DrCloud

You're quite right: the atmospheric reservoir of oxygen and many other gases is not at all fixed in the sense that it's the same molecules floating around all the time. They're constantly created (in the case of oxygen, by photosynthesis) and used up (combustion). This is why I referred to the "global cycles" of these gases. Globally, the atmospheric reservoir of any of them is a balance among creation processes, destruction processes, and exchange with other parts of the Earth system, such as the land (biosphere) and the oceans. (These other parts of the system are also reservoirs with their own creation and destruction processes.) It's hugely complicated because there are only estimates of some of the exchange processes available, and some of the creation/destruction processes are pretty obscure. What this all means is that your original comment is essentially correct: oxygen and carbon dioxide aren't independent in the atmosphere in the sense that their cycles are linked. My point was that the atmospheric reservoir of oxygen is so much larger than that of carbon dioxide that we don't tend to worry about the former too much. HPH

Adding CO2 in and of itself (not by creating it by combustion but by adding it from, say, tanks full) will decrease other gases in their percentage of the overall composition, like the red ball analogy. But creating it by combustion, after which it gets added to the atmosphere, also uses O2 in the process. All of this is embodied in the global cycles of these (and other) gases. Because the amount of oxygen in the atmosphere is so large (around 200,000 parts per million) compared to CO2 (not quite 400 parts per million, a factor of 500 less) not much attention is paid to it. In particular, the measurement uncertainty in its abundance is probably about as large as the effect you're asking about. So, in principle, yes there's an effect; in practice, it's not an issue. No doubt people are studying it, like just about everything is studied these days, but it's not an issue. HPH

^^ The grounded glaciers in Antarctica have calved state-sized ice floes (well, the size of those little northeastern states, anyway) without too much splash, at least on a global scale. Tsunamis are more effectively generated by undersea earthquakes in which significant crustal displacements occur over tens of kilometers. On the other hand, it wouldn't do to be on a ship close to some of this ice action. HPH

^^ Not exactly. The degree to which the circulation of the North Atlantic would change with (for example) the melting of the polar ice isn't fully understood. While there is some indication that the thermohaline circulation (what's also known as the "global conveyer belt") might be altered, the Gulf Stream is also part of the wind-driven circulation in the North Atlantic. So unless the atmosphere's current circulation changed beyond recognition, there would still be some poleward transport of heat by the oceans. Generally speaking, this part of the overall problem is a negative feedback loop, because when a temperature gradient builds up in a fluid (because one of the existing transport processes breaks down) instabilities develop to get that heat moving. Ultimately, that's why the atmosphere circulates. HPH

As noted, floating ice, when it melts, won't raise the level of the water in which it's floating, whether that water be in a glass or in the ocean. In the ocean, this stuff is generally called sea ice, and getting its behavior right in climate models is quite the trick. There is a fairly large group of people who have made it their careers to do so. Now, not all ice that appears to be on the ocean is floating. Some of the large Antarctic glaciers that flow to the sea are, in fact, grounded offshore, so their height above sea level is greater than it would be if they were floating. Thus, if they melt (or break off into floating icebergs), they'd raise sea level. All ice that melts permanently off continents (and isn't replaced by new snow) and runs into the ocean will raise sea level. Finally, one of the strongest and most interesting feedback processes in the climate system -- because it's a positive feedback -- is the reflectivity of snow and ice. It's positive because it's reinforcing: more ice implies more solar energy reflected to space implies a cooler planet implies more ice implies... (and it works the other way, too). HPH

^ Thanks for pointing that out -- I've been on vacation, offline, mostly, and hadn't seen it. At this point, of course, they're sort of shutting the barn door after the horses have left, because the official season is about 40% over. To do a real climate projection of any kind, you need to make your call before what you're calling begins to happen (or doesn't). After the fact "predictions" or projections are cheating. It's appropriate for them to lower their expectations, however, because this projection effort is more than an academic exercise. Its effect on the public's behavior is relevant, and they need to do whatever mea culpas are appropriate and try to stay as credible as possible. And as far as I'm concerned, a less active season than expected is just fine indeed. HPH

This is correct, particularly given the distinction we make between "predict" and what we (try to) do with climate, which is to "project" it. Seasonal hurricane patterns and trends are definitely "projected." This is done using methods pioneered by Prof. Bill Gray of Colorado State University. His technique involves, essentially, analogs from the past. 'Round about each April, his group looks at the current state of the climate and then looks for years in the past that were similar. Then they look at the hurricane seasons in those similar years and use various kinds of factor analysis to come up with a best estimate (including uncertainty estimates) of the coming hurricane season. Their methods have been shown to have "skill", meaning that they're better than either random guess or pure extrapolation from last year. Further, the skill level is high enough that the National Hurricane Center has adopted some of the methodology for their official seasonal outlook. Now, it's interesting that all of the people on the "natural cycles" side of the current hurricane discussion (the other side being the "global warming" crowd) are in the groups that use these projection techniques. They need the natural cycles explanation to be right for their seasonal projection techniques to be credible, so they're not entirely objective about the whole thing. (And, to be fair, the folks on the global warming side tend to be people who have a reputation for attention-seeking. They just love the limelight, and their current stand puts them smack in the middle of it.) I don't mean to suggest that the research is invalid on either side, because it has all undergone considerable scrutiny by outsiders in the peer review process. But such biases have ways of creeping in to everything. HPH

I've been trying to understand where the communication gap is in all this, and perhaps it's related to the following. At the most basic level, the general circulation of the atmosphere (as large-scale global wind patterns are known) is driven by the differential solar heating between the tropics and the polar regions. This heating differential sets up a latitudinal temperature gradient that is strong enough that, in combination with gravity and Earth's rotation, hydrodynamic instabilities in the atmosphere occur, resulting in winds. So all of the winds, from the jet stream to the trade winds, owe their existence to temperature gradients in a basic sense. But ascribing the "cause" or hurricanes to this really doesn't lend any insight to the problem of the topic of the thread. Hurricanes are tropical storms that reach a certain strength; tropical storms, in turn, are tropical depressions that get strong enough to be called storms; so the root cause of hurricanes is formation of depressions. There's also the issue of how many depressions turn into storms, and the thread implicitly deals with both of these. But neither of these is directly related to temperature gradients, beyond the fact that the trade winds themselves, as part of the general circulation of the atmosphere, are the result of the differential heating between the tropics and the polar regions. Depressions form via (positive) feedback mechanisms that amplify small disturbances in the trade winds (and, generally, these disturbance don't have any relationship to temperature gradients). The feedback involves evaporation from the ocean, rotation, and heating by condensation in clouds. Depressions strengthen into storms and then hurricanes if conditions are such that nothing interrupts this positive feedback process. Changes of wind speed and/or direction with height, for example, tend to slice off the tops of clouds before they can grow deep enough to turn into really violent thunderstorms, which would keep the depression growing. Or movement of the depression over cooler water tends to shut off -- or slow down -- the supply of water vapor from surface evaporation. So the real issue with hurricanes and global warming has less to do with temperature gradients directly than it does with these other factors as well as the overall response of the atmosphere to warmer ocean temperatures. And all this is a topic of study among the folks who do this for a living. The best way to keep up with current thinking is to follow the literature and be patient, because the point-counterpoint of the technical discussion is ongoing. The latest salvo was in Science last Friday, when one of the "natural cycles" advocates pointed out that recent papers claiming an increase in big storms in the past few years relied on (possibly) biased data. This won't be fully resolved until that data is re-analyzed using up-to-date methods, which is undoubtedly in progress. So, as I've said before, stay tuned. HPH

And what I've been saying, over and over, is that it's not. You're wrong. Further, you haven't provided any evidence to support your assertion (bascule's "admission" hardly constitutes evidence). I'll be off-line for some time now due to a travel commitment, so you'll have the chance to play with yourself in public and mislead these other folks into believing whatever they'll swallow without my interference. Have fun. HPH

Lance, I'm sorry, man, but you're just not getting it. There's more, at a very fundamental level, to both tropical cyclones (of which hurricanes are a regional [Atlantic] manifestation) and mid-latitude/polar cyclones than simply hot air rising and cool air flowing in to replace it. If hot air rising and cool air flowing in were the only thing happening, there would be no cyclones, just thunderstorms. Further, it's simply not true that rising air always forms over the hottest water, even locally. You can make this happen in simple, controlled laboratory experiments (heated pans of water, say, with extra-hot spots on their bottoms), but in the real world other dynamical factors enter in. In particular, the role of convergences set up in a quasi-random fashion due to the interactions in three-dimensional turbulence is critical to the location of updrafts. (Yes: I used the word "random". There's lots of it out there in the world. It's one reason that the specific location of a given thunderstorm tomorrow or the next day is unpredictable. It's not that we're not smart enough to predict it; it's just flat-out unpredictable. If you want to know how climate change is "predicted", let me know in such a way that you persuade me that you're really interested and not just wanting to bicker. I'm happy to educate people, but I'm not going to fall for debate tricks or the absurd "designated skeptic" role you've contrived for yourself.) You're the one who's asserting a particular phenomenon as the cause of something this time, so it's your responsibility to provide evidence to back up your assertion -- evidence that's credible. And, with all due respect, your own personal common sense and self-ascribed authority don't count. I've already given you a nice hint in the form of a text book. Like I said, I think some serious reading is in order. HPH

Wrong again, sport. Where's your evidence? Got data? Got theory? Got anything? You can make all the authoritative-sounding assertions you want, but without substantive, credible source material, you're just blowing smoke. "High temperature differentials" (whatever you may mean by that -- it's certainly not the terminology that either meteorologists or oceanographers use) have little to do with hurricane formation or intensification. What does have to do with those things are high temperatures, along with a variety of other factors such as the vertical and horizontal wind shear and the overall pressure pattern -- whether it's causing general lifting or sinking. The jury is still out about whether there are real trends in hurricane activity (yesterday, another brief paper was published arguing that the data in the 70s and 80s are just not good enough to use for this type of analysis, for example -- a good point). It's an interesting discussion to follow, a discussion being conducted by people who are making entire careers out of studying this. Interestingly, everyone involved in the discussion -- both sides -- recently put out a statement to the effect that it really doesn't matter what hurricanes are doing. What does matter, they say, is US government policy that, in effect, subsidizes people who choose to build in hurricane-prone areas. This subsidy (whatever the economic effect) puts people in harms way, and this is the real problem. So these folks are trying to figure out an interesting scientific puzzle, but they are working together on what really matters -- saving lives. HPH

Sorry, Lance, you don't know what you're talking about. "Surrounded by cooler water" has nothing to do with it. And comparing hurricanes with mid-latitude and polar cyclones shows how far from the real world your thought processes are. I suggest you go out and get yourself a solid meteorology textbook (Wallace and Hobbs comes to mind) and do some serious reading. But be prepared for differential equations. HPH

I seem to remember reading about such a thing in one of Clive Cussler's "Dirk Pitt" adventure/action novels. It gave me a good laugh. HPH

This business with the steel ball and the magnet is an interesting puzzle, and we need a good classical physicist to help out, because it's a little confusing to me, too. Swanson's brief comment helps, but here's more detail, via a couple of things to consider. First, energy is just force applied over a distance. So the steel ball gains gravitational potential energy relative to the surface it started on because the force applied by the magnet to the ball acts over the lifting distance. Second, suppose we do this same thing in the absence of gravity. Then the steel ball would accelerate because of the force acting on its mass and come to a stop when it smacks the magnet, dissipating its kinetic energy as heat. With gravity, it does the same thing (or not), depending on the relative strengths of the force on the ball from the magnetic field and from gravity. In a sense, then, all that gravity is doing is reducing the effectiveness of the magnetic field in accelerating the ball -- decreasing the magnetic field's strength, in effect. So your puzzling question comes down to this: when a magnet accelerates a mass, which results in kinetic energy, where did that energy come from? Where was it in the first place (energy, after all, needs to be conserved in this little thought experiment)? It seems pretty clear that the kinetic energy must have started out as potential energy, potential energy stored in the magnetic field and its interactions with the crystal structure of the atoms of iron in the ball, right? As the ball accelerates, that potential energy is converted to kinetic energy; this means that the closer the ball is to the magnet to begin with, the less magnetic potential energy there is -- that is, the field isn't constant in space, something we already knew. So this is consistent. With this in mind, we can add gravity. With gravity, the ball doesn't accelerate so fast, because the magnetic potential energy is being converted both to kinetic energy and to gravitational potential energy. I hesitate to say "QED", but I think I may have persuaded myself, at least. Maybe we can get a real physicist to weigh in. HPH

Of course, they do have a choice, of either living closer to the job or having a job closer to the country. In a way, there's already an implementation of this in a voluntary form on a bigger scale. The Chicago Climate Exchange deals, like a stock market, in carbon futures trading in anticipation of a quasi-rationing system imposed on industry. "Clean" industries can sell their rations to dirty ones. People can speculate on credits futures. It's a sort of free-market version of what some governments might mandate. I'm neither endorsing nor condemning it, and whether it will work remains to be seen. There are some oil companies, though, who are investing in planting trees as ways of improving their carbon credit/debit situation. HPH

Earth's climate, in terms of the planetary-averaged temperature [averaged also over at least a year, to eliminate summer-winter differences], has had its ups and downs over the time scale for which we have records from which temperatures can be inferred. It's important to keep in mind that regional variations (for example, Europe's "little ice age") aren't necessarily reflected in global temperatures. What this means is that reconstructions need to assemble as many datasets as they can, from all over, before they make inferences about global variations. The Michael Mann study, for example, did that, as has been discussed in the recent National Academy study and in other publications. At the same time, individual records can be valuable, because they provide more detail about the (inherently noisier) global changes. In the current configuration of the continents, our climatic era, the Holocene, has been rather warm compared to much of the rest of the recent several 100Ks of years of record in various cores. Ice ages happened at several times, and some of the cyclicity has been related to astronomical parameters related to Earth's orbit around the Sun (the Milankovic cycles). In the late 1960s and early 1970s, a great deal of attention was given to these cycles and how, given the past few 10ks of years, Earth would seem to be headed for another ice age. Because, however, the forcing associated with the Milankovic cycles is so small, stronger forcings associated with increasing atmospheric greenhouse gases garnered more attention, and interest in the scientific community in global warming has dominated for the past several decades. Volcanos and other climate forcing mechanisms play a role in short-term variations as well. The Krakatoa explosion, for example, produced "the year without summer" by injecting so much gunk into the atmosphere that sunlight to the surface was attenuated sufficiently to keep the planet cool for a year. With new observational techniques, just about any volcano of any significance can now be shown to have some effect on the climate, for a while at least. Another climate forcing that refuses to die quietly has to do with sunspots. Many climate parameters have been shown to correlate with the 22-year sunspot cycle. But correlations aren't enough: you also need a mechanism with which to explain the relationship before it becomes part of what we think of as our "understanding" of climate's behavior. The best candidate for a sunspot mechanism is their effect on the solar wind and, in turn, its effect on upper atmospheric clouds. But the link is tenuous and has never been shown to be solid. The notion of triggers in the system is one that also has received a lot of attention, because there are various positive feedback mechanisms that could amplify small forcings into big responses. The snow/ice feedback (snow is white, reflects sunlight, cools things, makes more snow, reflects more sunlight...) was what piqued interest in the 1970s in another ice age: very simple (overly simplified, in fact) models suggested that a small change could "jump" the climate into an ice age. In the middle of all this, it's useful to remember that climate variations have been relatively small for a long, long time. There's no really credible evidence that there was ever a "snowball Earth" (despite assertions by some to the contrary). There does seem to have been a time, when the continents were configured differently, when there was no permanent ice at the poles, however. But even then, global temperatures were such that life flourished. Not, however, life in any way that's similar to our highly tuned society. That's the real concern about global warming: our world is now sufficiently sensitive to relatively small changes that we could be making trouble for ourselves. HPH

...And I didn't even go near the messy topic of careful typing, spelling, and grammar. HPH

^^ It occurred to me that we haven't even been fully introduced... HPH

I don't know anything about WiSci, and I, per the suggestion, read the OP only by scanning it. Maybe this was addressed there and I missed it -- if so, my apologies. (And if I did miss this by scanning the OP, then maybe the scanning suggestion isn't such a good one.) I'm an editor in an as-yet not-public effort called Encyclopedia of Earth that is using the Wiki approach, and I'm giving it a go despite my contempt for the general quality of Wikipedia "information." What persuaded me that the EoE was potentially useful was two things: first, there are content editors, whose credentials have been vetted by a board of senior editors, who are ultimately responsible for the accuracy of articles in their areas. And, second, everything is attributed (although not necessarily publicly) -- that is, nothing is anonymous. This allows easy identification and banning from write privileges of "vandals" and other such sorts. Now, a problem with this is that it's proving difficult to get the thing spun up. We content editors face the daunting challenge of writing the initial articles in our areas or (conversely) having no content to edit until people emerge who are willing to have their names attached to what they contribute. Maybe there's a middle ground that WiSci could take both to ensure credibility and to maximize participation. But I'm of the opinion that anything anonymous is simply not credible. HPH

A comment by Atheist (my apologies for taking it slightly out of context) in another thread: "While I dislike ... the "we enlightened scientists step down from our high throne to point out your mistakes"-attitude..." struck a nerve with me, because I'm probably guilty of doing just that. I'm sorry for this, but I'm not quite sure how to do anything else sometimes. You see, I've run across discussions here that are so full of mis-information and confusion about topics that I'm really quite knowledgable about that I feel some responsibility to set the record straight. Perhaps I'm viewing this from an inappropriate perspective. I have this idea that people come here to discuss things with the intent of increasing their levels of understanding about the topic at hand, to learn. Is this somehow not correct? (And if it's incorrect, what's the point?) So...what's an approach that won't piss people off? HPH

Right. I didn't mean to veer completely off the topic; I was trying to merely to focus on the largest of these oceanic sink mechanisms. Yes, salps do all this; but the amount of carbon involved isn't really that significant in the global budget -- at least unless the population is orders of magnitude larger than thought. HPH

Not exactly (but close). The foraminifera to which I referred in the proxy thread ("How do we know temperatures thousands of years ago"; unfortunately, this has degenerated into the same bickering that other climate threads have) and the mud in the cooler Europe thread relate to this. That mud -- the ocean-bottom sediments -- consists of zillions of calcium carbonate shells of the forams. These little ocean creatures (not photosynthetic plankton; rather they're zooplankton that eat the green stuff) make little shells for themselves, and when they die their shells fall to the ocean floor. Eventually, it becomes limestone. First, though, it's fodder for the deep-sea drilling program, which sends out ships to take sediment cores. Then scientists (mostly graduate students) analyze the cores for the species of forams and, from abundances, infer ancient temperatures. (When I was a graduate student, people made their bones by spending hours and hours looking through binocular microscopes doing manual counts. I'm thinking it may be computerized by now, but I don't know.) This process represents one of the major, permanent sinks in the global carbon budget. Speeding it up somehow would be useful as a way to (eventually) balance the increased carbon loading in the atmosphere due to fossil fuel burning. One issue is the increasing acidity of the oceans (which is becoming measurable) associated with their uptake of CO2 from the atmosphere. This changes everything, including the survivability of the critters and the chemistry of their calcium carbonate production. I'm not suggesting anything catastrophic here, just something complicated. It's got the specialists in the field in something of a twitter. HPH

No doubt you know far more about this than the climate scientists who reviewed this manuscript, two of whom apparently had their criticisms incorporated into a pre-publication revision. Perhaps you should consider writing a rebuttal to the QJRMS. They just love such things. HPH

The "North Atlantic conveyer" is part of a global circulation also known as the meridional overturning and the thermohaline circulation. The last of these terms gives a clue to what drives it: temperature and salinity differences between the tropics and the polar regions set up density differences, and, because heavy water sinks and pushes lighter water up, a circulation gets going. This circulation is a strong contributor to the oceans' thermal inertia, their slow response to changes in forcing; because of the huge volume of water involved, there is also significant mechanical inertia involved. There are hints in the climatological record (mostly from proxy data derived from ocean-sediment cores) that the meridional overturning has slowed and perhaps stopped altogether in the past (we're talking thousands of years for a time scale here, though). And ocean circulation models show its sensitivity to changes in surface forcing -- modeled meridional overturnings are pretty easy to stop, all things considered. There have been several climate simulations in which they stop. However, in the ocean component of the climate models, key processes in the meridional overturning are not particularly well represented, so it's not clear how faithfully they represent the real oceans. Nonetheless, it's captured the attention of the research community and, by extension, the media. HPH

^ In the sense that "equation of state" refers to the behaviors of foraminifera, corals, flowering plants (pollen), and trees, yes. But not really in the sense of physics and chemistry. HPH