Population policies and car-based gas emissions

Re “U.S. Emits Half of Car-Caused Greenhouse Gas, Study Says,” June 28

This article describes a study by the “environmental group” Environmental Defense. Although the size of the U.S. population is growing rapidly -- adding the equivalent of a new California every decade -- to the best of my knowledge Environmental Defense has no U.S. population policy. I guess this group believes that all these cars just drive themselves.

BEN ZUCKERMAN

UCLA Professor of

Physics and Astronomy

Westwood

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In the article about the U.S. car fleet and greenhouse gases, we read that Rep. Henry Waxman (D-Los Angeles) has proposed legislation “that would freeze allowable levels of greenhouse gas emissions in 2010, reduce them by 2% each year through 2020, then reduce them further by 5% annually through 2050.” Waxman, his Democratic colleagues, the Senate and the president, meanwhile, have supported “immigration reform” that would result in tens of millions of new drivers. Perhaps Waxman can explain to us: How can we achieve greenhouse gas reductions while allowing immigration rates to drive our population to ever larger, unsustainable numbers?

TIM AARONSON

El Cerrito, Calif.