These are annual average temperature (top) and precipitation (bottom) in the United States from 1895 through 2007.
The magnitude of change in the trend lines, +1 degree in temperature, +2 inches annual rainfall, is interesting but not nearly as interesting as the slopes being almost identical and straight as an arrow. That’s an amazing correlation for there to be no direct causal factor in common. Warmer, wetter, and more CO2 are good things for agriculture. God help us all if those trend lines go towards colder and drier. If it does we’ll be inventing ways to make global warming happen.