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Earth & Climate

New Study Validates Lower Limits of Human Heat Tolerance: A Wake-Up Call for Climate Action

Human thermoregulation limits are lower than previously thought, indicating that some regions may soon experience heat and humidity levels exceeding safe limits for survival. The study underscores the urgent need to address climate change impacts on human health, providing vital data to inform public health strategies and climate models.

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The world is facing an unprecedented threat from climate change. Rising global temperatures are pushing the limits of human heat tolerance, making it essential to reassess our understanding of what we can endure. A groundbreaking study by researchers at the University of Ottawa’s Human and Environmental Physiology Research Unit (HEPRU) has confirmed that the lower limits for human thermoregulation – our ability to maintain a stable body temperature in extreme heat – are lower than previously thought.

Led by Dr. Robert D. Meade, former Senior Postdoctoral Fellow, and Dr. Glen Kenny, Director of HEPRU and professor of physiology at uOttawa’s Faculty of Health Sciences, the study involved exposing 12 volunteers to various heat and humidity conditions using thermal-step protocols. This technique allowed researchers to identify the point at which thermoregulation becomes impossible.

The results were startling. Participants experienced extreme temperatures – up to 42°C (108°F) with 57% humidity, equivalent to a humidex of approximately 62°C – for an extended period. The consequences were severe, with many participants unable to finish the 9-hour exposure due to heat stress.

“The findings are clear: our research provided important data supporting recent suggestions that the conditions under which humans can effectively regulate their body temperature are actually much lower than earlier models suggested,” states Dr. Kenny. “This is critical information as we face increasing global temperatures.”

The study’s implications extend far beyond academia. As cities prepare for hotter summers, understanding these limits can help guide health policies and public safety measures. By integrating physiological data with climate models, researchers hope to better predict and prepare for heat-related health issues.

“This research aims to spark important conversations about our safety and adaptability in increasingly extreme environments,” adds Dr. Meade. “The estimated limits for thermoregulation are being increasingly incorporated into large-scale climate modeling. Our findings underscore the urgent need to address the impacts of climate change on human health.”

As we face an uncertain future, this study serves as a wake-up call for governments and communities worldwide to take proactive steps in addressing the consequences of climate change. By acknowledging the limitations of human heat tolerance, we can work towards developing more effective strategies to protect ourselves and our environment from the devastating effects of extreme temperatures.

Air Pollution

Global Urban Environmental Quality: Mapping Air Pollution and CO2 Emissions Across 13,000 Cities Worldwide

In a sweeping new study of more than 13,000 urban areas worldwide, researchers have mapped air pollution levels and carbon dioxide emissions, providing comprehensive global analysis of urban environmental quality.

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The study, led by George Washington University in collaboration with scientists from Washington University in St. Louis and the University of North Carolina at Chapel Hill, has mapped air pollution levels and carbon dioxide emissions across 13,189 urban areas worldwide. This comprehensive global analysis provides a powerful snapshot of how urban environments are evolving across the globe.

The research team used data from satellite observations, ground-based measurements, and computer models to measure city-level air pollution and the average amount of carbon dioxide released into the atmosphere between 2005-2019. According to Susan Anenberg, professor of environmental and occupational health at the GW Milken Institute School of Public Health, “This study shows that progress is possible but uneven, with some cities seeing worsening pollution while others are experiencing cleaner air over time.”

Key findings from the study include:

* More than 50% of cities showed links between all pollutants, suggesting they likely come from the same sources and could be reduced together.
* Urban areas in high-income regions with aggressive environmental policies saw simultaneous declines in all pollutants.
* Cities in regions undergoing rapid population and economic growth, including South Asia and parts of Africa, experienced rising pollution and emissions levels.
* Satellite remote sensing provides an unprecedented opportunity to track pollution levels in all cities worldwide.

The study’s integrated approach offers policymakers, researchers, and climate advocates a valuable new tool for assessing the effectiveness of strategies to reduce pollution. By tracking historical pollutant trends and analyzing correlations across air pollution, nitrogen dioxide, and carbon dioxide emissions, the study offers insights into how urban areas can make progress on both climate and public health goals.

Researchers have also created an interactive map and dashboard to track air pollution in cities worldwide, providing a valuable resource for policymakers, researchers, and climate advocates.

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Climate

The Wealthy Elite’s Carbon Footprint: A Study Reveals the True Extent of Global Warming Since 1990

Wealthy individuals have a higher carbon footprint. A new study quantifies the climate outcomes of these inequalities. It finds that the world’s wealthiest 10% are responsible for two thirds of observed global warming since 1990 and the resulting increases in climate extremes such as heatwaves and droughts.

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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.

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Climate

Climate-Driven Wildfires Wreaking Havoc on US Health and Economy

Scientists say human-caused climate change led to 15,000 additional early deaths from wildfire air pollution in the continental United States during the 15-year period ending in 2020.

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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.

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