Is life possible on Mars?

If living on Mars becomes reality, they are many factors to take in account.
First, we wouldn't be able to walk around without a spacesuit because the Martian atmosphere contains only nitrogen dioxide (CO2) and its unbreathable for us. Then the air pressure is really low, around 7 millibar, that being 100% less than Earth.
It's also very cold... Between 62.60°F and -207.4°F. To go to Mars and come back it would take a lot of time, many months or even a few years. Life would only be possible in pressurized bases where the Earth's atmosphere would be reproduced.
But, scientists found, a 12.43 mile-wide lake of liquid water under solid ice, in Mars' pole. Good news for mankind, who'll need water to survive on Mars. And we'll need to create food, which is impossible to find on Mars.
Living on Mars is clearly not meant for tomorrow!