Global Warming... fact, fiction, or a little of both?

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The idea that ice = ice age is patently absurd. Ice will almost always exist someplace. Does that mean we are always in an ice age? Or are you saying that Ice Ages are always relative concepts specific to each location on earth?

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I wouldn't say that it's "absurd". Pretty much the only time you have a polar continent that's covered in an icecap is during an Ice Age, or in our case, an interglacial.Because you need a conveniently positioned continent as well as a favorable climate to accomplish this, ice ages are fairly rare in Earth's history, and by definition this is when you have a have a continental ice cap. In fact, I wouldn't say that we aren't in an Ice Age now, just not in a glaciation.

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Perhaps to stir the pot, let me be so bold as to suggest this has so far looked much like a creationist position. I have seen many exhortations that it must be and that people do bad things which will destroy us if we don't trust in that paradigm and so alter our behavior

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The part about our changing our behavior is an inherently political question. The science itself is independant of whether or not we can, will, or should sign treaties to reduce emissions. That kind of question is primarily for diplomats, economists, and partisan politicians to calculate.

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but the actual facts are not quite so forthcoming... and I did lay out some specific points.

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Well, we know that we're releasing CO2 and a half dozen or so other greenhouse gases into the atmosphere.We know that the ground reradiates heat as thermal infrared, and we know that GHGs absorb and reradiate that. Some component of that reradiated energy must be directed back at the ground unless there are some very bizarre physics going on up there that nobody has yet to discover.Not suprisingly, we know that the average global temperature is rising (BTW, Crichton apparently misunderstood the meaning of 'average global temperature' in his book, since his characters apparently travel to a station that shows a local trend of cooling.)So we can arrive at a hypothesis that our GHGs are causing a warming, and we can construct models that generate testable results.For a long time, it was pretty easy to doubt global warming because soundings and satellite temperature measurements contradicted the ground data. But in the last year or so, it was discovered that the satellite data was being cluttered by gradual orbit decay and that some of the diurnal signal they were getting was actually from nightime surfaces. For example, see Vinnikov and Grody, Global Warming Trend of Mean Tropospheric Temperature Observed by Satellites, Science, Vol 302, Issue 5643, 269-272, 10 October 2003 and a few similar papers in the same journal in recent years.Here's a good article posted on the 'net by one of the scientists involved:RealClimate: Et Tu LT?Further, there's a warming trend in the global ocean from 1948-1998 as measured at a depth of 3000 meters. Since the ocean has a lot of thermal inertia, this is pretty clear evidence that this is a true, global trend and not noise in the data. (Levitus et. al., Warming of the World Ocean, Science, Vol 287, Issue 5461, 2225-2229 , 24 March 2000)And the discrepancy in balloon-borne measurements just bit the dust as well:Sherwood, Lanzante, Meyer. Radiosonde Daytime Biases and Late-20th Century Warming, Science, Vol 309, Issue 5740, 1556-1559, 2 September 2005.From the abstract:

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Several characteristics of this trend indicate that it is an artifact of systematic reductions over time in the uncorrected error due to daytime solar heating of the instrument and should be absent from accurate climate records. Although other problems may exist, this effect alone is of sufficient magnitude to reconcile radiosonde tropospheric temperature trends and surface trends during the late 20th century.

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Now we have arrived at a point where the surface observations, ocean temperatures, radiosonde data, and satellite measurements are consistent with model predictions.That doesn't "prove" global warming and further testing and refinement of these models will continue as understanding of the climate and additional measurements accumulate. However, as of now the theory of anthropogenic global warming is perfectly good science.I know that bald links are discouraged, but I think these can add additional information for this debate to anyone interested. I think they are tangential to the debate but they cover topics that have been raised.This shows how closely models can approximate climate:RealClimate: Planetary energy imbalance?Here's an article on the myth that was already mentioned in this thread that scientists once believed humans would cause an ice age and that it somehow has a bearing on GW today:RealClimate: The global cooling mythAn article entitled "Michael Crichton's 'State of Confusion'"RealClimate: Michael Crichton’s State of ConfusionAnother installment from RealClimate, "Michael Crichton’s State of Confusion II: Return of the Science"RealClimate: Michael Crichton’s State of Confusion II: Return of the Science

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Hurricanes seem to be greater in number and strength every year. Between last year and this year more hurricanes have hit the US than any time before.

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Statistical analyses have shown that hurricane frequency is definately up in recent years. But there are multidecadal cycles in frequency that can also account for this. I'm not ready to pin on it global warming yet, but some papers have come out recently that now say that a warming could cause more, and more intense, hurricanes. They've also found a more convenient way to measure hurricane incidence and intensity by calculating the average heat dissipated by hurricanes instead of merely intensity or numbers. (If this trend of linking GW to hurricanes continues, it is a new development. Dr. Christopher Landsea resigned from the IPCC not too long ago because he thought that his superior was playing up last year's season as a result of global warming when the consensus at the time was that GW would not significantly increase hurricane incidence or intensity through 2070).

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These changes are also affecting my country. This week big pieces of hail have been falling (yes its true hail in a tropical island)

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That is exceedingly unusual, but I don't know that a direct warming of the atmosphere would cause it. I understand that the reason the tropics don't get hail is because the freezing line is so high up that it's hard to make hail in the first place and most of it melts or sublimates on the way down. If you are getting hail now, my first guess would be that the freezing line might have come down a bit, which would mean it was a little cooler aloft. Of course, climate is complex and predicting the consequences of warming for a particular place is very difficult to do. And it's also hard to try to construct a global trend from anomalous weather in a single locality.

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A friend of mine saw it and called me while it was happenning. He said the traffic stoped and everybody was looking and taking pictures of the tornado. If I get my hands on any of those pics Ill post them here.

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Please do that if you can. That would be a thing to see...While we're talking about weather oddities, Brazil got hit by its first recorded hurricane this season.This message has been edited by gene90, 09-14-2005 06:05 PM

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I disagree. I find it highly consistent, or at least not inconsistent. Anthropogenic climate change doesn't mean that the warming trend persist forever. The warming trend itself has consequences, which may include stimulating a period of global cooling. For instance the rise in the temperature of the atmosphere allows it to contain more moisture; more moisture means more cloud albedo and thus less solar energy at the Earth's surface.

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That would be a self-regulating system, not the onset of a cooling trend. It would stay around an equilibrium.

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The question is then, is the new cooling trend limited by the same feedback effect? If it cools too fast, probably not. An expansion of glaciers and record snowfalls increase surface albedo, which prevents warming. Because of its reflectivity, a snowball Earth doesn't heat very quickly.

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Here's an interesting summary of a Perspectives column written in Science:

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OCEAN SCIENCE:
Global Warming and the Next Ice Age

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Andrew J. Weaver and Claude Hillaire-Marcel
There is a popular notion in the media that human-induced global warming will result in the onset of a new ice age. In their Perspective, Weaver and Hillaire-Marcel refute this view, explaining that global warming is unlikely to dramatically alter the North Atlantic ocean circulation. They also emphasize that elevated levels of atmospheric carbon dioxide lead to summer temperatures that do not allow glacier formation and growth.

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Science, Vol 304, Issue 5669, 400-402 , 16 April 2004This message has been edited by gene90, 09-15-2005 10:00 AM

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That's not what Jar said, so I'm not sure why you are saying my comment is incorrect. He said that simply if you have ice where you are it is an Ice Age. That to me is absurd terminology.

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Well, as I understand it ice has been historically rare on Earth outside of Ice Ages. Even now when we have midlatitude glaciers (for the moment) climate is still a bit colder than normal. There *might* have been some glacioeustacy in the Cretaceous, a paper like that was presented at GSA, I think last year. And that was definately a greenhouse climate. But as more of a general rule of thumb than an absolute statement of fact, and assuming we are talking about ice that persists yearlong, I would agree with jar.This message has been edited by gene90, 09-15-2005 10:05 AM

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As you broaden the range some important points regarding GW should start coming up. The first is that while temps are going up, and perhaps they are going up quickly, they do not necessarily seem as out of place in a geologic context.

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I tend to agree with that.

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I certainly did not learn that thus when there was any ice around (even for over a year) it was an Ice Age.

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Then maybe you will find this statement better: as a general rule of thumb across Earth history, the odds are against you finding permanent land ice unless you are in an Ice Age.That is because:(a) Today's climate is unusually cool.(b) It is unusual for there to be land masses near the poles.I do not mean that if I open my freezer and find ice there, I am in an Ice Age, although it could be argued that in that case it would technically be true.You might be find be able to find permanent land ice on Earth during non-Ice Ages if you scoured the planet. However, because the key definition seems to be "wherever jar happens to be at the time", and if jar has a random geographical occurence, then yes, the rule of thumb will usually hold true.

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2) We are not discussing rarity of ice outside of Ice Ages. Ice has existed throughout human civilization (even if not all have experienced it).

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Hence the need to divide the rather colloquial term "Ice Age" into glacials and interglacials. Human civilization is an artifact of our current interglacial. Alpine glaciers have occasionally devoured European villages but there aren't continental glaciers on North America or Europe like there were during previous glacials.

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Thus we are discussing the term Ice Age as humans use it. I provided a reference for that usage. It suggests that it is based on quantity of Ice, not existence of ice.

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Obviously the quantity definition is superior.About the only reason I have sought to defend the existance of ice definition is because I think it has some validity, in that land ice (notice I'm further qualifying it) is usually rare. Of course, this is now a non-issue because you have acknowledged this already.

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I certainly did not learn that thus when there was any ice around (even for over a year) it was an Ice Age.

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No, I'm thinking of it as a 'rule of thumb'. As a definition, in the context you seek to use it, it is clearly inferior.

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3) If any ice is indicative of an Ice Age, and thus we are in an ice age now (technically), then Jar's entire point collapses anyway as GW cannot be said to be the instrument of a NEW Ice Age.

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Technically that's true, but we're arguing semantics. There is a significant practical distinction to be made between the interglacial we live in and when glaciers eat Manhattan.This message has been edited by gene90, 09-15-2005 11:02 AM

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Heheheh... I agree. And thus the question becomes is GW consistent with a scenario where glaciers eat Manhattan? And I don't mean beyond 100+ years.

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It would probably take much longer than 100 years to produce significant continental glaciers even if it started tomorrow.Also, the idea of GW ever causing an Ice Age doesn't seem to be a consensus view, since Science seems to have recently ran a refutation of it in their "Perspectives" column. I posted the summary in this thread. It'll be a little while longer till we all get free online access to the compete article.This message has been edited by gene90, 09-15-2005 11:31 AM

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This is true. I have always felt that it is more the rate at which these changes are occurring that is of concern. The increases in atmospheric CO2 caused by anthropogenic emissions are occurring at a much faster rate than most of the processes which could potentially compensate for it (it's going to take several hundred years for the ocean to equilibrate, for example, and that's one of the faster ones).

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Naturally it's increasing faster than anything that could compensate for it, that's why the CO2 concentration has a positive slope.Though there's some science now that does imply a 'lag' in the warming of the oceans.

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Given that, straight physics says the temperature has to increase.

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A little, but more to the point heat has to increase, be it sensible (like you can measure with a thermometer) or latent.As has been said, really "climate change" is a better term than "global warming" for weasal purposes--because it is less specific...and if negative feedback loops conspire to not allow such a great increase in average temperature, climate still has to change to keep that temperature in check .This message has been edited by gene90, 09-15-2005 12:41 PM

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Now I really want to move away from Crichton. I can only assume this means you did not read his book. He discusses regional versus global temp issues. Now maybe you did read it and missed it, or somehow read into that section some meaning it didn't have, but I'd rather not get derailed into discussing the book. The only thing I have to say is that if you have not read it, and this came from critics, this is the second patently false statement I have seen about his book from critics.

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He may very well have made mistakes, but as yet none that anyone has placed in his typewriter.

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I haven't read it, and should have said so explicitly.

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As this is recent data, I am wondering (if you know) whether it has been corroborated by others, and if so if it is from original data or simply using the same generated data.

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Looking at:Global Warming Trend of Mean Tropospheric Temperature Observed by Satellites by Vinikov and Grody, Science, Vol 302, Issue 5643, 269-272, 10 October 2003.In the abstract they say:

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We have analyzed the global tropospheric temperature for 1978 to 2002 with the use of passive microwave sounding data from the NOAA series of polar orbiters and the Earth Observing System Aqua satellite.

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So they are using the entire dataset accumulated by a number of satellites over many years.There are other groups working on the contradictions between models and even between satellite datasets. For example:Santer et. al., Influence of Satellite Data Uncertainties on the Detection of Externally Forced Climate Change.Abstract:

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Two independent analyses of the same satellite-based radiative emissions data yield tropospheric temperature trends that differ by 0.1C per decade over 1979 to 2001. The troposphere warms appreciably in one satellite data set, while the other data set shows little overall change. These satellite data uncertainties are important in studies seekingto identify human effects on climate. A model-predicted "fingerprint" of combined anthropogenic and natural effects is statistically detectable only in the satellite data set with a warmingtroposphere. Our findings show that claimed inconsistencies between model predictions and satellite tropospheric temperature data (and between the latter and surface data) may be an artifact of data uncertainties.

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I think this segment from the body of the paper should do a fair job of showing the problem:

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The MSU record currently comprises measurements from 12 different satellites. Producing homogenous data sets requires accounting for such effects as intersatellite biases, uncertainties in instrument calibration coefficients, changes in instrument body temperature, drift in sampling of the diurnal cycle, roll biases, and decay of orbital altitude (2-6). Until recently, only one group (from the University of Alabama at Huntsville; hereafter, "UAH") had generated temperature records from the raw MSU radiative emissions data (1, 2). On the basis of these records, it has been argued that the troposphere has not warmed over the satellite era, thus casting doubt on the usefulness of climate models (which predict that anthropogenic warming should have occurred), the reliability of thermometer-based observations of surface warming, and the reality of human-induced climate change (7).

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A second group (Remote Sensing Systems in Santa Rosa, California; "RSS") has now constructed T2 and T4 temperature data sets from the same raw radiative emissions used by UAH (Fig. 1). Over 1979 to 2001, the global mean T2 temperatures estimated by the RSS group warm by roughly 0.1C/decade relative to the corresponding UAH data, which show little net change (6).

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So the situation is really more complicated than merely saying that satellite data either consistent or inconsistent with a global warming. It looks like the first group to reduce the data found no warming, but others using different instruments found a warming consistent with the models and with the observed surface trend.I'm not a climatologist, statistician, or physicist so I can't claim to really understand everything in that paper. But the parts I do understand seem pretty clear, that reducing data in different ways generates different results. I suspect some circularity in there since they "simulated" MSU temperatures with a model and then compared it data from channels T2 and T4, but you still have the old fashioned thermometers on the surface that, simply put, agree with one dataset and contradict another. I tend to side with the RSS based on this.

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Is this increase in increase a significant product of GHGs, or is it more of a synergistic effect between a natural and mandmade source?

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I don't know the answer offhand, but it seems likely that there are many other effects influencing climate. For example, the little cold spell around 1991--probably causd by the eruption of Mt. Pinatubo. Superimposed on that and the anthropogenic GHG component you have reductions in sulfate emission which could contribute to warming as well as other air pollution controls and you have a run up to around 2000 where Sun becomes more active (I have not checked to see if this cycle caused appreciable changes the radiation budget, but it is my understanding that increased sunspots are associated with slight increases in the solar constant).But I would count on there being other natural factors that for a few decades will enhance or detract from the warming attributed to GHGs. The real strength seems to not be that GHGs are the strongest climate driver, but the most persistant. Volcanic aerosols can cause a cooling but they don't seem to last very long.Actually separating out these factors is probably something that can only be done in the models. The good news is that you can measure temperature and aerosols and GHG concentrations, and testable predictions from the models. I am optimistic that while Earth sciences aren't quite as easy to reduce to the laboratory as chemistry or some of the other, 'harder' fields, it's good science and climate models aren't an exception.

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I think there still seem to be pieces missing. I get the correlation (there are rising temps and there are rising CO2 levels), specifically over the last few years, but not the causation... the connection.

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This is a very important point to make. Correlation is not proof of causality. GHGs may cause climate change but climate change probably affects the atmospheric concentration of GHGs. For example, imagine solar output goes up and warms the climate. That could thaw millions of square kilometers of permafrost and that would create a significant increase in atmospheric CO2. So, yes, that's a piece that may never quite fall into place simply from graphing the two, even though physics does strongly imply that GHGs "should" be absorbing and reradiating outgoing heat back to Earth.

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Actually what increases is energy. Heat is just one aspect of that increase.

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That's technically true, but in meteorology sensible heat is thermal, the term "latent heat" means the energy in a body of air, ie, the heat you could release through condensation. But yeah, you're right about the part that it's an energy increase, and my wording could offend people that know a lot more about thermodynamics.

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The energy lost by liquid water during evaporation can be thought of as carried away by, and "locked up" within, the water vapor molecule. The energy is thus in a "stored" or "hidden" condition and is, therefore called called latent heat. It is latent (hidden) in that the temperature of the substance changing from liquid to vapor is still the same. However, the heat energy will reappear as sensible heat (the heat we feel and measure with a thermometer) when the vapor condenses back into liquid water. Therefore condensation (the opposite of evaporation) is a warming process.

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All emphasis is original.Can't get much more explicit than that. That's from a freshman Introduction to Meteorology textbook, Meteorology Today, Fifth Edition, by C. Donald Ahrens, West Publishing Company, page 33.

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Look at the little difference in sea temperature for a large difference in the power of a hurricane, and you can see that straight {temperature\heat} increase is mitigated by transferal into energy systems.

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Your jargon is different from mine. I should have specified "latent heat" rather than "heat" in that sentence but we're on the same page regarding the actual process.This message has been edited by gene90, 09-15-2005 10:49 PM

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Given that 3/4ths the planet is water, I would expect most of that re-radiation to be (1) disbursed in the atmosphere (radiated omnidirectionally) and (2) mostly absorbed in the oceans. Given the heat sink that the oceans are, this would require a large influx of heat before much was noticeable (how much would be below the surface?)

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I don't see a lot of relevance to what I said and the actual point is eluding me but you might be interested in my previous reference in this thread to the warming of the oceans and also a Hansen paper in the June 2005 about a 'lag' in the warming of the system.

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Earth's Energy Imbalance: Confirmation and Implications

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James Hansen,1,2* Larissa Nazarenko,1,2 Reto Ruedy,3 Makiko Sato,1,2 Josh Willis,4 Anthony Del Genio,1,5 Dorothy Koch,1,2 Andrew Lacis,1,5 Ken Lo,3 Surabi Menon,6 Tica Novakov,6 Judith Perlwitz,1,2 Gary Russell,1 Gavin A. Schmidt,1,2 Nicholas Tausnev3

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Our climate model, driven mainly by increasing human-made greenhouse gases and aerosols, among other forcings, calculates that Earth is now absorbing 0.85 0.15 watts per square meter more energy from the Sun than it is emitting to space. This imbalance is confirmed by precise measurements of increasing ocean heat content over the past 10 years. Implications include (i) the expectation of additional global warming of about 0.6C without further change of atmospheric composition; (ii) the confirmation of the climate system's lag in responding to forcings, implying the need for anticipatory actions to avoid any specified level of climate change; and (iii) the likelihood of acceleration of ice sheet disintegration and sea level rise.

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This message has been edited by gene90, 09-16-2005 06:37 PM

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I was just picking on your use of "ground" rather than surface.

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I have no interest in discussing what I said when the meaning is clear.This message has been edited by gene90, 09-16-2005 07:36 PM

I noticed that Holmes quoted Dr. Landsea (an easily remembered name) on hurricanes, global warming, and that political debate that's ever present in the background. Landsea quit the IPCC last January because of what he viewed as distortion of his specialty (hurricanes and global warming) for political purposes.Letter of explanation:
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Intergovernmental Panel on Climate Change - WikipediaYeah, I understand that now there are two recent papers that could turn the climate community around, we'll wait and see. But even if it does, I think this is interesting from a political standpoint.

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There is indication that we may be near one such event: the loss of the "Great Ocean Conveyor" due to warmer fresher water in the area of the cold sink, blocking it. We could actually kick off an ice age with our slight shift in the energy equilibrium.

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I don't that's considered a very credible position.

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Science, Vol 304, Issue 5669, 400-402 , 16 April 2004

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Perspectives

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OCEAN SCIENCE:
Global Warming and the Next Ice Age
Andrew J. Weaver and Claude Hillaire-Marcel

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There is a popular notion in the media that human-induced global warming will result in the onset of a new ice age. In their Perspective, Weaver and Hillaire-Marcel refute this view, explaining that global warming is unlikely to dramatically alter the North Atlantic ocean circulation. They also emphasize that elevated levels of atmospheric carbon dioxide lead to summer temperatures that do not allow glacier formation and growth.

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A. J. Weaver is at the School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8W 3P6, Canada. E-mail: weaver@uvic.ca C. Hillaire-Marcel is at GEOTOP, Université du Québec Montréal, C.P. 8888, Montreal, Québec H3C 3P8, Canada

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