Where Have All the Butterflies Gone? Low Count Portends Sad Future for Biodiversity

A U.K. conservation charity sounded the alarm on Monday after a yearly butterfly count turned up a record low number of butterflies so far.

Participants in the count, which runs through August 4, are reporting a little more than half the number of butterflies as they did by this time in 2023, Butterfly Conservation said.

"The lack of butterflies this year is a warning sign to us all," the charity's director of conservation Dan Hoare said in a blog post. "Nature is sounding the alarm, and we must listen. Butterflies are a key indicator species. When they are in trouble we know the wider environment is in trouble too."

"So far this summer, I have not seen a single butterfly alight on the flowers. Desperate times."

The low numbers are one example of how the climate crisis exacerbates biodiversity loss. Butterfly numbers have plummeted by 80% in the U.K. since the 1970s, a decline driven by the climate emergency as well as habitat destruction and pesticide use. This year, the country experienced an abnormally wet, windy spring and a cooler than average summer.

"Butterflies need some warm and dry conditions to be able to fly around and mate," Hoare explained. "If the weather doesn't allow for this there will be fewer opportunities to breed, and the lack of butterflies now is likely the knock-on effect of our very dreary spring and early summer."

The climate emergency increases rainfall because warmer air holds more moisture. Spring 2024 was the U.K.'s sixth wettest on record and the wettest overall since 1986, according to The Guardian. March, April, and May saw almost a third more rainfall than usual for those months.

The heavy rain also followed a drought in 2022 that put a different kind of pressure on butterfly populations by decreasing the number of plants that caterpillars need to eat. The green-veined white and the ringlet species were especially hard hit and have yet to recover.

"Never known a year like it," author and climate scientist Bill McGuire wrote of 2024. "We have two huge buddleia 'butterfly bushes' that are normally swarming with at least half a dozen species. So far this summer, I have not seen a single butterfly alight on the flowers. Desperate times."

Since the count began on July 11, the number of butterflies reported in the U.K. is the lowest in the count's 14-year history, but there is still a chance that warmer, drier weather could turn things around. However, even if it doesn't, Hoare called for more citizen scientists to participate in the count by spending 15 minutes noting any butterflies and moths they see in a specific area and recording their totals on the website or via app.

"People are telling us that they aren't seeing butterflies, but simply telling us is not enough; we need everyone to record what they are or aren't seeing by doing a Big Butterfly Count as this will give us the evidence we need to take vital action to conserve our butterfly species," Hoare said.

The U.K.'s butterfly decline is not the only recent example of climate extremes harming wildlife. Extreme wildfires in Australia in 2019 and 2020 killed at least 1 billion animals, while a heatwave in Mexico this spring prompted howler monkeys to drop dead out of trees. In 2023 and 2024, the world's coral reefs suffered their fourth mass bleaching event.

The news of the butterflies' decline also follows a week that saw the four hottest days on record globally. 2023 was the hottest year in the past 125,000, and 2024 is expected by many scientists to surpass it. Every month since June 2023 has been the hottest of its kind on record and has seen average temperatures at or above 1.5°C higher than preindustrial levels, the more ambitious temperature goal enshrined in the Paris agreement.

"The extreme events that we are now experiencing are indications of the weakening resilience of these systems," Johan Rockström, director of the Potsdam Institute for Climate Impact Research in Germany, told The Washington Post on Saturday. "We cannot risk pushing this any further."