In the year 1999, I remember serious talk in the scientific and NASA world of trying to colonize different planets. To create suitable atmospheres in planets like Mars, over time, and try to engineer a hospitable planet. Water is still believed to be under Mars' crust.
They haven't achieved teraforming primarily because of two reasons. Low gravity (about 30-some percent of earth's gravity) and Mars lacks a magnetosphere. Earth has a magnetic field around it that is caused by earth's rotation and the magma in earths crust. This magnetic field creates the polarities and reflects most of the suns harmful rays. Don't get me started on the magnetosphere, unless you want to read a three page essay. You should, of course, research it for yourselves.
A number of other planets already complete with an atmosphere and promising other similarities have been found within the last few years, but climate and proximity to the sun has been the issue. I believe they are sending drones and such to them now for more data. But the major problem with that is the distance, of course.
Living in domes put on Mars might be probable, though. And more practical. They should attempt this on Mars, in my opinion. But, NASA is having problems with funding, and this would take a lot of money.
Also, in 1999, the Rain Forest was all the hype. Preventing the destruction of the rain forest and all that. Anyone as old as I am should remember how big that hype was. Now, in 2014, they are still doing it, and no one talks about it anymore.
But I do know one little fun fact. One volcanic eruption is equal to 100 (or maybe it's 1000) years of human air pollution.