Um, if you actually read my posts in full, you'd have found that the statistics I quoted referred to the death penalty being MORE EXPENSIVE that imprisoning someone for life, and that I never stated it would be CONVENIENT to just hang someone. Sorry, I can't make it any bigger, so if you miss that, you have major problems.
And, fyi, the morals of Australia and the morals of say, Iran are completely different, hence the different legal systems. YOu can't just liberally apply your morality to the entire world champ. That's why, IRAN has capital punishment and we don't. I'm not saying it's right (fuck, they hang people for their sexuality, which is more immoral than hanging for Crimes Against Humanity - Saddam Hussein anyone?), I'm simply pointing out that the Iranian morality (see: radical Islamic leadership) is different to our democratic system (note: Australia) in which we see "eye for an eye" as to be wrong.
The American system is divided, and this is recognised the division between states who still use capital punishment, have called a moratorium on capital punishment, and those who have outlawed it in full. Heck, America, the most democratic nation on Earth still has states using capital punishment.
Oh, and relating capital punishment to global warming is a really, really poor way to support your argument.