Drought has caused millions of dollars’ worth of damage in Hawaii in the past 20 years. A particularly severe event from 2007-2014 was especially damaging to ranching in the state.

According to the National Oceanic and Atmospheric Administration, the average drought causes more than 9 billion dollars’ worth of damage in the U.S. That puts abnormal dryness as the second most costly natural disaster, behind only hurricanes.

You might think drought isn’t an issue for Hawaii, with moisture-laden trade winds and a winter rainy season, but in fact it’s just the opposite. New analysis from the East West Center in Honolulu shows just how damaging drought can be locally.

Abby Frazier, a geographer at the East West Center specializing in drought research, recently explored the financial cost of a record-breaking drought that lasted from 2007 to 2014. That episode of abnormal dryness was exceptional both in its duration and severity. Frazier characterized the 7 year drought as unprecedented in 100 years of data.

“Revenue losses for the ranching industry on the order of about $44.5 million dollars. They lost over 20,000 head of cattle and it's expected to take another 10 to 14 years to recover fully,” Frazier said.

That recovery will cost an additional $4-6 million per year.

Data compiled in Frazier’s report shows the U.S. Department of Agriculture paid out $50 million from a livestock insurance program to compensate Hawaii’s ranchers for grazing loses from 2008 to 2017. Food crops are also frequently impacted. Drought stricken farmers in Hawaii have received $10 million in federal crop insurance payments since 1996.

$8 million of that was directed toward Hawaii’s most valuable food crop, macadamia nuts, with an additional $1 million going to coffee growers.

So what caused the historic drought? It’s difficult to identify any one factor. Weather trends like drought are a complex mix of precipitation, temperature, and global air flow that can be difficult to predict. But in Hawaii there is at least one clue.

The cyclical disruption of normal water and air currents in the Pacific Ocean basin known as El Nino/Southern Oscillation is known to be associated with drought conditions in Hawaii. The phenomenon occurs normal wind patterns and thermal ocean water currents breakdown, resulting in abnormal temperatures and rainfall across the globe.

Although ENSO typically brings dry conditions to Hawaii, even a powerful El Nino wouldn’t likely be enough to cause a 7 year drought.

Christina Karamperidou, an atmospheric scientist at the University of Hawaii at Manoa, says that it would require multiple, back to back El Nino events to create a drought event of that duration.

“El Nino events don’t last that long. It’s associated more with the decadal variability that we see in the Pacific,” Karamperidou said.

She added that while there were El Nino events observed during the drought period, none were large enough to have caused such a severe drought.

Researcher Abby Frazier says the slow moving nature and unpredictability of drought are what can make it so dangerous.

“The first day of a drought just seems like a sunny day,” she points out.

This summer, all 8 of the main Hawaiian Islands have experienced drought conditions. Only select leeward areas of Hawaii Island and Maui have moved into severe or extreme drought conditions, according to the U.S. Drought Monitor.

Correction: Christina Karamperidou was originally idetified as a geographer. She is in fact an atmospheric scientist.