Imagine that you have an ice cube sitting on the table in front of you. The room is cold and you can see your breath. It is currently twenty-five degrees. Ever so slowly, the room begins to heat up. Twenty-six degrees. Twenty-seven. Twenty-eight. The ice cube is still sitting on the table in front of you. Twenty-nine degrees. Thirty. Thirty-one. Still, nothing has happened. Then, thirty-two degrees. The ice begins to melt. A one-degree shift, seemingly no different from the temperature increases before it, has unlocked a huge change.
