Almost from the outset, 2021 has been a big year for electric vehicles. In January, General Motors said it aims to sell only zero-emission light-duty cars and trucks by 2035. Ford unveiled the electric version of its F-150 pickup truck, a member of the best-selling series of trucks in the country. Honda declared a target of all-electric vehicle sales in North America by 2040. With the transportation sector accounting for the largest share of greenhouse gas emissions in the U.S., EVs are widely seen as part of the answer to the climate crisis. Research makes it clear that warming will continue in coming decades even if the world adopts stringent mitigation measures, but the severity of that warming depends on greenhouse gas emissions.