[mlo]

"The thing is, it absorbs IR energy from all directions, and reemits it in all directions."

OK, I see what you mean. Yes, that's true. But in the case of CO2 in the atmosphere it's an imbalance because the incoming energy from the sun heats the earth, which radiates infrared. There's more infrared coming from below than above.

"Anyway, I hope I did not become hopelessly technical here."

Don't worry, I do technical.

[exDemMom]

There's more infrared coming from below than above.

In that case, CO2 should have an overall negative effect on temperature, by emitting proportionally more IR upwards than it receives from that direction.