We know that when the average temperature rises, more water evaporates from the earth’s surface into the air. Water vapor is a greenhouse gas, but unlike carbon dioxide or methane, it doesn’t stay in the air for long—eventually, it falls back to the surface as rain or snow. As water vapor condenses into rain, it releases a massive amount of energy, as anyone who has ever experienced a big thunderstorm knows. Even the most powerful storm typically lasts only a few days, but its impact can reverberate for years.
