Hi Sam, Been a while. I wouldn't have bothered with such a lengthy (yet still partial) explanation if I didn't like Chaz. I'm by no means convinced by the rush to green through carbon restrictions myself - what he says other than on the issue of the trace CO2 is pretty sound. Nice offer - I don't suppose we could extend it to the 12 year olds I've just wasted a few sessions on? I don't usually teach in schools, but was asked by a friend to bring a few of my more explosive demonstrations along to see if she could get at her class through entertainment (my grandson goes there so I felt obliged). Little swines could do with a bit of philosophical fundamentals! Bring a big stick!
On 21 Dec, 23:51, Sam Carana <[email protected]> wrote: > Chazwin, > > There is plenty of scientific information available on this topic. I > think your position results from a philosophical line of thinking, > which forces you into denial. I suggest that you rethink the > fundamentals of your philosophy. If you like, I'm happy to go over the > philosophical fundamentals with you, to see if it adds up. > > Cheers, > Sam Carana > > On Dec 22, 10:10 am, archytas <[email protected]> wrote: > > > > > There is a point at which more CO2 would be just like another set of > > shutters nailed over several others already blocking light. This > > point has long been factored in. Mars' atmosphere is thought to have > > been a lot thicker once. At some point in a pub crawl my mates tend > > to say 'are we doing one' when they want to move on. Usual notions > > for Mars' atmosphere 'doing one' are: > > Possible causes for the depletion of a previously thicker martian > > atmosphere include the following: > > Catastrophic collision by a body large enough to blow away a > > significant percentage of the atmosphere; > > Gradual erosion of the atmosphere by solar wind; and > > On-going removal of atmosphere due to electromagnetic field and solar > > wind interaction. > > Others suggest its magnetic field 'walked away' - hence that crap move > > The Core. It's not the CO2 on its own or even in combination with > > other stuff like methane. On Venus it's held warming isn't greenhouse > > at all. Indeed, 'greenhouse' is a misnomer - greenhouses heat up by > > restricting convection. This is the gist: > > > There is general agreement that the Earth is naturally warmed to some > > extent by atmospheric gases, principally water vapor, in what is often > > called a "greenhouse effect". The Earth absorbs enough radiation from > > the sun to raise its temperature by 0.5 degrees per day, but is > > theoretically capable of emitting sufficient long-wave radiation to > > cool itself by 5 times this amount. The Earth maintains its energy > > balance in part by absorption of the outgoing longwave radiation in > > the atmosphere, which causes warming (black body and all such jazz). > > On this basis, it has been estimated that the current level of warming > > is on the order of 33 degrees C. That is to say, in the absence of so- > > called greenhouse gases, the Earth would be 33 degrees cooler than it > > is today, or about 255 K (-0.4° F). There would be little need to > > keep the voddie in the freezer. Water is by far the most important. > > Although estimates of the contribution from water vapor vary widely, > > many sources place it between 90 and 95% of the warming effect, or > > about 30-31 of the 33 degrees. Carbon dioxide, although present in > > much lower concentrations than water, absorbs more infrared radiation > > than water on a per-molecule basis and contributes about 84% of the > > total non-water greenhouse gas equivalents or about 4.2-8.4% of the > > total greenhouse gas effect (this is a range bigger than economists > > often use in their 'highly accurate' predictions). This 33 degree > > increase in temperature is not caused simply by absorption of > > radiation by the gases themselves. Much of the 33 degree effect is > > caused by the Earth's adaptation to higher temperatures, which > > includes secondary effects such as increased water vapor, cloud > > formation, and changes in albedo or surface reflectivity caused by > > melting and aging of snow and ice. Accurately calculating the relative > > contribution of each of these components presents major difficulties. > > We aren't guessing, but it's clear there is room for dispute. > > Infrared radiation comes from two sources: the sun and the earth's > > surface. CO2 absorbs some of the infrared radiation and re-emits it in > > a random direction. If there is more CO2, the radiation is absorbed > > closer to the source. For radiation from the sun, this theory predicts > > that increased CO2 would cause cooling in the upper atmosphere and > > warming in the lower atmosphere. Thermometer measurements show that > > the lower atmosphere was warming between about 1906 and 1944 and > > between about 1976 and 1998, and either constant or cooling at other > > times. The validity of the temperature figures is hotly disputed. > > Traditionally, greenhouse gas levels are presented as dimensionless > > numbers representing parts per billion (ppb) multiplied by a scaling > > factor (global warming potential or GWP) that allows their relative > > efficiency of producing global temperature increases to be compared. > > For carbon dioxide, this scaling factor is 1.0. The factors for > > methane and nitrous oxide are 21 and 310, respectively, while sulfur > > hexafluoride is 23,900 times more effective than carbon dioxide. The > > GWP from carbon dioxide is primarily due to the position of its > > absorption bands in the critical longwave infrared region at 2, 3, 5, > > and 13-17 microns. The increase in the global energy balance caused > > by greenhouse gases is called "radiative forcing". > > > Geologists tell us that the residence time of CO2 in the atmosphere is > > on the order of five to ten years. In contrast, the IPCC says it is > > 50-200 years. Whatever the actual number, there is no question that > > emitting CO2 will cause it to accumulate over short periods. But other > > processes, such as sequestration, also work against it, causing the > > levels to decrease rapidly over time.The arithmetic of absorption of > > infrared radiation also works to decrease the linearity. Absorption of > > light follows a logarithmic curve as the amount of absorbing substance > > increases. It is generally accepted that the concentration of carbon > > dioxide in the atmosphere is already high enough to absorb almost all > > the infrared radiation in the main carbon dioxide absorption bands > > over a distance of only a few km. Thus, even if the atmosphere were > > heavily laden with carbon dioxide, it would still only cause an > > incremental increase in the amount of infrared absorption over current > > levels.Very little of the radiation from the sun at the wavelengths at > > which carbon dioxide absorbs reaches the surface of the Earth > > directly. Similarly, very little of the radiation at these wavelengths > > that originates at the surface makes it all the way to space. Most of > > the infrared at these wavelengths is produced by black body radiation > > from objects that have been heated up by absorbing radiation at > > shorter wavelengths. This means that even if the carbon dioxide levels > > increase, it will have little effect on the total amount of infrared > > radiation that is absorbed from the sun. The main effect would be to > > trap radiation originating at the surface at lower levels in the > > atmosphere than before, where it would be slightly more difficult for > > the heat to be re-radiated back into space. This is the principle on > > which most of the global warming predictions are based.Most of the > > ultraviolet light (below 0.3 microns) is absorbed by ozone (O3) and > > oxygen (O2). Carbon dioxide has three large absorption bands in the > > infrared region at about 2.7, 4.3, and 15 microns. Water has several > > absorption bands in the infrared, and even has some absorption well > > into the microwave region. There is already sufficient CO2 in the > > atmosphere to absorb almost all of the radiation from the sun or from > > the surface of the earth in the principal CO2 absorption bands. > > The net effect of all these processes is that doubling carbon dioxide > > would not double the amount of global warming. In fact, the effect of > > carbon dioxide is roughly logarithmic. Each time carbon dioxide (or > > some other greenhouse gas) is doubled, the increase in temperature is > > the same as the previous increase. The reason for this is that, > > eventually, all the longwave radiation that can be absorbed has > > already been absorbed. It would be analogous to putting more and more > > blankets on your bed -- it soon reaches the point where doubling the > > number of blankets can't make it any warmer. We may currently be at > > that point where the current ppms are analogous to one blanket and > > doubling them would be like adding a second. > > > If we start to sweat, you can bank on someone insisting we don't add > > any more water vapour to the atmosphere. Pressures on Venus make even > > absorption comparisons bad science by the way. My guess is that the > > IPCC has over-stated the case, but this isn't because of the puny > > amounts of CO2 -these are currently in critical concentrations, in the > > sense that variations have fairly substantial effects. The future > > memory may well be that carbon trading was as big a scam as > > Collateralised Derivative Options. Go forth and grok mate - I'd use > > stronger language but know we are both shrinking violets and would > > fade away before the sun gets its chance to fry us to crisps! Beer's > > Law is part of the calculation (with limitations) - I shall raise a > > glass tonight to the rest of what you say. > > > On 21 Dec, 18:51, chazwin <[email protected]> wrote: > > > > On Dec 21, 3:49 pm, archytas <[email protected]> wrote: > > > > > Come on Chaz - most of Mars' atmosphere did one when the magnetic > > > > field collapsed. > > > > Er - 'one' what? > > > The point I was making is that the numpties on the other NGs who > > > support AGW assume that more CO2 necessarily means more heat, but > > > there has to be a limit to the amount of heat according to the band > > > with of the radiation. > > > After a while more does not mean more. > > > > Venus, I seem to remember has loads of CO2 and is > > > > > unpleasantly hot - though not, as I understand because of the CO2. > > > > CO2 plays a role but there is much more besides, including a range of > > > acids. > > > > > There is loads of quantitative research, it's just that the media > > > > thinks no one can be arsed with any of it. You are conflating a 'tiny > > > > amount' of CO2 with its trace presence on a scale of vastness you > > > > don't grok. > > > > Grok? > > > > Your point has a compelling logic - when I put it to non- > > > > > scientists their heads start to nod. > > ... > > read more » -- You received this message because you are subscribed to the Google Groups "Epistemology" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/epistemology?hl=en.
