Drought ‘normal’ keeps changing

Missouri State Climatologist Zack Leasor works in an office divided by time. On the right sits the past – dozens of faded, scratched leather-bound books containing more than 100 years of handwritten climate data. One page – July 15, 1936 – shows a high temperature of 111 degrees Fahrenheit, the then-second-hottest day on record for the city of Columbia.

“Back then, because of the lack of technology, a climatologist was somebody just skilled enough to use (weather) instruments, get the measurements (and) record them well,” he said. “That took a lot of time.”

But now Leasor spends far more time on the left side of his office, behind his computer. His dual monitors are often displaying weather models – precipitation, stream flow, soil moisture, crop conditions and reservoir levels. He uses this data to, among other things, determine if there’s drought.

The job of a climatologist has changed a lot in a hundred years. So has the climate.

And those changes are making it more difficult to tell what is or isn’t a drought. That’s because drought is often defined as “drier than normal.” But if climate change is shifting what’s considered “normal,” what does that mean for drought?