Guess what? Cows are now a larger source of pollution than cars in Californias central valley, which still have a significant smog problem. So says a terrific story in todays Los Angeles Times, by Miguel Bustillo, one of the better environmental beat reporters in the country.
Once again, we see another vindication of Ronald Reagans much ridiculed view that there were lots of natural (or non-human) sources of smog. About 15 years ago the LA smog regulators did a study of emissions from trees, and concluded that they might not be able to meet the Clean Air Act targets for the LA basin unless they began to regulate . . . landscaping. The LA Times reported this quite well; It turned out that Japanese trees were lower-emitting trees than native American trees. The head of Tree People, a local tree-planting group, told the Times that they were very concerned, but would be sure to make sure that their members "planted low-emitting trees." Evelyn Waugh could hardly have written better satire.