security and global dominance is threatened by the insecurity of our oil sources. We’re already reaping the consequences of that vulnerability today.

    So we need to step up our work on alternative energy sources as a matter of national security and mere planning ahead.

    You don’t need much science to reach those conclusions. Just plain common sense. The global warming dialogue is interesting and all, but it’s really secondary to me.

  64. Seth:

    Be convinced. The only debate is how bad it will be. The Europeans have a lot at stake since, if the Gulf Stream shuts down, Europe will resemble Hudson Bay in climate.

    For the Europeans, even a small risk of Greenland ice melting and shutting down the Gulf Stream is untennable since the price is so high.

    Likely Cost = (probability) times (real cost).

    What is the real cost of the destruction of Europe? How many trillion dollars, not to mention the legacy and the future cost of losses. If the probability were .01 percent, then the Likely cost is still hundreds of billions of dollars. Should we spend a few tens of billions of dollars to avoid the likely cost? I would think so, especially if there are other equally catestrophic and likely outcomes such as sea level rise.

    As I said, the details vary, and they may be large details, but the net result is warming, even if Europe freezes over. Everywhere else will be warmer.


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