global warming causing irrational fear

I read today an article about a married couple from Argentina (Francisco Lotero, 56 and his wife Miriam Coletti, 22) that have committed suicide by shooting themselves. They also killed their two-year-old son by shooting him through the back, and attempted to kill their seven-month-old infant child (sex/gender unknown) but somehow that bullet did not hit any major organs and the infant was found alive three days later by the police.

The reason for this suicide and child murder? "The cops found a letter on the table alluding to the couple’s worry about global warming and their anger at the government’s lack of interest in the matter."

I understand why someone might be afraid that global warming was going to do in the human race, and angry that their government isn't stopping it -- propaganda is everywhere, and it's largely put out by states themselves. I can try to understand why the fear would cause someone to panic and end their life before the event they're fearing takes place. But how can someone decide that the best thing they can do for their children is to murder them, rather than letting them take a chance against global warming? Spite? Religion/life-after-death? Disillusionment with activism? ...No thought process whatsoever?