Study tracks increase in extreme conditions
FRISCO — Scientists taking a close look at the last 50 years — the modern global warming era — found that droughts and heat waves are happening simultaneously much more frequently than in the past.
The climate experts at the University of California, Irvine analyzed data gathered from ground sensors and gauges since 1960 and crunched the numbers with a statistical model to track the upswing.
“Heat waves can kill people and crops while worsening air quality, and droughts exacerbate those serious impacts,” said senior author Amir AghaKouchak, assistant professor of civil & environmental engineering. “With these two extremes happening at the same time, the threat is far more significant.”
For the purposes of the study, heat waves were defined as three to seven consecutive hot days, with temperatures in the 90th percentile of the historical record. Droughts were described as extended periods during which precipitation was 20 percent or less of the norm.
The study didn’t directly examine human-caused global climate change in this study, but AghaKouchak said an overall increase in the mean temperature worldwide is raising the probability of heat waves.
He cited the recent record-breaking high in Iran: NASA satellites and National Oceanic & Atmospheric Administration data sets documented a 115-degree Fahrenheit surface temperature – with a “comfort index” of 165 degrees – on July 31 in the city of Bandar-e Mahshahr.
More than 2,500 people died during a heat wave that gripped India in late May. A European heat wave in 2003 claimed about 70,000 victims, many of them seniors and children.
The findings appear in the journal Proceedings of the National Academy of Sciences.