Have you ever wondered which mode of transportation emits more carbon into the atmosphere: flying or driving? Here's a closer look at the implications of each. (Photo: BBC Science Focus)

Flying  

A round-trip flight for one person between San Francisco International Airport (SFO) and London Heathrow (LHR) on a full Boeing 737 emits approximately 3.5 tons of CO2 in economy class and about 5.2 tons in business class, according to MyClimate.org.

Driving  

For driving, a good metric for CO2 emissions is 20 pounds of CO2 per gallon of gas burned. While the chemical emission is about 10% less, it’s approximately 30% more when considering the entire process from oil extraction to delivery at the gas station. Thus, to emit 3.5 tons (7000 pounds) of CO2 by driving would require burning 350 gallons of gas. If a car gets 30 miles per gallon, that's 10,500 miles—about twice the distance from San Francisco to London. Therefore, flying can be up to twice as efficient per mile as driving in terms of CO2 emissions.

Context and Implications

This comparison does not favor either mode of transportation. To limit global temperature rise to 2°C, we need a rapid reduction in emissions. Unfortunately, the likelihood of achieving this appears slim. Consequently, climate change might self-regulate emissions by negatively impacting GDP through increasing disasters and catastrophes. A temperature rise of 3-5°C could trigger such economic downturns.

A recent study suggests that the economic damages from climate change are six times greater than previously estimated, with each 1°C rise in temperature potentially reducing global GDP by 12%. The study and a co-author's description can be found here (link). The paper, titled "The Macroeconomic Impact of Climate Change: Global vs. Local Temperature," argues that the Social Cost of Carbon should be set at approximately $1,056 per ton of CO2, significantly higher than the current $40 per ton under California’s Cap-and-Trade laws.

*Note:* The term "social cost of carbon" actually refers to the social cost of CO2, representing the economic damage caused by an additional ton of atmospheric CO2. Chemically, one ton of carbon produces about 3.67 tons of CO2 when combined with oxygen. This detail is often overlooked but is crucial for understanding the true impact.

Our results imply a Social Cost of Carbon of $1,056 per ton of carbon dioxide. This clarification ensures accurate communication of the economic damages associated with CO2 emissions.