"Population pressures are overwhelming the Portland region's ability to absorb the influx of new people, fueling congestion and rises in land and housing prices," the ecological research group Environmental Tipping Points concluded in an analysis. "Portland's growth rate is twice the national average. With these challenges ahead, it remains to be seen whether this growth will threaten the very assets that Portland's progressive land-use planning policies have managed to protect so far."
But recent US history suggests there are reasons for hope.
It's no coincidence, for example, that the modern environmental movement began about the same time that US population ticked past the 200 million mark 39 years ago.
Stanford University professor Paul Ehrlich's controversial book "The Population Bomb" had predicted that humanity's numbers around the globe would overwhelm natural resources, especially food production, in a Malthusian catastrophe.
Things haven't turned out that badly, given the dire signs of distress in that era.
It was a time when "our nation awoke to the health and environmental impacts of rampant and highly visible pollution – rivers so contaminated that they caught on fire, entire towns built upon sites so toxic that the only recourse was to abandon them," recalled Environmental Protection Agency Administrator Steve Johnson in a May speech.
He was commemorating the 35th anniversary of the EPA by pointing to the Cuyahoga River in Ohio and Love Canal near Buffalo, N.Y. He might have mentioned that the bald eagle – the nation's symbol – was headed toward extinction as well.
"But looking back, we see much to celebrate," Mr. Johnson added. "Our air is cleaner, our water is purer, and our land is better protected."
Generally speaking, that's true thanks largely to such groundbreaking federal laws as the Clean Water Act, the Clean Air Act, the Endangered Species Act, the Safe Drinking Water Act, and the Toxic Substances Control Act. Bipartisan coalitions on Capitol Hill and presidents of both parties enacted those statutes. Making them work, to the extent that they have, has involved full-time activists, grass-roots efforts at the community level, and courts of law.