It’s a wonder I continue to show up at Society of Environmental Journalists conferences when you consider how much of a downer some of these panels can be. And that’s doubly true about the ones on climate change. This afternoon’s session on global warming as a national security issue was an even darker affair than usual.

Leading off was retired Navy Vice Admiral Dennis McGinn, who’s involved with a group of former generals and admirals known as the CNA Military Advisory Board: “What we’re saying very clearly and very directly is ‘This is a national security problem. … Make no mistake, this is going to affect everybody in the world.'”

He continued: “Climate change is going to be a threat multiplier in unstable regions across the world.”

Think about it: If you’re in, say, Bangladesh and the ocean’s rising and you can’t grow food, where will you go? You might well try to get into India. The Indians don’t want that, so you have a massive conflict there on the border.

It gets grimmer. Dennis Dimick, an erudite National Geographic editor who has steeped himself in the climate issue, noted that recent studies show it has been 15 million years since there was this much carbon in the atmosphere. And seas were 75 to 100 feet higher at that time. Carbon’s now at something like 380 parts per million in the atmosphere. Even if it were capped at 450 ppm, as we’d be lucky to do, you’re probably talking about an ice-free world.

That’s huge! The disruption of water supplies can have massive implications. In the American West and across much of Asia, people count on annual snow fall and glaciers to melt to give them water to drink.

(Whew! See what I mean? Makes you feel like going on a search for razor blades and sleeping pills. Just shoot me now! There’s hope, though: Check out this report, “The Economics of 350” (PDF), which I learned about in a different panel. It says we can control greenhouse gases without breaking the bank. In fact, it should only cost about 1 to 3 percent of the global GDP. But now … back to disaster …)

Even before seas rise, it’s likely that wet places will get wetter, and dry places will get drier. So, in the Western United States, for example, how will we raise food if it gets even drier?

Said Dimick: “That’s a national security issue. The water is tied into food. … The systems you need are no longer viable. You get a slow, insidious decline in legitimacy” of governments as people get hungrier and hungrier.

Consider also that one of the supposed fixes for global warming — carbon-free nuclear — is predicated on having enough water around to boil to move the turbines to produce the juice. Is that going to be possible in places like the American West? Probably not.

Geoffrey Dabelko of the Woodrow Wilson International Center for Scholars posited that the world’s poorest and richest nations are the ones that stand to lose the most — the poor because they’re already on the edge, the rich because their whole lifestyle is so carbon-intensive.

He foresees a world in which climate refugees — there’s that term again — are created en masse. But he cautioned that it may not be obvious that they are in fact climate refugees. Did they leave because they were starving, or because they thought they’d get a better job in another country?

Said Dabelko: “Be suspicious of anyone who gives you a number of climate refugees” to expect. No way to do that for now.

If you’re strong enough to keep delving in the climate forecasts, here’s a pretty good report by McGinn’s group that just came out. Me? I’m headed for the SEJ membership meeting. Thank God there’s a cash bar.