☀️ What if the Sun became 10% brighter?
A rapid, severe warming — Earth has a thermostat, but it is slow.
The science
Solar output drives Earth's energy balance. A sustained 10% increase (about what the real Sun will deliver in roughly a billion years as it ages) would push Earth toward a moist-greenhouse state: oceans evaporate faster, water vapour (a greenhouse gas) amplifies warming.
Immediate consequences (modelled)
Large global temperature rise within decades to centuries in simplified energy-balance models.
Possible long-term consequences (hypotheses)
Possible runaway greenhouse over geological time — the eventual real fate of Earth as the Sun brightens.
Assumptions: Sustained luminosity change; feedbacks simplified.
Limitations: Does not model climate, geology, biology or engineering in full detail.
Reference: NASA / peer-reviewed planetary science