There will be a time, probably in our lifetimes, when overpopulation and lack of resources to sustain the population will become an issue.
Colonizing Mars would take a long time and the resources would have to come from Earth. Terraforming Mars also would take a long time, plus we do not yet know how to nor do we have the technology to do it yet, plus the cost to do it would be astronomical.
Every year the world population increases. There is roughly 6.8 billion people on this planet.
We reached 1 billion in 1804
We reached 2 billion in 1927
It took 123 years to reach another billion people
We reached 3 billion in 1960
It took 33 years to reach another billion
We reached 4 billion in 1975
It took 15 years to reach another billion people
We reached 5 billion in around 1988
It took 13 years to reach another billion
We reached 6 billion in 1999
It took 11 years to reach another billion
By 2012 we will reach 7 billion.
By 2027 we will reach 8 billion
By 2044 we will reach 9 billion
We are dependent on resources that are limited. Fossil fuels, coal, and nuclear are the 3 main resources for power that runs our world. There is only a limited amount of fossil fuels and coal in the world.
We need to start thinking about creating a world where even 10 billion people is not a problem.
We need to start really working on utilizing abundant resources like water, the sun, or even wind. We already use it, but it is only a fraction of the power that we use. Most of the power we use is from fossil fuels or coal.
We are going to be entering a turning point soon. On one hand we utilize abundant resources. We start preparing for the vast population of the future.
However, if we keep on the road we are now, we will not survive. We will be fighting wars for resources. America and China will be the big 2 that are fighting each other. It will be world war 3.
The chances of our species surviving is not good if we keep doing what we are doing.
Where I got the info about the population is here
population of the world