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Only dirty coal can save the Earth |
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| Apr21-09, 01:06 AM | #35 |
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Only dirty coal can save the Earth ) I'll give my spin.Evo is quite right to say there is climate change that doesn't correlate to the amount of CO2. Put another way... there's more to climate than CO2. No scientist anywhere has ever said that CO2 is all that matters. It stands out pretty clearly as the largest single global scale forcing, but to give any kind of credible account of climate you still need to consider:
Popular discussion focuses a lot on a single diagnostic number: a global anomaly. And it's a useful indicator. But if you look, every single actual global temperature anomaly being produced by any research group turns out to be a data product that gives "gridded" results distributed over the surface; and these grids are what are actually used in research and model comparisons and so on. The single value global mean, for any given month or year, is just a handy statistic for a much larger dataset. --- Here's an anecdote, relating directly to the research described in this thread. The research described here focuses on aerosols and black carbon. The work was conducted at NASA, under James Hansen's research group. Hansen is probably the most prominent climatologist in the world today, and he justly stands as a pioneer of work on anthropogenic greenhouse warming. So if you think AGW is a scam, you'll peg James Hansen as a fraud. Shortly after the paper being discussed here was published, a well known contrarian website speculated that Drew Shindell (the author of the Arctic warming paper) must now be in a difficult position, what with his boss being all gung-ho for carbon dioxide. When the guys as NASA heard this, they just laughed... because James Hansen has recently been very active in emphasizing the importance of aerosols and black carbon as well. (It's on the realclimate blog, which is largely an educational outreach by NASA climatologists.) It seems to be a solidly entrenched myth in some circles that the IPCC and scientists generally are fixated on CO2 to the exclusion of all other considerations, unlike the open minded contrarians who have all kinds of alternative suggestions. That is, of course, nonsense. Pretty much all the real progress on other factors is done by the same scientists who recognize the importance of CO2. All those effects work together. It's the people who think they can actually replace the CO2 elephant-in-the-room with something else who are being naive. Aerosols don't replace greenhouse as a theory; they add on to it. The author of this Arctic report, for example, makes no bones about the fundamental importance of CO2 for global climate. That doesn't alter in the slightest his inference of the importance of aerosols and black carbon, both globally and as a particularly strong regional Arctic forcing. See, for example, this interview. It was pretty funny: Shindell doesn't like the term "global warming". He thinks it sounds too cosy, and suggests instead "climate meltdown". Cheers -- Sylas |
| Apr21-09, 01:11 AM | #36 |
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2. The arrow is positioned at 1967. The (US) Clean Air Act regulating SO2 emissions was passed in 1970. The kink in the Arctic temperature anomaly appears at 1967. 3. There is yet a stronger kink in the Arctic anomaly at about 1915 (coincidentally, another low point in the AMO). So, the 1967 kink is not the only distinct (let alone most distinct) kink in the anomaly record plotted in that figure. 4. As I understand it, the actual figure 2 in Shindell (2009) is primarily meant to show the large divergences in the correlation coefficient between global anomalies and different regional anomalies; not to "show" that the effect of aerosol forcings can be "seen" in the Arctic anomalies. 5. Was there a "sharp change in aerosol emissions" around 1967? From the little digging I've done, I've seen plots that say things between (a) there was a sharp decrease in US sulfur emissions around 1970, and (b) there wasn't much of a decrease in North American + European + East Asian sulfur emissions until late in the '70s, but there was a slow down in the increase starting around 1970. Most of the figures I looked at didn't cite the original sources, so I'm not sure how accurate they are. (Example: http://adamant.typepad.com/seitz/ima...p_image002.jpg ). But as a layperson, I have a question relating to your above paragraph: From a rough estimate, I would guess that about 5/9 (or about 56%) of the Arctic latitudes (i.e., lats above 60N) lie below 70N lat, which you mention is the upper boundary for the AMO data. This looks like a large fraction to a casual observer like me. Is this number irrelevant (or insignificant due to its value, contrary to its appearance to me) to a statement (not exactly yours) that the AMO is essentially inconsequential to Arctic climate (which I assume includes the area weighted anomalies shown in Fig 2)? If such a statement is true, is there a reasonably accessible-to-layperson explanation for why this is so? |
| Apr21-09, 02:59 AM | #37 |
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| Apr21-09, 03:00 AM | #38 |
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By the way. We're all lay amateurs here. I'm a novice with an appetite for physics and too much time on my hands. I've learned a lot by reading and playing around for myself, to the point where I feel pretty comfortable talking with experts, but not as an equal. I am an egg. Cheers -- Sylas |
| Apr21-09, 10:28 AM | #39 |
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A general reader is likely to over interpret the graph and see things in terms of one particular year. I did it myself when I first saw the graph, even without the arrow. There's no great damage done as a result. The shift is pretty abrupt, even if you can't really use the data to pin it to a single year. The key point is that there is a definite shift in trend associated with changes to aerosol emissions. That is the hypothesis, well argued in the paper. The arrow points to a time where there is a plain shift in the trend, that the paper associates with a shift in historical trends for aerosol emissions, of which the clean air act is an important part. One of the major points in the paper is that this indicates some possible ways to mitigate Arctic warming. Hence the indicated shift is actually pretty fundamental to the paper. To show what I mean about over interpreting a smoothed average, I picked up a time series for latitude 64 and north, based on the same NASA data used by Shindell and Faluvegi. (Zonal timeseries available here). Shindell and Faluvegi plotted latitude 60 and North. Here is latitude 64 and North, both the data and a 9 year average, as applied in the paper. Note that the actual analysis work uses the underlying gridded product, which divides up the planet with a grid and gives separate anomalies to each cell. The paper itself identifies three distinct phases, as 1880-1930, 1931-1975, and 1976-2007. If I am following this correctly, the middle period was selected to be large enough to include the shifts, rather than trying to pick out a specific year of change. In the analysis of the historical record, setting the middle time period to 1931-1975 was based on the clear shifts in temporal trends around 1930 and 1975. However, it also has the advantage of allowing us to avoid the influence of spurious trends that are thought to have been introduced around the time or World War II, whose influence gradually faded out by the mid-1960s. [ ]-- Shindell and Faluvegi 2009, supplementary information The forcings they derive are inferred from those curves. After some detailed consideration of how this derivation works, they then see if their inference from the anomaly curves can be matched with historical emissions. The inference from the anomaly is first. They are not basing their argument upon the historical data, but rather using the data as a check on their model based argument. In fact, the historical data is in some respects not adequate for making this inference. The authors go on to make speculations for aspects of the history that are rather unclear. It's a neat piece of work; and much stronger that merely taking historical emissions as the basis for forcings. Any graph of a comparatively abrupt transition is likely to have a local minimum that will draw the eye, and no additional explanation is needed beyond this for "kinks". The paper itself definitely identifies the shift in aerosol emissions as the cause for that shift in the anomaly that you can see at a glance when you look. Given noisy data there are random variations that might make one year or another stand out as the minimum in the graph. It's your prerogative to speculate, of course; but temperature timeseries show heaps of natural short term variation that is always present along with any other longer term trends. Furthermore, most of the Arctic is landlocked behind Siberia and Canada. The polar amplification of warming extends right across the whole Arctic, not just the bit adjacent to the Atlantic, whereas we should expect any AMO influence to be more localized. It is quite possible that the AMO will have some impact on the Arctic, but I would expect any impact to be localized. Cheers -- sylas |
| Apr21-09, 07:04 PM | #40 |
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Breaking news!
Drew Shindell has just put up a fairly lengthy guest post at the realclimate blog, specifically to talk about his research. Guest post from Drew Shindell, NASA GISSThis is not peer reviewed comment so it is technically not a legitimate reference for this forum, which is amusing. I think the physicsforum rule is a very sensible one and has obvious advantages. On the other hand, this is written by the first author of the study we are discussing here, and it is specifically intended to give the kind of background context that interested amateurs like most of us here really need. So here's the link, which is useful if you want to know how the authors of the peer reviewed article would explain it at a more accessible level. We'll continue to refer to the peer reviewed article as a basis for discussion, but I think it is fair enough to have a link to Drew's own comments as a resource and aid to understanding of the article in question. I beg the indulgence of mentors. Cheers -- Sylas |
| Apr24-09, 11:54 AM | #41 |
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In fact, the analysis in the paper is not particularly well suited to pinpointing even a single decade during which aerosol emission changes may be inferred from the difference between observed regional trends and modeled results of warming from GHGs + Natural forcings + Ozone since it only analyzes correlations for the linear trends over three multidecadal periods (Fig 4 and related discussion). As for my mention of the AMO/PDO, it was partly based on (my now somewhat foggy) memory of a paper I had read in the context of another thread ( linked here ). I was therefore only mildly surprised when, upon reading the Shindell paper, I got to this part in the concluding section (emphasis mine): Creating the impression that one can easily eyeball correlations (to say nothing of causation) in a complex many-variable system is a bad idea. It's just the kind of thing, in my opinion, that has resulted in the gazillions of climate blogs penned by Tom, Dick & Harry, who have overnight become armchair climate scientists because they have easy access to historical data. It is what I think has led to a gross misrepresentation of climate science, to the extent that every T, D & H now feels qualified to referee and refute the work of professionals. PS: That took too long. I don't have the time or energy to keep this debate up. I imagine we will likely disagree on the broader point here. I will be happy to read any response you have (if you wish to write one), but if I do not follow up, it is not out of disrespect or disregard. |
| Apr24-09, 10:01 PM | #42 |
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Moving on, there are other aspects of this research that can be usefully emphasized. Can dirty coal help save the Earth?? The title of this thread is funny, but it is directly in conflict with the research being described. I'm guess it was intended as a joke, and not as a serious inference. One could only think that dirty coal can save the Earth if they looked at one graphic alone, and not the caption, or the rest of the press release, or the other diagrams. In fact, dirty coal is just as likely to increase the Arctic aerosol warming effect being described. In the press release, and in the associated paper, there's a consistent parallel recognition of two major aspects of the aerosol impact: warming from black carbon, and cooling from sulfates. Though there are several varieties of aerosols, previous research has shown that two types -- sulfates and black carbon -- play an especially critical role in regulating climate change. Both are products of human activity.The main research paper concludes by looking specifically at ways that Arctic warming can be mitigated. This is a consistent thread through all Shindell's research. He's not only interested in describing the science, but seeing how it can be applied. The concluding paragraph of the main text in the paper takes up this theme. Our calculations suggest that black carbon and tropospheric ozone have contributed ~0.5 - 1.4 C and ~0.2 - 0.4 C, respectively, to Arctic warming since 1890, making them attractive targets for Arctic warming mitigation. In addition, they respond quickly to emissions controls, and reductions have ancillary benefits including improved human and ecosystem health.Sulfates are not mentioned here, because they are NOT an attractive target for Arctic warming mitigation. You'd have to increase sulfates, and that's a dreadful idea. The associated damage to health and ecosystems is appalling. Think acid rain. This is why we have the clean air policies in the first place!-- Shindell and Faluvegi (2009), concluding paragraph, p298 The simplest mitigation step is to help clean up the dirty combustion processes that generate black carbon. Most especially this arises from inefficiently combusted diesel fuels, the extensive use of biomass (like wood) as fuel, and small scale and domestic use of inefficient coal burners. Dirty coal also contributes to this load of black carbon. The best approach is moving to cleaner combustion technologies, which also brings additional benefits of health and standard of living for people living in the highly polluted urban centers in Asia, especially. Sources of misunderstanding Sometimes misunderstanding arises just from careless reading. It's always possible to improve the presentation of a press release; but some responsibility lies also with a reader for basic common sense; even with a complete novice. The figure we've been talking about has a labeled arrow for the clean air act, and nothing about black carbon. The text in the caption is as follows: Since the 1890s, surface temperatures have risen faster in the Arctic than in other regions of the world. In part, these rapid changes could be due to changes in aerosol levels. Clean air regulations passed in the 1970s, for example, have likely accelerated warming by diminishing the cooling effect of sulfates.Read in isolation, someone might skip over the word "example" and get the incorrect impression that this is mostly about reducing sulfates with the clean air act; but even a complete novice reader should be expected to see more than just the last diagram of the press release in isolation. The diagram above it, and the main text, all explains the dual impact plainly.-- Caption to a graph: NASA press release While black carbon absorbs radiation and contributes to warming, sulfates reflect it and tend to cool Earth.At the risk of being controversial, the wider response to this paper online and in popular media shows a more serious problem than novices failing to pick up the whole picture at first glance.-- Caption to images of aerosol and black carbon particles: NASA press release for publication of Shindell and Faluvegi (2009) There is strong popular objection to the notion that human influences are driving the trend of global warming, and to the idea that carbon dioxide or other greenhouse gases are the major factor involved. This is fostered by a steady stream of material from various pundits and bloggers and social commentators, ranging from scientifically dubious to demented pseudoscience. In fact, the primacy of anthropogenic greenhouse gases as the major global forcing in the modern era is basic physics. There's plenty of room to investigate other impacts; but it is nonsense to say that anthropogenic greenhouse gases are unimportant. Their central role in global trends is taken for granted by Shindell and Faluvegi. Indeed, Drew Shindell in particular is a major figure in the development of modeling for climate and atmosphere, which shows the global greenhouse impact clear as daylight. The level of misunderstanding in popular debate goes well beyond misreading a press release. The speed at which Shindell and Faluvegi's work has been picked up and passed around by the usual suspects in this game, as if it was some kind of refutation of conventional climatology and greenhouse warming, shows more than mere misunderstanding. Masking global warming The paper argues that most of the temperature increase in the Arctic arises from a regional aerosol impact. It does not mention the clean air act directly; but there is one mention of "clean-air policies" in Europe and the USA, in a single sentence that also speaks of black carbon. During 1976-2007, we estimate that aerosols contributed 1.09 +/- 0.81 C to the observed Arctic surface temperature increase of 1.48 +/- 0.28 C. Hence, much of this warming may stem from the unintended consequences of clean-air policies that have greatly decreased sulphate precursor emissions from North America and Europe (reducing the sulphate masking of greenhouse warming) and from large increases in Asian black carbon emissions.From the numbers, Shindell and Faluvegi are obviously not saying it is all up to aerosols and black carbon; there's still a substantial contribution from a mix of other effects, including the global greenhouse impact and internal regional variability. The method applied in the paper is to take the general global trend, which is a mix of greenhouse, natural and ozone forcings, (G+N+O in the paper) and then identify the local regional impact that drives any local difference from the global trend.-- Shindell and Faluvegi (2009) p298 I'll give the last word here to Drew Shindell himself: Its also worth considering how to interpret the effects of decreasing sulfate during the past 3 decades. To try to make sure that the complex role of aerosols wouldn't be misunderstood, when referring to the recent warming due to aerosols at Northern Hemisphere mid-latitudes and in the Arctic, we stated in the conclusions of the paper:Cheers Sylas |
| Apr25-09, 09:52 AM | #43 |
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(Regarding the controversy issue you raised) I don't see why a novice skeptic of AGW would care for anything in this paper. After all, the analysis is based on a composite of some 20-odd climate models, most of which presumably attribute a sensitivity of somewhere between 1.5C to 4.5C per doubling of CO2. If you ("you" being the skeptic) believe the real number is closer to zero, then you are essentially rejecting the starting point of the paper. Fig 1 in the paper ought to make you stop reading right away, as you doubtless will have noticed that the (1 sigma) error bars on the response per unit forcing from CO2 are way smaller than the error bars from the other types of forcing.
So what is in this paper that it has the skeptics all interested? Why not simply pooh-pooh it in the same way that you'd pooh-pooh any other paper that uses a significant sensitivity to CO2? |
| Apr25-09, 12:00 PM | #44 |
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Anything they can cherry pick in order to form a specious argument is fair game. They know that their audience in general will ignore the contradictions in logic. |
| Apr25-09, 04:44 PM | #45 |
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| Apr25-09, 05:16 PM | #46 |
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You are suggesting a causal link with no statistical basis. |
| Apr25-09, 06:19 PM | #47 |
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| Apr25-09, 09:31 PM | #48 |
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And Al Gore is NOT a member of the scientific community. Neither is the IPCC Chairman. Edit: I notice this is now drifting away from the science in the paper cited in the OP and getting into a discussion of sociological and/or political issues, neither of which belong in this thread and if continued, could well lead to its locking. |
| Apr25-09, 11:24 PM | #49 |
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The carbon capture and storage technology might increase coal usage by up to 40% (for the equivalent energy produced) and cut down CO2 emissions leaked to the atmosphere by 90%. So it would increase the global dimming effect and dampen global warming effect.
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| Apr26-09, 02:38 AM | #50 |
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