Based solely on the Earth’s reflectivity and the Sun’s luminosity and distance from us, water on the Earth’s surface would be frozen even today without the atmosphere’s warming effect. Although we legitimately worry about too much heating in today’s atmosphere, the Earth would be too cold without the greenhouse effect of carbon dioxide, methane, water vapor, and nitrous oxide that keeps it warmer. Liquid water currently exists on Earth only because of these greenhouse gases, which absorb infrared light and warm the planet, thereby establishing equilibrium.
