The Pentagon, the CIA, and a host of other national security experts are concerned about climate change too.There are times in life when you're best off playing the game on the other guy's court. Say, for instance, you're at a Memorial Day family barbecue, locked in a conversation with your uncle, and the subject jumps to climate change, which he dismisses as an overblown hoax. Or you're watching hoops at the bar with a buddy who served two tours in Iraq and some flowery Prius ad flashes across the screen, prompting a jibe about smug treehugging yuppies. Don't panic. This is your chance to take this climate change and clean energy discussion onto their turf.Because there's a boatload of bulletproof evidence that global warming and our stubborn dependence on fossil fuels-particularly oil-represent a couple of the gravest threats to our national security right here in the United States. This is not, for the sake of this conversation, an environmental issue to be fretted over by effete, knuckle-knawing, liberal arts-educated, coastal types. Rather, it's a security issue, and you're going to be talking about war and intelligence and the military and terrorism. (And, by the way, here's what not to mention: Al Gore, polar bears, Europe, and any celebrity or politician who didn't play a Terminator.)You can make these arguments because the Pentagon, the CIA, and a veritable cavalcade of other national security experts have already made them for you.There has been a flood of studies released over the past couple of years that tie global warming to global instability. Perhaps none has been as influential as the series of reports by the Military Advisory Board of the Center for Naval Analysis, a Pentagon-funded think tank serving U.S. defense agencies. The panel of 12 distinguished retired generals and admirals-including Marine General Anthony Zinni, the former head of U.S. Central Command-are far from environmentalists, some have said they came into the process as skeptics. But no more. Said Sherri Goodman, who chaired the board, "It's now a mainstream security issue, not a fringe movement for tree-huggers and Birkenstock wearers." Gen. Zinni put it even more bluntly: "We will pay for this one way or another. We will pay to reduce greenhouse gas emissions today, and we'll have to take an economic hit of some kind. Or we will pay the price later in military terms. And that will involve human lives. There will be a human toll."Back in April 2007, the CNA's first report, "National Security and the Threat of Climate Change" report (pdf), found that "climate change can act as a threat multiplier for instability in some of the most volatile regions of the world" by "seriously [exacerbating] already marginal living standards in many Asian, African, and Middle Eastern nations, causing widespread political instability and the likelihood of failed states." And that was just the military community's first take. Ever since, the risks have been amplified and the threats honed.The Center for Strategic and International Studies and the Center for a New American Security boiled down the security implications to a handful of key points in their "The Age of Consequences" report (pdf), which warned of:• heightened internal and cross-border tensions caused by large-scale migrations;• conflict sparked by resource scarcity, particularly in the weak and failing states of Africa;• increased disease proliferation, which will have economic consequences;• some geopolitical reordering as nations adjust to shifts in resources and prevalence of disease.The first-ever National Intelligence Assessment of climate change (pdf), completed by the National Intelligence Council, found much of the same.One of the authors of "The Age of Consequences" was Jim Woolsey, a former director of the CIA who has served under two Republican and one Democratic presidents, and advised Senator John McCain on energy issues during his campaign. These days, Woolsey is jazzing up talks about climate and security with some role-playing, during which he channels the spirits of environmental forefather John Muir and General George S. Patton, legendary commander of the Third Army. The two men, as imagined by Woolsey, begin with far different concerns-Muir worries about climate change while Patton storms on about terrorists. The two ghosts are surprised to find such overlap in the problems and in the common solutions-solar panels, plug-in hybrids, and so on. (In a novel twist, it's Woolsey's Muir that leaves nuclear power on the table, and his Patton who takes it off for threat of proliferation.)The terrorism link might seem at first like something of a leap, but Admiral T. Joseph Lopez, the retired top NATO commander in Bosnia, begs to differ. "Climate change will provide the conditions that will extend the war on terror," Admiral Lopez warned in the first CNA report. "You have very real changes in natural systems that are most likely to happen in regions of the world that are already fertile ground for extremism...More poverty, more forced migrations, higher unemployment. Those conditions are ripe for extremists and terrorists."Consider Egypt. The Nile Delta is the most fertile around, but arable land is disappearing. Mass migrations are already underway. Or Somalia, which we already worry about as a breeding ground for terrorism. How would the starving, displaced masses-who are now enduring the worst drought in a decade-react if they felt that rich Westerners were worsening their plight with our lavish lifestyles and enormous carbon footprints? That's certainly the message Osama Bin Laden sent back in his late 2007 video message, when he singled out global warming as the "greatest of plagues and most dangerous of threats to the lives of humans" that America is inflicting on the Muslim world.Or consider Bangladesh. Millions of poor, desperate Muslims will be permanently displaced. Now Bangladeshi Muslims have long been moderate and peaceful-the antithesis of Islamic extremists. But after losing their homes and struggling to survive, with no place to go and nothing to lose, will they stay moderate and peaceful when given someone to blame?General Zinni doubts it. "These places are Petri dishes for extremism and for terrorist networks." That's why the Pentagon and various other wings of the American defense infrastructure have been devoting so much attention to climate change over the past two or three years. Even while the Bush administration denied the scientific reality, the military was getting serious about transitioning to cleaner energy operations, and to start figuring out exactly what a warming world will mean to our own security here in America and around the globe. It's clear from their early findings that climate change isn't just a national security issue, but that it will be one of the most urgent national security issues of this century.