Yeah but what if that 70% means that Europe, America and China are completely wiped out?

What good would those resources be to the Africans who just want food and water rather than a 4x4 and a pina colada?

It depends really whether we're talking about saving "The World" or whether you're talking about the people on it?

If it's the former then HK's is really the best suggestion, get rid of as many humans as physically possible.

If it's the latter then it's basically an unsolvable problem, my individual solution would still be to remove as many people from the planet as possible (except people like me and there will be a test) enjoy a quiet life on my homestead, with my own land, growing my own food and with everyone minding their own business. I would go back to a barter system with local businesses working for local people. Anyone who started showing signs of getting lazy, not taking care of their own or turning to crime would be ostracized and left for dead.

Basically, I want a world where people work for what they want, nothing is given freely but time and effort, kids are raised with a sense of responsibility and natural selection takes care of the idiots.

I know that won't work for everyone, but it's my ideology.

Terraform and colonise Mars.

To paraphrase 4Hero from their track "Terraforming" on the 1994 album "Parallel Universe",

"It seems a shame to have to go and terraform Mars, when we could just stay here and terraform Earth."

As a student of economics is say: What infinate resources therefore no need for money there would be a perfect world!!!

But again as economics shows us this is beyond impossible. But it is fun however I think economics A-level has ruined that for me.

Remove emotions? It's the future, don'tcha know!

Has it been established that the world needs saving?

There are lots of oak forests around the south coast of England. Nobody notices them much today, but 200 years ago they were planted at immense expense, in modern money it would be several billions of pounds. You might ask yourself why this was done? The answer is that it was obvious to all at the time that England faced a giant disaster, one which would destroy our way of life... We would run out of oak with which to build our warships and be doomed to lose our empire. The royal navy is notable today for its lack of wooden ships, and the British are richer without their empire than they ever were with it.

I would advise anyone who thinks they can predict what disasters await our grandchildren to think upon that and stop being so silly. Let alone those inbred types who believe that all economic progress inevitably leads to greater consumption of oil/water/food/land and therefore the end of the world is nigh. Some people just can't learn from history, no matter how many lessons it offers them.

And from what?