The warming of the planet influences the amount and distribution of precipitation. Although there are exceptions, in general, wet areas are expected to become wetter and dry areas drier.

Wet areas will become wetter because warmer air can hold more water vapor. Also, warmer air, along with warmer oceans, causes more evaporation of water from oceans into the atmosphere. When the moist air cools, it condenses into tiny droplets that become clouds. As the droplets get bigger and heavier, they fall as rain. Because there is more moisture in the atmosphere, there is more rainfall.

This process is magnified because some of the water that fell as rain is recycled. The water that fell to earth as rain returns to the atmosphere through evaporation where it once again falls to the earth as rain.

But to make an area wetter, this process needs to start with a source of water like an ocean and the proper wind currents to move the moist air over land.

Conversely, in a desert, we are either not close to an ocean or the wind blows moist air in the wrong direction. In this case, warmer temperatures cause more evaporation of the already limited soil moisture in the desert, making the desert even drier.

These changes will impact agriculture. In places where farming is already marginal due to a lack of rainfall, these areas will get drier, making farming even less feasible. Areas with sufficient rainfall will get more rainfall, potentially causing water-logged soils, delayed planting, soil erosion, flooding, and other problems. Whether wetter or drier, these changes in precipitation will impact agricultural production.

This article is part of a series focused on the causes and consequences of a warming planet. See the Ag Decision Maker website (https://www.extension.iastate.edu/agdm/energy.html#climate) for more from this series.