How Long Can Life on Earth Survive?

 Live Science, one of my favorite news sources (yay, science!) recently published this fascinating report. It's perfect for futuristic science-fiction world-building!

From the article: Life on Earth could continue for another 1.8 billion years, according to new research. This figure, which is based on complex climate models, is far longer than many previous studies indicated.

As the sun evolves, it is getting brighter. Our star is currently producing about a third more energy than it did at the dawn of the solar system 4.5 billion years ago. And it will continue to get hotter until it eventually dies in about 5 billion years.

 In 1982, James Lovelock and colleagues estimated that Earth's photosynthetic biosphere — which includes all plants and forms the basis for most of the planet’s biology — would end about 100 million years from now. Successive studies have pushed back the deadline for the death of all life on Earth. Published  in the journal JGR Atmospheres, researchers suggest that plant life could continue about 1.8 billion years into the future. That nears the time when Earth would lose its oceans to space, either through radiation splitting water atoms or runaway evaporation, in about 2 billion years.

Life on Earth relies on photosynthesis, the process used by plants, algae and some bacteria to turn sunlight into energy. The mechanism chemically converts carbon dioxide and water into sugars and oxygen. It requires both CO2 and sunlight.

But at certain temperatures, plants' photosynthetic machinery shuts down. Eventually, the sun will warm Earth to the point that plants are no longer able to photosynthesize, which would in turn cause entire food webs to collapse and all life to perish.

Another issue is that as the sun dies and it gets brighter, there will be less carbon dioxide in the atmosphere, effectively starving plants.