Back in December, I was passing some time in the San Francisco Airport, awaiting my flight home to Toronto, when I noticed a poster with the following message:
“Over the past 10 years, SFO has planted over 2,000 trees of more than 15 species around the Airport, resulting in annual sequestration of approximately 120 metric tons of carbon dioxide.”
Sounds impressive. But what do those numbers actually mean? I pulled out my phone to see what I could find out.
It turned out that my plane, a Boeing 737-400, emits 9.36 kilograms of carbon dioxide per kilometer. Toronto is 3632 kilometers from San Francisco. Doing the math, my flight home was about to emit 34 metric tons of carbon dioxide – over one quarter of what those 2000 trees were sequestering in an entire year. And that’s only one of the 450,000 flights that the SFO handled last year.