That's actually a pretty difficult question to answer. As a Night Elf, he has a bit of an innate link with nature, so it's hard for him not to care. However, he has kind of a feud with his brother over Druidism, so he's not exactly of the "oh look it's nature it must be protected" view of things. The easiest way to sum up his thoughts on the matter is that he thinks nature is important because of what it supports, not for its own sake, and he's willing to do great damage now to help things out later (like blowing up the northern continent to get rid of the Lich King).