"The warmer the Earth is, the more rapid the removal process becomes," Brownlee says.
So despite the fact that the sun has gotten much brighter, the Earth has remained fairly consistent because of a gradual reduction in carbon dioxide.
"That's the magic thing that has kept the Earth as nice as it is," he adds.
This may seem a bit confusing because of the current concern over global warming resulting from an increase in carbon dioxide in the atmosphere, but Brownlee says that's just a brief blip in the grand scale of things.
"In the short term, that's a big problem," he says. "But in the longer term, hundreds of millions of years, it's a decline of carbon dioxide that's really the major problem."
Going Down in a Blaze of Glory
Carbon dioxide is the "food of life," providing the critical nutrient that allows plants to grow, which in turn are consumed by animals.
The plants, thus, will starve to death because of a lack of carbon dioxide. And the animals won't be far behind.
He says the end won't come suddenly. Some critters will retreat into the sea in an effort to escape the rising heat, thus reversing the evolutionary process as we move back towards green slime, or wherever we came from.
But even the seas will be doomed. The sun will continue to expand, turning into something astronomers call a "red giant," and the Earth will become so hot that the oceans will gradually evaporate.
That process will take a few hundred million years.
Then, the prospects get really grim, according to Yale University solar physicist Sabatino Sofia. For awhile, the sun will contract, then expand rapidly into a red supergiant as it blasts off about a third of its mass through "thermal pulses."
That exploded material will become super hot as it expands, probably engulfing the Earth, and the sun's inner core "will settle down as a hot, nuclearly inert, dense object, a white dwarf star," according to Sofia.
The sun will be about the size of the Earth at that point, and at the end of its evolution. It will "slowly cool and darken to forever disappear from the view of our galactic neighbors.
"This dark cinder and the even darker outer planets that have not been swallowed up by the sun during its expanding stage, are all that will remain of our solar system," Sofia has written.
And our brief moment in the sun, so to speak, will be over.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.