DOES CLIMATE CHANGE AFFECT CICADAS?

2024 is the year of the cicadas.

This spring, billions of cicadas will emerge in the US due to a rare “double-brood” event. Both broods – one that lives on a 13-year-cycle and another that lives on a 17-year-cycle – will emerge from underground at the same time.

The last time these two broods emerged simultaneously was in 1803. That’s 221 years ago.

In the south, at sites from North Carolina to Georgia, cicadas are already starting to emerge. In one South Carolina county, they were so loud that concerned residents called the sheriff’s office. The Northern Illinois Brood, which is on a 17-year-cycle, is predicted to emerge in the next month.

It is well-documented that climate change can impact ecosystems in a variety of ways. From where species live and the timing of biological events to the rates of species extinction, climate is an important environmental influence on our natural world.

But how do rising global temperatures impact these insects? Will cicadas start to emerge earlier?

A LITTLE BIT OF BACKGROUND

Known for their cacophony of buzzing and clicking noises, cicadas are well-known for emerging from underground en masse – and then disappearing four to six weeks later.

While there are more than 3,000 species of cicadas, they generally fall into two camps: annual cicadas, which are seen on a yearly basis, and periodical cicadas, which spend the majority of their lives underground.

The lifespans of these two broad categories of cicadas also differ. Annual cicadas generally live for two to five years and periodical cicadas, which are unique to North America, can live for up to 17 years.

Once a brood emerges, cicadas “crawl up trees to mate, and the females lay eggs in tree branches.” After they hatch, young cicadas “drop to earth and burrow into the soil.” Then, periodical cicadas will spend either the next 13 or 17 years underground– it depends on the brood – before they emerge again to mate (and so on and so forth).

THE MYSTERY OF HOW CICADAS KNOW WHEN TO EMERGE

Cicadas typically emerge when the ground temperature reaches 64°F. They also are cued by the “annual cycles of their host plants.” While underground, juvenile cicadas – called nymphs – live off of root fluids.

However, scientists still don’t know how broods manage to emerge at the same time.  If it were only about ground temperature, cicadas would come out in small groups and would be “quickly wiped out by predators” because, for example, a cicada that happens to be a couple of feet underground will experience cooler temperatures than one closer to the surface.

In the US, cicadas typically emerge around late April or May in the South and late May to early June in the North.

As our planet warms, spring will begin to arrive earlier, and among many other impacts, University of Connecticut researchers predict that warming temperatures “will lead to an increase in unexpected, oddly-timed emergences, and, in the extreme, a breakdown of periodicity in these insects.”

Warming temperatures could cause periodical broods of cicadas to come out earlier in the spring. In fact, it wouldn’t be a first-time occurrence.

In the springs of 2020 and 2023, for example, “a smattering of confused cicadas belonging to Brood XIII and Brood XIX were spotted” after emerging off-cycle.

Although scientists aren’t entirely able to predict the impacts of climate change on periodical cicadas, it’s possible that because this past winter was unusually warm in some regions and extremely cold in others, we may see cicadas emerge at different times across the country.

The mystery of how and when cicadas determine when to emerge – and the role of rising global temperatures – persists.

WHAT CAN WE DO ABOUT RISING GLOBAL TEMPERATURES?

While how cicadas determine when to emerge remains one of nature’s greatest mysteries, they are far from the only ones that are affected by our shifting climate. 

In fact, it’s already happening. For example, one new study found that as climate change causes spring to arrive earlier, migratory birds are struggling to adapt. Last year, white butterflies filled Johannesburg’s skies earlier than usual. Bears are waking up early from hibernation, or struggling to hibernate at all. The list goes on.

The climate crisis is flipping the script and throwing our natural systems out of balance. As heat waves and other forms of extreme weather become more frequent and even more dangerous, people are being impacted, too.

It’s clear: we have a narrowing window to take bold climate action to slash our emissions and fight rising temperatures. But we need you with us. Help us fight for the just, clean energy future that we desperately need and learn what you can do by joining our digital community of advocates around the world today.