False piety

The trouble with church people, based on my limited experience, is that we generally don't know how to be good.  Our sense of the world is based on abstractions that are so far from empirical reality that when we try to do something "right", like for instance, buy a more fuel efficient car, we often end up doing more harm than good. 

As an example, I'm seeing more Priuses show up in church parking lots in KW than ever before, which leads me to suspect that something in the pious mindset of church-goers motivates them to purchase a fuel-efficient vehicle as an action that represents their commitment to Creation Care.  But because they don't know that the amount of carbon emissions that are produced in the manufacture of a car is about equivalent to its lifetime emissions from driving, they're unaware that it would probably be better for them to just keep driving their old car.  (UNESCO, date unknown)

  

There's a problem with the way knowledge viewed and used (or ignored) in the church.  While Christians are familiar with certain powerful concepts, such as loving one's neighbours and enemies, turning the other cheek, the log in your eye, and God, we have more or less lost, or de-emphasized, the importance of knowledge, which can even be found in our own tradition expressed in Bible passages like, "Go to the ant, thou sluggard" and Proverbs 2:1-5.

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As a final note, this argument is misleading for many reasons that someone with a graduate degree in Environmental Studies should be able to identify.  Its most obvious flaw that if driving your old car consumes X mmBTU over its lifetime, and making a new one consumes Y, then the comparison that needs to be made in order to answer the question "Will buying a new car have a lower energy impact than continuing to drive my old one?" is: Y vs. X*(proportion of lifetime remaining)=Z.  

If Z is lower, then it's better to keep driving your old car than to buy new.

For example, using AskPablo's numbers, if driving a car consumes roughly between 327 and 726 mmBTU over its lifetime, and making one consumes 113 mmBTU, and you expect your car to last another 3 years, then the calculation is (worst case scenario) 726*(years remaining/total years) = 726*(3/10) = 218 mmBTU.  So in that case, Z > Y so based on energy alone it would be better to buy new.  But that's based on the number for the Highlander SUV.  If your old car was a Corolla or Civic, consuming let's say 500 mmBTU over its life, you'd get Z = 150

Hm... let's ask the question differently.  Let's ask, is it better to drive my old car for one more year (think of that as the marginal environmental cost) or to buy new?  Then 726*(1/10) = 73, which is lower than buying new.  Therefore the energy used in driving your car for another year is lower than the energy of making a new vehicle.   

Darn... 

This is complex...choosing a valid metric is not trivial.  

And then there are so many other factors that go into converting this energy calculation into a comparison of carbon emissions, and more broadly into a measure of long-term societal benefit.  All I can say is, don't just ask Pablo.  Spend time in school and learn how to do your own proper research.