Three months ago, at a Northeast Sustainable Energy Association public forum in Boston, green PR guru Solitaire Townsend said the movement to overcome climate change needs to tell its equivalent of Martin Luther King’s “I Have a Dream” speech, rather than what it’s has been doing, which she called, “I Have a Nightmare.”

Townsend has a good point. Environmentalists have been militating for decades for drastic changes from businesses and consumers, and for most of that time, all it really gained us was a reputation as do-gooder killjoys. Frickin’ treehuggers.

Nowadays, of course, our cause is everywhere. But is it a merely yet another bubble, about to burst? That could be, but I doubt it; a serious problem needs to be addressed, regardless from the whims of fashion.

Oops, I called it “a serious problem.” Is this what Townsend is talking about?

One facet of current fashionableness is the idea that technology can now accomplish what once would have required hard sacrifice. Used to be I had to get a smaller car and drive 55 if I wanted to save gas; now I can buy a Prius. (I did.) Used to be that I had to remember to turn off the light when I left the room; now I can just buy a motion sensor.

And those solutions, especially the second one, are practically quaint by modern standards. Last week Gregory Sottile of New York-based Research Frontiers, Inc., gave a presentation at the Clean Technology show touting suspended-particle-device glass, which makes the window its own window shade. With a small amount of current, the window goes from opaque to clear all but instantaneously.

Because it offers not only privacy but also full shading, this is even better than liquid-crystal glass, which you may remember from the movie “Philadelphia.” When the craven law partners wanted privacy to talk frankly with AIDS-stricken Tom Hanks, they flipped a switch and the clear glass turned forebodingly white.

Not only can the glass be hooked up to sensors and a central climate system to match shading with the sun’s intensity, it can also be governed by a motion sensor. That means when no one’s there, the windows could darken, cutting the need for cooling dramatically.

Pretty cool stuff: salvation with a side of glitz. But opinion is hardly unanimous on whether technology can do nearly enough to remove the problem. At that same NESEA forum in March, flame-throwing author James Howard Kunstler assured the audience that “we’re not going to organize our ways out of this, and we’re not going to tech our way out of it.”

I wonder if he’s taken Townsend’s suggestion to mind any better than I have, though I doubt it.

When I consider the magnitude of the problem, it hard not to join his more hard-line outlook. According to a World Wildlife Fund report in 2006, if everyone on the planet consumed resources at the pace we do, we would need five Earths to accommodate everyone. For decades, we just took, and it was “OK,” at least in gross terms, because others weren’t taking their shares.

But as has been endlessly documented, that is changing rapidly, as the most populous nations on earth rapidly join the same economy we’ve all but had to ourselves. Just consider all the Indians and Chinese who’ll want cars, and all the resources that will be required to produce and operate them.

Even if there weren’t climate issues, it’s not hard to contemplate the chaos that competition for finite resources could bring. That, in fact, is the important point of “peak oil”: Up till now, oil producers been able to pump out more fuel whenever anyone wanted more, but once we reach the top of that cycle, anyone who wants more oil than before will have to get it at the expense of someone else who used to get it.

By necessity, technology that eases the demand on resources is going to provide a major portion of the solution — if we’re all riding on hydrogen, who cares if the oil is running out? But can it really not only sustain Americans’ level of consumerism, but also make possible the growing consumer appetites of a couple billion others?

I doubt it. Of course we’re going to need technology’s help, but we’re going to have to get used to less, even if that’s some Americans’ worst nightmare.