Global EV sales are steadily increasing with help from regulators, but that won't matter if existing gasoline and diesel vehicles aren't retired quickly, new research argues.

"The slow speed of fleet turnover presents a substantial barrier to deep decarbonization," researchers state in a new book on energy transition (via Axios).

Researchers compared emissions policies, like the United Kingdom's plan to end sales of new gasoline and diesel cars in 2030, with average vehicle lifespans. They found significant "turnover lag" between the start of new regulations and the retirement of internal-combustion vehicles. 

So achieving emissions reductions significant enough to limit climate change will require "both rapidly phasing out emitting vehicle sales and significantly accelerating fleet turnover," Emil Dimanchev, one of the book's authors, explained in a Twitter thread detailing the thesis.

To limit global warming to 1.5 degrees Celsius—a goal in line with the Paris Climate Accord—sales of internal-combustion vehicles would have to start phasing out in 2025, but the lifespan of those vehicles would also have to be reduced from 16 years (the current average in the United States) to nine years, Dimanchev argues.

This reiterates that, because of slow fleet turnover rates, the shift to EVs will take awhile without policy intervention. It also raises lots of questions.

Cash for Clunkers tradeins: Mercury Sable and Toyota Camry

Cash for Clunkers tradeins: Mercury Sable and Toyota Camry


Should automakers give their current gasoline and diesel cars shorter lifespans, ensuring they don't last beyond an anticipated transition to EVs? While that ensures the fleet will turn over more quickly, it also implies a lot of waste. It would almost be a throwback to the heyday of auto industry planned obsolesce in the 1950s, when consumers were encouraged to trade in their cars annually in line with styling changes.

This also begs the question of whether incentives should focus on retiring internal-combustion vehicles rather than buying new EVs. It wouldn't be unprecedented; 2009's "Cash for Clunkers" program forced the retirement of older cars built to less-strict emissions rules.

A new program specifically targeting gasoline "superusers" might be a good place to start. California has had a "gross polluter" retirement program, which perhaps could be retooled and expanded. The state wants to end sales of new internal-combustion vehicles by 2035. Should existing gasoline cars be coaxed into retirement before that?