July 06, 2006
Is It Getting Warm in Here, or is it Just Al Gore?
from - smijer
Skepticism is a virtue. I don't like to discourage it. So, if a person is skeptical of a scientific result - evolution for instance, or global warming, (yes, I'm looking at you, RW & Buck), I try (not always successfully) not to be too "in-your-face" when I take up for the scientific side. After all, you guys aren't bought & paid for like a couple of the global warming skeptics, or single-mindedly intent on fleecing a religious flock, like some evolution skeptics.
So, if your mechanic tells you that you need an expensive new fuel pump, then, you have a right to be skeptical. But, if every mechanic in town tells you that your fuel pump is going out, and your car is stalling out sometimes lately, it may be time to be socking away some money and maybe at least checking around at the junkyards, even if you don't plan to buy the expensive new fuel pump your mechanic says you need.
I saw An Inconvenient Truth Friday night. I'm glad the movie is out there, and I'm sorry so many people will not see it, because it will not play in their area, because they don't like the "star", they've been discouraged from seeing it by radio, tv, internet or print personalities who have poisoned the well one way or the other, or they just don't have any interest. The critics have a few fair points - the movie is rarely clear on just how certain or uncertain any particular relationship is between CO2 and any individual element of climactic change, and that makes it easy for a non-skeptical watcher to assume the worst. I mean, not smoking-gun may be a mushroom cloud type stuff... just difficult to analyze finely without having done some prior research on the issue.
The big point of the movie, and one that is made relatively well, is that there is something wrong with the fuel pump in our car, and every mechanic in town thinks so. The flaw in the analogy is that the mechanics aren't selling new fuel pumps... They are just suggesting we start looking in earnest.
I don't want to critique the movie, but I do want to offer some analysis of the various claims and arguments against global warming, where they come from, and whether they have merit. None of this will be original, either the arguments or the responses. I'm not the expert. I'm relying totally on others who have earned my trust by using a method that consistently produces useful results. The first few arguments against, I'm lifting from here, with curtsies and hat tips to my friend RW:
- "Yeah, I heard that. Something between one and two degrees over the last hundred years, right?"
Answer: Yes, Farenheit. A little less than a degree Celcius. It doesn't sound like much to me either, but climate scientists give several reasons why it is significant. One is that this change is a global mean, but reflects larger, faster changes at the poles, where we keep most of our ice. Another is that 9 degrees average temperature is all that separates us from the last big ice age: in other words, climate is very sensitive to very small seeming changes in global mean temperature. Another is that 1 degree over a course of 100 years is believed by most scientists to be much faster than natural, cyclical changes that have historically been encountered during this or other periods of relative climate stability. But, the biggest reason is that, at the rate greenhouse gases are being pumped into the atmosphere, every climate model predicts even bigger temperature increases to come.
- You’d think that with the industrial revolution in the first part of the century & there being virtually zero precautions taken against emissions, and less efficient engines everywhere (taking into account the smaller number, one must factor in the lack of environmental insight at the time) that we’d have been worse a bit earlier.
Answer: If, 100 years ago, there had been 6 & a half billion people in the world, with a very large fraction of them daily operating two automobiles, running electric air conditioning, watching electric televisions, buying mostly manufactured products from socks to breakfast cerial, disposing of and replacing those manufactured products as frequently as is the case now, and doing so with less efficient engines and zero precautions against emissions, then, yes - the problem would have been much, much worse then. But "taking into account the smaller number" means acknowledging that the the world population has tripled in the last 100 years, and that there was far less energy consumption per capita then than now.
One of the points in Al Gore's movie was that it took until the year 1800 - ten thousand years after the advent of civilization - to reach a world population of 1 billion. It took another 125 years to add a second billion. And we've added on four and a half more billion people in the last 80 years. These are vast numbers.
- Forgive me if I don’t take as gospel the temperature gauge readings from the year 1906, where Zeke laid down the foundations for future generations prior to taking a sh!t outside & going to a leeching”. Then again, I won’t deny that we’re warming. I dunno.
Answer: In fact, temperature observation and recording was less precise one hundred years ago, a fact which is reflected in the greater margins of error from pre-1950 measurements used by scientists calculating temperature change. But, Zeke probably didn't have much to do with it. Neither did Albert Einstein, but it was in 1905 that he published his paper on the photoelectric effect, showing that light energy moved in discrete particles, the special theory of relativity, and used brownian motion to support the atomic model that Dalton and others had set forth a couple of decades before. A hundred years before that, Jacques Charles and Joseph Louis Gay-Lussac discovered the relationship between temperature and pressure in a gas - a feat that wasn't accomplished without the ability to accurately measure temperature. The mercury thermometer was invented in 1714, and by 1900 there existed several other means of recording temperature with greater precision.
I guess the larger point is this: no matter how skeptical you and I may be of the accuracy of 100-year-old temperature measurements, climate scientists, by nature of their profession, have had greater skeptics among them. They seem to have found a way to satisfy themselves that there is useful data to work from, and that the consensus estimates of temperature increase are accurate. I quote from here:
Annual values are approximately accurate to +/- 0.05°C (two standard errors) for the period since 1951. They are about four times as uncertain during the 1850s, with the accuracy improving gradually between 1860 and 1950 except for temporary deteriorations during data-sparse, wartime intervals. Estimating accuracy is a far from a trivial task as the individual grid-boxes are not independent of each other and the accuracy of each grid-box time series varies through time (although the variance adjustment has reduced this influence to a large extent). The issue is discussed extensively by Folland et al. (2001a,b) and Jones et al. (1997). Both Folland et al. (2001a,b) references extend discussion to the estimate of accuracy of trends in the global and hemispheric series, including the additional uncertainties related to homogeneity corrections.
The mechanics offer us the choice of accepting their analysis, or checking it for ourselves. We could ignore them altogether, but we may be sorry when we are waiting for the tow truck to come pick us up. One route is to check with several different mechanics. They all seem to agree it's the fuel pump. Even if they disagree on how much failure it has already experienced, or how quickly it will fail completely.
- [...] the sun has gotten hotter.
Put very simply, yes. Now this is a decent point, and possibly the best point put forward by global warming critics. Because, on the one hand, the sun has apparently grown warmer lately, and on the other hand, because the phenomenon of variation in solar irradiance, and its effects on climate are not well understood yet. There is little data - in fact, we are in much the same position now with regard to variation in solar irradiance was we were thirty years ago on greenhouse gas based climate change. So, we in fact cannot say with complete certainty that the increase in sun temperature has negligibe effects on climate. We can, however, say with fair certainty that the variation in solar activity (by itself) appears to have much less impact than greenhouse gases (by themselves), according to the data that we do have. I quote:
The variation of solar irradiance with the 11-year sunspot cycle has been assessed with some accuracy over more than 20 years, although measurements of the magnitude of modulations of solar irradiance between solar cycles are less certain (see Chapter 6). The estimation of earlier solar irradiance fluctuations, although based on physical mechanisms, is indirect. Hence our confidence in the range of solar radiation on century time-scales is low, and confidence in the details of the time-history is even lower (Harrison and Shine, 1999; Chapter 6). Several recent reconstructions estimate that variations in solar irradiance give rise to a forcing at the Earth’s surface of about 0.6 to 0.7 Wm-2 since the Maunder Minimum and about half this over the 20th century (see Chapter 6, Figure 6.5; Hoyt and Schatten, 1993; Lean et al., 1995; Lean, 1997; Froehlich and Lean, 1998; Lockwood and Stamper, 1999). This is larger than the 0.2 Wm-2 modulation of the 11-year solar cycle measured from satellites. (Note that we discuss here the forcing at the Earth’s surface, which is smaller than that at the top of the atmosphere, due to the Earth’s geometry and albedo.) The reconstructions of Lean et al. (1995) and Hoyt and Schatten (1993), which have been used in GCM detection studies, vary in amplitude and phase. Chapter 6, Figure 6.8 shows time-series of reconstructed solar and volcanic forcing since the late 18th century. All reconstructions indicate that the direct effect of variations in solar forcing over the 20th century was about 20 to 25% of the change in forcing due to increases in the well-mixed greenhouse gases (see Chapter 6).
Reconstructions of climate forcing in the 20th century indicate that the net natural climate forcing probably increased during the first half of the 20th century, due to a period of low volcanism coinciding with a small increase in solar forcing. Recent decades show negative natural forcing due to increasing volcanism, which overwhelms the direct effect, if real, of a small increase in solar radiation (see Chapter 6, Table 6.13).
Recommended further reading deals with some isolated papers that hype the link between solar variation and climate change, here.
More... much, much, much, more here (PDF) on the subject, from the 2001 IPCC report.
So, solar forcing of global temperatures appears to be real, and appears - at this point - to be very small, but that may change. It will not change the fact, however, that our atmosphere is becoming increasingly saturated with CO2 gas and other greenhouse gases. So, yes, if you are sitting in the car with the windows rolled up, you'll get hot faster on a hotter day than on a cooler one. But that doesn't make it smart to keep them rolled up when the temperature is rising.
- They can't predict the weather a few days ahead. How can they forecast doom & gloom over decades or centuries?
Answer: Short answer: weather versus climate.
An amusing hypothetical exercise-analogy here.
Longer answer: Weather systems are non-linear systems. That means they are sensitive over time to "initial conditions" (or small changes introduced into the system, as the case may be). That's why weather is so hard to predict. It's like a stick in the hornets nest. The stick sets the hornets to flying, but it's hard to guess where the hornets will fly from where you insert the stick, at what angle, or with how much thrust. Climate systems are the cumulative effect of billions of whether changes. A weather system is a stick stuck in a hornet nest. Climate is a billion sticks and a billion hornets nests... You still can't tell where the hornets will fly, but if you know how many sticks are going into how many nests, you can get a fair idea of how safe a walk through the pasture is going to be.
- Water Vapor traps more heat than CO2
Answer: Yes, it does, but water vapor does not accumulate in the atmosphere at levels that create much climate change. (link)
- I remember the '70's when the environmentalists were all warning of doom from an imminent ice age. Why should I believe them now, when they've switched from ice age to greenhouse oven?
Answer: A few scientists did publish some important and well-publicized papers about the possibility of our interglacial period coming to an end, "before long". Newsweek and other popular outlets did hype these studies, and it didn't sound much different than some accountings of global warming we get from the popular press today. So, skepticism on this grounds is quite understandable, however wrong it may be. Real Climate has a piece about this. The central point is this:
The state of the science at the time (say, the mid 1970's), based on reading the papers is, in summary: "...we do not have a good quantitative understanding of our climate machine and what determines its course. Without the fundamental understanding, it does not seem possible to predict climate..." (which is taken directly from NAS, 1975). In a bit more detail, people were aware of various forcing mechanisms - the ice age cycle; CO2 warming; aerosol cooling - but didn't know which would be dominant in the near future. By the end of the 1970's, though, it had become clear that CO2 warming would probably be dominant; that conclusion has subsequently strengthened.
Probably the best summary of the time was the 1975 NAS/NRC report. This is a serious sober assessment of what was known at the time, and their conclusion was that they didn't know enough to make predictions. From the "Summary of principal conclusions and recommendations", we find that they said we should:
1. Establish National climatic research program
2. Establish Climatic data analysis program, and new facilities, and studies of impact of climate on man
3. Develope Climatic index monitoring program
4. Establish Climatic modelling and applications program, and exploration of possible future climates using coupled GCMs
5. Adoption and development of International climatic research program
6. Development of International Palaeoclimatic data network
Which is to say, they recommended more research, not action. Which was entirely appropriate to the state of the science at the time. In the last 30 years, of course, enormous progress has been made in the field of climate science.
Most of this post has been about the science of 30 years ago. From the point of view of todays science, and with extra data available:
1. The cooling trend from the 40's to the 70's now looks more like a slight interruption of an upward trend (e.g. here). It turns out that the northern hemisphere cooling was larger than the southern (consistent with the nowadays accepted interpreation that the cooling was largely caused by sulphate aerosols); at first, only NH records were available.
2. Sulphate aerosols have not increased as much as once feared (partly through efforts to combat acid rain); CO2 forcing is greater. Indeed IPCC projections of future temperature inceases went up from the 1995 SAR to the 2001 TAR because estimates of future sulphate aerosol levels were lowered (SPM).
3. Interpretations of future changes in the Earth's orbit have changed somewhat. It now seems likely (Loutre and Berger, Climatic Change, 46: (1-2) 61-90 2000) that the current interglacial, based purely on natural forcing, would last for an exceptionally long time: perhaps 50,000 years.
Finally, its clear that there were concerns, perhaps quite strong, in the minds of a number of scientists of the time. And yet, the papers of the time present a clear consensus that future climate change could not be predicted with the knowledge then available. Apparently, the peer review and editing process involved in scientific publication was sufficient to provide a sober view. This episode shows the scientific press in a very good light; and a clear contrast to the lack of any such process in the popular press, then and now.
So, scientists were very carefully avoiding real-world predictions of an ice age, they were also looking at the ice-age cycle for the first time, considering the effects of some known cooling mechanisms (and, some warming mechanisms - including greenhouse gases), and asking questions about how to model all of this to make it useful for climate prediction. And the press was blowing it out of proportion.
Contrast that with the present day: scientific consensus is making predictions on real-world climate change (some strong, some tentative). In the movie, Al Gore mentioned this survey of 928 randomly chosen papers published between 1993 and 2003 indexed with the words "climate change", and pointed out that none of them expressed skepticism of the consensus view of climate change from human activity. And though I don't have a link to the study, he points out that a similar study from the popular press shows 53% of those articles are skeptical of the consensus scientific view. (Caveat: most of the papers did not explicitly endorse the majority view, though some did, while others implicitly endorse that view, and 25% take no discernable position. However, none from the survey sample reject it. Peiser claims to have
cherry-pickedfound 34 papers in the same database - not part of any random sample, of course, that reject the consensus view. Peiser's critics show that he was a little over-zealous in his count.)
The point: blame the popular press, not the scientists.
- Global warming is a pipe dream of socialist liberals who want to tax our right to all the energy we can buy.
Answer: With the caveat that this report was created as a worst case scenario, it is is worth noting that the Pentagon is looking at the possible fallout from global warming seriously. As is the not-so-liberal World Bank. Secretary of the treasury Paulsen is certainly no liberal. In fact, see the item above. Sure, maybe the majority of climate scientists are liberals - not all of them are. But damn near all of them support the consensus view that humans are causing global warming, and that it will have adverse and costly impacts on us soon enough to be a cause for concern today. If political ideology played into scientific conclusions so much in the first place, one would expect a divide along partisan lines among scientists. But the fact is ideology is not enough to create skepticism within the science community, though in certain rare cases big money from the oil industry can buy some.
Hell, the list can go on and on... but, I can't. I'll leave you with a couple of generic links on questions of warming controversies...
Fact vs. Myth
Global Warming Skeptic Bingo
How to talk to a global warming skeptic
Posted by smijer at July 6, 2006 10:53 PM