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Short and simple arguments for why climate can be predicted

Filed under: — rasmus @ 12 August 2006

Sometimes, I encounter arguments suggesting that since we cannot predict the weather beyond a couple of weeks, then it must be impossible to predict the climate in 100 years. Such statements tend to present themselves as a kind of revelation, often in social settings and parties after I have revealed for some of the guests that I’m a climatologist (if I say I work for the Meteorological Institute, I almost always get the question “so, what’s the weather going to be like tomorrow?”). Such occasions also tend to be times when I’m not too inclined to indulge in deep scientific or technical explanations. Or when talking to a journalist who wants an easy answer. In those cases I try to provide a short and simple, but convincing, explanation that is easy for most people to understand why climate can be predicted despite the chaotic nature of the weather (a more theoretical discussion is provided in the earlier post Chaos and Climate). One approach is to try to relate the topic to something with which they are familiar, such as to point to empirical observations which most accept (I suppose with hindsight it could be similar to the researchers in the early 20th century trying to convince that nuclear reactions were possible – just look at the Sun, and there is the proof! Or before that, the debate about whether atoms were real or not – just look at the blue sky, and you look at the proof…). I like to emphasised the words ‘weather‘ and ‘climate‘ above, because they mean different things.

Fig. 1: Temperature variation at 10E/60N from ERA40

It is true that we cannot predict the weather indefinetely (or even beyond a couple of weeks), because of the chaotic nature and infinitesimally small uncertainties in the state as we know to day, will affect how the weather evolves in a few weeks (the ‘chaos effect’). But, still I say that I know with certainty that there is a very high probability that the temperature in 6 months will be lower than now – when winter has arrived (it’s summer on the northern hemisphere at the present). In fact, the seasonal variation in temperature and rainfall (wet and dry seasons in the tropics) tends to be highly predictable: the winters at high latitudes are cold and summers mild (if anyone doubts, read on here); the southeast Asian Monsoon usually starts over India in the first days of June. I don’t usually bring with me maps and figures to social events, but it would be nice to show a picture such as the one in Fig. 1 to illustrate. If the person is not convinced, I may continue with other arguments for why the climate is predictable: take the latitude for instance – the poles are cold and tropics warm. Furthermore, maritime climates at higher latitudes with wet and mild (small day-to-day or season-to-season temperature variations) are distinct to continental climates far away from the sea (dry with great temperature variations). It is well-established that high-altitude places tend to have lower temperatures and greater temperature variations. Most hikers and mountaineers have experienced that. These are local climatic properties that we can predict if we know the geography, even if we cannot predict the weather on an exact day far in the future. To convince further, I may add that empirical evidence suggesting that (local) climate is not unpredictable, but rather systematically influenced by external factors (boundary conditions) is that Northern Europe enjoys a mild climate: Oslo is roughly on the same latitude as the southern tip of Greenland. There is a reason for that – Oslo has a considerably warmer climate because of the effects of oceanic heat transport/capacity and prevailing winds. I also remind that people really have known for centuries that there are systematic factors influencing the local climate, it’s just that this fact sometimes gets forgotten by those who claim that we cannot predict climate. Isn’t it silly? I may ask if there is any reason to think that the predictability stops at the seasonal and geographical variations.

Fig. 2: Mean 2m temperature from ERA40

I may continue with in a hand-wavy manner: In a similar fashion as seasonal and geographical effects, changes in Earth’s orbit around the Sun alters the planetary climate by modifying the amount of energy received from our star (but because of terrestrial response, the atmospheric composition is modified as well, enhancing the effect even further), and changes in the atmospheric composition affects the climate because grenhouse gases absorb heat that otherwise would escape into space – greenhouse gases are transparent to sunlight, but opaque to infrared light due to their molecular properties and their ability to absorb energy (if I say it’s quantum physics, people tend to understand it’s getting a bit technical). I stress that the greenhouse effect is also beyond doubt – without it, the energy balance between total energy Earth intercepts from the Sun and the energy lost through black body radiation implies that Earth’s surface on average would be about 30K cooler than we know it. Volcanoes also affect our climate, and we have theories explaining why. Furthermore, looking to other planets, the observation that Venus has higher surface temperature than Mercury, despite being further away from the Sun, can only be explained as a result of different absorbing properties of their respective atmospheres (a strong greenhouse effect at Venus).

So, my question is, do you think people get the message that I try to convey this way? Is it too simple or too complicated? Somebody who knows of every-day examples demonstrating the central principles? Any suggestions on how to explain for laypersons not connected to the Internet?


219 Responses to “Short and simple arguments for why climate can be predicted”

  1. 51
    Ike Solem says:

    All of the examples in this post would work well, but as usual it all depends on the audience.

    What people want from weather forecasts are temperatures, precipitation, and wind speeds – these are calculated based on the location of high and low pressure systems, jet stream positions, and current land and sea surface temps. This is rather like calculating a trajectory; a decent analogy is the path a ball takes as it is dropped into a spinning roulette wheel (people are always interested in gambling). You might guess the first bounce position, but after that ‘sensitive dependence on initial condition’ takes over; the same is true for weather systems. There is some interesting history here as well – in the 50′s, there were those who dreamed of controlling the weather on large scales (yes, military planners who wanted targeted blizzards, etc.) but the work of people like Ed Lorenz put an end to that – how can you control what you can’t even predict? (Cocktail parties must always include tasty tidbits).

    Climate study involves oceanic circulation and ice sheet/glacier dynamics, and the timescales involved are fairly long (not nearly as long as geologic-tectonic process timescales, however). The turbulent mixing of the atmosphere occurs on much faster timescales, which is really what limits the weather forecasts to a week or so. Weather models rely on a constant stream of data from satellites and weather stations to make their predictions. Even if ‘perfect’ knowledge of the current state of the atmosphere down to every cubic millimeter was available, weather prediction would fail in something like two weeks, according to the experts – there is in the study of chaotic systems a relationship between timescales, probabilities and predictabilites – beyond that, you’ll have to ask a mathematician for the details.

    Climate is the averaged weather over long timescales, and again the roulette wheel analogy is useful. The house always wins in the end, because they get one more slot then the players do; they rely on averages rather then specific events, and the same is true for climate models. So if we take the pre-industrial greenhouse effect as the level playing field, and anthropogenic forcing as the sum effects of deforestation and fossil fuel combustion, then we are playing with loaded dice. Keep in mind that averages can hide a lot of variablity – there is always the risk that a random series of big wins will wipe out the house (Katrina, for example).

    The most succint explanation I’ve seen of the greenhouse effect is by Kerry Emanuel from MIT, writing in the Aug 06 issue of Physics Today, p74: http://www.physicstoday.org/vol-59/iss-8/p74.html – (a nice article on hurricane physics)

    “The outgoing IR radiation is strongly absorbed by clouds and by trace amounts of certain gaseous components of the atmosphere, notably water vapor, carbon dioxide, and methane. Those constituents reradiate both upward and downward. Remarkably, the surface receives on average more radiation from the atmosphere and clouds than direct radiation from the Sun. (my italics) The warming of the surface by the back radiation from the atmosphere is the greenhouse effect.”

    Most people will be surprised by the italicized statement. Since the ‘atmospheric IR window’ is not saturated with respect to the greenhouse gases, adding more CO2 means more back radiation to the surface. I don’t know if trying to wow the audience with jargon is a good idea, but this does lead into quantum physics and ‘perturbations of the radiative-convective equilibrium state’.

    Climate models, just like weather models, are influenced by field data on ocean circulation and ice sheet dynamics – but the longer timescales involved mean a longer range of accurate predictions. A hundred-year climate forecast then seems reasonable; a million-year climate forecast would be viewed as nonsense (but not a million year plate tectonic forecast!). At this point in the party (hopefully you aren’t depressing everyone) one could bring up the melting ice sheets and tropical glaciers, the warming oceans, the melting permafrost, the destructive hurricanes, the ecological disruption, the record heat waves, the drowning islands and the waves of environmental refugees – essentially we’ve got a looming catastrophe of truly epic proportions.

    However, the ‘explosive catastrophe’ portrayed in “Day After Tomorrow” really seems like the wrong approach; those who concern themselves with ‘image and message’ seem to think that people only respond to shock treatment. Consider Ebola virus (a terrifying ‘flesh-melting’ virus) vs. HIV – the slow virus is the more dangerous one, since it ‘sneaks along under the radar’; thus AIDS kills far more people and has had greater economic effects than all the ‘Hot Zone’ viruses. Likewise, global warming will do more damage then all the oil spills and industrial accidents put together. The real test of the adaptive value of human intelligence is whether or not we can respond to long-term problems that play out over many generations.

    A common question is “Well, then why can’t scientists all get together and give us a straight answer?” – but that is exactly why the IPCC was formed – to gather data and opinions from a wide variety of climate scientists who work, as scientists do, on narrow problems – from those who collect ice cores all over the world to those who couple atmospheric models to ocean circulation models to those who study tropical disease epidemiology. However, if you follow the news you learn that the fossil fuel industries have funded a massive public relations campaign to confuse the issue and prevent any regulations that would limit CO2 emissions from being put in place – and part of that campaign as been a series of very public attacks on the IPCC reports.

    You can point out that those vested interests could reinvest in renewables (and reforestation) on a very large scale – and then they would no longer have to foot the bill for the public relations campaign (they won’t do this without government involvement). This often leads into a discussion of whether renewables can actually do the job or not – which is another topic, but by this point, perhaps you’ve managed to convince the audience of the reality of the problem. Renewables are capable of doing the job, and you have to replace a global fossil fuel energy infrastructure that is valued at something like $10 trillion – and the technology does exist to do this. There are many corollary benefits – less pollution, lots of jobs, and fewer conflicts over scarce energy resources. If you are going to discuss the problem, it’s always good to end on a positive note – unless you want the party to dissolve in a fit of depression and despair.

  2. 52
    pat neuman says:

    Ron,

    I’m bothered by the comments from the Meteorologist In Charge (Mike Stewart, MIC Duluth NWS office).

    In the excerpt below, who do you think the NWS MIC is speaking for when he says:

    … “Bottom line is we’re not really sure what is causing global warming or if it is even going on,” …

    http://www.northlandsnewscenter.com/Reports/default.aspx?preview=&type=SR&NStoryID=2785

  3. 53

    Re #52 Pat, Thanks for that link. I think the answer that Rasmus needs is contained there. It ends

    Because of the accumulating evidence, Dr. Wilson thinks we need to act now to slow or stop global warming.

    - I don’t think you can wait until the ambulance comes around the corner until you take some corrective action, and that’s why I’m in favor of developing a balanced plan to do that now instead of waiting until it is too late.

    Dr. Wilson feels the best way for people to take corrective action is as simple as trading a gas guzzling vehicle in for a smaller one.

    He did that himself recently.

    ============================

    Rasmus, if you tell your party guests that you are an expert and that you have bought a smaller car, then they will believe you!

  4. 54
    Steve Sadlov says:

    The 3 month lead forecasts done by the US NWS are an example where “weather” forecasting is really at the lower bounds (temporally) of climate forecasting. If I were a young and ambitious PhD candidate, I might well consider a study looking at the success record of such forecasts. I might then look at some of the errors and determine there root causes, and finally propose improvements to the GCMs to remedy them.

  5. 55
    Jonathan says:

    Rasmus,
    For perspective, my research is in carbon sequestration. So in addition to the problem you have I then have the problem of answering ‘what can be done’, ‘why do you think this is possible’, and (because I live in NYC) ‘aren’t hybrids the complete solution’. And worst of all this is inevitably at parties where I don’t really feel like explaining what carbon sequestration is to an audience that probably doesn’t care about the details nor feel like giving a mini-lecture. Anyone care to venture a stock paragraph covering climate change, carbon neutrality, and carbon sequestration?

    My last thought is unfortunately a downer. How come it is perfectly acceptable to claim that Rasmus’ job is ultimately a completely and total lie right to his face: ‘Oh, you predict climate? That’s not possible.’ But it would be considered a major faux pas to go up to a stock broker, lawyer, or anyone really and tell them you don’t believe their job is possible. I don’t imagine any other scientist would be so approached nor any other job where presumably the person in the field has gone through the trouble of studying the issue in depth. Not that I ever raise such a thing in public, but whats the take home message for a young scientist on that particular issue?

  6. 56
    Ron Taylor says:

    Re 52

    Pat, I really do not understand the disconnect between NOAA and NWS, since I thought the latter was part of the former. I cannot imagine who Mike Stewart was speaking for, but he seems not to have read this page from NOAA, updated on January 11. Hmmm. A careful rereading of the page reveals that it never actually says that climate change is due to human activities, though one could easily make that deduction from the information presented. Puzzling…

    http://www.research.noaa.gov/climate/t_observing.html

  7. 57
    Pekka Kostamo says:

    I beleve there are at least two problems.

    One of them is that the climate changes are too slow to register with most people, even if the change is easily perceived by a focused expert. Something dramatic must occur – a new world record is perhaps a minimum requirement. In fact the “temperature record” claims have generated a lot of attention already.

    Another point in my opinion is that the “global average temperature” is an abstract concept. It does not relate directly to anyone’s daily concerns. One degree this way or that, why should he/she care? Developing more meaningfull descriptions of the impacts is a priority (it is a difficulty, too). Precipitation changes are already much more significant, a great many people can see their impact on basic agricultural production, or the tap water supply.

  8. 58
    pat neuman says:

    re 54.

    Steve,

    1990s studies by scientists in NOAA’s National Climatic Data Center showed that rainfall intensity increases with climate warming. Based on my studies and career (1976-2005) in hydrologic modeling and river forecasting, rainfall intensities and flooding have been increasing in the Midwest. I think the day to day weather forecasts are already there, unless I don’t understand your terminology for ‘lower bounds of climate forecasting’.

  9. 59
    Mark Shapiro says:

    Re: 25, 42 – Bryan Sralla asks about the recent loss of ocean heat (OHCA data) in Lyman et al since it poses a question for the models, which predict heat gain in the oceans. The link –

    http://www.pmel.noaa.gov/~lyman/Pdf/heat_2006.pdf

    Lyman observes a loss of 3.2 x 10^22 Joules of heat from upper ocean between 2003-2005.

    Hank Roberts asks in 29: >loss of heat – loss of ice? So here’s a back of the envelope calculation:
    How much heat does it take to melt one cubic kilometer of ice?
    Latent heat to melt ice: 355,000 j/kg x 1,000 kg/cubic meter x 10^9 cubic meter/cubic km
    = 3.55 x 10^17 joules to melt one cubic kilometer of ice.

    And then how much ice is melting? Jianli Chen in Science thinks Greenland is losing 239 cubic km per year, and Antarctica is losing 150 cubic km per year according to Velicogna and Wahr. If total ice loss in 2 years was a round 1,000 cubic km, the total latent heat loss is: 3.55 x 10^20 joules.

    This is 1% of the heat loss that Lyman found. Then there is the heat to warm all that ice, first to melting point and then to the average temperature of the ocean.

    How’s my arithmetic so far? And what is the temperature of the oceans that the ice melt mixes with?

  10. 60
    Steve Sadlov says:

    RE: #58 – this is an example of what I was referring to:

    http://www.weather.gov/climate/l3mto.php

  11. 61
    Nick says:

    You can then look at hindcasts (forecast made for the past, but performed in such a way as if it were in the future so that the observations against which you want to evaluate the model are not used in making the predictions.

    ———————

    The major problem with hindcasts is that people just select the ones that work. It is human nature. That means that hindcasts are biased, in a major way.

    ie. You build a model.

    You configure it that it fits the test set. (1)

    You then test it as a hindcast against data after the test set

    You then throw away the models that don’t work in a hindcast (2)

    (1) For a financial model, this is fine. For a climate model, its wrong. The model should be based on physical constants first, then on observation if you can’t get that to work. Empirical models in my opinion are suspect.

    (2) Throwing away the hindcasts introduces a bias and effectively makes the test data used in the hindcast part of the set of data used to fit the model.

    Nick

    [Response: That's not how it works. The tunings are done on present day climatology (mean observations over the satellite period for instance). The tests are done on the transients (volcanic forcing, 20th Century etc.). The physics is not adjusted to make the transients fit better. - gavin]

  12. 62
    Bryan Sralla says:

    Jonathan, your comment is thoughtful but misses the point. No one is claiming that the modelers job is a “lie” or that modelers do not have great value in this current revolution taking place in understanding the earth/atmosphere system. Many other science-educated people are mearly issuing a caution to the most eager in the community, not to promise too much, lest the entire scientific community lose credibility when the predictions fail to come true. This was articulated well recently by the Roger Pielkes. How can this statement possibly be controversial? It is indeed an extreme viewpoint to hold to the notion that we have all the answers to this amazingly complex system, when the science is only about 30 years old. If we cannot reach common ground here, carrying any discussion forward will be difficult. Regardless of the theoretical controversy about whether or not the climate system is chaotic from a strict technical definition, the point should be that climate is not now predictable across yearly, much less mult-decadal time, as graded by the measuring sticks agreed upon by the climate science community at large. To perpetuate a belief that they they indeed are (contrary to the evidence), falls more in the realm of faith than science.

  13. 63
    Hank Roberts says:

    And note the depth to which they’re reporting cooler water, this isn’t just a surface water change.

    I wonder how one can distinguish an actual radiative loss — energy leaving the planet — from a decrease in surface temperature connected to deep abyssal water warming.

    I recall that although no change due to global climate warming is expected to show up for decades or centuries, changes in the deep ocean temperature (increases) have shown up several places — there was a report a few years ago from a Japanese oceanographic survey, and this long time sequence from the Nordic area:
    http://ams.allenpress.com/amsonline/?request=get-document&doi=10.1175%2F1520-0442(1999)012%3C3297:TAOTNS%3E2.0.CO%3B2#i1520-0442-12-11-3297-f02

  14. 64
    Hank Roberts says:

    Here’s the other abyssal warming story I recalled, though the newspaper doesn’t give the Nature cite it should be identifiable by author and approximate date:

    http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2004/03/01/MNGEL5B7VE1.DTL
    My excerpt, see link for full text

    “Masao Fukasawa of the Japan Marine Science and Technology Center in Yokosuka, Japan, and five other researchers discovered the temperature change by going to sea on three research vessels and measuring deep-water temperatures across the North Pacific. Then they compared those temperature measurements to measurements made by researchers in 1985.

    “The warming isn’t caused by an impending El Niño, one of those quasi- cyclical Pacific warming episodes that turn California either into a floodplain or a drought land, experts say. That’s because El Niños concentrate farther south and in shallower water.

    “… the Nature article reports that by some unknown means and much faster than assumed, the solar-heated water is finding its way to the ocean floor in decades, not centuries. In fact, the researchers estimate it reached the bottom within 50 years.

    “But how?

    “The Fukasawa team’s findings show a warming in the deep North Pacific over a “shorter time scale and larger spatial scale than (has) ever been believed,” Fukasawa said in an e-mail. “As (far) as I know, our result is the first which shows such a large-scale temperature change in the global thermohaline circulation,” that is, in global heat and salt circulation via ocean currents.

    Joseph Reid, a veteran oceanographer at Scripps Institution of Oceanography in La Jolla (San Diego County), not associated with the research, said the undersea heating “is surprisingly large over that period of time, some 20 years. It’s the first convincing evidence of warming at that depth. I can say I was surprised.”

    “It’s much too soon to blame global warming for the deep-sea warming, Reid and other experts caution. “To go from this (observation) to say, ‘This is global warming,’ is just a guess,” Reid said. In any case, “this (Fukasawa result) is something that should be watched very carefully.”

    “At the very least, the Fukasawa finding indicates that computer models of ocean circulation — which are vital for monitoring climate change — are badly in need of a tuneup. The discovery was not explicitly predicted by any known computer models of ocean circulation. “

  15. 65
    pat neuman says:

    62. reads: … Many other science-educated people are mearly issuing a caution to the most eager in the community, not to promise too much, lest the entire scientific community lose credibility when the predictions fail to come true. … How can this statement possibly be controversial?

    Bryan, there is nothing controversial about the fact that many of the world’s best scientists have observed that rapid climate change has been going on already. That needs to be acknowledged by everyone.

  16. 66
    Lynn Vincentnathan says:

    I’ve brought this up before, but there are also examples from social sciences. Sociologist Durkheim noticed that suicide rates stay fairly stable year to year, which led to his dictum “social facts (not psychological facts) cause social facts.”

    So while each individual suicide may have its unique causes & have to do with psychological aspects & be quite unpredictable at the individual level, the fairly constant & predictable (year-to-year) suicide rate is affected more by social aspects (I won’t bore you with Durkheim’s theory of anomie).

    It’s a matter of the level of analysis — climate & weather are 2 different levels.

  17. 67
    Bryan Sralla says:

    Re: #59. Good idea, but unfortunately I do not believe it is correct (Levitus et.al,2000) . The change in ocean heat storage (OHCA)is equal to the non-equalibrium forcing (Pielke, 2003). Put more simply, the ocean heat change is approximately equal to the net radiative imbalance at the top of the atmosphere. What you are describing is a transfer of heat from one component of the system to the other, not a loss of heat to space.

    A viable possility however, is that the heat is still in the system, like the deep ocean. Gavin Schmidt really knocked that idea in the head however in his critique of the maligned Bill Gray. Your viable options to explain this statistically significant global cooling are thus: 1) the heat has been transfered to the deep ocean like some kind of solid nuclear waste, 2)aerosols negatively influenced the amount of shortwave reaching the ocean surface, 3) a negative flux in shortwave reaching the top of the atmosphere, or 4) a strongly negative water vapor feeback.

    I knew no one would like 4, so the list narrows!!

  18. 68
    Bryan Sralla says:

    Re:#65. Agreed, I do not think there is much controversy here.

  19. 69
    Hans Erren says:

    A forecast has a likelihood, the likelihood of weatherforecasting
    limits itself to ten days. Combined all the likelihoods of the input
    parameters and the uncertainties of the parametrisations for climate
    makes it impossible to make a forecast with a 70% likelihood for the
    next 50 tyears:

    Let me list the uncertainties in climate for 50 years:

    Sun:
    Some say a new maunder minimum is imminent, others extrapolate
    the current increase. That alone accounts for an uncertainty of at
    least a full degree (+0.5 or -0.5) for the next 50 years.

    Volcanos:
    Every Pinatubo like eruption causes a drop of 0.2 degrees
    over two year. We cannot predict plinian eruptions.

    El Nino: we cannot predict long range el nino.

    These are only the uncertainties in natural factors.

    Anthropogenic factors:

    Emission uncertainties:
    Nobody can predict economic growth, that’s why there is a huge
    bandwidth of SRES scenarios, all optimistic. However: China is having
    currently a major boom, this will without doubt lead to a worldwide
    recession when they hit their first growth limitations, unaccounted
    for in all SRES scenarios.

    The richer the country the lower the emission rate, the younger the
    economy the faster the technological adaptations (look at Japan,
    Korea and Singapore)

    So we cannot predict CO2 emissions for the next 50 years

    Sink uncertainties:
    CO2 emissions need to remain in the atmosphere in order to have a
    climate forcing. Sink modeling assumes either a sink saturation
    (Joos) or an increasing sink (Dietze).

    Climate sensitivity uncertainties:
    The range of climate sensitivity for CO2 is between: 0.5 (negative feedback) and 3 degrees (positive feedback) for CO2 doubling.

    Which for the next 50 years means that the uncertainties in natural
    factors still outnumber the antropogenic effect.

    Therefore we cannot predict climate for the next 50 years.

    [Response: That is exactly why we (mostly) talk about projections, storylines and scenarios. -gavin]

  20. 70
    Eric (skeptic) says:

    Lynn, to pick a less depressing social analogy, the people who believe in AGW, dire consequences and the need to do something represent local warming. The ones who don’t know or care are steady climate, and the skeptics and denialists represent cooling. The global average temperature or global AGW sentiment can be added up by adding up all the people. But there are social forcings and feedbacks occuring. The broadest forcings are media stories, Al Gore’s movie, etc which I would liken to CO2. The feedback comes from political changes brought about by general awareness of warming through more media buzz, discussion, education, etc. Denialists with a media outlet provide the opposite feedback.

    I would maintain, as I have all along, that modeling such a complex system would require modeling prototypical people, just like prototypical weather, the lower layer. Without that modeling you really will have no accurate notion of how one person’s opinion, or the local weather, will change based on overall awareness or climate. But as some here will argue incessantly, people can just be parameterized and averaged for good enough model results.

  21. 71
    Eric (skeptic) says:

    I should have said, the Denialists provide the opposite *forcing* (not feedback).

  22. 72
    Chuck Booth says:

    RE#57 “‘Global average temperature’is an abstract concept. It does not relate directly to anyone’s daily concerns.”

    A good analogy that people do readily understand is body temperature: It varies greatly depending on where, and how, you measure it. But, measured consistently and in the right location, it is an index of mean body core temperature and conveys meaningful information about your state of health. As I’ve noted on other threads,it takes only a very small change in body temperature to make us sick: A one degree C rise is classified as a fever, and is a sign that something is wrong. A three degree C rise is, for an adult, a severe fever that could put the patient in the hospital. And a 1-3 degree C temperature rise is in the ballpark for predicted temperature increases due to AGW; I like to point this out when skeptics scoff at such a small change being important to living organisms.

  23. 73
    cat black says:

    For an analogy that most people will “get” at once, use Las Vegas gambling. Even though everyone understands in advance how to play the games (the materials, physics, rules, odds, etc) people play exactly because of chance, and not knowing the outcome. This is like weather; even understanding every single issue, there is chance in the outcome. Climate has an element of chance, but is less like gaming and more like the house take. The house will *always* be profitable. We know this. The exact profit and how it will be made is unclear, but it will happen with utter certainty. That’s why there are gaming houses at all. We play the odds while they play the certainty. These co-exist within the same system. If they could not co-exist the game would be over. Weather uncertainty and climate prediction co-exist in much the same way, as they are about very different things.

    It’s a BAD analogy. I didn’t say it was good, I said people would get it. Sometimes you gotta go with what you got.

  24. 74

    Given the “we can’t predict weather past 5 days and you want to tell us what’ll happen in 2100?” argument, I usually say something like, “Don’t confuse weather and climate. I don’t know what the temperature will be in Cairo, Egypt, tomorrow, but I’m pretty darn sure it will be higher than the temperature in Stockholm, Sweden.”

    -BPL

  25. 75
    Ike Solem says:

    Note that using the latent heat of melting as the basis for predicting melting glaciers misses the dynamics of ice sheets (they slide, in other words). If the ice ends up floating in the ocean, the heat balance is still there – but what if you have patches of dark ground where there was once white ice? Then you have to add in an albedo effect on the total heat budget. This is different from the Heinrich ice-rafting events during glacial maximums; I don’t know their causes ( http://en.wikipedia.org/wiki/Heinrich_event ).

    We may be entering a climate regime that hasn’t been around for millions of years – see the Hank Roberts post above on the warming ocean depths – hard data to get as you can’t just look at sea surface temperatures. The reports of ‘dead zones’ (better known as oxygen minimum zones; anaerobic bacteria like these areas, not much else) off the Oregon coast and in other areas make one wonder if global ocean stratification will set in, resulting in a new era of oceanic deep-water hydrocarbon formation like the one some 90 million years ago that produced the Mideast oilfields. This kind of shutdown is quite unlike the proposed ‘cooling effect’ that would presumably weaken the Gulf Stream. (Please note that it would take many more millions of years of tectonics and heat/pressure to actually form deposits of oil).

    http://www.sciencedaily.com/releases/2004/08/040810091946.htm
    “New Hypoxic ‘Dead Zone’ Found Off Oregon Coast”

    This is just random speculation… I just noticed how long my earlier post was – that approach would probably require a captive audience.

  26. 76
    Bryan Sralla says:

    RE:#7 Not so fast Pat. If you had looked at the trend from 2000-2005 in Alaska, you might have predicted a continuation of the warming in 2006. Alaska has cooled significantly in 2006 however, and the first half of 2006 was one of the coolest for the same period in the last 20 years. The climatology found at the Alaska Climate Research Center will support me on this. I also have noted that summer sea ice in 2006 is back near the 2000 level after a huge reduction in 2003. It is still diminished, but looks to be on the rebound. No predictions here, but I wouldn’t bet the farm on a warm 2006 Minnesota winter.

  27. 77
    pat neuman says:

    re 72. 57. “‘Global average temperature’is an abstract concept. It does not relate directly to anyone’s daily concerns.”

    Climate models and temperature observations have shown greater warming in higher latitude regions and higher elevation areas.

    A one degree F increase in globally averaged temperatures over the last century does not mean that 1 degree F warming is evenly spread throughout the world at all locations.

    Scientists did not expect to see warming in in low elevation areas within mid and low latitude regions during the last century.

    References:
    1. Greater warming in higher latitude regions:
    http://www.realclimate.org/index.php/archives/2006/01/polar-amplification

    2. Andes study shows it gets hot faster at high altitude
    26 June 2006
    http://www.scidev.net/news/index.cfm?fuseaction=printarticle&itemid=2935&language=1
    from=blog_permalink_mainindex&ref=/blog/weather/

    Note: also being discussed in an Aug 7 The Weather Channel blog entry.
    http://www.weather.com/blog/weather/8_10133.html?

  28. 78

    Re #62 and “It is indeed an extreme viewpoint to hold to the notion that we have all the answers to this amazingly complex system, when the science is only about 30 years old.”

    Fourier discussed the greenhouse effect in 1824, Tyndall showed that carbon dioxide absorbed infrared light in 1859, and Arrhenius made the first quantitative estimate of global warming under doubled CO2 conditions in 1896. How do you get “only about 30 years old” from that? The year at present is 2006.

    -BPL

  29. 79
    Bryan Sralla says:

    Re: Barton, thank you for challenging me on this. There has been a revolution in climate science in the last 30 years. I give a good deal of credit to the modelers, because they have challenged many of the antiquated ideas. Let’s give credit where it is due. So I think it is fair to say that the modern era of climate science really began in earnest around 30 years ago.

    With these new tools (and better data collection), there have come a new set of paradigms, questions, and hypotheses (technical and ethical). Like scientific history has shown, often new insight raises more questions, and these new questions are different from the old ones. In my opinion, this is about where we are in this process.

  30. 80
    pat neuman says:

    re 56.

    Ron,

    Although I think I have a pretty good understanding on how NOAA and NWS operated until 2005, I have no connections to what’s going on at NWS now (not since I was handed a July 15, 2005 Memorandum to Remove me from government service). NWS managers and staff were not shy about their skepticism of global warming, not even when Gore was V.P. I think they were insulted by Al Gore’s comments about global warming in the mid 1990s, especially in that Gore was not even a meteorologist! I had a similar problem in talking about global warming, being a hydrologist without a meteorology degree. Things got worse for me after Oct 2003, after I did a press release on climate change in the Upper Midwest. I was told by my supervisor that John Mahoney, NOAA Administrator and head of the Climate Change Science Program (CCSP) for the administration wanted me fired because of the press release. I suppose that’s the real reason it happened. BTW, it used to be that federal agency heads, like the director of NWS, were allowed to run their own agencies. I think that all changed about 4 years ago. Now NWS is called NOAA’s NWS by the Vice Admiral and others in management.

    I can’t explain what the disconnect might be now between NOAA and NWS because I’m no longer there and have no connections (no going away party for me). Perhaps someone more knowledgeable about the latest on NOAA/NWS can fill you you in here.

  31. 81
    Bryan Sralla says:

    RE: Ike: #75 Oregon coast and in other areas make one wonder if global ocean stratification will set in, resulting in a new era of oceanic deep-water hydrocarbon formation like the one some 90 million years ago that produced the Mideast oilfields.

    Ike, I am glad you are finally talking about hydrocarbons. FYI, the Middle East hydrocarbon source rocks were deposited in the Tethys Sea. This was a shallow inland sea, that generated restricted anoxic marine source rocks. The massive carbonate reservoirs of the Middle East oilfields are mainly shallow water karsted and fractured dolomites. You are so far off base on this, that it is really hard to even begin to take what you said seriously. Wrong tectonic setting, wrong source rock environment, wrong reservoirs, wrong structural setting. Try again! Global ocean stratification forming oilfields? I have never heard of this in my career as a petroleum geologist. There is way too much junk science on this website.

  32. 82
    Mark Shapiro says:

    Re 67: Bryan –

    I could only get the melting of the ice to account for 1% or so of Lyman’s lost heat (in #59), but I would call it is a transfer of heat from atmosphere and hydrosphere to the cryosphere, and as you point out it is not radiated to space. And the other 99% of the heat could be going deep into the ocean, as Hank suggests in #63 and #64.

    Re 75: Ike – I agree that ice can slide off into the water as well as melt directly. I was only estimating the amount of latent heat from global ice melt as a way of finding some of Lyman’s lost heat. Just noting that if a lot of ice slides into the ocean it will suck heat out while it melts.

  33. 83
    Gareth says:

    Re #76: I also have noted that summer sea ice in 2006 is back near the 2000 level after a huge reduction in 2003. It is still diminished, but looks to be on the rebound.

    You might care to note, however, that if you take a slightly larger view (as the NSIDC do), the modest positive ice anomalies north of Alaska are more than offset by huge areas of negative anomalies, especially north of Russia.

    More like sloshing around than a rebound. Or slushing around, perhaps.

    [Response:The sea ice tends to blow around - i.e. moves with surface winds and ocean currents. In addition, there are freezing and melting processes. -rasmus]

  34. 84

    Re #81, there is a graph showing the state of the Artic sea ice at the site you cited: http://nsidc.org/data/seaice_index/n_plot.html

    It shows that last year’s July ice was a record low, and this year’s July ice was yet another record low. It seems that we have passed the tipping point for Arctic sea ice and it is only a matter of time until it disappears completely :-(

  35. 85
    nick says:

    Gavin, re 69

    Response: That is exactly why we (mostly) talk about projections, storylines and scenarios. -gavin]

    This is what worries me. This statement comes across as spin. By not making a prediction with a confidence interval, there is no mechanism where the models or GW itself can be shown to be wrong.

    Lets say there is a prediction of average temperature + 1.5 degrees +- 0.2 degrees in 10 years. In 10 years, if the average temperature is 0.5 degrees rise, then we have shown that the models are wrong, and we should not trust them.

    There are lots of people laying the ground such that things can be plausable denied if the ‘climate p*o*r*n’ predictions don’t pan out.

    At the end of the day, the science is the science and there is a scientific method. Prediction and test is at the core.

    Nick

    [Response: I think there is a confusion here between the word 'prediction' as used in a scientific context (which is a tightly constrained concept) and prediction in the colloquial sense of what's going to happen. A scientific theory is successful if it makes predictions in very prescribed conditions where as much of the experiment is controllable as possible. So for instance, radiative transfer theory predicts that the infra-red absorption will change in a specific way when CO2 is increased (holding everything else constant). This theory has been shown to be accurate over and over. On a larger scale, increasing the aerosol optical depth in the lower stratosphere following a large volcanic eruption can be predicted to cause cooling because over the short term that is relevant very little else is changing. These kinds of predictions were made in the immediate aftermath of Pinatubo and came in very accurate. But when you start going forward 50 years or so, you are no longer in the realm of a controlled scientific experiment. Scientists and policy makers recognise that and act accordingly. If any of the storylines end up being reasonable approximations of what happened to emissions, the projections for the climate response can be evaluated. This is exactly what has happened with the projections made by Hansen in 1989 - the scenarios closest to what happened gave climate responses closest to what was observed. Contrary to the belief of some, the scientific method is alive and well. - gavin]

  36. 86
    Dan says:

    re: 76. July Northern Hemispheric sea ice extent is now at its lowest on record:
    http://www.ncdc.noaa.gov/img/climate/research/2006/jul/jul-seaice-extent-plot-pg.png

  37. 87
    Alexander Harvey says:

    Taking your last question.

    Any suggestions on how to explain for laypersons not connected to the Internet?

    I think that we have all been rather badly let down by the broadcast media. I am knocking on a bit so I can recall a time when hard scientists could command serious dedicated air-time. Not often, but much more commonly than now.

    I can recall that the BBC once gave over a whole evening to particle physics! Quarks, gluons, spin, strangeness, charm, up & down, symmetry groups, the works. That was an extreme example. I can also recall Herman Bondi giving a series of lectures on Relativity and Cosmology.

    The media were, it seems, more prepared to risk enlightening at the hazard of boring some or many. However it could be argued that those that turn off are not the ones that you need to communicate with.

    At a guess, many of the people, in positions to move the debate forward are of a similar age as I. Baby boomers, and one time protesters and hippies. People with strong self-opinionated positions that are commonly disillusioned with science. For children that grew up with sputnik, it can seem that much was promised and so little delivered.

    Media output that is preachy or scare-mongering cuts very little ice with us. Many of us are simply too jaded or wise to take any of it at face value. What is required here is depth and doubt. Doubt is important. Appeal to our scepticism! The expression of the doubts gives weight to the stuff that we are know lots about, like the propagation, absorption and scattering of EM radiation by gases.

    Presentations that say that it is a done deal cuts no ice with people when they have heard it all before. You should be advised that I was in junior school when we were being prepared for the next ice age. Catastrophic global freezing was looming. Global warming was strictly Sci-Fi, as in “The day the earth caught fire” (Film 1961).

    So what should one do. Firstly it would be good if the media could take it all a bit more seriously. Regular slots, climate strands, one off science productions dealing with the hard science. The hard science ought to be a strength, thermo-dynamics has a good track record, think of all the things that rely on it (Cars, power stations, jets, steam engines). The basis for the effect of CO2 on IR radiation was illuminated by Einstein (1917) in work that also gave us the framework for MASERs and LASER light, and we all know that works. The precise way that absorption bands are built up is detailed and complicated and is described in quantum-mechanical terms. Now we should know that quantum mechanics works (this message is being brought to you by solid state electronics).

    If, with all our knowledge and technology we can not get the basics across at varying levels of depth to match the receptive powers of the audience segments then one must wonder if we can tackle the greater challenges of fixing the problem itself.

    If the mass media is no longer interested in getting serious points across without burdening them with a lot of spin, then perhaps the situation is hopeless. For, in one sense, the alternative, (the internet) is the last field on which one would wish to fight this battle. It is too democratic in its most pragmatical partial sense. Those that have the most time, patience, money and sheer bloody-mindedness will win the argument by simply out-shouting (out-Googling) the rest.

    Finally, I would say that, in one sense, predicting the future climate is irrelevant. Sorry about that! The basic science tells us that if we progressively block one or more of the channels by which the earth cools itself then the system will evolve in ways that compensate for this. This is enough to shout “Climate Change”. If you poke a frog hard enough it will jump, it is not really necessary to know where that it will end up. There is a strong correlation between the amount of energy that you put into a system and the increased dynamism of that system. What it will do precisely is a complicated question. That it will not be the same again is basic science.

    You might disagree, but for me, it is not that the future will be warmer on a globally averaged sense by 1C, 6C or 10C. It is that I have know idea what the parochial effects will be. The parochial, anecdotal evidence is that things have changed and that the changes are accelerating. The scale of these parochial changes is, seemingly, at odds with the limited increase in global temperatures. The climatic system is operating at a higher or at least different level, akin to when an economy is over-heating or a reactor moves outside it design parameters. We are operating the climatic economy using energy budgets that are beyond our reference points. What precisely it will do is irrelevant provided we can accept that the climate system must rapidly evolve and that we might not like the consequences. Are you feeling lucky?

    Here I would depart and say that future climate might have some shocks install just like future weather does. There could be some serious regime change, the system could start to behave in unanticipated ways with consequences sufficiently sudden and dramatic that we would be simply along for the ride.

    I think that effort should be concentrated to getting over enough basic science and a few home truths about what could happen. Arguing over whether it is X degrees C or X+1 degrees C is almost akin to counting angels on a pin head. That we have embarked on a global climatic experiment that could soon spiral out of control is a strong message. Worrying as to whether one is going to burn, or freeze, drown or dehydrate, starve or be annihilated by a dominant world power during a water war is not the issue, that these outcomes are becoming increasingly likely is.

    I think that only the mass media organisations can get the message over in a consistant fashion. If they are no longer prepared to tackle hard subjects squarely and fairly then perhaps we have got what we deserve and have only ourselves to blame.

    I apologies to any scientists or people of a certain age that I may have offended with unfavorable generalisations.

    [Response:By waiting for the evidence - outcome -why then bother with making predictions? The ability of making predictions, or at least plausible scenarios for the future, is in my opinion one of the reasons that we can call ourselves a highly civilised society. -rasmus]

  38. 88

    Re #25,
    Bryan,

    I do not believe you can make the assumption that just because someone cannot explain something means that they do not have a good understanding of their subject. Complex and non-linear systems can be notoriously difficult to explain, sometimes even impossible to some people. Many people have minds that can only deal with linear concepts.

    My brother, for example, is a Doctor of Mechanical Engineering. He correctly identified the flaw in the Mathematical models used by the Finite element analysis software packages that are used by many truck makers to design their Chassis. He actually wrote his own modeling software that correctly factored in the non-linear inputs and it was so accurate that it could identify damaged Chassis rails (to the surprise of the Truck owners). And yet, he has great difficulty describing his ideas simply.

    I guess most languages do have limitations in dealing with non-linear relationships.

  39. 89
    Bryan Sralla says:

    RE; #84 and #83. Good points. I should have been more precise in what I was talking about (Alaska and the region). Your points about the overall trend of NH summer sea ice are noted and acknowledged.

    Overall, it can also be seen that the current high latitutde SST anomolies are also very positive. Since they are negative for a good swath of the southern ocean, this is no doubt an important regional effect. Because the sea ice extent is diminished, the albedo to incoming shortwave is also reduced over the high latitude oceans. This makes the overall heat loss for the entire ocean even more interesting.

  40. 90
    pat neuman says:

    52: … “Bottom line is we’re not really sure what is causing global warming or if it is even going on,” … (NWS chief in Duluth, May 2006)

    65: … there is nothing controversial about the fact that many of the world’s best scientists have observed that rapid climate change has been going on already. That needs to be acknowledged by everyone. (My Aug 14 post at RC)

    68: Agreed, I do not think there is much controversy here. (Bryan Aug 14 post at RC)

    Question: What do you think needs to be done regarding comment in 52?

  41. 91
    Bryan Sralla says:

    #88. Thank you for your response. I may be wrong to apply this broadly , but it is certainly true with me. The important point is my reponse in #62.

    Regardless of the theoretical controversy about whether or not the climate system is chaotic from a strict technical definition, the point should be that climate is not now predictable across yearly, much less mult-decadal time, as graded by the measuring sticks agreed upon by the climate science community at large. To perpetuate a belief that they indeed are (contrary to the evidence), falls more in the realm of faith than science.

    I predict that there will now be a crusade by some to destroy these measuring sticks they had already agreed upon. Gavin Schmidt’s response to Roger Pielke Sr. on the Climate Science website sure indicates that this may be the case.

    [Response: You are reading way more into this than is warranted. Please keep focussed on scientific discussion though. - gavin]

    [Response:I'd like to add that chaotic systems tend to have a 'strange attractor', i.e its states tend to be confined in some way. The limit to predictability is typically referring to a given state on this attractor (e.g. weather). But, it is possible that the shape or the location of this attractor is affected in a systematical way by external forcing (a climate change). To illustrate this, let's consider following thought experiment: imagine that you have a very powerful spacehip and some vert strong long cables. You fix the Earth to the space ship and tow it away from the Sun. What do you expect, that the surface mean temperature is constant as the distance between the Sun and the Earh increases? I don't think so, but I'd like to see an argument to the contrary if somebody has one to offer. In this thought example, systematic forcing changes the systems (Earths weather) strange attractor. This is more about a principle, rather than the prediction skill of a model. Now, the next question is: how well can we predict the climate? Let's start at the shallow end - the annual cycle. Don't forget that most climate models reproduce the annual cycle of the temperature rather well. The seasonal variations in the recived solar energy at a given latitude and the temperature response represent a basic test for how well the models handle variations in the forcing, at east on a local scale. However, there are a number of issues relating to the field of model evaluations, and this is just one of them. It is interesting to note that with the state-of-the art very-high resolution climate simulations coming out from Japan, it's hard to see the differnce between the model results and those from observations (satellites). I haven't had the chance to carry out objective assessments/evaluations for these simulations (but I have for other climate models), but these arguements follow the spirit of the post - to argue in a hand-waving style at the party... Then there is the difference between a scenario and a forecast. A scenario could be regarded as a conditional forecast: given that the forcings behave in certain way, then the predictions tell us what to expect. -rasmus]

  42. 92
    Bryan Sralla says:

    Re: #89 Thankfully, I am not a government employee. Really have no idea how all of this works.

  43. 93
    Dan says:

    Actually Pat, I think it is more than just that many of the world’s best scientists have observed rapid climate change. They have observed, documented, and published the results in peer-reviewed scientific journals rather than the grey literature or places such as the WSJ op-ed pages. Which should carry much more weight that someone just giving the “bottom line” off the top of his/her head per the NWS Duluth chief comment. Sadly it often appears that it does not, due in part to the lack of science leadership from the top. Such as in the White House. Just consider who the President’s past science advisor was, their background and where they are now.

  44. 94
    Bryan Sralla says:

    Re: #91. Gavin, If I read too much into this, I aplologize. It may be a really good idea for me to step back and let this thing run its coarse (as it inevitably will) before drawing too many conclusions. Thank you for the clarification.

  45. 95
    Joseph O'Sullivan says:

    # 89 (and others from Bryan Sralla)

    There is too much emphasis on one paper, the AGU paper about a possible cooling in the ocean. It’s like a “reverse hockey-stick” strategy. Contrarians threw all of their efforts to cast doubt on one study to bring down all climate science. The emphasis on this one AGU paper is supporting one study to cast doubt on many parts of climate science.

    Any one paper needs to examined carefully and examined in relation to all of the research before a valid conclusion can be made.

  46. 96
    Steve Sadlov says:

    RE: #76 – In fact, the entire West Coast had a really cold Spring and a cool early Summer. We had an unprecedented “Siberia Express” pattern (due to its lateness) right into mid June. Only at the actual Solstice did the Pacific High finally assert itself in the manner which normally occurs 6 weeks earlier. Late June was a bit warm but nothing remarkable – the temperatures were what would normally be expected late April through late May (e.g. prior to the normal Summer marine layer – offshore flow cycle setting in). July started with a heavy onshore push with rain in the north. Only during the second half of July did this break. When it did, a set up more typical of September or early October, with a triple barrel High (Rockies, Four Corners, East Pacific) increasing heights and resulting in the infamous “heat wave.” This is of interest, for rather than expressing some “expansion of the tropics” what it really meant was a synoptic regime typical of Early Fall at 40 deg N latitude happening 2 months early. Now, we are in the midst of a rather cool August, with the jet dipping well south. The rains are knocking on the door and we have a squeeqie effect driven 2500 foot thick marine layer on the southern half of the coast. One long range forecast actually states a chance of showers as far south as the Central California Coast both this coming weekend as well as again the following week. Interstingly, the NWS called for above normal temps and below normal precip for California for Aug-Sept-Oct. I am closely observing what actually happens. In September I will make my own call regarding the likelihood of an early start of the Gulf of Alaska Storm / rainy season.

  47. 97
    Steve Sadlov says:

    RE: #81 – As a degreed geologist myself, I concur with the Tethy’s sea mechanism for the formation of the petroleum deposits of Southern Asia and extensions of that belt. The association with the karst topo also is how I learned it. UC, ’84. ;)

  48. 98
    Bryan Sralla says:

    Re: #95. This will be my last entry on this for now. John, the purpose of pointing out this new paper or any other serious technical work, is that it helps us better understand how this climate system actually works. It is not at all my intention or the intention of most other real scientists, to discredit climate science. To the contrary, there is tremendous scientific progress being made. As the science matures and is refined, it will have great benefits for society in general. In science however, new understanding occurs through professional, spirited debate and discussion of the technical work. This process works, and is a beautiful thing. To dismiss other truly outstanding scientists who have a different viewpoint, and try to chill discussion by calling them names like “contrarians” is not at all productive if you really want to get to the right answer. If one’s goal is something else, that is a discussion I am not interested in.

  49. 99
    Steve Sadlov says:

    RE: #83 – Here is something for yet another young, ambitious PhD candidate. A study looking at the changes in salinity in the Arctic between 10 and 100 Deg E Latitude owing to the massive diversions of North flowing rivers by the USSR (and maintained by the CIS). That would be an amazing study.

  50. 100
    Tom Fiddaman says:

    Re 69

    Sink modeling assumes either a sink saturation (Joos) or an increasing sink (Dietze)

    There’s a huge difference here. Dietze asserts that CO2 has a short half life in the atmosphere, based on a 1st order model and a few cherry-picked years of data. Since his model is linear, the sink feedback has a constant gain, and sink uptake rises with increasing atmospheric CO2. Such a model neglects chemistry (partial pressure of CO2 rises faster than concentration in seawater) and biology (CO2 is not the only limiting nutrient etc.). In fact, it doesn’t even conserve carbon. Worse, Dietze’s parameters aren’t even correct; reestimating the model making full use of available data leads to longer time constants.

    The saturating sinks in carbon cycle models like Bern and ISAM aren’t simply assumed in; they are based on structure that conserves physical quantities, experimentally-verifiable behavior (buffer chemistry) and calibration to a much wider range of data (including bomb isotope distributions). If one wants to assess uncertainty in CO2 concentrations for a given emissions trajectory, it makes sense to start with a good model, then look for alternate parameters or structure that remain consistent with the data and first principles. If one chooses instead to beleive that Dietze’s deficient model reflects genuine uncertainty, one might as well also believe that perpetual motion machines will solve our emissions problems.


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