's Forum Archives - Non-Cycling Discussions

Archive Home >> Non-Cycling Discussions(1 2 3 4 )

Question on greenhouse gasses.(18 posts)

Question on greenhouse gasses.Len J
Dec 5, 2002 5:32 AM
All of the SUV/Bashing for environmental reasons got me thinking about the increase in CO2 gasses that appears to be the root cause of global warming (or at least the theory of the day).

Remembering my basic biology, I think that humans breath in air & exhale co2 and that plants breath in Co2 & exhale (or produce) Oxygen (I know they don't breathe but I'm simplifying). Why doesn't anyone attribute global warming to the dramatic increase in world population coupled with the concurrent deforestation of the planet? It seems to me that this would have a much more dramatic impact on CO2 production levels than SUV's.

Anyone understand this?

they domohair_chair
Dec 5, 2002 8:23 AM
People have been talking about the destruction of the rain forest in Brazil for this very reason. Less plants = less processing of CO2. But those people are tree huggers and enviromental wackos (said sarcastically).

Bashing SUVs is a much more fun and passionate topic than not cuttting down the rain forest. It's a homegrown topic for one thing. The rain forest is so far away. Plus, you can make demographic assumptions about people who drive SUVs. Class warfare is always fun. And you see SUVs every day, so you can physically point to them as The Problem. Almost everyone hates SUVs according to some surveys, which doesn't make sense given the sales of SUVs.
It's not just deforestation but.....Len J
Dec 5, 2002 8:27 AM
the combination with the population explosion.

well then...mohair_chair
Dec 5, 2002 8:53 AM
Now you're anti-children and anti-family! (said sarcastically)

I don't think anyone thinks overpopulation is good, but the fact is, few people are really interested in talking about it anymore. Mainly this is because there is no solution.

Oh sure, everyone knows what the solution is (condoms/birth control), but this has become such a religiously charged third rail issue thanks to the Catholic Church and others. And anyway, is it realistic to think that people in the third world are going to use birth control? No, it isn't.

Do we want to do what China does and forbid couples from having more than one child, forcing abortions if necessary? I'm not sure anyone wants to get to that level, but at least they are trying.
No.........Len J
Dec 5, 2002 9:25 AM
I'm not anti kids or pro legislation to mandate birth control. I would be a hipocrite if I took these positions as I have 4 children (Good Irish Catholic boy that I am).

I hae honestly just started processing along these lines. What I am really asking is : Why is this never discussed as part of the green house gas discussion? I can't believe that SUV, or even auto emissions generate as much CO2 as the increase in population does.

Is it because it's not true?
Is it because it is too politically charged?
Is it because it is too complex?

Dec 5, 2002 9:35 AM
They force sterilizations, but saying abortion is good for stiring up the shi_.

This is how it works, animals and fires emmit CO2, so do plants at nite. Green plants absorbe CO2 and emmit O2 in the presence of sunlight. The vast majority of green plants are in the oceans, thus the population of aquatic plants is what controls the CO2 levels in the atmosphere.

Incresed CO2 levels cause an increase in average temperature at the surface due to the so-called "green house effect". There is a negative-feedback mechanism where too high of an average temperature will cause an increase in the population of marine plant life. This results in a decrease in atmosphereic CO2 and a corresponding decrease in temperature and decrease in marine plant life. The cycle continues as it has for eons. The warm end of the cycle is pretty warm, and the cold end is damn cold, hence the periodic ice-ages. these cycles take a long time. Most of human existance has occured since the last "bottom" of the cycle about 50,000 years ago. We are still comming up the temperature cycle, but I don't know how hot it will get before it starts to cool down.

The questions that normal TV-watching folk discuss these days are 1)is the increase in world human population upsetting the balance? 2)Is the deforestation of S. America upsetting the balance? 3)Is the use of fossile fuels in power plants and automobiles upsetting the balance?

Theses are all good questions, its the answers that concern me. 1)I don't think the human population is making any difference, since other mamalian populations have gone down at the same time. 2) Deforestation is probably not an issue, since land is a small fraction of the earth, and forest is a small fraction of the land. Marine plants are the governing CO2 absorbers. 3) Fuel burning is probably a very small fraction of CO2 production compared to mamalian breathing, but I don't have any figures in front of me.

In general, the next hot age may kill us all, if our species survives, we will probably survive the next ice age, so the picture is not completly bleak. BTW there is nothing we can do about it. Have a nice day.
Some stats I've heard...VertAddict
Dec 6, 2002 5:36 PM
There are a lot of other gases in the atmosphere that create the greenhouse effect besides just CO2. The stat I've heard is that CO2 makes up only 3% of total greenhouse gases.

Of CO2, the stats I've been given are that the earth "breathing" ie. natural CO2 production outside of human industrial influence, is ~750 gigatons/year. Supposedly the net human output is only 3 gigatons/year. (If someone can firm these up, please do so).

And for a point near and dear to my heart...Canada produces only 2% of that human output. So someone explain to me why we are ratifying Kyoto? We're the only country in the world that is going to take any pain on this over the next ten years: the third world has opted out indefinitely, US and Australia were smart enough to walk away, and Europe cheated their way into not having to do anything new. They did this by setting the arbitrary benchmark date to 1990, before Britain closed its coal-fired power plants and before they cleaned up East Germany. Then they treated Europe a group instead of individual countries, and voila - thanks to Britain and Germany, overall emissions are down from 1990 so no one in Europe has to do a damn thing. Ditto Russia due to their massive recession.

If you can tell I'm a little worked up about this, it's because my region in western Canada is about to get economically bent over a barrel and rogered for the sake of an agreement that is based on shakey science and assumptions, to try to effect a change that is immaterial at best anyway, while no one else does anything to help. In fact, the third world/US will actually benefit from the new energy projects which will be built there instead of here. And yet our government maintains this is the "right thing to do". Bottom line is, our Prime Minister wants his legacy intact before he leaves office, even if we have to pay for it (is he some kind of European jock sniffer?).

OK, rant over, I'm done. But you wonder why I'm an unhappy Canadian.
Are these the stats you're looking for?PdxMark
Dec 7, 2002 1:11 PM
Here's the site:

It seems to show that the total global atmoshperic level of carbon is 750 Gigatons, with natural atmospheric and terrestrial plant fluxes moving about 120 gigatons a year (each way, back and forth between plants and the atmoshpere). The site also implies that atmospheric and oceanic fluxes are balanced at 90 gigatons a year (total back and forth between the atmoshpere and the ocean surface).

In this context, man-made CO2 amounts to 7.1 gigtons a year, about half of whch ends up in the atmosphere. So, if these numbers are right... (who knows?)... then we're adding 1/2 percent per year to the total atmospheric CO2 load.

As a percentage of the flux into and out of the atmoshpere, 3.3 Gt is not much. But the implied natural NET change into the atmoshpere is zero (ie, all balanced). The 3.3 Gt is the amount that's OUT of balance -- net change (or so it seems). Compared to zero natural net change, 3.3 Gt is a lot. In a big, otherwise balanced system, 1/2 percent-per-year seems like a potentially big cumulative effect over time. That's the magic of compound interest. :)
Thanks for the info - two follow up questionsVertAddict
Dec 10, 2002 7:04 AM
Two things still aren't making sense to me.

First, you say that the system is in a static state of balance. I have a hard time believing that it is, or at least that it stays at the same level of balance. What about odd events such as volcanic eruptions? That has to mess up the balance at the time it occurs, and on a geological time scale eruptions are a very regular occurance (just think how many major eruptions we've seen in the past 2000 years). Clearly, the system is able to deal with the imbalance that this event creates - it must be able to adjust to variances.

Also, I would wonder if you wouldn't see variances year over year just due to things like routine changes in ocean temperature, a particularly hot/cold winter/summer in a certain area, etc. This would be happening constantly, the system seems to be able to accomodate it - so would the 3.3 Gt be accumulating, or is it absorbed? On that note, I would think we have as much more to fear from deforestation than we do from CO2 emissions.

The second question I have is still around the overall percentage of greenhouse gas that CO2 makes up. If it is only 3% of the total greenhouse gas, then in truth our contribution to this system, balanced or otherwise, is only 3.3/750 * 3%, which is only .013%. I have a hard time believing that could be causing any kind of material change.

If you could respond to these questions, I would appreciate it. I have an admitted predisposition against the Kyoto accord, but at the same time I am trying to see if the arguments I've heard against it make sense.
I'm for more populationKristin
Dec 6, 2002 6:01 PM
The grocery store 3 miles from my house. I'd like one within walking distance. I still have to drive 5 miles to get to the nearest shopping mall. And for goodness sake, the nearest Starbucks is 6 miles away!! No, we need more employees so we can build more stores.
And defending SUVs ignores the difference between...PdxMark
Dec 5, 2002 1:22 PM
the effects of one large vehicle (Lincoln Navigator) emitting 12 tons of CO2 a year (at 13 mpg and 15k miles) and tens of millions of large vehicles emitting hundreds of millions of tons a year.

As for the relative effects of deforestation and burning fossil fuels, one set of numbers shows that all fossil fuel sources emit about 5.6 gigatons of carbon, and "changes in tropical land use" effectively emit 1.6 gigatons. The hundreds of millions of tons from large vehicle use correspond to the tenths places in these gigaton numbers, I think.

So, really, no one of us has any affect on these CO2 levels on our own. The problem is that none of us has the planet to ourselves. Each of our choices is adopted by, and the effects multipled, by a factor of millions or tens of millions. Shirking responsibility for the effects your one car is based on a fantasy that yours is the only car like that. It's not. It's the millions of cars like that that create a measureable effect.

If choice of car can reduce CO2 emisions by factors of 2 or 3, then from that one set of numbers, car choice DOES measureably affect global CO2 levels.

I'm no climate scientist, just a googler who should be working. Here's te site for the car info.
The rainforest isn't that far awayKristin
Dec 6, 2002 5:53 PM
Well the one in Brazil may be, but we have rain forests in the US too. Isn't N. California and Oregon considered rain forest?
Some coastal forests are considered temperate rain forests...PdxMark
Dec 7, 2002 12:53 PM
like the forests on the Olympic Penninsula of Washington state. The non-coastal mountain forests aren't usually referred to as rain forests. As for the coastal forests in general, I think it depends on how much rain they get... :)
Alaska has onemohair_chair
Dec 9, 2002 7:20 AM
The Tongass National Forest
Does it rain there? Or just snow? ;-) nmKristin
Dec 9, 2002 8:57 AM
re: Question on greenhouse gasses.Steve98501
Dec 6, 2002 5:34 PM
PDXMark beat me to it. The effects you mention are also important, but the upshot is that the exhaust of smokestack industries and internal combustion engines account for a much larger share of CO2 emissions. Therefore many of us point to SUVs as poor judgement or lack of judgement when functional transportation equivalents are available that pollute much less.

It's difficult to make cultural changes among people who don't see their family size as part of the problem. It's difficult to make cultural changes among people who see an immediate need to clear forest land for short term agricultural gains, like feeding themselves. And it's hard to make cultural changes among people who can afford a Chevy Suburban and want one to haul their bike in. I think these cultural changes are not all on the same scale.
Links debunking Kyoto mythVertAddict
Dec 7, 2002 12:25 PM
From what I understand about overpopulation...empacher6seat
Dec 9, 2002 6:57 PM
Is that it's not a problem. There's enough resources for everyone on the plant; the problem lies with the western world using the majority of resources the world has.