As the climate change conference opened in Paris, ads appeared around the city, many from sponsors of the conference — or were they? The ads looked genuine, but the messages were a bitingly satirical.

We’ve had the guy with the shock orange hair. The hermit with the scraggly beard. The gamer living with mom. The misogynist virgin. The disgruntled office worker. The Korean American college kid. The African American veteran.

Until Wednesday’s rampage at a holiday party in San Bernardino, Calif., the only thing we hadn’t had was a woman picking up guns and slaughtering innocent people. But now police tell us we have a Muslim couple with a 6-month-old baby — Syed Rizwan Farook and his Pakistani-born wife, Tashfeen Malik — to add to the ranks of mass shooters and our country’s endless, exhausting gallery of gore.

With each of these rampage shootings — we’ve had more of them this year than we’ve had days — we try to pinpoint what triggered the violence. It’s the mental health system. It’s video games. It’s the recession. It’s religious fanaticism. It’s racial hatred.

Yes, these are all contributing factors. But the real common thread among these shooters is obvious: their access to guns.