With all photosynthetic organisms gone, atmospheric oxygen can no longer be replenished, and it is eventually removed by chemical reactions in the atmosphere, perhaps from volcanic eruptions. Eventually the loss of oxygen will cause all remaining aerobic life to die out via asphyxiation, leaving behind only simple anaerobic prokaryotes. When the Sun becomes 10% brighter in about a billion years, Earth will suffer a moist greenhouse effect resulting in its oceans boiling away, while the Earth's liquid outer core cools due to the inner core's expansion and causes the Earth's magnetic field to shut down. In the absence of a magnetic field, charged particles from the Sun will deplete the atmosphere and further increase the Earth's temperature to an average of around 420 K (147 °C, 296 °F) in 2.8 billion years, causing the last remaining life on Earth to die out. This is the most extreme instance of a climate-caused extinction event. Since this will only happen late in the Sun's life, it would represent the final mass extinction in Earth's history (albeit a very long extinction event).
With all photosynthetic organisms gone atmospheric oxygen can no longer be replenished and it is eventually removed by chemical reactions in the atmosphere perhaps from volcanic eruptions Eventually the loss of oxygen will cause all remaining aerobic life to die out via asphyxiation leaving behind only simple anaerobic prokaryotes When the Sun becomes 10% brighter in about a billion years Earth will suffer a moist greenhouse effect resulting in its oceans boiling away while the Earth's liquid outer core cools due to the inner core's expansion and causes the Earth's magnetic field to shut down In the absence of a magnetic field charged particles from the Sun will deplete the atmosphere and further increase the Earth's temperature to an average of around 420 K (147 °C 296 °F) in 28 billion years causing the last remaining life on Earth to die out This is the most extreme instance of a climate-caused extinction event Since this will only happen late in the Sun's life it would represent the final mass extinction in Earth's history (albeit a very long extinction event)