A team of British scientists warned on Monday that if greenhouse gas emissions continue unchecked and droughts become more frequent and extreme, several butterfly species could become extinct as early as 2050.
The extinction could be mitigated by land conservation efforts in the United Kingdom, such as reconnecting butterfly habitats fragmented by human activities like agriculture. But, the scientists warn, this might only delay the species' collapse by a few decades.
Because there are centuries of monitoring data for butterflies, it is easy for scientists to model future population trends. Their fate can serve as an early warning for how climate change could impact other species, such as dragonflies, bees, moths and beetles, said Tom Oliver, an ecologist at the Natural Environment Research Council and lead author of the new research.
"They are a 'canary in the coal mine' if you will," he said. These impacted species "provide essential function for humans, such as pollinating crops, eating pests and other disease vectors and decomposing waste. We should really be concerned at the potential for climate change to impact species and the important functions they provide."
Biologists long predicted that climate change-induced extinctions would start late this century, if not early next century. But this study, published in the peer-reviewed journal Nature Climate Change, is the latest in a string of recent research that finds species are declining much faster than previously thought. Several animals—including high-elevation species like the pika and ones dependent on sea ice like the polar bear—are declining so fast scientists predict they could go extinct in the next several decades, or by 2050 at the latest.
"Those of us who have worked on this for a long time, we did think we had longer," said Camille Parmesan, a biologist at Plymouth University in the UK who studies climate change's impacts on wildlife. "Emission rates have increased every year, the climate is changing more than we thought and some systems are more sensitive than we thought."
Oliver and his colleagues studied butterfly population data dating back to the 1760s at 129 monitoring sites throughout the UK. They identified six drought-sensitive species—including the Cabbage White, Speckled Wood and Large Skipper butterflies—that experienced population declines following a 1995 drought, and tracked how long it took them to recover.
Climate change is expected to cause more frequent, severe and widespread droughts throughout England, Scotland and Wales. The scientists then modeled how the butterflies would fare under various future greenhouse gas emissions scenarios and land conservation efforts.
Oliver and his colleagues discovered the butterflies would go extinct as early as 2050 under a "business as usual" scenario with no emission reductions. To give the species a 50 percent chance of surviving to 2100, carbon emissions would have to be drastically reduced and the fragmented landscape restored, the scientists found.
The 1995 drought conditions were mild compared to the drought currently plaguing wide swaths of the American west, Parmesan noted. It shows just how sensitive certain species are to small climatic changes, she said.
"There's this view that evolution can handle everything, but this shows no, it can't," Parmesan said. "Species are closely adapted to very small climate envelopes. This is especially true for a lot of the endangered species we care about. Get beyond those narrow conditions and most species can't cope."