Heat and Habitat: Bees Suffer from a Perfect Storm

The world is facing an unprecedented decline in insect numbers, with some studies suggesting that their biomass has almost halved since the 1970s. This alarming trend can be attributed to habitat loss due to agriculture, urbanization, and climate change. While these global change drivers have been well-documented, their interaction and impact on insects are not as well-known.

Researchers at Julius-Maximilians-Universität Würzburg (JMU) conducted a study at 179 locations throughout Bavaria, part of the LandKlif research cluster coordinated by Professor Ingolf Steffan-Dewenter within the Bavarian Climate Research Network bayklif. The results, published in Proceedings of the Royal Society B: Biological Sciences, reveal a complex and concerning relationship between heat, land use, and insect populations.

Bees are particularly affected

The study found that insects from different trophic levels react differently to the combination of higher temperatures and more intensive land use. Bees were particularly affected, with their numbers reduced by 65 percent in urban areas compared to forests. The researchers attribute this decline to not only hot daytime temperatures but also warmer than average nights.

Dr. Cristina Ganuza, a biologist involved in the study, highlights the significance of night-time temperatures: “Precisely because average night-time temperatures rise even faster than daytime temperatures.” This previously unknown effect on insects reveals a new threat that requires further research to uncover the underlying physiological mechanisms.

Key findings

The researchers summarize their findings in three key points:

1. Warmer daytime temperatures lead to higher numbers and diversity of bees, but only in forests and grasslands, the most natural habitats. Therefore, preserving and creating interconnected natural habitats within agricultural and urban areas is crucial.
2. Higher night temperatures lead to lower bee richness across all studied habitat types, highlighting a previously unknown negative effect on insects.
3. Climate change and land use interact, affecting insects at different trophic levels in distinct ways, which could disrupt food webs and important ecosystem functions like pest control and pollination.

The study emphasizes the importance of addressing climate change and land use to protect insect populations, particularly bees. By preserving natural habitats and creating interconnected areas within agricultural and urban landscapes, we can mitigate the negative impacts on these vital pollinators.

The study published in Nature Climate Change sheds light on the disproportionate impact of the world’s wealthiest individuals on global warming since 1990. According to the research, the top 10% of the global population is responsible for two-thirds of observed global warming and the resulting increases in climate extremes such as heatwaves and droughts.

The study assesses the contribution of high-emitting groups within societies, finding that the top 1% of the wealthiest individuals globally have a carbon footprint 26 times higher than the global average when it comes to monthly 1-in-100-year heat extremes. This also applies to Amazon droughts, with these emissions being 17 times more detrimental.

Lead author Sarah Schöngart explains, “Our study shows that extreme climate impacts are not just the result of abstract global emissions but can be directly linked to our lifestyle and investment choices, which in turn are linked to wealth.”

Using a novel modeling framework combining economic data and climate simulations, researchers were able to trace emissions from different global income groups. They found that emissions from the wealthiest 10% in the United States and China alone led to a two-to threefold increase in heat extremes across vulnerable regions.

The study’s findings are clear: if everyone had emitted like the bottom 50% of the global population, the world would have seen minimal additional warming since 1990. Coauthor Carl-Friedrich Schleussner emphasizes that addressing this imbalance is crucial for fair and effective climate action.

Moreover, the research highlights the importance of emissions embedded in financial investments rather than just personal consumption. Targeting the financial flows and portfolios of high-income individuals could yield substantial climate benefits.

“This is not an academic discussion – it’s about real impacts of the climate crisis today,” says Schleussner. “Climate action that doesn’t address outsize responsibilities of wealthiest members society risks missing one most powerful levers we have to reduce future harm.”

The authors suggest that their findings could motivate progressive policy instruments targeted at societal elites, noting such policies can foster social acceptance of climate action. Making rich individual polluters pay can also provide much-needed support for adaptation and loss and damage in vulnerable countries.

In conclusion, the study emphasizes the need to rebalance responsibility for climate action in line with actual emissions contributions is essential not just slow global warming but achieve more just resilient world.

Climate change is having a devastating impact on the United States, particularly when it comes to wildfires. A recent study published in Nature Communications Earth & Environment has found that human-caused climate change led to an additional 15,000 deaths from wildfire air pollution in the continental US during the 15-year period ending in 2020.

The study, led by Oregon State University researcher Bev Law, is the first to quantify the number of people dying due to a warming climate causing fires to release increasing amounts of fine particulate matter into the air. This phenomenon, known as PM2.5, can be inhaled deeply into the lungs and even enter the bloodstream, posing serious health risks.

The researchers estimate that during the study period, a total of 164,000 deaths resulted from wildfire PM2.5, with 15,000 of those attributed to climate change. This means that absent climate change, the total would have been 149,000. The average annual death rate from wildfire PM2.5 during this period was 5.14 per 100,000 people, roughly double the US death rate from tropical cyclones like hurricanes.

The economic burden associated with these extra deaths is staggering, estimated at $160 billion. This figure takes into account productivity losses, healthcare costs, and a concept known as value of statistical life, which assigns a monetary value to reduction in mortality risk.

California, Oregon, and Washington bore the greatest economic burden from climate-driven wildfire PM2.5, according to the study. “Without efforts to address climate change,” Law noted, “wildfires and associated fine particulate matter will continue to increase.” The researchers project that by midcentury, relative to the decade ending in 2020, mortality from smoke will rise by at least 50%, with resulting annual damages of $244 billion.

The study highlights the urgent need for action to address climate change and mitigate its impacts on human health. As Law emphasized, exposure to PM2.5 is a known cause of cardiovascular disease and is linked to the onset and worsening of respiratory illness. The ongoing trends of increasing wildfire severity track with climate projections, underscoring how climate change manifestations like earlier snowmelt, intensified heat waves, and drier air have already expanded forest fire extent and accelerated daily fire growth rates.

The research was conducted by an interdisciplinary team from Oregon State University, the University of California, Merced, the US Environmental Protection Agency, the Woodwell Climate Research Center, and Beth Israel Deaconess Medical Center of Harvard Medical School. Their findings serve as a stark reminder of the need for collective action to address the climate crisis and protect public health.