Arctic warming may be driving more persistent dry and wet spells

A new study led by Rutgers University has revealed that persistent weather conditions, including wet and dry spells, have increased in the United States and may be a result of Arctic warming. Sustained weather conditions can lead to extremes such as prolonged cold, heat waves, drought, and storms that cost millions of dollars.

The investigation was focused on daily precipitation data at 17 weather stations across the United States. The team also examined large upper-level circulation patterns over North America and the eastern Pacific Ocean.

The researchers found that dry and wet spells lasting four or more days have occurred more frequently in recent decades. In addition, the frequency of persistent large-scale circulation patterns over North America increased when temperatures in the Arctic were unusually warm.

According to the researchers, the Arctic has been warming at least twice as fast as the global average temperature in recent decades. Study lead author Professor Jennifer Francis explained that the persistence of warm Arctic patterns has also increased, suggesting that long-duration weather conditions will occur more often as rapid Arctic warming continues.

“While we cannot say for sure that Arctic warming is the cause, we found that large-scale patterns with Arctic warming are becoming more frequent, and the frequency of long-duration weather conditions increases most for those patterns,” said Professor Francis.

The team plans to expand its analysis to other regions of the Northern Hemisphere, and will develop new metrics to investigate causal connections. The researchers will also assess future risks from extreme weather events linked to persistent patterns. “When these conditions last a long time, they can become extreme events, as we’ve seen so often in recent years,” said Professor Francis.. “Knowing which types of events will occur more often in which regions and under what background conditions – such as certain ocean temperature patterns – will help decision-makers plan for the future in terms of infrastructure improvements, agricultural practices, emergency preparedness and managed retreat from hazardous areas.”

The study is published in the journal Geophysical Research Letters.

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By Chrissy Sexton, Earth.com Staff Writer