Some of the first emissions regulations in the world came about because of the way the Los Angeles Basin is shaped.

Reports of smog in southern California started with the Conquistadors, and by the Sixties, LA was notorious for its foul air. California began regulating auto emissions before the U.S. Environmental Protection Agency even existed, and motor vehicles have been a focus of emissions laws ever since.

So-called criteria pollutants (carbon monoxide, hydrocarbons, and nitrous oxides) have been reduced by more than 90 percent since 1970. Vehicle emissions of greenhouse gases, primarily carbon dioxide (CO2), are inversely proportional to gas mileage: The higher the mileage, the lower the CO2 output.

2010 Toyota Prius ad comparing its emissions to those of a sheep

2010 Toyota Prius ad comparing its emissions to those of a sheep

With fuel economy levels set to rise to 34 mpg by 2016, and total U.S. vehicle miles traveled flat or increasing just slightly, many environmental analysts believe greenhouse gas emissions from vehicles may actually decline over the coming decade.

But there's another segment of industry that emits massive amounts of carbon as well, and does so completely and totally unregulated.

It's food production and, more specifically, the highly carbon-intensive business of raising animals for meat. According to the EPA, fully 20 percent of methane emissions in the U.S. come from livestock.

The whole transportation sector--including personal vehicles, long-haul trucks, buses, trains, and airplanes--accounts for roughly 30 percent.

Yet no one has ever proposed putting catalytic converters on the backsides of sheep.

As the ad above, from Toyota's ad agency in Israel, neatly points out.

But then, almost any other country in the world has more adventurous, humorous, or socially relevant auto ads than in the U.S.

Just consider another famous Toyota ad, this one for Australian TV, known only as "Bugger." It highlights the company's newly powerful pickup truck, using only a single word.

Watch it and weep. Then consider giving up that sheep.

[Copyranter via Jalopnik via Autoblog Green]