Novelist and journalist John Lanchester's new book "The Wall", imagines a world dealing with catastrophic climate change. Fear of rising sea levels and desperate migrants fleeing from uninhabitable lands have led to the building of a giant concrete wall around an entire island nation that is very much like the U.K.

In the novel, Joseph Kavanagh, a new Defender, has one task: to protect his section of the Wall from the Others, the desperate souls who are trapped amid the rising seas outside and are a constant threat. Failure will result in death or a fate perhaps worse: being put to sea and made an Other himself.

This is our first episode about a novel, which may help us understand with how individuals and society might react to a world where average annual temperatures have warmed by about 9 degrees F (2 degrees C).

Would we panic and be even more fearful or xenophobic than we are today? Would older people, who failed to act on climate change before it was too late, face bitterness and blame from younger generations?

"I think it's psychologically very difficult to imagine what climate change would be like," John tells us. It's a very difficult subject to look straight at.. It's not the thing we can get our heads around and easily process."