I just climbed off an airplane at Boston’s Logan Airport. The day began in Monterrey, Mexico — and though I was tired, I was also feeling pretty good. Our big day of action on Oct. 10 has been building to a crescendo: Yesterday we broke our record from last year, registering more than 5,500 actions for the big Global Work Party.

But I’d barely turned on my computer when that good feeling turned to a kind of nausea. There were emails from people all saying the same thing: Have you seen this? “This” was a gross video making its way around YouTube, purporting to show people being blown up for not believing in climate change. It’s been pulled down from the website of its creators, the British climate group 10:10, but it hasn’t been pulled down from YouTube. 

Climate denier Marc Morano’s Climate Depot website is assailing it as the latest example of eco-fascism. Morano and other climate skeptics are right to crow. It’s the kind of stupidity that really hurts our side, reinforcing in people’s minds a series of preconceived notions, not the least of which is that we’re out-of-control elitists. Not to mention crazy, and also with a completely misplaced sense of humor.

We at 350.org are spreading the word that we had nothing to do with it. We didn’t see it till it had made its way around the web, and as soon as we did, we let people know we thought it was disgusting. We’ve known the creators for years — they put out a statement apologizing for their lapse. But it’s the kind of mistake that will haunt and hurt efforts.

What makes it so depressing is that it’s the precise opposite of what the people organizing around the world for Oct. 10 are all about. In the first place, they’re as responsible as possible: They’ll spend the day putting up windmills and solar panels, laying out bike paths, and digging community gardens. And in the second place, they’re doing it because they realize kids are already dying from climate change, and that many, many more are at risk as the century winds on. Killing people is, literally, the last thing we want.

There’s no question that crap like this will cast a long shadow over our efforts, and everyone else who’s working on global warming. We’re hard at work, as always, but we’re doing it today with a sunk and sad feeling.