Yes, global warming is a big deal and a big challenge. But sometimes I get so frustrated by conservation and environmental NGO’s for not being able to chew gum and walk at the same time — in other words, for failing to appreciate the real lesson of greenhouse gas emissions.

The real lesson is there is no such thing as succeeding at local conservation (and no such thing as protecting your backyard or local community’s natural heritage) without paying attention to global pollution as a whole – of which greenhouse gases are but a few of many.

The National Academy of Sciences has just released a study of global sources of local pollution that is revealing and compelling in its analysis of the long-range transport of pollutants into and out of the United States.

Do you know what’s landing in your backyard? Try ozone, particulate matter, mercury and persistent organic pollutants that have all traveled halfway around the globe from Asia and North Africa, according to the study.

We also give what we receive — the pollution we produce travels to Europe and Canada. There i