Greenhouse Effect

The Earth's greenhouse effect is a reasonably well-understood physical phenomenon. Scientists believe that in the absence of the greenhouse effect, Earth's surface temperature would average about -0.4°F (-18°C), which is below the freezing point of water and more frigid than life on the surface of the Earth could tolerate over the longer term—except, perhaps, organisms deriving their energy from hot deep-sea vents. The greenhouse effect maintains Earth's surface at an average temperature of about 59°F (15°C). This is about 59.5°F (33°C) warmer than it would otherwise be.