Impossible is an adjective, but when it preceded by the definite article the, it becomes a noun.
"It has become her lifeline. She said: “I never thought I’d end up in that position, standing for half an hour in the cold for food. I used to be on nearly £30,000 a year and I think, ‘How did I end up here?’"
The word cold is an adjective. However, in this context it comes after the definite article the. Question: Is it a noun?
Yes, and this is very common.
She is a champion for poor people. She is a champion for the poor.
I don't like cold weather. I don't like the cold.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.