It’s a few hundred million years, not a few hundred thousand, before the photosynthetic cycle is disrupted by silicate weathering from increased brightness.
Wikipedia has a summary:
“The luminosity of the Sun will steadily increase, causing a rise in the solar radiation reaching Earth and resulting in a higher rate of weathering of silicate minerals. This will affect the carbonate–silicate cycle, which will cause a decrease in the level of carbon dioxide in the atmosphere. In about 600 million years from now, the level of carbon dioxide will fall below the level needed to sustain C3 carbon fixation photosynthesis used by trees. Some plants use the C4 carbon fixation method to persist at carbon dioxide concentrations as low as ten parts per million. However, the long-term trend is for plant life to die off altogether. The extinction of plants will be the demise of almost all animal life since plants are the base of much of the animal food chain on Earth.”
https://en.wikipedia.org/wiki/Future_of_Earth
It links to additional academic sources in the footnotes.
Oh, I thought I had written millions as in my source instead of thousands, I shouldn’t write comments at 2 am, two mistakes. I didn’t know about the silicate issue but the estimated remain consistant with my initial source.
Yeah, no worries. Hundreds of thousands of years would be very rapidly impending doom though!
What’s interesting is that we’re at about the halfway point in terms of complex life on Earth. The Cambrian Explosion happened about 538 million years ago and complex life likely has about the same time left. Interesting that humans happened to emerge right around the midpoint of that journey, and makes you wonder what kind of life will be around in the waning years.
