Dec. 14 (UPI) -- As temperatures rise, so do the odds of a record-breaking period of rain or drought. According to the new research, global warming is driving rainfall extremes.
Scientists in Europe analyzed weather and temperature data from 50,000 weather stations across the globe. Their analysis showed higher temperatures correlated with prolonged periods of rain or drought.
Over the last few decades, prolonged periods of heavy rain were most likely to fall in the central and eastern United States, northern Europe and northern Asia, while prolonged droughts occurred most frequently in Africa.
"We took a close look at observed monthly rainfall data -- if it's not just a few days but several weeks that are record wet, this can accumulate over time and lead to large river floods, or to droughts if it is record dry," PIK researcher Jascha Lehman said in a news release.
Since 1980, the United States has experienced a 25 percent increase in record wet months. Similar increases were recorded in parts of South America, Europe and Russia.
In Africa, record dry months have been on the rise.
Strict statistical tests confirmed the culpability of global warming. Researchers published the results of their study this week in the journal Geophysical Research Letters.
"This implies that approximately one out of three record-dry months in this regions would not have occurred without long-term climate change," said study co-author Dim Coumou, researcher at Free University Amsterdam's Institute of Environmental Studies. "A central conclusion from our study is that, generally, land regions in the tropics and sub-tropics have seen more dry records, and the northern mid- to high-latitudes more wet records -- this largely fits the patterns that scientists expect from human-caused climate change."
Scientists designed climate models to predict the frequency of record wet and dry months without the influence of climate change.
"Normally, record weather events occur by chance and we know how many would happen in a climate without warming," said Lehmann. "It's like throwing a dice: on average, one out of six times you get a six. But by injecting huge amounts of greenhouse gases into the atmosphere, humankind has loaded the dice. In many regions, we throw sixes much more often with severe impacts for society and the environment."
The globe has experienced a single degree of warming. At the Paris agreement, world leaders and policy makers agreed to limit warming to 2 degrees Celsius, though many argue a limit of 1.5 degrees would be ideal.
"If they do not agree on solutions to limit warming to well below 2 degrees, we're headed for 3 or 4 degrees within this century," Lehmann said. "Physics tells us that this would boost rainfall extremes even further."