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I commented yesterday but the comment disappeared. Sigh. Here it is from memory:

To be fair, someone estimated that for a walker getting calories from the typical American diet, greenhouse gas emissions per mile are similar to those emitted by a car, because of the inefficiency of meat production:

http://bicycleuniverse.info/transpo/energy.html

So Orcutt, who didn't do any research before shooting his mouth off, unintentionally said something that isn't actually completely insane.

anti

Thats assuming that the cyclist uses incremental calories to cycle. If they are substituting cycling for going to the gym, say, they are burning the same amount of calories, but getting transportation out of it. If they are not doing any exercise, and are overweight, then by taking up cycling they can burn the same amount of calories, but reduce their weight. I suppose there are sedentary people with normal weight, but thats kind of austere in my opinion.

ACyclistInTheSuburbs: sure, i'm not saying there are no other scenarios. I'm just trying to point out that the congresscritters utterances have been ridiculed in a way that is ignorant of the kernel of truth they contain.

I disagree that there is a kernel of truth there.

Really? I think it's clear that there can be significant greenhouse gas release in order to provide calories for any form of exercise. I don't see how you can completely dismiss the concept; i think it makes us as cycling advocates look bad when we dismiss things out of hand because we're not willing to do the math.

Exercise does not cause greenhouse gas release. It's the way we grow food and transport it does, and yes most of us eat this food and use the energy from it to exercise. But exercise, in and of itself, doesn't cause greenhouse gas release.

The higher the amount a person is overweight, the more likely they are to buy a larger, less fuel efficient vehicle. So if they're not hitting the gym, they're causing more greenhouse gasses.

Yes, that's what i meant when i wrote "in order to provide calories for any form of exercise". The point the guy meant to make is that you don't completely sidestep the greenhouse gas issue by choosing a different mode of transport, and that is a valid point regardless of whether he got the specific mechanism of release correct. The impression i've gotten from most of the coverage of the story is that the critics are even more ignorant than the congresscritter.

[Last post answer to washcycle, not Crikey7; sorry to be unclear.]

In fact, i suspect he had heard about the food-supply emission calculation second-hand (maybe from a constituent) and was regurgitating it in a confused form.

The point the guy meant to make is that you don't completely sidestep the greenhouse gas issue by choosing a different mode of transport

Sure you do. Biking and walking create no greenhouse gases. It's just that easy.

and that is a valid point

No, it really isn't. Not even in this context since the person was arguing there should be no tax on biking because it doesn't pollute. It's not a valid point to then say that biking indirectly causes pollution because of fertilizer.

In fact, i suspect he had heard about the food-supply emission calculation second-hand (maybe from a constituent) and was regurgitating it in a confused form.

Well then, it sounds like he's ready for the Senate.

washcycle, it most certainly is valid to compare externalities when performing a thorough cost-benefit analysis. If you don't understand this, well, i find that a bit alarming. I thought you were more serious.

Apparently i'm spam again.

washcycle, it most certainly is valid to include externalities when performing a thorough cost-benefit analysis. If you don't understand this, well, i find that alarming. I thought you were more serious.

Eating is not a negative externality of biking.

What you're talking about is some sort of weirdly bounded life-cycle analysis. Under those bounds everything pollutes and it does so exactly evenly.

Because not only do I need to eat to bike, but I need roads. And I need all the infrastructure needed to deliver my bike to me and I need police to keep the roads safe and I need a military to make the oil that makes the food that I eat possible....etc. Until we can just divide up all the energy used per person.

But that isn't where you should draw the boundary for a pollution balance analysis. It's ridiculous to do otherwise.

I don't know where you're getting this theory that everything pollutes exactly evenly. Cycling pollutes less than walking. Cycling while fueled primarily by vegetable calories pollutes less than cycling while fueled primarily by meat. Driving a fuel-efficient vehicle pollutes less than walking while fueled primarily by meat—it takes less time and burns far fewer calories.

You need a road of some kind either way. You need police either way. But *all other things being equal*, if you eat a typical American diet, and you walk, you're effectively producing more greenhouse gas than if you drive a reasonably fuel-efficient vehicle the same distance. You don't have to deny this reality in order to make a good case for walking and cycling.

"Driving a fuel-efficient vehicle pollutes less than walking while fueled primarily by meat—it takes less time and burns far fewer calories."

except the reality is about a third of americans are obese. The majority are overweight. Many who are not engage in other forms of exercise. The folks who are sedentary but normal weight have to be less than a quarter of the population, and probably many of them have more sustainable diets.

In fact I find myself inclined to eat more healthily (more vegetables and less processed junk) after I've been riding.

acyclistinthesuburbs: i'm afraid don't know what your point is. An overweight person who eats a typical American diet is still going to be responsible for less carbon when driving a fuel-efficient vehicle than the same person walking the same distance.

I don't know where you're getting this theory that everything pollutes exactly evenly.

If you spin the web out far enough, then all activity is connected, and if so then all energy use is activity, so eventually all activity is related to all energy use. It's not really a theory, it's carrying things out to their logical conclusion.

Once again cycling and walking don't pollute. Agriculture often pollutes. But those are two different, unrelated activities, despite your attempt to tie them together by food. It's not the biking that pollutes - or even the eating - it's the growing and transporting.

Yes, all activity is related to energy, but that doesn't mean all activities consume energy at the same rate.

I count calories. If i cycle for an hour, i might burn 800 of them. There's simply no question that that is related to food and ultimately to agriculture. It would take about 200 grams of meat to provide those calories. If you want to continue refusing to see the connection, that's up to you; again, i thought you were more serious, but you're making it clear that you aren't. Oh, well.

anti, what you sewn unable to grasp is that most people won't alter their food intake to walk a few miles--the calories they consume would have been consumed whether they walk or whether they drive.

Mike, where in the world do you get that idea? Most people replace calories burned through exercise; some even gain weight as a result.

And, in any case, the whole point is simply that exercise does, in fact, result in greenhouse gas emission because of the increased food demand. You can quibble about how much, but to rewind back to where this all started, the point Orcutt was ineptly trying to make has some basis in fact. He didn't deserve to be ridiculed; he deserved to be corrected.

I'm in favor of cycling and walking as alternatives to driving. There are a lot of reasons for it. But you can't just claim without evidence that it saves on greenhouse gas emissions. There are a lot of variables. If you want reduced carbon footprint to be a benefit of your mode of travel, you have to do the arithmetic and adjust those variables—it isn't a free ride.

again, i thought you were more serious, but you're making it clear that you aren't. Oh, well.

Ok. What the hell is this??? You can't persuade me to see things your way and that must be MY flaw? You sound like one of those guys who would strike out with a girl and then call her a lesbian.

Maybe your argument just sucks? Maybe you aren't very persuasive? Have you at least considered that for a second? My God, you sound arrogant.

And, in any case, the whole point is simply that exercise does, in fact, result in greenhouse gas emission because of the increased food demand.

We get the point, it's just that it's wrong. Exercise, on average, leads to more eating. That's true. But eating only leads to more greenhouse gas production because of choices that are unrelated to transportation mode. The cake is already cooked at that point. By your definition, simply going someplace causes GHG production. [And not going someplace can be shown to cause GHG too]. So that's not what we're talking about.

You have to lay the blame at the place where the choice is made. And the place this choice for GHG is being made is in the farming and the transporting.

Let me put it another way:

Is there any way that driving your average car could be done in a way that doesn't lead to more greenhouse gas production. [Answer: No] GHG production is inherent in driving.

Is there any way that riding a bike could be done in a way that doesn't lead to more greenhouse gas production. [Answer: Yes. If you eat food you grow and transport without any fossil fules] GHG production is not inherent in biking.

And that is the difference.

I get that idea because I actually read the article, and all the caveats, and I just don't believe that someone is going to eat an extra 1/4 pound of beef just because they walked a mile.

Once you start talking about distances great enough to need more food (in this country!) you're talking about recreational or fitness walking, and a straight up comparison with auto transportation miles makes no sense at all.

But putting this all back into context, the suggestion to tax cyclists for this remains completely insane. If you're really worried about the carbon load of beef, the appropriate thing to tax is beef, because the amount collectively consumed by people sitting in cars vastly outweighs the differential consumed by cyclists (to the point where the cyclist contribution is insignificant).

Mike, thank you. That's the way to think about it. If we had a carbon tax, where would we apply the tax? Would we tax biking? No. We would not. We would tax fossil fuel use in agriculture and transportation.

washcycle, i fully agree that a carbon-based tax on cyclists would make no sense. The tax would rightly belong on agriculture; arguably the tax should not be limited to fuel because livestock themselves are a major source of methane, which is a more potent greenhouse gas than carbon dioxide:

http://epa.gov/climatechange/ghgemissions/gases/ch4.html

But then, i never said i thought there should be a tax on cycling. This wasn't a discussion about taxation, and there are plenty of other incorrect things in Orcutt's statements. My sole point was a simple fact to which you have remained obstinately resistant: increased energy demand results in increased greenhouse gas production, if the typical American diet is the source of the energy.

Certainly there exist ways to bike without significantly increasing greenhouse gas production. As i've stated a bunch of times, the significant increase happens when the cyclist is burning a typical American diet, which includes a lot of meat. You keep trying to move the goalposts in order to construct a tableau from which you can deny a simple truth—one that shouldn't be contentious. Here's what i originally wrote; let me know if you can find a way to actually refute this, instead of one of your straw men: "To be fair, someone estimated that for a walker getting calories from the typical American diet, greenhouse gas emissions per mile are similar to those emitted by a car, because of the inefficiency of meat production."

Mike, of course, one wouldn't eat an extra 1/4 pound of beef because he or she walked a mile. Walking a mile would only burn around 100 calories for a person of normal weight, so that would be compensated by less than an ounce of lean beef. But you really should read more widely than this article before you conclude things about how people compensate for exercise. There's a lot of research on the matter. People do, in fact, replace calories. And you, like washcycle, can try to pick weird corner cases where maybe the effect disappears, like a one-mile walk, but the claim is about the general mode of transport, and as i said above, shouldn't be contentious.

I am not a vegetarian, by the way.

e; let me know if you can find a way to actually refute this, instead of one of your straw men: "To be fair, someone estimated that for a walker getting calories from the typical American diet, greenhouse gas emissions per mile are similar to those emitted by a car, because of the inefficiency of meat production."

I'm not sure what strawman I've been using, but it's simple to refute.

Walking doesn't create any greenhouse gases. When I'm done walking a mile, the amount of greenhouse gas in the air is exactly the same as when I started (not counting respiration, but that is not "new" CO2).

But to go farther, that estimate by "someone" is likely wrong.

> Walking doesn't create any greenhouse gases.

That would be one of your straw men. That wasn't the claim; it's an absurd restatement of the claim. This is a neat example of what i mean when i say i thought you were serious. It is not a serious response.

Your link doesn't work for me. But as i've also said already, you can quibble over quantities; that doesn't refute the underlying hypothesis.

Link.

I'm not quibbling over quantities alone, but you did ask me to refute that.

That wasn't the claim

Of course it is. The claim is that "for a walker...greenhouse gas emissions per mile" is x. So if you walk 0 miles then it is 0 and the GHG emissions are directly proportional to the miles walked. Therefore, the claim is that walking creates GHG. How is that not the claim?

More directly, you're claiming that

1. Walking burns calories
2. Calories are replace by eating.
3. Eating requires food
4. Food has to be grown and shipped.
5. The way we grow and ship food creates GHG

Therefore walking creates GHG. Isn't that your claim?

Walking results in GHG, but "walking creates GHG" is an absurd simplification, which you you only "refute" by then reinterpreting the simplification as a statement about the local emissions from the walker's respiration. That's fine; your determination not to respond is quite clear. It's uncharacteristic, in my view, for a person who has, in other areas, seemed to be interested in contemplation of the gestalt, hence my disappointment.

I didn't realize the word "create" was the sticking point.

Fine. Walking doesn't result in GHG production, either.

The sticking point, again, is that you don't respond to the point; you respond to a misstatement of the point, a straw man. It's a simple and obvious fact, with actual numbers to support it, but that doesn't interest you, because you are obstinately staked out on a false principle that walking is a zero-emission activity.

I suggest we move on.

OK. Let's try this again. Am I correctly stating your claim here?:

1. Walking burns calories
2. Calories are replace by eating.
3. Eating requires food
4. Food has to be grown and shipped.
5. The way we grow and ship food creates GHG

Therefore walking results GHG.

For a clear statement of my claim, you may refer to my earlier comments. The claim is stronger than what you have restated above; it involves comparison with other modes of travel in a particular scenario. The purpose of the claim was to illustrate that one part of Orcutt's statement was, if unintentionally, based in fact, but that that part of his statement was roundly ridiculed by people apparently unaware of the factual basis, simply because he identified the wrong mechanism of GHG release. This ridicule, in my opinion, does a disservice to serious and complete discussion of how we can balance our transportation choices with their ultimate environmental effects.

Is that clear?

No. Not really. I'm trying to boil your claim down to it's simplest parts so as to avoid future confusion, and because I believe that one has to be able to explain someone else's position to credibly oppose it.

So let's start with my framework. Is it correct (yes or no)? If no, how would you change it (other than fixing the typos)?

Again, the amount of calories burned does not raise to the level of demanding increased intake for any reasonable scenario involving walking as a transportation mode. The effects don't become significant until you start talking about very long walks, which are recreation/exercise and are completely irrelevant to a discussion about transportation choices.

Add to that what washcycle suggested before, that the data in your article is somewhat bogus anyway. (It seems that the formula is just multiplying average MPG times distance, and ignoring the fact that cars have significantly lower fuel economy and much higher emissions during their warm up period. The emissions piece may not be relevant to something that's specifically intended to discuss the GHG effects of diet, but is extremely relevant to a discussion of transportation policy. This also tremendously skews the data for the kind of short trips we're actually talking about when walking is worth discussing as a viable transportation alternative.)

Finally, back to the original point, none of this in any way supports what Orcutt said, because he was talking about cyclists, not walkers, and even your source shows that GHG emissions are tremendously lower for cyclists than automobiles regardless of the scenario.

"Mike, where in the world do you get that idea? Most people replace calories burned through exercise; some even gain weight as a result."

if that were the case, then there would be no association between a sedentary lifestyle and obesity. Which is not my personal experien

ACyclistInTheSuburbs> if that were the case, then there would be no association between a sedentary lifestyle and obesity. Which is not my personal experien

Folks, really, can some of you do any of your own research? or possibly start reading carefully, e.g. the words "most" and "some" in the factual statement you were responding to?

antibozo: decide whether you're talking about transportation policy or exercise, please. the conflation is confusing.

anti

Are you here to quibble, or to discuss policy? As a matter of policy, biking that replaces driving decreases GHG's and one of the reasons for that is that very large numbers (i do not know exactly how many) of people who take up cycling will NOT significantly increase their caloric intake, because they are overweight and will reduce their weight after taking up cycling.

I was never talking about transportation policy, and i don't know where you might ever have gotten the idea that i was—i've gone far out of my way to be completely clear. I was talking about the uninformed ridicule coming from people who are unaware that, while cycling-related GHG emissions might not actually *exceed* emissions from cars, said emissions are not insignificant—actually at a similar order of magnitude—if you consider the actual mechanics of things.

There are two concepts here.

1. Energy use. There is no doubt that biking uses less energy than driving. We usually view this as a good because less energy use means less need for energy production and energy production has - on average - some negative inputs. But really, energy use isn't the problem. Using energy doesn't create GHG.

2. Energy production. This is where GHG are created. When you drive a car, you produce energy while simultaneously using it. If you had a solar powered car, this wouldn't create any GHG, but you probably don't, so your car creates GHG when you drive it. But it's the production of energy that does it, not the using. When riding a bike, you're only using energy, not creating any. If you then eat food from your garden or fish you caught in the stream by your house, there is no GHG production associated with biking. Because you've changed your choice of energy production.

If you change the means of energy production, you change the GHG production. If you change the means of energy use, you don't. That's why it's wrong to assign GHG production to biking and walking.

Because it's all about how you make energy. You can only say that riding a bike results in GHG if you have to replace the calories burnt with calories that were produced in a way that creates GHG. But the "if" is false. You don't have to. That's why biking isn't the "cause" of any GHG. Agriculture and shipping is.

Let me put it this way.

How many kg of GHG does food production from cradle to mouth (or trash) create?

How many kg of GHG does all the activities we do (biking, walking, praying, getting it on, etc...) using energy we got from food create?

By your definition the answer to 1 would be equal to 2 because they're equivalent. But that means we're double counting all those kg - once for agriculture and once for doing stuff. That's ridiculous. Either agriculture results in GHG or doing stuff does, but it isn't both. And as it turns out creating food (and only some food) creates GHG, but praying does not.

On a bike, you can easily change your energy source to become cleaner or even 100% clean. You can't do that with a car, because energy production happens onboard.

That's why even your overly forgiving interpretation of what the state legislator said still means he's wrong. And it's why everyone is right to ridicule him.

If you choose to ridicule him after thinking about it thoroughly, i might disagree with you, but then it's a matter of opinion.

But that isn't what most people did—most people ridiculed him because to them it was patently obvious that he was wrong. It was only obvious, however, because they hadn't thought about it. That's not a matter of opinion; it's a matter of ignorance.

washcycle> You can only say that riding a bike results in GHG if you have to replace the calories burnt with calories that were produced in a way that creates GHG. But the "if" is false. You don't have to.

Yes, that's what i said, every single time i said anything. You don't have to, but if you eat a typical American diet, which *most people do*, then the "if" is true. This caveat is what you studiously ignore.

In addition, let's look at your analysis a little bit:

You try to distinguish between energy use and energy production, but you completely mix up the categories for the activities you mention.

Riding a bike and driving a car are both producing and using (a.k.a converting) energy. The dynamic difference between the activities is in how the energy is stored: as fuel in a tank or as glycogen in your bloodstream. Either way, an oxiding process is used to recover the stored energy, transforming into kinetic energy, while releasing carbon dioxide. The primary difference in CO2 release is the different mass of the objects being moved. A gasoline engine is actually about as efficient at converting energy to motion as a cyclist (25-30%). Cars, of course, are much heavier than bikes, and also encounter more air resistance at the speeds at which they are typically used, so a lot more energy needs to be converted to travel the same distance.

So the cyclist converts less energy to get from A to B than the car does. But it took a lot less energy to pump fuel out of the ground and get it into the car's fuel tank than it did to make the glycogen in the cyclist's bloodstream if that glycogen is converted from large livestock protein. So even with the ten- to twenty-fold difference in mass, the net CO2 release ends up being far more similar than most people would expect.

You don't need to convince me to ride a bike. I rode 4000 miles last year because i enjoy it, because it saves me money, and because it keeps me fit. I'm helping a little bit with the GHG problem at the same time, but not as much as some people would like to think. That's okay—cycling doesn't have to be perfect in every way to be a pretty good option. It also doesn't save as much money as most people expect, because, if you're exercising, you need calories, and decent calories cost money. That's a whole other can of worms.

Your blog just ate another comment of mine, one that took a little time to compose. This is getting pretty tedious.

but if you eat a typical American diet, which *most people do*, then the "if" is true.

No. The if isn't true. I think this is the sticking point.

But it took a lot less energy to pump fuel out of the ground and get it into the car's fuel tank than it did to make the glycogen in the cyclist's bloodstream if that glycogen is converted from large livestock protein.

Well, not all food is large livestock, so you're cooking the books a bit there, but nonetheless, the place where the CO2 is produced is in the livestock production.

The primary difference in CO2 release is the different mass of the objects being moved.

More relevant is that the CO2 released by breathing represents CO2 that was already in the atmosphere (and part of the natural cycle) but the CO2 released by burning fossil fuels is "new".

This is all about where you draw the boundary, you want to reach back to agriculture and include all the CO2 produced in making the food the average person eats. If that's valid, why not include all the CO2 produced in making the clothes the cyclist wears (or at least the share of it for that time)? That food was shipped on roads and rails - why not include all the cyclist's share of the CO2 created to make those things? If you're going to have roads and rails you need property laws and laws of the road and all the infrastructure needed to create those laws and enforce them (courts, police, legislatures, etc..) - why not include the cyclist's share of the CO2 produced by all of those things? And if we're going to have laws and property then we need a military to protect those things - so why not include the cyclist's share of all the CO2 those things create?

My point is that I think I'm drawing the boundary line at an easily defensible point - the inputs and outputs of the system as the activity is being done. So take a cyclist and a bike, measure the current state of things, then have them ride 1 mile and measure the change in the state. Repeat for a car.

This is valid, because nothing needs to be changed with respect to cycling from a GHG production stand-point. The problems lie elsewhere. This isn't true of driving.

Your boundary, I submit, is more arbitrary. You want to reach back to include some things, but not others, which makes sense, because once you move the boundary there is no other reasonable place to put it and the expanse becomes so large and all-encompassing as to be overwhelming. If you included everything it would be too hard.

washcycle> You can only say that riding a bike results in GHG if you have to replace the calories burnt with calories that were produced in a way that creates GHG. But the "if" is false. You don't have to.

antibozo> but if you eat a typical American diet, which *most people do*, then the "if" is true.

washcycle> No. The if isn't true. I think this is the sticking point.

Well, make up your mind. You concede that you can say that if the calorie production generates GHG, which is what i have said consistently. But you insist on using a straw man that removes that caveat in order to deny what you just conceded.

washcycle> This is all about where you draw the boundary, you want to reach back to agriculture and include all the CO2 produced in making the food the average person eats. If that's valid, why not include all the CO2 produced in making the clothes the cyclist wears (or at least the share of it for that time)?

We've already gone over this. Again, the cyclist and the driver both wear clothes. If you want to, you could include differences in those clothes, e.g. if Spandex requires more CO2 than a suit. I don't have that information available, but feel free if you do; i suspect this won't work in the cyclist's favor, however. As for shipping the food, again, cyclists and drivers both eat; i would say that since food is only a fraction of the mass shipped via freight, the amortized difference between shipping an extra, say, 50% of the calories needed for the cyclist is not going to be measurable. But feel free if you want to, again, it will not favor the cyclist. There's also the cost of making the car versus the bike to consider; one could factor that in. Please feel free if you have the numbers (there's been some research on this question in the past). But the cyclist probably owns a car anyway, so much of that distinction is a wash. The cyclist additionally owns a bike, so that will not work in the cyclist's favor. In other words, we're being generous to cyclists already in the GHG production department if you want to factor in any identifiable difference.

You concede that you can say that if the calorie production generates GHG.

No I didn't. For someone who criticized others for not reading carefully, you should perhaps take your own advice.

Here's what I wrote - emphasis added.

You can only say that riding a bike results in GHG if you have to replace the calories burnt with calories that were produced in a way that creates GHG.

Replacing calories that way is not required. So it is not a result of biking. It is a result of food choices. There is an option point in between the two actions.

Please feel free if you have the numbers

You're missing the point entirely. I'm not arguing that these should be included. I'm arguing that they're just as valid as including the food. And so, if you believe that the food should be counted, then why have you skipped all these other items?

This is not about comparing biking to driving, it's about your claim that biking results in GHG emissions. So why have you ignored all these other items in your estimates? Do you not feel they're valid?

And can you drop all the "not serious" and "strawman" bullshit. It detracts. I can disagree with you - or even be wrong - without it being a moral failing or deceptiveness. Play your cards, not the opponent.

I'd like to mention, for the sake of comity, that i'm not interested in making you wrong. In fact, when any cycling-related matter comes up in conversation, such as the scofflaw myth, or helmet policy, i'm very likely to refer people to your writings on the particular subject. This is why i'm mystified that you've staked out the position you have, as i think it's quite indefensible. I hope we can come to some sort of agreement.

Latest comment eaten again.

washcycle> Here's what I wrote - emphasis added.

washcycle> You can only say that riding a bike results in GHG if you have to replace the calories burnt with calories that were produced in a way that creates GHG.

Correction noted; my mistake in misreading your earlier statement. I suppose i misread it, however, because it is completely illogical to me. We're looking at what happens when someone decides to switch modes from driving to cycling or walking for a given trip. I don't follow why you will only consider the GHG effect if it's a matter of necessity, rather than one of practice. Do you expect that most people choosing to walk will suddenly alter their diets to be more GHG-efficient at the same time?

washcycle> You're missing the point entirely. I'm not arguing that these should be included. I'm arguing that they're just as valid as including the food. And so, if you believe that the food should be counted, then why have you skipped all these other items?

I get that point entirely. You seem to be missing the point that the expected outcome of including additional factors makes cycling a less attractive mode from a GHG production standpoint. But i choose to include what i do because those are the numbers we have at hand. If you have additional numbers that you think move things in the other direction, as i say, feel free to cite them.

You could, for example, argue that even though the cyclist probably owns a car as well, the life of that car will be extended by use of the bicycle, and this may offset the GHG cost of producing the bike. As i say, there's been research on the matter; you could look it up. It might or might not help you defend your position.

I don't follow why you will only consider the GHG effect if it's a matter of necessity, rather than one of practice.

Because then it derives from a different action.

Do you expect that most people choosing to walk will suddenly alter their diets to be more GHG-efficient at the same time?

No. But it doesn't matter.

You seem to be missing the point that the expected outcome of including additional factors makes cycling a less attractive mode from a GHG production standpoint.

Actually, this IS my point. You're including additional factors that shouldn't be included and it makes cycling a less attractive mode from a GHG production standpoint.

But i choose to include what i do because those are the numbers we have at hand.

So does this mean that you think it would, in fact, be reasonable to include the cyclists share of the CO2 created by the military in the process of making free movement possible in the total CO2 that resulted from that cyclists choice to bike (and you don't include it only because you don't know what that share is)?

You seem to be missing the point that the expected outcome of including additional factors makes cycling a less attractive mode from a GHG production standpoint.

Not missing it, but it's irrelevant, since I'm not trying to make cycling more attractive in that respect. I'm trying to show that including these external items is silly.

antibozo> I don't follow why you will only consider the GHG effect if it's a matter of necessity, rather than one of practice.

washcycle> Because then it derives from a different action.

… which is a consequence of the first.

antibozo> Do you expect that most people choosing to walk will suddenly alter their diets to be more GHG-efficient at the same time?

washcycle> No. But it doesn't matter.

… because…?

washcycle> So does this mean that you think it would, in fact, be reasonable to include the cyclists share of the CO2 created by the military

Sure, if you think it is altered somehow by the choice of mode. I don't think it is.

I'm not sure where the bit about only bothering to factor in things that are actually altered by the mode choice is falling on the floor. The mode choice affects the traveler's energy requirement. In the case of cycling, it affects the need for additional gear. It may affect the traveler's available time for other things, assuming the car trip takes less time than the cycling trip, which is not always true. Other than those, i haven't seen you demonstrate that there are differences that should be accounted for. One additional difference you alluded to earlier might be that the cyclist might use trails that had lower production cost, but in fact it's hard for me to see that that use would have obviated the building of the road the car needs; it's really just an additional cost of cycling.

Sure, you can relegate all of these things to "silly" if that works for you. I think it's just putting the blinders on, and i don't see why it's necessary to do that; like i say, cycling may not be perfect but it's still pretty good all things considered. I'm going out for a spin right now, in fact.

because…

Because, it's a separate action.

Sure, if you think it is altered somehow by the choice of mode.

Why does it matter if it is "altered" by the choice of mode?

There is no "choice of mode" here. You're position is that biking and walking result in GHG emissions. That's it. That's not a comparative analysis. It just is or isn't true.

And so, again, do YOU think it is reasonable to deduce that cycling results in GHG emissions created by the military that supports freedom of movement? It's a yes or no question.

washcycle> Why does it matter if it is "altered" by the choice of mode?

Because if it isn't, it is common noise in both signal paths, and therefore doesn't need to be estimated. I'm sure you understand differential signaling. If we're comparing modes, there's no point in considering factors that are identical irrespective of mode.

I have more to say, but no time at the moment. Maybe later this week.

Play ifnromtaive for me, Mr. internet writer.

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