In parts of Montana, salt concentrations in soil water, have reached those double those of seawater.

Although native Africans domesticated some plants in the Sahel and in Ethiopia and in tropical West Africa, they acquired valuable domestic animals only later, from the north.

Take air quality in the United States today: It's about 30 percent better than it was 25 years ago, even though there are now more people driving more cars.

I've always been interested in a lot of things, and a lot of things at the same time, and I always tried to explain them to myself. I ask a lot of questions.

For anyone inclined to caricature environmental history as 'environmental determinism,' the contrasting histories of the Dominican Republic and Haiti provide a useful antidote. Yes, environmental problems do constrain human societies, but the societies' responses also make a difference.

Federal elections happen every two years in this country. Presidential elections every four years. And four years just isn't long enough to dismantle all the environmental laws we've got in this country.

Civilization originates in conquest abroad and repression at home.