Friday, March 21, 2008

Walking Is NOT Carbon-Neutral and Zero Emission

A Prius is more energy efficient over its lifetime than a Hummer, right? Walking has to be much more environmentally-friendly than driving a car for a short trip, doesn't it? Well, as economist Steven Levitt points out, "When it comes to saving the environment, things are often not as simple as they seem at first blush." This CD post yesterday showed that driving a Toyota Echo is 5X more energy efficient as a Toyota Prius, and even a Hummer H3 might be better than a Prius over the lives of the vehicles.

Could it also be the case that driving a car is actually "more green" than walking? From NY Times science columninst John Tierney:

Chris Goodall, the author of “How to Live A Low-Carbon Life," is a member of the Green Party in Britain and a devout environmentalist. But he also questions how much good is being done by eliminating short trips by car. In fact, he says that in some circumstances it’s better to drive than to walk.

How can that be? Because Mr. Goodall takes into account something that a lot of environmentalists don’t: the human energy expended in averting fossil-fuel use. “Walking is not zero emission because we need food energy to move ourselves from place to place,” he writes. “Food production creates carbon emissions.”

If you walk 1.5 miles, Mr. Goodall calculates, and replace those calories by drinking about a cup of milk, the greenhouse emissions connected with that milk (like methane from the dairy farm and carbon dioxide from the delivery truck) are just about equal to the emissions from a typical car making the same trip. And if there were two of you making the trip, then the car would definitely be the more planet-friendly way to go.


Comment: Perhaps Native Energy and other groups that sell carbon offsets could add walking to their list of activities for which individuals can buy offsets?

26 Comments:

At 3/21/2008 8:42 AM, Anonymous Anonymous said...

"In fact, he says that in some circumstances it’s better to drive than to walk."

Well this is getting silly, but if you are going to factor in the food requirements for walking then we will also need to factor in the health costs of being a couch potato. These are quite high as has been recently documented in the JAMA. Walking is a very inexpensive way to get the needed exercise to prevent obesity and all its accompanying maladies.

 
At 3/21/2008 9:31 AM, Anonymous Is said...

I'm not sure what simply citing health costs has to do with assessing the carbon footprint impact. I agree it is less healthy for the person, but I fail to see how it relates to the argument as stated. This wasn't about assessing how healthy the people were. It was about assessing the health of the environment.

Instead, we need to look at the carbon impact of the health costs. If we all choose to drive cars instead of otherwise getting beneficial exercise (assuming one does not get it elsewhere), resultant health treatment (operating hospitals, running machines, medical professionals transportation to and from work, etc.) would increase carbon footprints.

I agree this is getting silly.

 
At 3/21/2008 9:40 AM, Blogger Chris said...

Can you remind me why are we discussing carbon footprints of everything in relationship to the environment? Can anybody post a link to a scientific proof that carbon emissions are affecting the climate?

 
At 3/21/2008 10:38 AM, Anonymous Is said...

Chris,

http://www.climatecrisis.net/

:)

 
At 3/21/2008 10:52 AM, Blogger Paul said...

Please. You can render down nearly any activity into a series of carefully selected data points to support nearly any stupid theory. While you can argue for the case that a glass of milk (what kind of milk, and from where?) is inferior from a carbon emissions perspective to a ride in the car (what kind of car? how many stops in between points? what kind of weather?), you can't argue on behalf of overall environmental impact.

Burning petroleum in a car has many other impacts on the environment, including air quality, road safety, and wear and tear costs on the vehicle and roads. That's just the local impacts - on a larger scale, the oil you burn has gone through a bevy of polluting steps, including the drilling, transportation and refining processes.

Suddenly, that glass of milk looks pretty good.

And why milk? That's an easy target - cows generate a massive quantity of methane, a potent greenhouse gas. Why not a few ounces of wheat, or chicken, or vegetables? What do food impacts from the thousands of other sources look like then?

This also requires you to ignore the benefits of walking, both tangible and intangible. But because even children know that exercise is good for you, let's skip that.

Finally, this thought process requires us to ignore the carbon cycle. ALL forms of life respire and create CO2 and other gases. In a normal, functioning system these gases are captured by other life forms and used, creating an endless loop of sequestering and releasing carbon. You may consider this obligate, unless you consider life on this planet optional. Burning hydrocarbons, however, are not obligate. We're taking carbon that was sequestered millions of years ago and reintroducing it to our atmosphere. We are, in essence, injecting carbon back into the atmosphere that has been out of the cycle for hundreds of millenia.

Anyway, I'm sure this was just an exercise in cherry picking data to further an agenda. But I figure, hey, I have a few minutes to interject with some common sense. So there ya go.

 
At 3/21/2008 11:32 AM, Anonymous Anonymous said...

Paul said...

Please. You can render down nearly any activity into a series of carefully selected data points to support nearly any stupid theory...

...Anyway, I'm sure this was just an exercise in cherry picking data to further an agenda.


Thank you Paul for a great observation.

 
At 3/21/2008 12:01 PM, Anonymous Anonymous said...

.........and let's not forget that time is money. Sure, I would love to get out some days and get the excercis but it would take me 20 to 25 minutes to walk one and a half miles. Not to mention I would need to get back home. So, I am trading a 10 minute round trip car drive for a 50 minute walk. With my schedule, it's not going to happen. Welcome to the real world.

 
At 3/21/2008 12:57 PM, Anonymous Anonymous said...

Excellent points, Paul,

Would also add that the argument is premised on the assumption that people consume more calories to replace the calories burned even when they are engaging in a very moderate form of exercise such as walking. In other words, the argument is based upon data that has not been introduced into evidence but merely assumed.

We are told that "experts" have found this to be the case but we have no way of verifying whether this statement is true or a mischaracterization.

The one argument that I disagree with in your post is the assertion of "cherry picking". All of us have identified different weaknesses in the original argument which I believe was the intention, namely, developing critical thinking.

I don't think that anyone who was cherry picking would pick such a flawed argument to support their position. The post would seem to be more useful in helping us to question what we read rather than accepting arguments based upon our perception of the trustworthiness of the speaker.

 
At 3/21/2008 1:42 PM, Anonymous fred said...

As an engineer (a branch of economics!) I understand life cycle costs. It is the way engineered products are sold to business.

"Anyway, I'm sure this was just an exercise in cherry picking data to further an agenda."

No irony here, eh? Normally, when something in the fridge turns green, it gets thrown out. When someone's brain turns green, we let them run loose doing things that seem green locally but, are in fact globally (or just somewhere else) destructive of the environment and peoples' lives.

 
At 3/21/2008 2:20 PM, Blogger Trevre said...

Proving global climate change is being caused by the emission of human generated green house gases is similar to proving a recession is being caused by bad economic policy. We look at economic indicators like unemployment, inflation rates, growth rates of certain sectors, tax rates, etc. We try and correlate these data in the past and attempt to apply it to our current economic indicators to try and predict what is actually happening to the economy.

Based on these factors we decide what the most "likely" causes are for our current economic situation (i.e. recession or boom (any one know the what we call the opposite of a recession?)). It is by no means an exact science but go with what seems likely from our past experience.

The same goes for looking at the what is happening to the global climate. I would argue the indicators here are much easier to measure than the indicators we use for the economy. Temperature for example is an indicator. Read what the temperature is at the same spot over a period of time, that is pretty hard to screw up. Measuring the ppm of greenhouse gases in the atmosphere, while slightly more advance is also not that difficult, and there is even lake sediments that date back ten thousand years that give us fairly accurate data about carbon concentration in the atmosphere. Again, this is not nearly as arbitrary as measuring unemployment or inflation.

Just like in economics we create correlations for climate change. Surface temperatures were on average cooler 100 years ago than they are now by about 0.5 degrees C and it is in direct correlation with an increase in greenhouse gases which have increased 100 ppm or 30% over that same time period. Temperature anomalies (variations in specific locations) have also varied more heavily in the last 100 years. another correlation indicating the climate is changing. There are not a lot of other factors that could cause the temperature changes we see (at least that we know about yet) so it is reasonable to think that it is due to a rise in green house gases.

The same way you wouldn't toss all your money into the stock market if you knew it was going into a recession, you wouldn't continue to add to the green house gases knowing the climate is changing because of it.

Now you can argue that climate change isn't bad, but that is an uphill battle. Our local infrastructures are build on local climate and cannot change quickly without high costs.

You can argue whether it is better to walk or drive.

But only the inevitably bankrupted would argue that climate change is not occurring and that it is not going to affect us.

Figures are easy to find with this kind of data.
Based on these factors we decide what the most "likely" causes are for our current economic situation (i.e. recession or boom(any one know the what we call the opposite of a recession?)). It is by no means an exact science but go with what seems likely from our past experience.

The same goes for looking at the what is happening to the global climate. I would argue the indicators here are much easier to measure than the indicators we use for the economy. Temperature for example is an indicator. Read what the temperature is at the same spot over a period of time, that is pretty hard to screw up. Measuring the ppm of greenhouse gases in the atmosphere, while slightly more advance is also not that difficult, and there is even lake sediments that date back ten thousand years that give us fairly accurate data about carbon concentration in the atmosphere. Again not nearly as arbitrary as measuring unemployment or inflation.

Just like in economics we create correlations for climate change. Surface temperatures were on average cooler 100 years ago than they are now by about 0.5 degrees C and it is in direct correlation with an increase in greenhouse gases which have increased 100 ppm or 30% over that same time period. Temperature anomolies (variations in specific locations) have also varied more heavily in the last 100 years. another correlation indicating the climate is changing. There are not a lot of other factors that could cause the temperature changes we see (at least that we know about yet) so it is reasonable to think that it is due to a rise in green house gases.

The same way you wouldn't toss all your money into the stock market if you knew it was going into a recession, you wouldn't continue to add to the green house gases knowing the climate is changing because of it.

Now you can argue that climate change isn't bad, but that is an uphill battle. Our local infrastructions are build on local climate and cannot change quickly without high costs.

You can argue whether it is better to walk or drive.

But only the enevitably bankruped would argue that climate change is not occuring and that it is not going to affect us.

 
At 3/21/2008 3:04 PM, Anonymous Anonymous said...

Trevre,

Climate monitoring is scarcely a simple matter of watching the mercury go up & down. Climatology is if anything more complicated than the subject of economics rather than less.

If it is as easy as you assert, then how is it that the NASA weather service made a mistake in their assessment of the warmest year of the 20th century? How is it that the NASA weather service recently had to issue a correction acknowledging that the warmest year was not 1990 but back in the 1930s?

Like most subjects complex subjects, we are still learning. The most recent IPCC scientific report, for example, disclosed that increased intensity of tropical storms that had been predicted in the previous report had been disproved by the actual results patterns experienced.

Scientific knowledge is advanced by questioning theories and trying to find patterns that are not explained by existing models.

"A foolish consistency is the hobgoblin of little minds"

 
At 3/21/2008 3:19 PM, Blogger Paul said...


"Anyway, I'm sure this was just an exercise in cherry picking data to further an agenda."

No irony here, eh? Normally, when something in the fridge turns green, it gets thrown out. When someone's brain turns green, we let them run loose doing things that seem green locally but, are in fact globally (or just somewhere else) destructive of the environment and peoples' lives.


Fred, I'm not an engineer - maybe that's why I don't understand your comment. I get that it's a metaphor about how 'green' thinking is destroying the global environment (also: wtf?), but I don't get how that relates to my comment. Could you point out where my comment is factually incorrect or off base, or at the very least where the irony is?

Thanks.

Anon: I'm willing to go along with your assumption that the article was written in good faith, and was intended to stimulate critical thinking (not as a way to poison a genuine conversation about personal impacts). Works for me.

 
At 3/21/2008 3:47 PM, Blogger Trevre said...

Anonymous,

I beg to differ. I never stated that it would gauging climate change was easy, just that it is a lot easier than gauging economics. Yes I am sure there are all sorts of mistakes in the data taken, and if you want to waste good blogging time bringing up specific examples of incorrect data that is fine. I would however put my weight on the widely held belief by climate scientists that most of the temperature and green house gas data is fairly straight forward and mostly accurate. When the hottest year was doesn't change anything I said(since I was talking about average temperatures), and I didn't say anything about tropical storm intensity predictions which involve a much higher uncertainty than trying to determine if the earth's average temperature is or is not changing and why.

I will take you debate, but you must bring something more to the table than two examples of data errors. How about you show me the graph of data that shows me average temperature is not changing over the last 100 years?

Oh wait, no one has that graph.

I am not saying we should walk everywhere instead of drive. But we can't not accept the predictions because we are afraid someone will make bad policy decisions based on them.

 
At 3/21/2008 5:38 PM, Anonymous Anonymous said...

Paul,

Thinking further of your argument regarding the carbon cycle being closed whereas burning of fossil fuels released carbon dioxide that has been sequestered. Don't major volcanic eruptions and massive forest fires do the same thing causing the rapid release of millions of tons of carbon dioxide into the atmosphere?

Trevre,

It is very clear that average global temperatures have risen in the past 100 years. On that point, you and I and the international scientific community agree.

What is far less clear is the extent to which this warming is due to "green house gases" or the natural warming factors such as increased cloud cover. The predictions being made are largely based upon computer modeling in the absense of data.

One of the most controversial pieces of evidence which was taken as a smoking gun was the hockey stick graph of Dr. Michael Mann. 2Canadians have proven that Dr. Mann's algorithms tended to produce hockey shaped graphs even with random data. The presentation of this graph in the IPCC report is what lead to the Kyoto protocol.

Where the temperature graph in previous IPCC report indicated that the medieval warming period was warmer than today, Dr. Mann's graph virtually eliminated the medieval warming period.

There is a great deal that we still do not know. There is very little historical data tracking ice thicknesses for example. There is no mapping of the ocean floor under the polar ice cap including the volcanic ridge. There is in fact very little data on ocean temperatures and no data of ocean temperatures under the polar ice cap.

With a molecular structure as simple as CO2, we are in fact talking about a substance which is very difficult to eliminate.

Is it a good thing that we are trying to limit the number of trips we make by car, insulate our houses or shop with canvas bags. Sure. Perhaps, we will eventually think cars are now uncool like the the majority of young people in Japan (only 27% want a car).

As a boomer, I have recently become more aware of the legacy of the 1960's. The environmental movement began to use mass media manipulation and political pressure tactics to achieve their objectives. This radicalization has meant the abandonment of science in favor of emotion and the politics of fear dividing the conservation movement between conservationists and environmental activists.

When one sees an issue being driven by hype, populism, hysteria and attacks on anyone who dare to ask questions or present alternatives to the orthodoxy, it doesn't look much like science at work. It looks a lot more like a cascade which very often results in disasterous public policy.

 
At 3/21/2008 9:34 PM, Anonymous Anonymous said...

Anon 5:38 said...

When one sees an issue being driven by hype, populism, hysteria and attacks on anyone who dare to ask questions or present alternatives to the orthodoxy, it doesn't look much like science at work. It looks a lot more like a cascade which very often results in disasterous public policy.

That just about sums up the Bush administration.

 
At 3/21/2008 10:14 PM, Anonymous Anonymous said...

Quite frankly, I fail to see what the Bush administration has to do with this or any other the subject. After all, they will be gone in Nov. Good news for all those suffering from Kreutzfelt Jakob Syndrome Cheney-Bush variant to use Charles Krauthammer's vernacular.

We're a long way from the proposition that walking to the store has a greater carbon footprint than driving your car to the store. Digressing to the original question for a moment...Is there anyone who actually finds this argument holds water?

From the posts above, it would appear that most of us think this argument is fallacious.

 
At 3/22/2008 8:08 AM, Blogger DADvocate said...

I wonder how bicycling compares. For many years, I've read bicycling is the most efficient form of transportation of all. I used to ride a lot for fun and practical purposes but now heavy auto traffic where I live makes it too dangerous.

 
At 3/22/2008 9:46 AM, Anonymous Anonymous said...

"That just about sums up the Bush administration"

Precisely. It's politics at work.

 
At 3/22/2008 1:49 PM, Blogger juandos said...

"Can anybody post a link to a scientific proof that carbon emissions are affecting the climate?"...

Sure...

'Global Warming': An Official PseudoScience ...

"ALL forms of life respire and create CO2 and other gases"...

So if Al Gore and his like minded ilk all commit suicide will that show up as a massive decrease greenhouse gases?

Then again according to real scientists (Australian kind) the earth has been cooling...

Then again American scientists have been saying that for quite some time now...

 
At 3/22/2008 3:34 PM, Blogger Paul said...

Anon,

That's entirely true - the system is only 'closed' if you don't consider catastrophic impacts.

Massive forest fires eject a tremendous quantity of CO2, but it's all relative. Consider this report on four large California wildfires; the total CO2 output of the burn: about ten million tons. Now consider the CO2 output of the US from fossil fuels in 1998: 3.6 billion tons. (source). The burning of about 144,000 acres of forest emitted about 1/400 the carbon dioxide of our total fossil fuel emissions. If you want some perspective, there are 745 million acres of forest in the US. We would have to burn 8% of ALL of our forests every single year to match our fossil fuel outputs. At that rate, every single tree in the US would have burned within 13 years.

Numbers aside (and the numbers are way more complicated than above), forests are replaced with forests. The carbon lost to the burn is sequestered, in time, by other trees. Fossil fuels are replaced by nothing.

I don't mean to diminish forest fires as a source of greenhouse gases - decades of mismanagement have left many of our forests in a sad state, and the fires contribute more every year to our total GHG output. Unfortunately, forest fires are a positive feedback of climate change, and we can expect to see those numbers grow in coming years.

Volcanoes do erupt, and while they emit a lot of CO2, their net effect is a cooling of the planet. Volcanoes also put out vast quantities of light-reflecting sulfates. These sulfates increase the atmosphere's albedo, preventing sunlight from even entering the earth's lower atmosphere.

 
At 3/22/2008 4:32 PM, Anonymous Anonymous said...

Juandos,

Even dying releases carbon although one must balance the reduced levels of hot air of Mr. Gore in one's calculations.

Paul,

With regard to carbon dioxide, how are these estimates actually derived. How does one actually measure the weight of a gas? Have you looked at the algorithms involved? One must start from real data and extrapolate. Isn't there a very large opportunity for inaccuracy particularly where release of carbon dioxide in the past would at best be a guestimate?

Not to put too fine a point on it but we have seen two supposedly credible sources of information namely Dr. Michael Mann, climatologist and the NASA weather service create complex algorithms containing errors that have skewed the data. Estimated rises in sea level are another area that seem to vary wildly in these projections: 17 inches (source IPCC) to 40 feet (Al Gore).

One area that has received little media attention is the subject of cloud cover and water vapour. We know that water vapour comprises a higher percentage of GHGs than carbon dioxide. A long term cloud cover study carried out in Europe found that atmospheric cloud cover has increased.

Trevre,

Could you please name another branch of science where our knowledge is complete; No further research needed.

The only example that I can think of comes from the ancient philosopher, Aristotle whose theories stood for centuries as established doctrine.

The lesson of the 1960's was that a small group of citizens could gain their objectives not by running for election and engaging in a debate of ideas, but by saturated the media and galvanizing public outrage so that a small group could leverage its influence over public policy. The tactic set up an extra-political system (ie. outside the normal elected political process) to target politicians on single issues.

Part of the strength of the political process is that candidates' programs are heavily scrutinized. At no time, is this more on display that during primary season.

 
At 3/22/2008 4:56 PM, Blogger David said...

The walking-vs-driving analysis may be correct, but the Hummer-vs-Prius analysis is suspect. I don't see how the $3.25/mile energy cost for the Prius could possibly be true. That would imply $325,000 for energy alone over a 100K-mile life of the car. Paid for by whom? The owner won't pay anywhere near that much. Toyota subsidizes the Prius, but by maybe a couple of thousand $, not by hundreds of thousands. And the suppliers of parts & subassemblies, and the sellers of energy to them, certainly aren't subsidizing anything.

 
At 3/23/2008 6:25 PM, Anonymous Anonymous said...

David,

Think that what is being used is the hefty cost of the battery in the Prius that is being added to the cost of gas.

From the standpoint of payback on the cost of the hybrid technology in gas savings, have read from several sources that the premium paid for the technology Prius is not paid back over the life of the asset in energy savings. One is paying for a very expensive vehicle for the privilege of green bragging rights.

 
At 3/24/2008 12:09 PM, Blogger Paul said...

I'm not sure anyone is active on this thread anymore, but I'll throw a response out there for posterity.

Anon,

Determining the weight (more precisely, the mass) of CO2 from a combustion event is pretty straightforward when dealing with fossil fuels. Determine how much carbon is in the source material, then add two oxygen atoms. It basically triples the mass of the carbon. Fossil fuels also contain hydrogen (hence the term, hydrocarbons), but hydrogen is extremely low mass and represents a tiny fraction of the combustible material's overall mass.

If you want the algorithm, it's simple chemistry: C8H18 + O2 -> 8CO2 + 9H2O.

Obviously estimates will have a degree of wiggle room, but it's a fairly straightforward task determining the average mass of, say, wood in an acre and going from there. And for fossil fuels it's even easier - nearly every barrel of oil and every train load of coal is accounted for in our system.

I can't speak to the research of other scientists, but I do hope that if they're right they get attention they deserve. It's common to feel that these 'rogue' scientists are being shunned by the community at large, but that's pretty common for research that runs counter to established research conclusions. Taking that risk sometimes pays off in a big way, and I do hope that people continue to take risks in the search of empirical truths.

Finally, as to the role of water vapor, I'll defer to this link. You may have other questions answered at the index URL. I'm not a climatologist and do not understand climate well enough to answer any of your questions directly.

David,

You're pointing to one of the, um, intriguing choices made in the study. What's being indicated is the added cost of the R&D to perfect a mass produced hybrid drive. The Hummer, in contrast, runs on a technology that's been amortized over several billion cars this past century.

 
At 3/24/2008 10:44 PM, Anonymous Anonymous said...

Paul,

Thanks for the information & links.

Some interesting stuff although the second link with instructions on how to argue with skeptic seems short on scientific data and long on rhetoric. The kind of Q&A that one would imagine being directed to non-scientists rather than climatologists.

http://www.telegraph.co.uk/news/graphics/2006/11/05/warm-refs.pdf

You might be interested in the above document by Lord Moncton further to a series of written articles debating climate change with Al Gore which was published in the Sunday Telegraph. (Document is entitled Apocalypse Cancelled in case you have trouble with the above link).

It's been an interesting link. Have enjoyed our discussion. Look forward to discussing other ideas with you.:)

 
At 6/28/2008 11:41 PM, Blogger veganmatty said...

I assume this very well could be true, and thus would be shocking. I'll try to find the study, or I would like to see a large legit scientific study done on this.

As the United Nations admits, what we eat has the biggest impact on the environment - for the planet, eat low on the food chain, go vegetarian and eat as little animal products as possible (or none). -Matt

 

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