From: Marc Comensoli 18/03/99 10:36:33 Subject: Gobal Warming ?? post id: 4226 Hi Karl; I find it a bit rich to belive, what all these Geenies preach re Global Warming. We humans have been measuring tempreture onlY for the last 140 years, and until someone can tell me the exact tempreture in Sydney on the first Tuesday in March 1323, i can't see how we can possibly say that there are changes occuring in our weather. WHAT DO YOU THINK ??? From: Dr. Ed G (Avatar) 18/03/99 10:45:03 Subject: re: Gobal Warming ?? post id: 4233 Greenies aren't predicting it, scientists are. Who are the industrialists to say that it can't happen? When they reproduce a planet identical to the Earth and then show that putting BILLIONS OF TONS of carbon dioxide, sulphur dioxide, methane, and HCFC's into the atmosphere DOES NOT cause changes to the climate, THEN I'll believe THEM! Soupie twist, Ed G. From: Matt 18/03/99 10:45:41 Subject: re: Gobal Warming ?? post id: 4234 Its not so much a thing about predicting the temperature at a given time and place but more the average temperature over time all over the world that will increase. And your right its very unpredictable in terms of specific times and places. Weather can be deduced from various things and the main point of global warming theory is the effect of what we put into the atmosphere over a relatively short space of time. We know what the weather was like in various places back quite a few hundred years. Which is more than enough I think to predict changes over the next 50. From: Martin 18/03/99 21:04:41 Subject: re: Gobal Warming ?? post id: 4328 I don't think that it is possible to get a particular Tuesday's temperature 600 years ago however I think the science of finding out average temperatures over a longer time is well established. The idea is that you work out what the sea level was in 1323 from archaeological evidence. The sea level is determined by how large the icecaps are (as any extra melted icecaps end up in the Oceans) and icecap size depends on how warm the entire earth is at that time. So, it is possible to work out the Earth's temperature in 1323, or 1500BC to a reasonable accuracy. I think that no one has yet been able to prove that the Earth is getting warmer quickly yet as year by year changes are so small. The thing is that frozen air bubbles in Antarctica tell us what atmospheric Carbon Dioxide levels have been for a long time and we can measure the increase in that. Theory takes this on to a rapid increase in global temperature. Only very, very small changes in average temperature are enough to submerge Pacific islands and modify climate! From: Trevor Wilson (Avatar) 19/03/99 19:16:16 Subject: re: Gobal Warming ?? post id: 4385 Greenies, huh? How about the US Environmental Protection Agency. As nation that contributes the most to Global warming, one coulr reasonably expect that the EPA would be gagged. Instead they have allowed the world to look at their numbers. Check 'em out, they're on the web. Remeber this: About 0.5% of all climatologists beleive that the Earth is not warming, due to human activity. The rest, do. That 0.5% are, curiously enough, in the employ of coal, oil and gas companies. Ya gotta wonder! From: bob 20/03/99 23:42:52 Subject: re: Gobal Warming ?? post id: 4434 I gotta wonder at Trevors figure of 0.5% of scientists that he says don't believe that carbon dioxide will cause global warming and how he figures that they are all in the employ of power companies. I for one am not employed by a power company and I believe that the effect of carbon dioxide on earth temperature is very small compared to the effect of WATER in the atmosphere. The amount of water contained in the atmosphere is many times that of CO2. I think that of all the things that humans have done, clearing of forest has had the greatest effect on climate. From: Megan 23/03/99 16:09:50 Subject: re: Gobal Warming ?? post id: 4629 Yes, clear-felling trees is incredibly significant contributor to global warming - guess why? Forests are carbon "sinks" and store carbon in a form that is locked away and not released to the atmosphere. Until, the trees are felled, thereby releasing the loccked carbon into the atmosphere, thus increasing CO2, hence global warming. From: Horace 23/03/99 16:30:21 Subject: re: Gobal Warming ?? post id: 4634 I have to disagree some what. Felling a tree doesn't automatically release carbon in to the atmosphere. Now don't get me wrong I'm not saying that we should go and cut down all trees but use of wood as a renewable resource is good for the atmosphere. The problem is when a forrest is removed and the land used for another purpose. A mature forrest no longer removes much CO2 from the atmosphere. This is because wood matter is decomposing and releasing carbon into the atmosphere as well as being produced and removing carbon from the atmosphere. If forrests are planted, then cut down for wood, then replanted (and so on) it makes a more efficient carbon sink. The carbon sink includes the forrest as well as all the houses etc that have been produced. Trees are a renewable resource, plastics and metals are not. From: Terry Frankcombe 23/03/99 16:37:46 Subject: re: Gobal Warming ?? post id: 4637 Here's a good point. Disregarding the fuel used to do it, an effective carbon sink would be to continually regrow and clear-fell plantation forests (or indeed start with old-groth!) and store the wood, say, deep underwater or in a dry environment where it will not rot. From: Dr. Ed G (Avatar) 23/03/99 16:53:04 Subject: re: Gobal Warming ?? post id: 4640 As I recall the greatest single contributor to oxygen generation and CO2 reduction is not trees on land but phytoplankton in the oceans. Unfortunately this doesn't get humanity of the hook because guess what the result of ozone depletion is? Ozone depletion increases UV radiation, which forces phytoplankton to greater depths below the ocean's surface, significantly decreasing their ability to convert CO2 to O2. So, in fact, ozone depletion is a greenhouse issue. Soupie twist, Ed G. From: bob s 25/03/99 7:36:08 Subject: re: Gobal Warming ?? post id: 4764 I am not thinking of just the increase in carbon dioxide by burning of cleared trees but to the vastly increased area of ground which heats to 80 degrees C or higher in daytime. The air is heated from the hot ground by contact. This causes strong vertical currents as any glider pilot or hang glider user will tell you. Ground surface temperatures in forested areas are very much lower. Carbon dioxide freezes to solid at temperature higher than the lowest atmospheric temperature BUT only if the pressure is high enough. Carbon dioxide then remains as gas everywhere in the atmosphere and so does not reflect heat as does condensed water (cloud). The only mechanism for global warming by carbon dioxide is by re-radiation of the heat absorbed by it. It is my belief that the effect of carbon dioxide in the atmosphere on earth average temperature is very small compared to the effect of water in the atmosphere which is present in much larger amounts. Water too due to its very large latent heat of vapourisation 596 calories per gram contributes massivly to transfer of heat in the atmosphere. From: Horace 25/03/99 10:03:13 Subject: re: Gobal Warming ?? post id: 4775 It is my belief that the effect of carbon dioxide in the atmosphere on earth average temperature is very small compared to the effect of water in the atmosphere which is present in much larger amounts. I think that on the whole this is quite true. But we need the earth to have a Greenhouse Effect to some degree. However the extra carbon dioxide could be the "straw that breaks the camels back". Think of a planet existing with nice comfortable temperatures. Now imagine that these conditions are somehow upset (say by pumping a stack of CO2 into the atmosphere). This might cause a small temperature increase. A higher temperature causes the atmosphere to hold more water vapour, which causes a temperature increase which cause more water vapour... etc etc. The effect becomes magnified. True, the increase in CO2 could be insignificant to the greenhouse effect but the evidence (provided your not selective) tends to suggest that there will be global warming (or gobal warming :-)). Evidence such as temperature measurements and computer models. Now you're suggesting that the temperature increase which has occurred may not be due to the increase in CO2 but due to a change in the reflectivity of the ground due to deforrestation. I would tend to disagree here because I'm sure that a dark geen forrest has a lower reflectivity than bare ground. ie a forrest would absorb more heat from the sun. From: Terry Frankcombe 25/03/99 16:00:21 Subject: re: Gobal Warming ?? post id: 4865 Carbon dioxide freezes to solid at temperature higher than the lowest atmospheric temperature BUT only if the pressure is high enough. Yeah. So? I can get water to freeze at 100 deg C if I put under enough pressure. What's the point? Carbon dioxide then remains as gas everywhere in the atmosphere and so does not reflect heat as does condensed water (cloud). The only mechanism for global warming by carbon dioxide is by re-radiation of the heat absorbed by it. It is my belief that the effect of carbon dioxide in the atmosphere on earth average temperature is very small compared to the effect of water in the atmosphere which is present in much larger amounts. Water too due to its very large latent heat of vapourisation 596 calories per gram contributes massivly to transfer of heat in the atmosphere. What exactly is your point? Are you trying to suggest that forming clouds is heating the planet? You are forgetting that these same clouds absorb pretty much the same amount of heat when they disperse. As for water vapour, yes, it is a greenhosue gas, a very strong one. But water on this planet is in (or has been in) a fairly stable equilibrium. Water evaporate, water condenses. Same amount of water vapour. How is human activity directly increasing the amount of water vapour in the atmosphere? You also seem to be neglecting the potential moderating effects of cloud: pump CO2 into atmosphere -> higher temperatures due to greenhouse effect -> higher water vapour content in atmosphere -> more clouds -> more solar energy reflected by clouds -> temperature drops. Appart from all this, what are you suggesting we do? Construct planetary dehumidifiers? From: Horace 25/03/99 16:15:32 Subject: re: Gobal Warming ?? post id: 4868 Terry, I think that what Bob was saying was that CO2 is insignificant as a Greenhouse gas compared to water vapour. This is quite true but then went on to say that because it is so insignificant (as a greenhouse gas) must therefore be insignificant for the observed temperature increases. Bob then suggested that the observed temperature increases (Global Warming) might be explained not by the increase in CO2 emissions but because of the man made changes in the reflectivity (of the sun's radiation) of our environment (suggesting deforrestation). I agree with you though, as I outlined earlier that, the evidence suggests that CO2 is responsible for global warming and that the change in reflectivity due to deforrestation would have the opposite effect. From: Rhys 25/03/99 16:56:48 Subject: re: Gobal Warming ?? post id: 4870 Terry, now you've got me confused. You're saying that by dramatically increasing the pressure in a vessel of water you can freeze it 100 degress celcius? Well, I used to work for Nestle confectionary making Kool Mints and putting boiling water under pressure was a daily routine.. we did it so we could force the water though the system to clean out the gooey minty residue. Now, by increasing the pressure of the water we increased the temperature: approx 1 deg for every psi. It was essential to have to the water hotter than 100 degrees in order to remove the candy from the pipes. So.. can you please explain how you freeze water at 100 degrees if under great pressure? From: Terry Frankcombe 25/03/99 17:50:56 Subject: re: Gobal Warming ?? post id: 4884 Rhys, what you're saying is true. For a start, think about your superheated water. By pressurising the water you are keeping it liquid at a temperature that you would normally expect it to be steam. The same applies for the ice. By pressurising it, you are keeping it frozen at a temperature you would normally expect it to be liquid. You'd probably be happier with this at a low temp, say 10 degrees C. Now up the pressure. Sure, as you increase the pressure the temperature will increase. So cool it without letting off the pressure. From: bob s 25/03/99 23:44:20 Subject: re: Gobal Warming ?? post id: 4913 I got cut off by the cookie expire so will make this shorter I would like to see you produce ice at 100 degrees C. Increasing the pressure on ice at 0 degrees C melts it. I have seen it stated in a book that carbon dioxide forms a layer high in the atmosphere and thus REFLECTS heat back to earth. Now carbon dioxide as gas will not reflect heat and it will not freeze because the pressure and temperature conditions do not allow it. Water condenses to cloud and even ice and therby does reflect heat both away from earth and back to it. You never get a frost in temperate zones if there is just a suggestion of cloud but on a clear night in dead still air the temperature of exposed objects can be at least two degrees lower than the surrounding air. The carbon dioxide in the atmosphere does not stop this. What I am saying about cleared ground is not to do with reflectivity but to the fact that it heats to at least 80 degrees in full sun and therby heats the air in contact by conduction. This causes upcurrents on an increased scale and so must affect the climate. Get a wind blowing from exposed ground and you find the temperature is much hotter than wind from a forested zone. That is not all but ny cookie may expire again so here From: Rhys 25/03/99 23:49:23 Subject: re: Gobal Warming ?? post id: 4914 Bob.. if you get the cookie expire, or fear you might.. copy your text to the clipboard (cntl-c) before you submit. That way, if the cookies expire you can re-paste it into a new message (cntrl-v) I think you can just hit the back button on your browser too.. if you haven't copied the text it should still be in the buffer. rhys From: bob s 26/03/99 0:00:52 Subject: re: Gobal Warming ?? post id: 4915 continued No I am not suggesting that we construct planetary dehumidifiers that was your suggestion. What I am suggesting is that we go hell bent on restoring some of the lost forest. The point about condensed water is that it reflects heat BOTH ways. As carbon dioxide is not condensed in the atmosphere it never acts as a reflector. The point about exposed ground is not the reflectivity of it but the fact that air is heated by contact with it. Increased area of exposed ground heats more air and to higher temperature. I have measured exposed ground temperature and it can be as high as 80°C but only to a shallow depth. I have seen an experiment performed with thermometers against a surface placed in the center of cordial bottles placed in the sun and with different gases inside. A higher temperature in the bottle with the CO2 was deemed to show that CO2 would indeed contribute to global warming. Now the higher temperature in the CO2 bottle was not due to absorbtion of infra red by the CO2 but to the lower thermal conductivity of CO2 than the other gases used. It is my belief that the supposed effect of carbon dioxide on global temperature is over rated. The real crunch for humanity will be when fuel supplies become scarce. From: Dr. Ed G (Avatar) 26/03/99 11:25:09 Subject: re: Gobal Warming ?? post id: 4930 Well, here's the correlation between CO2 concentrations and Antarctic temperatures for the last 160,000 years. You'll get no argument from me that we should be reforesting as part of an integrated greenhouse strategy, but it seems to me there's a link between CO2 and global warming somewhere. Soupie twist, Ed G. From: Terry Frankcombe 26/03/99 16:41:17 Subject: re: Gobal Warming ?? post id: 4949 Hrmph. Freaking cookie got me too. Here goes again! Just to clear up this ice thing: I would like to see you produce ice at 100 degrees C. Increasing the pressure on ice at 0 degrees C melts it. This is true. That is one of the really funky things about water which make life on this planet possible. However, I draw your attention to Atkins, Physical Chemistry, 5th edition, figure 6.5 page 187. This is a phase diagram for water. Note that above 1 bar the ice-liquid transition slopes backwards to lower temps. This is why ice normally melts when you put it under pressure (assuming you keep it around 0 deg C). In is related to the structure of ice vs water, and that water is at it's most dense at 4 deg C. However, above about 2000 bar the transition sloped forward again, due to a change in the structure of the ice. Water at this pressure then behaives like most substances... increase in pressure means increase in freezing temperature. Just to make a point, I draw your attention to the following quote from the same page: "Ice-VII, for instance, melts at 100 deg C, but exists only above 25 kbar." Back to the speculation on the relative contribution of water vapour and carbon dioxide. Firstly, absorption and thermalisation of incident radiation is just about the only physical means that the sun can infuence our planet physically (photosynthesis is really a small effect). This is wht gets your ground to 80 deg C. Surely then this would be a prime candidate for the cause of the greenhouse effect, particularly if you start altering the concentrations of gasses that do it particularly effectively (such as carbon dioxide, methane and water vapour)? Secondly, allow me to make an observation arrising from my youth in Tasmania. If you got a frost, then you were going to get a nice warm day. No frost, cold. Why? Because the quality of the day was generally controlled by the same thing as the frosts... the cloud cover. So if there was cloud cover then you got warmer nights, as Bob pointed out, but the days were colder. Why? Because cloud cover turns back far more solar energy into space than there is energy radiating from the earth to turn back. Thirdly, what is the connection between deforestation and water vapour that you are expousing, Bob? Sure, if there were large souces of radiative energy on earth, then cloud cover would trap it. But you yourself made the point that hot ground transfers energy by conduction rather than radiation. Cloud cover does not effectively trap conducted heat. Finally, The real crunch for humanity will be when fuel supplies become scarce. Why? What do you mean? From: Bob S 27/03/99 7:33:45 Subject: re: Gobal Warming ?? post id: 4987 Terry Ok I accept that the pase conditions change for water at very high pressure but this is a red herring it has nothing to do with atmospheric conditions. My point is that water (cloud) reflects heat both ways but CO2 is never frozen in the atmosphere because the pressure is everywhere not high enough. Then although it absorbs radiation at a couple of discrete frequencies it never acts as a reflector. The atmospheric content of water is vastly greater than that of CO2 and water also absorbs radiation. My point about trees is not a connection between water vapour and forest although this may well be considered. It is about ground temperature and resultant air temperature by conduction from the ground. Thus if there is a North wind from the vastly deforested areas of NSW into Victoria the wind will be hotter than if the trees were still there. Also the volume and extent of vertical currents will be increased by deforestation. Your point about a warm day after frost. This is because the day after a frost is usually but not always clear of cloud so solar gets in. A night of cloud is warmer because the cloud reflects the heat back but the day is cooler because the cloud persists into the day. And about finally The present living conditions for a large proportion of humanity depends critically on the use of the so called fossil fuel and this is not inexhaustable but is being wasted in a fashion that seems to assume that it is. From: Bob S 27/03/99 7:45:44 Subject: re: Gobal Warming ?? post id: 4988 I note Dr Ed's statement that CO2 level and polar temperature has benn correlated for 160,000 years. How was the temperature estimated for so long in the past and how much can we trust the temperatue estimate. From: Terry Frankcombe 28/03/99 17:26:48 Subject: re: Gobal Warming ?? post id: 5042 Yes, Bob, whether water can be coaxed into freezing at 100 deg C or not is a moot point. In your original post I simply did not understand the relevance of frozen carbon dioxide to your argument. Your argument about clouds reflecting heat back to the earth isn't a significant effect, as I said. Cloud reflects radiation, not thermal heat. Appart from the poles, not a great deal of energy leaves the planet as radiation. When it is cloudy then you get very little energy leaving as radiation at all. This is all demonstrated by the fact that it is usually colder on a cloudy day than a clear one. My point about trees is not a connection between water vapour and forest although this may well be considered. It is about ground temperature and resultant air temperature by conduction from the ground. Thus if there is a North wind from the vastly deforested areas of NSW into Victoria the wind will be hotter than if the trees were still there. Also the volume and extent of vertical currents will be increased by deforestation. This is true. Are you saying that because of deforestation the earth is trapping more energy? Ask yourself why wooded areas don't get as hot. The present living conditions for a large proportion of humanity depends critically on the use of the so called fossil fuel and this is not inexhaustable but is being wasted in a fashion that seems to assume that it is. My understanding is that we are not in danger of running out of hydrocarbon fuel. It's just getting more expensive to get. Are you trying to make a connection between this and global warming? From: bob s 30/03/99 0:49:33 Subject: re: Gobal Warming ?? post id: 5122 No I am not trying to make a connection between the eventual extinction of ground based hydrocarbon fuel and global warming. What I did say was that I believe that deforestation has had a greater affect on climate change then has the increase in carbon dioxide. From a web address supplied by Dr Ed it is stated that world oil production is estimated to decline in ten (10) years time and be back to 1950 levels in another 30. Oil will certainly be more expensive if this estimate is true. World coal is expected to last for at least 300 years. The present usage of energy from burning hydrocarbons will not be sustainable by burning plant regrowth. I do not believe that carbon dioxide has caused any but insignificant global warming. From: Terry Frankcombe 30/03/99 12:59:24 Subject: re: Gobal Warming ?? post id: 5136 OK, Bob, are you proposing that deforestation causes the planet to catch more energy from the sun? From: bob s 1/04/99 1:02:49 Subject: re: Gobal Warming ?? post id: 5272 No I am NOT saying that clearing forest causes the earth to catch more energy from the sun. What it does do though is dramatically alter the pattern of air currents. It also causes measured temperatures in many areas to be higher than they would be if the forests had not been cleared. My main point is that I believe that the effect of increased global temperature due to increased carbon dioxide is highly overestimated. Water in the astmosphere completely swamps the effect of CO2. This forum is un-moderated. The views and opinions expressed are those of the individual poster and not the ABC. The ABC reserves the right to remove offensive or inappropriate messages.