After a day in the clean, clear air of the Front Range mountains, I returned yesterday afternoon to find Denver enveloped in a brown haze. Many western cities, including Denver, Phoenix, Salt Lake City and Los Angeles, are known for their "brown clouds;" located in valleys or basins and fully or partly hemmed in by higher terrain, these cities experience frequent inversions, where a layer of cold air, trapped beneath warmer air, fills with pollutants. The brown haze is primarily due to particulates, which are a special problem in the dry, dusty West.
In reality, the western "brown cloud" cities are just poster children for a worldwide dilemma. All major cities are prone to air pollution and the "developing" regions, where industry is outpacing technology (and will power), the problem is especially severe; the upcoming Olympics in Beijing will surely highlight this issue. Yet, all of us are polluters; if we drive a car, heat our home or use electricity, we are complicit in this threat to the global environment. And who pollutes more: the country resident who commutes forty miles per day in his SUV or the urbanite who takes a bus, subway or bicycle to work?
We humans are multiplying at an unsustainable rate. Having no natural predators other than microbes, parasites and other humans, we seem to be unable or unwilling to control our own exponential growth. Technology, designed to minimize our impact on the environment, will never eliminate the need for human population control.
