Pub #brownchem: @alpha137
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*** LizK (gloworm4@206-40-144.ipt.aol.com) has joined channel #brownchem
LizK: hello
alpha137: hello
LizK: I read the chapter and made a list of the greenhouse gasses
alpha137: You must have that list of greenhouse gases.
alpha137: What are they?
LizK: CO_2 is the most prominent, then comes CH_4, then N_2O, then H_2O then O_3 then CCl_3F then CCl_2F_2
LizK: And they decrease in concentration as they increase in their greenhouse factors
alpha137: By most prominent what do you mean?
LizK: THere is the most of it in the atomosphere, the concentration is the highest
alpha137: So you are saying that carbon dioxide is more concentrated in the atmosphere than water?
LizK: Ok, so no its not, but in general, it is more concentrated than the other pollutants (water does more good than bad)
alpha137: Water absorbs lots of "heat" radiation so why is it not a "powerfull" greenhouse gas?
LizK: Because it doesn't trap it in the earth, and it reflects some of it back into space (like clouds)
LizK: Plus, it is in a cycle
LizK: But then, so is CO_2, but we are not making more water
alpha137: Water absorbs radiation from 5.5 to 7.5 micrometers.
alpha137: In another unit 5.5 to 7.5 microns.
alpha137: This is "heat" radiation.
LizK: Ok,
LizK: As opposed to IR radiation
LizK: ?
alpha137: Water is a greenhouse gas, and it is the most abundant greenhouse gas in the atmosphere
LizK: yes, but its a good one
alpha137: I am using "heat" radiation to mean IR radiation.
The infrared could be thought of light with a wavelength from 1 micro (micrometer) to the longwavelength IR 15 micron or a bit greater. 1 micron corresponds of 10,000 Angstroms. In terms of energy these are weak sources. Since E = h*frequency = hc/wavelength the longer the wavelength the smaller the energy in the photon. 10,000 A would correspond to 120 kJ/mol. A molecular bond might correspond to several hundred kJ/mol.
LizK: Thats what I thought
alpha137: So why do you think that people ignore water when discussing the greenhouse effect?
LizK: Because water does more good than bad, without water we wouldn't be alive and all of that, but also, we are not producing water and spewing it out into the atomosphere like we are with CO_2 and other greenhouse gasses
alpha137: Right. There is a huge water reservior in the oceans and water is essentially constant.
LizK: ok
alpha137: We must have a dynamic equilibrium with water. That is, there are fluctuations depending on temperature and pressure variations, but the average must be constant.
LizK: yes
LizK: we talked a little bit about that before
alpha137: Do you think that the temperature of the earth, pleasant as it is now, is due to the water vapor or to the carbon dioxide?
LizK: Probably some combination of both
LizK: But more towards the water side
alpha137: I think, more towards the water side.
alpha137: But the water is constant and so it must be increases in other molecules that would cause long term temperature changes.
LizK: Yes
LizK: Such as CO_2
alpha137: You mentioned methane. Where does that come from?
LizK: THere are lots of places, it is released when things decompose, or natural gas, and agricultural increases, like more sheep and cows and rice paddys
alpha137: Biomass decay ?
LizK: At least vegetable matter decay
LizK: The book said that the City of NY was using the methane released from its landfil to power part of the city
alpha137: Yes, that seems to be a coming thing.
alpha137: I have a text, by Colin Baird-no relation, that states a relative warming effectivness for molecules.
LizK: I think thats a good Idea
LizK: What does that mean?
alpha137: For carbon dioxide he gives an index of 1 and for methane 23 and for CFC-11 14,000. What might the meaning of this be?
alpha137: I am asking you.
alpha137: What could it be?
LizK: OH, I see, their effectiveness at being a
LizK: "greenhouse gas"
alpha137: Yes, and how is that?
LizK: Their capability to absorb heat and trap heat and let light in but not out
LizK: corresponds to the number
alpha137: Yes, their ability to absorb IR radiation. However, what goes in does go out!
alpha137: Unless there are collisions to convert the vibrational energy into kinetic energy.
LizK: Thats what I meant
alpha137: The molecules radiate the IR in all directions. Throughout a sphere. A lot escapes into space.
LizK: ok
alpha137: A fraction comes back to earth to be absorbed.
LizK: ok, but that fraction is what is the problem right? if that increases, the temp of earth will prob. increase too
alpha137: From the point of view of light comming from the sun, what are the factors that would go into making warming-considering constant greenhouse gases?
alpha137: You are right, the fraction of light comming back to earth is important.
LizK: The amount of light, like what season and all the other cosmic variables
LizK: and, If greenhouse gasses are constant, won't the temp vary by just natural fluctualtion?
alpha137: OK, we have constant light bathing earth. What happens, what are the variables?
alpha137: You mentioned one earlier-clouds.
LizK: oh, clouds, or any volcanic eruptions on earth that might reflect some light,
alpha137: The polar ice caps!
LizK: And also, yes, but if they are constant then they are always the same
alpha137: The point is that the radiation getting to the earth gets here by complicated processes.
LizK: Yes,
alpha137: The greenhouse effect, simple when looking at a closed auto, is obviously complicated when looking at the earth.
LizK: of course, there are more variables some whic we probably don't even know about
LizK: or at least don't know too much about
alpha137: One part of the problem is the light getting to earth and not being reflected by the cloud cover and the polar caps, etc. Another part is that once here the radiation can be trapped by greenhouse gases.
LizK: ok
alpha137: Lets focus on the greenhouse gases.
LizK: ok
LizK: thats fine with me
alpha137: And you are going to pick on carbon dioxide, right?
LizK: ok
LizK: because that is the most common,
LizK: by a lot,
LizK: but then I would talk about methane and nitrous oxide
LizK: after that its all the CFC;s and ozone, and they have their own problems to deal with
alpha137: OK. I have this very good book by "Wally" who is a geo prof at Columbia. In it he gives a concentration for CO_2 and CH_4 for three geological times.
LizK: ok
alpha137: We can look to geology to help understand this problem.
LizK: yes
alpha137: Wally gives these times Glacial, Interglacial and Today I will call them G, I, and T.
LizK: Ok,
alpha137: CO_2 G = 195 ppm, I = 280 ppm, T = 350 ppm
alpha137: CH_4 G = 0.4 ppm, I = 0.8 ppm, T = 1.7 ppm
LizK: how long ago were the Glacial and Interglacial periods?
*** XII (~batman12@ldha110.lss.emc.com) has joined channel #brownchem
XII: hello?
LizK: hello
alpha137: Hello XII we are discussing the greenhouse effect
XII: Sorry this is an interruption- I've been trying to get this thing to work for days. AT least now I know where I can find you
alpha137: You interested in this?
XII: I've been keeping up with the discussions posted on the website. I'm definately interested
alpha137: Well, join in.
XII: thanks.
alpha137: LizK and I are focusing on carbon dioxide and methane and I am looking at a geology book by "Wally" at Collumbia.
alpha137: Columbia that is.
XII: ok
alpha137: The question is: "Why does carbon dioxide change from 195 ppm in the so called glacial period to 280 ppm in the interglacial period to 350 ppm today?
alpha137: And in the case of methane G = 0.4 ppm, I = 0.8 ppm and T = 1.7 ppm
XII: Could the high concentration today be due to industry?
LizK: Maybe, but it was increasing long before the industrial revoluton
alpha137: No doubt, the industrial revolution is contributing high concentrations of carbon dioxide, but as LizK says there were increases before.
LizK: How long ago were the Glacial and Interglacial periods?
XII: An increase in Animal populaion after the glacial period could produce much more CO_2
XII: or is that minimal?
alpha137: Glacial maybe 15,000 years ago or earlier. I am not sure.
I asked Dr. Clemens and the Glacial period is a max of 21,000 years ago, the Interglacial about 126,000 years ago. These can be seen on his graphs below.
LizK: ok, just curious
alpha137: Also, I think that animal and vegetation would be responsible for the variations in methane.
LizK: ok, that makes sense
XII: yes
alpha137: In order to believe the existance of the greenhous predictions geologist need to explain these variations.
LizK: ok
alpha137: I think what they say is that, due to glaciation, there was less vegetation and therefore less methane from decomposition. Sound reasonable?
LizK: Yes, i think so
XII: Yes-
XII: Were there also less animals?
alpha137: So assuming that kind of thing takes care of methane and that methane is minor compared to carbon dioxide lets consider CO_2.
LizK: ok
alpha137: Yes, there must have been fewer animals.
XII: Less animals would produce less CO_2
alpha137: But the effect of animals would be first as a sink for carbon (reducing carbon dioxide) and then as a source of methane from decomposition.
XII: I see
alpha137: We need to consider a carbon cycle-sources and sinks.
LizK: ok
XII: ok
alpha137: What are some sources of carbon?
alpha137: You know, that can end up in carbon dioxide.
LizK: respiration, decompositon, (now there is deforestaion,and industrial stuff) and then other regular biochemical processes like the decompositon of limesone
LizK: limestone
XII: Decomposing materials (oxidized)
XII: Volcanic Eruptions
alpha137: And then what are some sinks for carbon-things that remove it from the atmosphere and distribute it into various parts of the biosphere, etc.
LizK: like trees
LizK: there was an article about that
alpha137: Go on.
alpha137: By the way, limestone has to be a biggie.
XII: I still need to read a lot of these articles
LizK: oh, it was talking about how there are these big sinks around the world and soemtimes scientiests dont' know what they are, but at any rate, there was a forest of trees in Siberia that they think was absorbing lots of CO_2
alpha137: Thats OK XII just use your wits.
alpha137: Yes, there was an interesting article about someone studying the absorption of carbon dioxide by plant material. After all there is photosynthesis.
LizK: yes
alpha137: Can this be a factor in the greenhouse problem?
alpha137: Give me some thoughts.
alpha137: I meant to say "after all there is photosynthesis."
LizK: perhaps, but then at the end it was talking about how this forest was above the previous tree line or something ( because the temp had warmed up) and so that is good, but somewhere else a desert is probably being created where there once was trees
alpha137: By the way, XII send me an email James_Baird@brown.edu with you name so I will know who you are.
XII: If deforestation is such a problem, less CO_2 would be absorbed by trees
alpha137: Well, how about the plant matter on earth as a whole.
XII: I already have- my email is batman12@mindless.com- I'm Jesse Winer
alpha137: Thanks
alpha137: Deforestation has to be a problem.
alpha137: We are trying to enumerate the sources and sinks of carbon so we can understand the CO_2 question.
LizK: ok
alpha137: Limestone was mentioned as a source. Could it be a sink as well?
LizK: yes, because it both decomposes and is made
alpha137: There is one big sink you all have missed. What is it. It is obvious.
XII: Grass?
LizK: The ocean?
XII: Low ocean temps would absorb more CO_2
alpha137: Actually, grasses have to be very important. And yes, the ocean is a huge sink for CO_2
LizK: ok
alpha137: We, or someone, better understand how CO_2 gets into the ocean and what happens once it is there.
alpha137: So, if carbon dioxide gets into the ocean (water that is) what happens to it?
XII: It is used by algae and oceanic plants. I think some animals (like corals) can use it to produce their skeletons
LizK: ok
alpha137: Yes, XII, the use of plants in the ocean is a very important sink for carbon.
XII: It gets into the ocean because our air is always dissolved in some concentration in the water. At warmer temps, less air can be dissolved, and that's why fish die in the summer, or they "sleep" ont the bottom of the body of water where they live
XII: And since there is CO_2 in the air...
LizK: yes, and that is why there is thermal pollution in some places
XII: exactly
alpha137: Here is a simple chem question. When CO_2 dissolves in water what happens to it?
XII: Carbonic acid
LizK: yes
alpha137: Right, carbonic acid. What happens to it?
alpha137: What do we get?
XII: It partially dissociates (a weak acid). You can make calcium carbonate (chalk) with it and Calcium ion
alpha137: That is the point, XII, this is a way for carbon to get into limestone on the ocean bottom.
XII: ok
LizK: ok
LizK: i see
alpha137: The ocean is a huge source and sink for carbon.
alpha137: By the way "Wally" is prof. Wally Broecker of Lamont-Doherty Geo Observatory at Columbia U.
XII: So when the ocean got much colder during the glacial periods, less CO_2 was dissolved which would mean more CO_2 was in the atmosphere- unless it was all converted to limestone.
alpha137: Yes, XII, that kind of thing. But there are complications. You mentioned algea, etc.
XII: yes
LizK: yes
alpha137: Wally says the obvious: "Organisms living in surface water fix CO_2 into organic matter."
LizK: ok
XII: Algae photosynthesize- were there higher levels of O2 in the atmosphere during the glacial period?
alpha137: And he says: "Part of this organic matter is transported to the sea's interior where it is oxidized and returned to inorganic form."
alpha137: There may well have been higher levels of O_2 due to photosynthesis.
XII: ok
LizK: ok
alpha137: The amount of biologic activity will depend on phosphorous and nitrate ratios just as in a garden!
LizK: oh,
XII: right
alpha137: The point of all this is that to really understand the greenhouse effect we need to understand some geology
LizK: yes
XII: ok
alpha137: We need to see the complexity.
XII: It seems very complex
LizK: yes
alpha137: According to Wally, who I am getting fond of quoting, "Microorganisms require about one phosphorous atom per 128 carbon atoms and 16 nitrogen atoms per 128 carbon atoms."
LizK: ok
alpha137: And he says, "were all the nutrients ...extracted from the surface water by plants, then the atmospheric CO_2 content would be about 150 ppm."
alpha137: He says: "..were the ocean steril, then the atmospheric CO_2 content would be about 470 ppm."
alpha137: Think about these two numbers.
LizK: those are pretty different numbers
XII: the plants are definately needed to keep the CO_2 levels down- but also nutrients from the earth, and from the nitrogen cycle
alpha137: These carbon dioxide concentrations are being controlled by plant life in the ocean. This is one factor.
alpha137: Yes, nitrogen cycle is important. All these things are connected.
LizK: ok
XII: ok
alpha137: It turns out, obviously, that these geological processes are quite complex and not fully understood. Even this biologic explanation has its problems.
XII: biology isn't very predictable, relatively speaking
alpha137: Is this greenhouse problem really a problem?
LizK: thats true
LizK: I think so
XII: If it is, it's misunderstood
alpha137: Since we do not understand all of the geological questions what can we do to nail this question down-that there is, or is not a greenhouse problem with carbon dioxide.
XII: Make assumptions. Lots of them
LizK: Well, we obviously need more data and experiments
alpha137: Here is a typical problem of the interface between science and the public.
LizK: true
XII: yep
alpha137: We have a complicated science problem whose details most of us cannot understand. Yet we may need to make a decision!
alpha137: What to do?
LizK: I think it starts with public awareness, but thats just my opinion
alpha137: Today, in Providence, is a very hot day. The public is aware of that. Good enough?
XII: Cut back on things that we can control-(industry, deforestation). It's pushing 100 up here in Boston, and I'm well aware of it.
LizK: No, today we have a code red here too, but ther eare still people out driving cars and exersicing, even though that isn't terribly good for the environment or themselves
XII: But people will find things like Air Conditioning to make it cooler at a personal level, not thinking about the global reprocussions.
LizK: I'm talking about telling people the facts of the problem, the differnt side, the pros and cons, so that they can make some sort of decision on some level
alpha137: There is one factor we have left out of the geo processes. Time. How long does it take for these carbon sinks and sources to work?
alpha137: Geologists usually think in terms of "geological time" you know thousands of years is a short time for them.
LizK: Probably a fairly long time before they could make a difference, but also, there is the problem of how these molecules take a long time to desintigrate,
LizK: But of course, in geological time, its all shore
LizK: short
XII: It takes a couple hundred years to make a big forest. I don't know about the ocean- the temp stays pretty constant
alpha137: How long ago was the industrial revolution?
LizK: Like two hundred years ago
XII: About a hundred years- no time at all, but look what we've changed
LizK: oops. yeah
alpha137: Yes, no time at all, geologically speaking.
XII: It's much easier to destroy things than fix them.
alpha137: Perhaps we are not lost yet. We need to be quantitative and we need to understand the oceans, etc. but all this industrial activity happened yesterday.
LizK: ok, thats true, so what can we do?
alpha137: Right, it is much easier to distroy than fix. We should probably be conservative in our actions.
LizK: And we don't even know what the consequences of these new solutions will be- no one thought CFC's were going to be such a problem, they seemed great when they were invented
alpha137: We can investigate the carbon dioxide concentration in the atmosphere and see if there is any anomaly around 100 years ago.
XII: yes
LizK: yes
alpha137: By the way, CFC's were an almost perfect solvent. Not harmful to people, etc.
XII: would anything show up 100 years ago, or is the IR just affecting us now?
LizK: Exactly
alpha137: In the basement of this GeoChem building there is a scientist named Clemens who measures CO_2 vs time.
LizK: What has he found?
alpha137: Clemens, looking at sediments and their carbon and oxygen content, finds evidence for carbon dioxide from 3.5 million years ago to the present.
According to Clemens, and others, there is a tectonic origin to this carbon dioxide. As the Himalyas grew this caused changes in CO_2. I will try and find a link to this interesting work.
Click for some plots of atmospheric carbon dioxide and global ice volume. The carbon dioxide is measured as trapped gas.
Click on this for carbon dioxide concentration from 150,000 year ago to the present.
Click on this one for the recent measurements. This is the red line on the previous graph.
LizK: wow
alpha137: There are fluctuations like mad. I will get his graph and post it.
See the links above.
XII: The levels 3.5 million years ago were high, no?
alpha137: Basically, as I remember, there is a spike around 1800 of CO_2 continuing to the present.
LizK: So that implies that human activites made a difference
alpha137: I am not sure what the level was at 3.5 million years ago, but it could have been high-it goes up and down dramatically.
XII: We found uses for coal and fossil fuels, and there was also a population (human) increase around then
alpha137: And yes, human activity made a difference.
LizK: yes
XII: So can human activity make a difference in the opposite direction?
LizK: lets hope so
alpha137: There are fluctuations through the millenia and the explanations are to be found in those geo processes discussed by Wally and others.
alpha137: Human activity can make a difference in the other directions, but there is politics to deal with. And there is greed, etc.
LizK: ok
LizK: thats true
XII: human emotions don
XII: 't help much in this case
alpha137: Let us say that we believe the greenhouse effect to be true and that we have some quantitative numbers, or estimates. What do we do?
XII: I think we are pretty stuck in changing our ways- we have to find ways to reverse the effect
LizK: Yes
alpha137: So, how do we do that. If we were Laurent Kabila we would just kill those who did not obey our plans.
LizK: I'm sorry, I have to go now, I have a dentist appointment, I'll see you tommorow at 9:30?
alpha137: Right, I must go as well.
alpha137: Tomarrow at 9:30 am
LizK: thank you, and goodbye
LizK: ok, bye
*** Signoff: LizK (Leaving)
alpha137: XII see you tomarrow too?
XII: I'll try to be here- I've gotta work, but I may be able to find a computer for a while
alpha137: What might be a better time?
XII: I usually don't get home untill 6 or so- I'm at work now, and it's not a problem.
alpha137: They let you get away with this?
alpha137: Where do you work?
XII: I'm supposed to be watching tests on computers- they usually run for 12-48 hours, so while they are running, there's not much for me to do.
alpha137: Well, that is good. You can do this computer thing.
XII: I work at a company called EMC. It's about an hour west of Boston
alpha137: I will look them up on the net if they have a web page.
XII: www.emc.com
alpha137: I would have guessed.
alpha137: E = MC^2 would have been more physical.
Of course, it turned out to be EMC^2.
alpha137: Anyway, I must sign off as well. Bye.