Rain Needed to Bust the Drought
As Earth warms from the buildup of greenhouse gases, the increase in temperature means more water evaporating into the atmosphere. The increase in evaporation has paradoxical effects. More evaporation can dry out the land more quickly, potentially worsening droughts. However, it also leads to heavier precipitation in the storms that form.
The Southern Plains have recently provided an example of both types of behavior in extreme precipitation (or lack thereof). Early this spring, parts of Oklahoma and Texas were in the Extreme Drought category set by the U.S. Drought Monitor, then a deluge at the end of May effectively ended the drought for several weeks. As the August heat settled in, another drought developed, escalating to Extreme Drought in parts of Texas, Louisiana, and Arkansas. The cycle repeated in late October as heavy rain pushed in to the Southern Plains and all but erased the drought again. Even if it is too early to attribute this alternating extremes to the buildup of greenhouse gases, what we witness is definitely a preview of what will be more and more common in the future, absent any mitigation of our emissions.
The ongoing California drought, meanwhile, is so entrenched that it’s now well into its 4th year. This drought has repercussions nationwide, particularly in the availability and cost of food. According to the USDA, in 2014 California accounted for 60 percent of the U.S. production for fresh-market vegetables, and 73 percent of processed vegetables.