Was early Mars wet and warm, or dry and cold? Yes.

We know there's water on Mars. And lots of it.

Thing is, it's frozen. With the polar caps, and under the surface even down to mid-latitudes, when you talk Martian water you're talking ice.

While there may be scattered pockets of liquid water under the surface, if you want copious liquid water on the surface then you need to time travel, back to, oh, say, 3 billion years ago (better warp extra fast around the Sun or bring a few extra banana peels). Back then there was quite a bit of surface wat...