Make hay while the sun shines.
That stupendous power house (just imagine the sound effects) our source of  life, that is the sun, will undergo change. In about 5 billion years, as a red giant, the sun will grow and grow out to earth's orbit and earth could well be incinerated or our water will be boiled away and our air escape into space. What we know of will not last forever. (Data from Wikidedia)