Many of us have seen media coverage of earth’s atmosphere now exceeding 400 parts per million of carbon dioxide, a level not seen during the entire period of human civilisation. And many of us are anxiously waiting for President Obama’s long-delayed decision to approve, or block, construction of the Keystone XL pipeline. Indications are that he will approve it, to the dismay of those who accept overwhelming scientific evidence that our climate is at a dangerous tipping point. And disappointing those who, like me, had high hopes of action to stop climate change.
If the pipeline is approved, are there any alternatives? Here is a quick, back-of-the-envelope calculation that points to one possible way forward. According to ThinkProgress.org, the pipeline will carry and emit 181 million metric tonnes of carbon dioxide. And, according to the US Environmental Protection Agency, the average passenger vehicle in the US emits 5.1 metric tonnes per year, at an average fuel efficiency of 21 mpg.
My simple calculation, perhaps overly simplified, shows that an increase of 1 mpg across the US passenger vehicle fleet would save about 76 million metric tonnes of carbon dioxide. Does that mean that mandating an overall fuel-efficiency increase of 2.4 mpg would more than compensate for the carbon dioxide associated with the Keystone XL pipeline?
If I’m right, then an interesting tradeoff might be possible. Check my math, and comments welcome!