Why can't it be viewed as a source of comfort? At a longer time scale, even life on earth won't exist as the sun dies. At a sufficiently long time scale, none of this stuff on earth matters, the universe continues to move on. As these highlight the transitory nature of life on earth, there is no reason for why one can't "let go" after a point. I find that a tremondous source of comfort, as I often face the problem of when to "let go" in many contexts.
I won't get into a detailed discussion of the purpose of existence (a natural counter-question to the above), or why one should still strive in one's own way to tackle issues like climate change up to "one's capacity" (which depends on accepting the purpose of existence).
These fundamental questions are extremely hard to address. It took me a long time and a lot of thought to have a reasonably satisfactory answer to these questions - though of course what answer one is satisfied by will vary from person to person. For me, the bulk of the answer came from a study of the Indian Vedantic tradition (chiefly Adwaita Vedanta) through the "Complete Works of Swami Vivekananda" among other such books, and the works of Leo Tolstoy. Mileage may vary of course.