Terraforming is the alteration of a planet's natural situation, to edit the climate and landscape. But is it a good idea? With an expanding population it would be a good idea for a percentage of the people to skip to Mars and leave us with more space. However, terraforming would take an unreasonable amount of time, it is estimated it will take 100,000 years to change the planet to be livable.
Finally, terraforming would not be a reasonable idea, a change of enviroment would be a catastrophic violation of human rights because humans can't evolve quickly and would suffer great consequences.