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Cicadian rhythm: Reuters claims ‘global warming’ could ‘permanently change’ 17-year cicadas into a 13-year cycle’




Getting up close with cicadas to find climate change clues


Excerpt: With air temperatures and surface soils warming from climate change, scientists are also keen to learn how the creatures are responding.

Temperatures affect when cicadas emerge and their underground growth. Scientists witnessed large numbers of 17-year cicadas surface years ahead of schedule in 2017, which entomologists suspect could be related to global warming.

“The biggest questions are: Is climate change changing their life cycles? And then, how does it change them?” said Chris Simon, an evolutionary biologist at the University of Connecticut who has studied the insects for more than three decades.

With a better understanding of how cicadas know when to emerge, scientists may be able solve whether and how climate change is having an impact, Simon said. Eventually, we could see 17-year cicadas “escape through time” and permanently change to a 13-year cycle.

Scientists have a hypothesis for how climate change might be disrupting the insects’ internal clocks. While underground, cicadas receive chemical signals from trees through the sap they feed on — signals that may help the insects mark time. When trees burst into leaves in the spring, the pace of cicadas’ development picks up, then it slows again in winter as leaves fall to the ground.

But climate change is shifting these growing seasons. “As the climate gets warmer, you get a longer growing season. And if you get a longer growing season, the cicadas can get bigger every year,” Simon says. “So there’s more ready to come out four years early.”

Some insects pop up four years too early or late. That has led Simon and other scientists to suspect the insects somehow track when four years have gone by — a mechanism that could be disrupted by climate change.