freetown fred wrote:Come on Larry, you're a brainiac---everything is relevant

The data I saw indicated that every ton of Hydrogen gas that gets converted into Helium in the center of the Sun forces the Sun to contract just a little bit and that raises its temperature just a bit. The sun will as a consequence be outputting 10% more energy in 1.1 billion years.
If I may be permitted to linearize this exponential function over this 1.1 billion year period, that becomes 1% more energy every 110 million years. This is clearly however exponential in nature, so it probably can be linearized as I have just done (for 10 x 110 million year periods) only over such short time spans, and due to the exponential nature of this the Sun's percentage of gain in output in the past such incremental periods of 110 million years was far less than it will be in the future.
My wild guess is that when life first started on Earth, the sun was outputting only about 95% of the energy that it currently outputs. The Earth may have been warmer back then though, due to its own internal heat.