No presidential debate has ever provided much succor for environmentalists, but last night’s was literally devoid of any mention of environmental issues, save one:  In a discussion of Bush’s tendency to be “certain but wrong,” Kerry wedged “global warming” into a list of subjects about which the president is ignoring facts.

What’s significant is not just that green issues were passed over, but that they were passed over in a debate focused on foreign policy.  In the U.S., environmentalism is still considered a matter of domestic politics, a “special interest.”  It is frequently portrayed as a lifestyle quirk, a preoccupation of the leisure class — as when Dick Cheney notoriously dismissed energy conservation as a “sign of personal virtue.”

But in years to come, environmental problems will likely manifest primarily as foreign policy issues.  Sir David King, Tony Blair’s chief science advisor, got an avalanche of press recently for baldly asserting that climate change is a greater danger to the world than terrorism.  

It was an artless way of making a perfectly legitimate point.Our emissions are connected to climate change: droughts, floods, and violent storms. Climate change is connected to means of subsistence: agriculture, fishing, tourism, and energy production.  Means of subsistence are connected to upheaval:  starvation, disease, population displacement, and armed conflict.  The knee bone’s connected to the hip bone.  The hip bone’s connected to the thigh bone.  We’re all stuck on the same planet.

The U.S. is blessed to occupy a large swath of temperate, fertile land, separated by oceans and immense wealth from much of the rest of the world.  We will be sheltered from the harshest effects of climate change, toxic pollution, water shortage, viral infection, and energy scarcity for some time.

Nevertheless, there are many large, densely populated places on earth suffering those effects now, with a severity and frequency that will only increase.  Even should it choose to remain morally insensate in the face of large-scale disruptions in other countries, the U.S. will not remain unaffected.  World’s greatest superpower or not, America faces a massive trade deficit with China, where an energy crisis looms.  It relies precariously on oil from the Middle East, where water wars loom.  It is vulnerable to an outbreak of disease from Africa, where famine and civil war are already underway.  No country is an island.  Except, you know, Japan.

These issues are the stuff of foreign policy, and it bodes ill that a presidential debate should pass without their serious consideration.