This summer, people across the UK may be noticing more dead bumblebees on the pavement than usual, and scientists say there is a reason behind the phenomenon.

The pattern results from a combination of naturally short life cycles, elevated temperatures, and long-term changes in land use, according to Senior Lecturer in Zoology Alex Dittrich of Nottingham Trent University, who explains that extreme heat, pesticides, habitat loss, and other environmental pressures can make survival more difficult for these important pollinators.

Bumblebee workers usually only live for four to six weeks. The colony is arranged to allow this turnover; if a worker dies, the other bees in the hive remove the body to prevent the spread of disease. It is therefore not uncommon to find dead bees on sidewalks. Although this rate of death is normal, further environmental stressors can make survival even more difficult.

A Summer of Record Heat

June recently saw the warmest temperatures ever recorded in England, while the UK as a whole experienced its second-highest June temperatures on record. High temperatures affect bumblebees by interfering with their development, reproduction, and ability to fly.

These temperatures can also push colonies beyond the limits of their natural cooling mechanisms; although bees keep the temperature inside the hive down by waving their wings, this method is only effective up to certain temperatures, and prolonged heat exposure can alter development and threaten long-term population stability.

Higher temperatures also interfere with the timing of biological events. Climate change can also contribute to phenological mismatch, in which species that depend on one another become out of sync with seasonal changes. For instance, bees might emerge from hibernation before flowers are available, or flowers may bloom and then die off before the bees are active. In these situations, the bees are left without access to nectar at crucial times.

Pesticides Compound the Problem

Chemical exposure also affects bumblebee populations. Although the EU and UK have banned the most harmful neonicotinoids, other insecticides like organophosphates, synthetic pyrethroids, and phenylpyrazoles are still widely used. These chemicals can paralyze or kill bees and also interfere with their ability to navigate. Herbicides can also reduce the availability of important food sources, such as dandelions, which are a major source of nectar at the beginning of the season.

Habitat loss also makes these problems worse. Housing development, intensive agriculture, and road construction have reduced the amount of natural land available for bees to nest and find food. The loss of these habitats reduces the ability of bee populations to cope with extra stress caused by heat and chemical exposure, worsening the impact of their naturally brief lifespans.

Why It Matters Beyond the Garden

The number of European wild bee species considered at risk of extinction has increased from 77 in 2014 to at least 172 now, about 10% of the total species assessed. Bees pollinate an estimated 75% of global crops and play a significant role in pollinating nearly 90% of flowering plants.

Dittrich suggests leaving the herbicide out when dealing with dandelions, letting parts of the lawn grow uncut, planting native species, and exploring non-chemical pest-control options first, using chemical treatments sparingly. For a bee struggling on hot pavement, a mixture of two parts sugar to one part water can help revive it. If it is safe to do so, people can also move the bee to a shady spot or flower.

While these measures will not eliminate the wider pressures affecting bumblebees, they can reduce some of the stressors that make it harder for them to survive. As temperatures rise and habitats keep changing, it will become more important to ensure that bees have reliable sources of food and shelter.

Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.

New analysis of dust deposits left after the massive asteroid hit Earth around 66 million years ago suggests the event created a thick, worldwide dust blanket that drove heat down toward the planet’s surface, resulting in global wildfires.

The researchers behind the new study said the evidence for a post-impact dust blanket and resulting heat wave adds new fuel to the debate about what role, if any, the Chicxulub asteroid played in their extinction, by suggesting most unsheltered animals would have died instantly.

Scientists Debate Connection Between Asteroid Impact and Dinosaur Extinction

While scientists agree that a massive chunk of space rock slammed into Mexico’s Yucatan Peninsula 66 million years ago, they have continued to debate the event’s impact on the end of the dinosaurs‘ reign. Still, the timing of the two events, and the evidence for a mass extinction of animals incapable of seeking the necessary shelter to survive the asteroid’s impact, has led most to connect the two events to some degree.

Further studies of the impact have shown that the event’s immense heat and pressure vaporized a massive amount of rock, resulting in a huge cloud of dust and rock vapor high into the Earth’s atmosphere. As some of that dust condensed into tiny rock ‘spherules’ and slammed back into the surface, the friction between them and the air generated a corresponding heat pulse.

According to the authors of the new study, many theories suggested that this heat pulse acted like a planetary-wide broiler, including “radiating enough heat to sizzle thin-skinned animals without shelter,” but not enough for plants to suddenly burst into flames. The team said that this result temporarily caused researchers to move away from the idea that the immediate impact event caused the dinosaur’s extinction rather than a longer, more drawn-out event.

Now, after years of new ideas, the team said that a 2023 discovery once again changed the debate, leading to their new proposal.

Atmospheric Layer of ‘Post-Impact’ Dust Would Have Magnified Heat Wave 3.5 Times

According to the team’s statement, the 2023 discovery involved a layer of “extremely fine post-impact dust” that could have formed from rock vapor that did not condense into spherules.

“It reinvigorated my interest in what happened to the leftover vapor,” explained Brandon Johnson, a planetary scientist at Purdue University and lead author of the study detailing the new theory, “that’s where this work started.”

To determine what effect such a post-impact dust layer might have had on dinosaurs and other terrestrial animals, the team plugged the new data into previous simulations of the Chicxulub event. Johnson and colleagues especially wanted to know how the dust layer would boost Earth’s retention and release of heat energy generated by the falling rock spherules.

After running several simulations, the team determined that the dust layer would have increased the surface heat by 3.5 times compared to an event that only included the falling spherules. Unlike earlier models, this new version with the dust layer included showed that the heat pulse would have been enough to “kill animals and start spontaneous forest fires.”

“We’re in the realm where we might be essentially killing off everything within that first hour or two,” Johnson explained.

Notably, the researcher said his team’s concept is not unlike alternative extinction theories that credit a global post-impact winter for the eventual mass extinction of dinosaurs and other lifeforms.

“It seems counterintuitive,” Johnson said, “but actually it’s the same effect.”

The research compared the idea to how an insulated mug can keep hot coffee hot and iced coffee cold.

“Once the spherules finished falling and the fires petered out, massive dust clouds could have blocked warmth from the Sun for years to decades and caused a global winter,” the authors explained.

Results Could Help Unravel Why Some Animals Survived, and Others Didn’t

When discussing how the team’s findings might affect the ongoing debate about dinosaur extinction, Johnson said the work seems to offer strong support to the impact extinction theory.

“This work of ours supports this idea that it really is the impact that was devastating to terrestrial life and caused the mass extinction,” the researcher explained.

Although the team suspects that the global fires caused by the dust amplified the heat wave, they point out that a more complete geological record would likely be needed to provide confirmation. Alfio Alessandro Chiarenza, a paleontologist at University College London who was not involved with this study, said researchers could find a record of global wildfires, but “we just don’t have it so far.”

“It would be great to figure out which animals survived right at the impact and what their biological features were,” Chiarenza added. “This could finally tell us why some animals made it when others, like the dinosaurs, didn’t.”

The study “Heat and wildfires during the K-Pg mass extinction enhanced by fine dust” was published in the Journal of Geophysical Research: Biogeosciences.

Christopher Plain is a Science Fiction and Fantasy novelist and has spent the last six years as Associate News Editor and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him at christopher@thedebrief.org

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