That is because we haven't actually been trying to change the Earth, what we have done has shown us that if one were to push it to extremes it would drastically change the environment.

The idea is if you did this on a planet like Mars with intent you could do it within a generation or so and make the planet hospitable for life as we know it.

Man has quite intentionally changed Earth, although not fundamentally, and has been successful. If we had 2000 year old satellite images, you would see some obvious differences. For instance, gone are many of the big forests of central Europe and England intentionally replaced by farmland, land in Florida has been "reclaimed", we've dug canals, built dams, etc. But this has taken a lot of effort and resources that wont be available on a different planet.

And where have you been the last 20 years? I would say that there exists a political if not will then intent to change Earth, aiming for changing about 0.01% of the atmosphere and cooling it slightly, and it doesn't seem to go anywhere

I'm sure there are ways to change the environment drastically, but that's not the point, is it? It's about changing it into something very specific, not just anything new. Big difference.

The idea is if you did this on a planet like Mars with intent you could do it within a generation or so and make the planet hospitable for life as we know it.

I would say that there exists a political if not will then intent to change Earth, aiming for changing about 0.01% of the atmosphere and cooling it slightly

But this has taken a lot of effort and resources that wont be available on a different planet.

Who said anything about reworking the ground?

Read the wiki link I posted or look up videos and articles on how one would terraform Mars. It is not as hard as you might think.

I have never heard of anyone with these goals...

Post #7, paragraph 2

Not within a generation, no. It would take very much longer than that.

In my second sentence of the original post: "Terraforming means to change a planet so that its atmosphere and surface ...". For instance, on Mars one major rework of the ground would be to cover large parts of it with water.

by generation I mean along the lines of 100+ years

I would love to see a terraformed moon before a terraformed mars, the moon is way closer!

This discussion would go more smoothly if everyone would either use words by their established definitions, or failing that specify what exactly they mean.

I would love to see a terraformed moon before a terraformed mars, the moon is way closer! But terraformation by itself is breathtaking, isn't it?

Zubrin addresses all of those topics in the paper I linked

Again, a lot of infrastructure, and frankly, it sounds as realistic as saying that we could fix global warming on Earth by pushing Earth to a higher orbit arguing that "as little as 10% of Earth will be required for propellant".

And I think these numbers illustrate a basic problem. A 100 km mirror? Even on Earth a facility capable of mining and processing that requires a lot of infrastructure, and then it should be done in vacuum and nearly 0 G.

Few are very successful in predicting the technology of the future.

We need to send stuff there first, a lot, so humans can arrive to something comfortable, key in the door and everything.

And in almost every case, when people try to predict what technology will be available in a century, the predicted capabilities of that technology usually falls short of what actually will exist, so if we predict that terraforming can be done with 21st century tech, then it is quite likely that it can be.