Category: Climate Change And Biodiversity

New research shows flies can tolerate temperatures 2.3°C lower than bees before losing motor function, making them particularly vulnerable to climate change and raising concerns about their crucial role as the world’s second most important pollinators.
The study, conducted across three countries, reveals that flies’ sensitivity to heat is especially concerning for crops like chocolate that depend on fly pollination and for high-altitude ecosystems where flies are the dominant pollinators.
Insect populations are declining by nearly 1% annually (projected 24% decrease in 30 years), prompting urgent calls for conservation as these creatures are essential for pollination, nutrient cycling, and overall ecosystem function.
Individuals can help protect pollinators by creating diverse habitats in their yards through native plant gardening, reducing pesticide use, providing nesting sites, and supporting conservation organizations.

Life can’t function without insects. At least, not for long. They pollinate, break down waste, cycle nutrients, and touch every node in the web of life, filling endless niches across the planet.

As global temperatures continue to rise, some of Earth’s most important but overlooked pollinators, the flies, may be at greater risk than previously thought. According to a new study, flies may be more sensitive to climate change than bees. In warming experiments, researchers found bees could tolerate temperatures about 2.3 degrees Celsius higher than flies before losing motor function.

“Even though it sounds small, two Celsius degrees can actually be a pretty significant average temperature that can impact foraging, ecology, behaviors, reproduction and so on,” lead author Margarita López-Uribe of Penn State University told Mongabay.

Flies are the second most abundant category of pollinators after bees, yet they rarely receive the same attention or conservation focus. North America hosts more than 61,000 fly species alone, making them one of the continent’s most diverse insect groups. They can be found pollinating plants from mountain peaks to seashores, though they are especially crucial in colder, high-altitude regions.

“It’s time we gave flies some more recognition for their role as pollinators,” López-Uribe said.

A fly on a milkweed plant. Image courtesy of Michelle Borsey via flickr (CC BY 2.0)

“When we look at pollinator communities along altitude and latitudinal gradients, flies become more dominant pollinators in colder areas of the planet,” López-Uribe said.

Flies’ preference for cooler conditions may help explain their greater sensitivity to heat compared to bees. Bees evolved in arid environments and can generate and have ways to regulate their own body heat, while flies appear to be more strictly dependent on outside temperatures.

This study emerged as a response to COVID-19 lockdowns, with students conducting experiments in their backyards across three locations: a high-altitude site in Colombia and two subtropical sites in Texas and California. Using a water bath setup, researchers tested over 400 insects to determine their critical thermal maximum, the temperature at which they lose motor control.

While the study provides insights, López-Uribe notes some limitations. “The sampling was limited to urban and suburban areas, which implies there may be a bias for species that are already somewhat tolerant to higher temperatures due to urban heat island effects. Even with this bias, flies were still more heat-susceptible than bees.”

This sensitivity becomes particularly concerning, given the pace of global warming. The planet has already warmed by about 1.1°C since pre-industrial times. Scientists warn we could exceed 1.5°C of warming within the next decade – a rate of change that may be too rapid for many species to adapt to. At current trajectories, experts say we could see temperature increases of 2.4-3.5°C by 2100 without more aggressive climate action, which could push many heat-sensitive insects beyond their thermal limits.

These implications could be concerning for crops like cacao, used to make chocolate, which relies heavily on tiny flies called midges for pollination.

“The cacao pollination system is incredibly delicate,” said López-Uribe. “The flowers are very small and the pollen is viable for very few hours during the day. Changes of even a couple of Celsius degrees could actually impact the ability of pollinators to forage and potentially impact pollination of these crops.”

*Theobroma cacao* flowers will be pollinated and grown into the fruit that makes chocolate. Photo by Marc via flickr. (CC BY-NC-ND 2.0)

The findings suggest that conservation efforts need to consider flies alongside more celebrated pollinators like bees and butterflies. López-Uribe emphasizes the importance of creating diverse microhabitats within human-modified landscapes that can serve as refuges for heat-sensitive insects.

“Understanding these differences in tolerance and susceptibility to heat may lead to stronger arguments for why we should be designing spaces and landscapes where these diversity microhabitats are thought and planned in design,” she says.

The study comes amid growing global concern about insect declines. Research shows insect populations are declining by about 1% annually, amounting to 24% fewer insects in 30 years and 50% fewer in 75 years if current trends continue.

According to a 2021 meta-analysis, insect populations are suffering from “death by a thousand cuts” or a combination of multiple stressors. Climate change, habitat degradation, and agricultural practices (and use of pesticides) are identified as the three most significant factors driving insect declines globally.

A bumblebee on flowers. — An assessment of 66 bumblebee species documented declining numbers because of pesticide and herbicide use. Image by mikaelsoderberg via Flickr (CC BY 2.0).

However, there are ways that individuals can help protect both flies and other important pollinators in their own yards and communities. Conservation experts recommend creating pollinator-friendly habitats by planting a variety of native flowering plants that bloom throughout the growing season to provide consistent food sources. Leaving some areas of bare ground and hollow plant stems provides nesting habitat for many species while reducing lawn mowing frequency allows flowering “weeds” like clover and dandelions to provide additional forage.

Simple actions like installing “insect hotels” made from bundled hollow stems or blocks of wood with holes drilled in them and leaving dead wood and leaf litter in place create microhabitats that many insects need for nesting and overwintering.

Equally important is avoiding pesticides, herbicides, and other harmful chemicals that can directly kill beneficial insects or persist in the environment

Finally, supporting conservation organizations working to protect insects through donations or volunteer time helps advance broader efforts to study and conserve these essential creatures.

As biologist Edward O. Wilson once observed, “If human beings were to disappear tomorrow, the world would go on with little change… But if invertebrates were to disappear, I doubt the human species could last more than a few months.”

Banner image of a fly mid-pollination by Stig Nygaard via flickr. (CC BY SA 2.0)

Liz Kimbrough is a staff writer for Mongabay and holds a Ph.D. in Ecology and Evolutionary Biology from Tulane University, where she studied the microbiomes of trees. View more of her reporting here.

Disaster interrupted: How you can help save the insects

Citation: López-Uribe, M. M., Appert, M. K., Delgado, A. X., Herrera-Motta, A. F., Jimenez, A., Martín-Rojas, R. D., … & Gonzalez, V. H. (2024). Critical thermal maxima differ between groups of insect pollinators and their foraging times: Implications for their responses to climate change. Journal of Melittology, (122).

FEEDBACK: Use this form to send a message directly to the author of this post. If you want to post a public comment, you can do that at the bottom of the page.

Oil and gas companies have the ability to become a significant source of climate financing, a new study in Climate Policy argues.
The study looked at oil and gas profits from 2022, when the Russian invasion of Ukraine spiked energy prices across the globe, boosting realized companies’ earnings by 65%, or around $495 billion.
If governments had imposed an additional 30% tax on the profits of private oil and gas companies, it would have raised $147 billion, the study said.
Climate financing was the focus of the COP 29 climate conference, which only managed to come up with $300 billion in annual support for developing countries.

The international community is struggling to come up with enough funding to adequately address climate change, especially for developing countries that are impacted the most.

At the latest climate change conference, COP 29, leaders tripled annual funding for developing nations combatting climate change to $300 billion annually, but it still fell short of the $1.3 trillion experts say is needed.

The $300 billion, negotiated in Azerbaijan, renews an agreement made in 2009 to provide poorer nations with $100 billion to transition away from fossil fuels and address droughts, natural disasters and other impacts of climate change. But many critics said they want more money and more creative solutions.

“Fossil fuel-producing countries continue to promote their own interests, jeopardizing both the COP negotiations and the fate of humanity,” said Jack Corscadden, a climate campaigner for the Environmental Investigation Agency. “Continued fossil fuel extraction and consumption is not compatible with limiting warming to 1.5°C.”

One study, published ahead of the conference, argued that policymakers haven’t been asking enough of sectors with the highest emission rates, most notably oil and gas. Companies have the ability to make significantly higher financial contributions than they are right now — especially when they see unexpected profits.

“There is a clear case to include fossil fuel profits on the agenda of [UN] climate finance negotiations and to pursue an international agreement on minimum fossil fuel production taxes,” said the study, which was published in Climate Policy.

The study looked at oil and gas profits from 2022, when the Russian invasion of Ukraine spiked energy prices across the globe, boosting realized companies’ earnings before interest and tax by 65% compared to expected earnings, or around $495 billion. The crisis began when Russia cut off 80 billion cubic meters of pipeline gas to Europe.

Four companies alone made an additional $123 billion in unexpected profit that year, including Aramco, Petrobras, PetroChina and Gazprom.

“The windfall profits alone taken in by oil and gas companies due to the 2022 energy crisis would have been sufficient to cover the existing commitments of the industrialized nations for nearly five years,” the study argued.

Gas flaring on the Napo River in Ecuador. Photo by Peter Prokosch/Grida. CC BY-NC-SA 2.0

These unexpected profits, known as “super” profits, were nearly five times larger than the annual $100-billion climate finance goal established in 2009, and 700 times larger than the initial pledges at the climate conference in 2023 to assist with losses and damage from climate change.

Most of the oil and gas companies that benefited from the 2022 price spike were government-controlled, but they weren’t obligated to divert profits towards climate change efforts. The study said 70% of government-controlled super profits weren’t required to contribute to the 2009 climate change commitment.

If governments had imposed an additional 30% tax on the profits of private oil and gas companies, it would have raised $147 billion, the study said. Had they taxed them at 100%, it would have raised $324 billion on top of the $425 billion made through current tax structures.

“The sheer magnitude of these numbers illustrates that there is ample potential for governments to raise funds for climate action,” the study said.

One downside to this approach is that oil and gas companies currently use unexpected profits to “cushion” against financial losses in the future. Setting the tax rate too high could hurt companies’ growth and even lead to solvency. At the same time, the study argued that there is overinvestment in oil and gas, and that growth should be in renewable energies.

Reliance on oil and gas has been especially challenging for climate finance goals in Latin America, where major economies like Mexico and Argentina struggle to prioritize renewable energy and other climate change initiatives. Both countries received significant financial support to fight climate change yet also relied on revenue from carbon-intensive activities, according to the Sustainable Finance Index (SFI) 2024.

Guatemala and other Central American countries have done a better job at increasing climate mitigation efforts through redirecting annual budgets to fighting climate change while deprioritizing revenue from fossil fuels.

But leaders at COP 29 maintained that developed countries like the US and China — as well as oil-rich countries in the Middle East — need to carry more of the burden of climate financing.

While the $300 billion deal is disappointing for many, they’re hoping that it will set up more productive — and more ambitious — negotiations for next year’s climate conference in Brazil.

“The end of the fossil fuel age is an economic inevitability,” UN Secretary-General António Guterres said in a statement. “New national plans must accelerate the shift, and help to ensure it comes with justice.”

Banner image: An Exxon crude oil refinery. Photo courtesy of Columbia Law School.

FEEDBACK: Use this form to send a message to the author of this post. If you want to post a public comment, you can do that at the bottom of the page.

See related from this reporter: