The meaning of the term 'environment' depends on the context it is used in. When used in the context of evolution, usually it means everything that affects the succesful procreation of a creature. So you have to take into account not only temperature, radiation, etc., but also the presence of predators, whether those predators move slower or faster than our creature, whether or not possible sexual partners find our creature attractive, whether or not it is strong enough to survive a flooding of its habitat, whether or not it is smart enough to go and find a softer nut instead of exhausting itself on an uncrackable one, whether or not it is camouflaged well enough not to be picked off of a tree, whether or not ...
The list is endless.
You could even take it a step further and say that the creature itself is part of the environment. For that, you have to look at it not from the viewpoint of the creature, but from the viewpoint of the
genes. In the end, it's the genes that "want" to be copied. It's their sole "aim".
"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.