Worse than no rain is negative rain.
“Every year we have a certain amount of rain that we expect as a result of historical patterns,” Andy Wood, a climate scientist at the National Center for Atmospheric Research, told The Daily Beast.
“Negative precipitation [comes] when you have a departure from that.” That’s exactly what happened in California this year, said Dan Mcevoy, a climate researcher at the Desert Research Institute.
Usually, he explained, a few big storms will provide enough moisture to dampen possible fuels and effectively end the fire season.
Alongside his “negative rain” tweet, Elvington posted a map showing what’s called the Evaporative Demand Drought Index (EDDI).
The EDDI is a tool developed by researchers including Wood, Hobbins, and Mcevoy.
Elvington posted that tweet just a day before the Camp fire began.
Unprecedented dryness from heat, winds, low humidity & lack of precipitation.” Not all of these environmental changes are attributable to climate change, Mcevoy noted.
But by raising global temperatures, he said, climate change is absolutely making things worse.
The Sierra Nevada—the region of California that’s battling the Camp fire—had its second-hottest summer on record in 2018.