No, Arrehenius didn't say "halving of CO2 would decrease temperatures by 4–5 °C (Celsius), but doubling of CO2 would cause a temperature rise of 5–6 °C". He found a symetrical effect which he estimated at 4°C for each doubling of CO2. Neither has anyone experimentally demonstrated a temperature change in climate from man made greenhouse gasses.
>>Actually, he DID say that, Brian. You're lying.
"Arrhenius estimated that halving of CO2 would decrease temperatures by 4–5 °C (Celsius) and a doubling of CO2 would cause a temperature rise of 5–6 °C."
-Wikipedia, "Svante Arrehenius"
I have an objective standard for my belief climate change mitigation is a hoax; the experimental record. What would cause you to change your mind about climate change mitigation?
You have nothing but Denial, Brian, and the need (even obsession) to constantly post the same idiotic, unsupported, and dishonest claims. That makes you a Denier Troll, Brian. And that's all you seem able to do here.