Coal Power Plants Contribute to Cooling via Sulphate Pollution
Frank Hermann/Getty Images
The presence of sulfate air pollution causes clouds to darken and reduces sunlight. This factor could contribute to recent temperature increases beyond just greenhouse gas effects.
“Two-thirds of the global warming observed since 2001 is attributed not to rising CO2 levels, but to decreasing SO2 levels,” says Peter Cox from the University of Exeter, UK.
While some sunlight is reflected and some is absorbed before being released as heat, increased carbon dioxide levels enhance the retention of this heat. This greenhouse effect is a primary driver of global warming, but the albedo, or reflectivity of the planet, significantly influences temperature.
Since 2001, satellite instruments like Ceres have measured sunlight reflection and absorption. These observations reveal a decline in sunlight reflectivity, indicating a darker planet with diminishing albedo, leading to more intense warming.
Factors contributing to this reduced albedo include diminished snow and sea ice as well as fewer clouds. However, Cox and Margaux Marchant’s analysis of Ceres data spanning 2001 to 2019 suggests that the most significant contributor is the darkening of clouds.
Industrial and maritime sulfate emissions are known to enhance the density of cloud droplets, improving their reflectivity. This principle underpins a proposed geoengineering technique called Marine Cloud Brightening. However, recent shifts away from high-sulfur fuels like coal have led to reductions in these emissions.
Thus, Merchant and Cox explored whether the observed loss of cloud brightness is linked to reduced SO2 levels and found correlations. They presented initial findings at the Exeter Climate Forum recently.
These findings are promising, as the accelerated warming trends indicate that some researchers fear the global climate sensitivity (the temperature rise associated with increased atmospheric CO2) could be at the upper range of estimates. While the short-term effects of reduced pollution contribute to warming, this suggests greater warming potential as CO2 emissions rise if cloud darkening results from increased CO2.
“If this darkening signifies a genuine shift in cloud feedback indicating greater sensitivity than previously thought, rather than a mere result of decreased SO2 emissions, it is promising news,” stated Laura Wilcox from the University of Reading, UK, who was not involved in the research.
Wilcox notes limitations in the datasets utilized by Marchant and Cox; for instance, the SO2 contamination data may have changed since their analysis.
Furthermore, two recent studies suggest dimming is largely due toreduced cloud cover, not darker clouds. “The factors behind these recent darkening trends are currently being intensely debated,” she says.
Overall, Wilcox adds that her research supports the view that the recent acceleration of global warming is chiefly driven by reduced air pollution, and this effect is likely to be temporary.
According to the most comprehensive assessment, glaciers around the world have been shrinking by more than 5% on average since 2000. This rapid melting rate has accelerated by more than a third over the past decade as climate change continues in stages.
It is said to be “a problem of warming level for glaciers.” Noel Goomeren At the University of Edinburgh, UK. “They are climate change barometers.”
The new numbers come from a global consortium of hundreds of researchers known as the Glacier Mass Balance Intercomparison Exercise. This group sought to reduce uncertainty about how much of the planet's 200,000 or so glacier melted by assessing different size measures using standard procedures. This includes gravity and elevation measurements from 20 satellites, as well as ground measurements.
Between 2000 and 2011, glaciers melted at an average rate of approximately 231 billion tons of ice per year, researchers found. This melting rate increased to 314 billion tonnes per year between 2012 and 2023, an acceleration of more than a third. In 2023, a mass of approximately 548 billion tons was recorded.
These numbers are consistent with previous estimates. But this comprehensive look “gives a little more confidence in the changes seen in the glacier,” says Gourmelen, part of the consortium. “And there's a clear acceleration.”
Overall, thawing of roughly 7 trillion tons of glacial ice since 2000 has increased sea level by almost 2 centimeters, melting into the second largest contributor of sea level rise, resulting in the expansion of water from warming oceans. Ta.
“This is a consistent story of glacial changes.” Tyler Sutterley At Washington University in Seattle. “Areas that have had glaciers since ancient times have lost these ice symbols.”
Alps glaciers have lost more ice than any other region, shrinking nearly 40% since 2000. In the Middle East, New Zealand and the West, glaciers have seen more than 20% reductions. Depending on future emissions, the world's glaciers are predicted to lose quarter to half of the ice by the end of the century.
Lead pollution likely lowered the average IQ of ancient Rome by 2.5 to 3 points, a study has found.
The study is based on analysis of lead concentrations in ice cores taken from Greenland.
The findings provide evidence that lead may have contributed to the fall of Rome, an issue that historians and experts have debated for decades.
In ancient Rome, toxic lead was so prevalent in the air that it likely lowered the average person’s IQ by 2.5 to 3 points, a new study suggests.
The study, published Monday in the Proceedings of the National Academy of Sciences, adds to long-standing questions about what role, if any, lead pollution played in the collapse of the empire.
The authors link lead found in Greenland ice samples to ancient Roman silver smelters and determine that the incredible background pollution they produced would have affected much of Europe. .
Researchers used research on lead exposure in modern society to determine how much lead was likely in the Romans’ bloodstream and how it affected their cognition. was able to judge.
Lead, a powerful neurotoxin, remains a public health threat today. There is no safe amount to ingest into the body. Exposure is associated with an increased risk of learning disabilities, reproductive problems, mental health problems, and hearing loss, among other effects.
The researchers behind the new study said the discovery was the first clear example in history of widespread industrial pollution.
“Human and industrial activities 2,000 years ago were already having a continent-wide impact on human health,” said the study’s lead author, a researcher at the Desert Research Institute for Climate and Environment, a nonprofit research campus in Reno, Nevada. said scientist Joe McConnell. . “Lead pollution in Roman times is the earliest clear example of human impact on the environment.”
Stories of ancient pollution are buried in Greenland’s ice sheet.
Ice cores are extracted from the Greenland ice sheet. Joseph McConnell
The chemical composition of ice there and in other polar regions can yield important clues about what environments were like in the past. As snow falls, melts, and compacts to form a layer of ice, the chemicals trapped inside provide a kind of timeline.
“In environmental history, you’ve been building this layer cake every year,” McConnell said.
By drilling, extracting and processing long cylinders of ice, scientists can measure properties such as carbon dioxide in the atmosphere in past climates or, as in this case, lead concentrations over time.
Researchers analyzed three ice cores and found that lead levels rose and fell over roughly 1,000 years in response to important events in Rome’s economic history. For example, levels rose when Rome organized its rule over what is now Spain and increased silver production in the region.
A longitudinal ice core sample awaits analysis for lead and other chemicals at the Desert Research Institute in Reno, Nevada. Jesse Lemay / DRI
“For every ounce of silver produced, 10,000 ounces of lead can be produced,” McConnell said. “Just as they produced silver, the Romans were smelting and mining silver for coinage and economy, and they were introducing large amounts of lead into the atmosphere.”
McConnell said lead attaches to dust particles in the atmosphere during the smelting process. A small portion of those particles were blown away and deposited in Greenland.
Once researchers determined how much lead was concentrated in Greenland’s ice, they used a climate modeling system to determine how much lead the Romans would have released to pollute Greenland to observed levels. I calculated the amount.
The research team then analyzed modern information on lead exposure to determine the health effects of atmospheric lead during the Pax Romana, a period of peace in the empire that lasted from 27 BC to 180 AD. has been identified.
Ice samples on a melter during chemical analysis at a desert laboratory.
The researchers found that average lead exposure is about one-third of what it was in the United States in the late 1970s, when leaded gasoline use was at its peak and before the Clean Air Act was enacted. Lead levels in Rome were about twice what American children are exposed to today, McConnell said.
Researchers believe that people who lived closest to silver mines on the Iberian Peninsula (now Spain) would have had the most lead in their blood.
“Virtually no one got away,” McConnell said.
However, these results likely do not tell the full story of the health effects of lead in ancient Rome. This is because Romans were exposed through other sources, such as wine sweetened in lead-lined vessels, lead piping, and lead goblets.
Dr. Bruce Lanphear, lead expert and professor of health sciences at Canada’s Simon Fraser University, said lead was “ubiquitous” in ancient Rome. He was not involved in this study. Therefore, the new study is limited because it only assesses lead in the atmosphere, he said, and the authors acknowledge that.
A lead toy unearthed from the grave of Julia Graphis in Brescello. DeAgostini/Getty Images
“Their estimate is likely an underestimate,” Lanphear said.
Still, the study provides evidence that lead exposure may indeed have played a role, so the findings raise questions about how lead may have contributed to the decline of ancient Rome. may stimulate the ongoing debate.
“I believe that lead played a role in the decline of the Roman Empire, but it was only a contributing factor. It was never the only one,” Lanphear said.
Joe Manning, a history professor at Yale University, said most researchers believe Rome fell for a myriad of reasons, including epidemics, economic problems and climate change. Manning said it’s important to remember that ancient Rome was a tough place to survive, with an average lifespan of about 25 to 30 years.
“Under no circumstances do you want to go to a city in the ancient world. That would be the last place you want to go. ,” Manning said. “Reed has really bad hygiene.”
Last year, the obesity rate among U.S. adults decreased slightly for the first time in more than a decade, a study found.
Researchers suggested this may be due in part to the rise of weight loss drugs like Ozempic.
However, other drugs and factors (such as the effects of the coronavirus pandemic) may also have played a role.
Obesity rates among U.S. adults declined slightly last year, according to a study, but it was the first time in more than a decade that the country had seen a downward trend. Part of that may be due to the recent rise of blockbuster weight loss drugs like Ozempic, the study authors said.
The findings of the study were announced on Friday. Journal JAMA Health Forumthe most significant declines were seen in the South, especially among women and adults ages 66 to 75.
The study looked at BMI measurements for more than 16.7 million adults from 2013 to 2023 across different regions, age groups, genders, races, and ethnicities. BMI measurements are a standard but limited method for estimating obesity relative to body weight. Height to length was collected from electronic health records.
Researchers found that the adult obesity rate in the United States decreased from 46% in 2022 to 45.6% in 2023. (These are slightly higher rates than the U.S. adult obesity rate) Estimate from the centers for disease control and preventionThis means that from 2021 to 2023, approximately 40% of U.S. adults were obese. )
Benjamin Rader, a computational epidemiologist at Boston Children's Hospital and an author of the study, said the results were not uniform across demographics or geographic regions.
“Obesity has been on the decline in the United States as a whole, especially in the South, but this has not been the case in some regions,” he said. “Obesity among Black Americans also decreased significantly, but obesity among Asian Americans increased.”
Rader said the decline in the South was notable because the region observed the highest per capita intake of weight loss drugs, based on researchers' analysis of insurance claims. But he acknowledged that the possible link needed further investigation.
The study authors also noted that obese people in the South had a disproportionately high number of COVID-19 deaths, which may have influenced the overall data.
Dr. Michael Weintraub, an endocrinologist and clinical assistant professor at New York University's Grossman School of Medicine, said the results are consistent with the following: Recent data from the CDC Results showed a slight decrease in obesity prevalence among U.S. adults from 2021 to 2023 compared to 2017 to 2020 (although severe obesity increased during this period). ).
“This data is interesting and holds the promise that we may be on the cusp of changing this obesity epidemic,” said Weintraub, who was not involved in the new study. “However, I would hesitate to call the value of this downward trend in 2023 a trend.”
Even if weight loss drugs were the main factor in reducing obesity, experts say further studies over longer periods of time are needed to assess the true effects of new drugs.
“We know these drugs are very effective, but we need a few more years to see if this is really a trend, or if it's just a small spike and we're back to normal, or if things get much worse. Dr. Tannaz Moin, an endocrinologist and associate professor of medicine at the University of California, Los Angeles, said he was not involved in the study.
Moyn also pointed out that the new study only analyzed preparations of GLP-1 weight loss drugs (a category that includes Ozempic and Mounjaro). This type of drug is used to treat diabetes and obesity by reducing a person's appetite and food intake. This drug mimics the hormone that makes you feel full.
But GLP-1 drugs are only part of the prescription for treating obesity, and a more comprehensive study of different drugs could better capture changing trends, Moyn said. said. Weight loss drugs are also expensive, which can skew data about who can receive treatment.
Additionally, the study used insurance claims data, meaning those who were uninsured or who purchased weight loss drugs out of pocket were likely not included in the results.
Moin said he was surprised by the decline in BMI seen in older people.
“This group is not necessarily the group that I think is the biggest user of GLP-1 drugs, because a lot of them are in the Medicare age group,” she says, adding that weight loss drugs are the most popular for people on Medicare. may be difficult to obtain, he added. The Biden administration recently proposed a rule that would require Medicare and Medicaid to cover weight loss drugs for people seeking obesity treatment.
However, Weintraub cautioned that the observed decline does not necessarily indicate a long-term decline.
“We've been fooled until now by fluctuations in obesity prevalence,” he says. “We were excited about the downward trend in childhood obesity rates announced by the CDC in the early 2000s, but in the years since, obesity rates have increased even more.”
Global temperatures over the past two years have been even warmer than climate scientists expected.
A new study offers a possible reason: reduced cloud cover.
The study suggests that this decline may be a result of global warming, which could mean the Earth is heating up even faster than scientists thought.
Over the past two years, temperatures around the world have risen far more than scientists expected. This trend is creating the mystery of whether there are hidden climate change dynamics behind the sudden change.
Last year was the hottest summer on record, 2024 was likely to be even hotter.. Even after accounting for the expected effects of greenhouse gas pollution and El Niño (a natural pattern that generally increases temperatures), the researchers found that the roughly 0.2 degrees Celsius (0.36 degrees Fahrenheit) of warmer temperatures observed in 2023 I couldn’t explain the change.
A new study offers a possible explanation. Cloud cover has decreased over the past two years, meaning more light is now reaching and heating the Earth’s surface, rather than being reflected back into space.
In the research, Published in Science on Thursdaysuggesting that this dynamic, called an overall decrease in the planet’s albedo, is likely the cause of the observed temperature anomaly in 2023.
“This is broadly consistent with the observed recent further increase in solar radiation,” said study author Helge Goessling, a climate physicist at the Alfred Wegener Institute in Germany.
The expected cloud behavior in a warmer world is one of the most difficult aspects of the climate system to study and model. Answering questions about it will help scientists more accurately determine how sensitive the Earth is to greenhouse gas emissions.
If the decrease in low-level cloud cover is not a coincidence, it likely means the Earth is warming even faster than scientists thought.
“It’s not really clear yet how likely it is that some of this variation is variability that disappears again,” Gosling said. “This increases the likelihood of greater-than-expected warming.”
The new study is based on analysis of climate models and NASA satellite data on Earth’s reflectivity. It outlines three possible reasons for the decline in developing low clouds, but provides no conclusions about how much each factor contributes.
One option is that natural processes temporarily deviate from normal, causing a decrease in cloud cover. For example, natural fluctuations may be causing sea surface temperatures to rise more than expected, thereby changing the physics of how clouds form.
The second possibility is a change in maritime transport regulations. In 2020, the International Maritime Organization imposed limits on the sulfur content allowed in marine fuels. Some scientists believe that reducing the number of sulfur particles polluting the atmosphere may have the unintended effect of suppressing ocean cloud formation.
“They act as condensation nuclei for clouds, so they can make clouds brighter and last longer,” Goessling said of the sulfur particles.
A third option is that unidentified feedback loops within the climate system are causing clouds to decrease due to global warming.
If the latter two possibilities turn out to be the main culprits, it would mean that the climate is more sensitive to anthropogenic pollution than many scientists thought, and that humanity is therefore more likely than world leaders to It means we are closer to exceeding the targets set for emissions limits than previously realized. (The term “climate sensitivity” refers to how warm the Earth is. If the concentration of carbon dioxide and other greenhouse gases in the atmosphere doubled.. )
Still, many questions remain, said Zeke Hausfather, director of climate research at financial firm Stripe and a researcher at Berkeley Earth.
“It remains to be seen whether these changes in cloud behavior are due to short-term fluctuations and will return to more normal conditions over time, or whether they represent new and ongoing changes to the climate system. No,” he said. Email.
According to the National Oceanic and Atmospheric Administration, the average surface temperature of land and ocean in 2023 was about 2.12 degrees Fahrenheit above the 20th century average.
Efforts by world leaders to reduce greenhouse gas emissions remain insufficient. Global temperatures are on track to rise by more than 3 degrees Celsius (5.4 degrees Fahrenheit) on average, far exceeding the 1.5 degrees Celsius (2.7 degrees Fahrenheit) goal set by the Paris Agreement.
One study found that women who currently use oral contraceptives have lower rates of depression than women who previously used them. The study, which included 6,239 American women, suggests that reduced pregnancy concerns and potential “survivor bias” may explain this difference.
Researchers analyzed data from 6,239 women in the United States in the new study.
A recent study revealed that women who use oral contraceptive pills (OCP) are less likely to experience depression.
The study analyzed data from 6,239 U.S. women between the ages of 18 and 55. They found that current OCP users had a significantly lower rate of major depression at 4.6%, compared to 11.4% for women who had previously used OCPs.
The study was led by researchers at Anglia Ruskin University (ARU), along with experts from the Dana-Farber Cancer Institute in Boston and the University of California, Davis.
Possible explanations and observations
The researchers suggest two possible explanations for the study results that run counter to the commonly held belief that OCPs can cause depression.
One is that taking the pill relieves anxiety about unwanted pregnancies and helps OCP users improve their mental health. The results may also have been influenced by “survivor bias,” where women who experienced signs of depression while using OCPs stopped taking them and were placed in the category of former users.
This cross-sectional study used data collected by the Centers for Disease Control and Prevention and controlled for demographic characteristics, chronic conditions, and antidepressant use.
Among both users and former users, women who were widowed, divorced or separated, obese, or had a history of cancer were more likely to report depression. Additionally, among former users, depression was more commonly reported among women who were black or Hispanic, smoked, had lower education, or experienced poverty.
Meaning and comments
Dr Julia Gawronska, lead author and postdoctoral researcher at Anglia Ruskin University (ARU), said: “Contraception is an important component of preventive health care. Most women tolerate oral contraceptives without experiencing symptoms of depression, but some women experience unpleasant side effects and even depression. It is possible to develop a disease, and the reasons for this are not entirely clear.
“Unlike some previous studies, we found that women currently taking oral contraceptives reported more clinically relevant depression than women who previously took oral contraceptives. Turns out it’s much less likely.
“Taking the pill may have positive mental health effects for some women simply by relieving them of anxiety about pregnancy. A ‘survivor effect’ may also be at play. Women who experience symptoms of depression are more likely to stop taking the drug, placing them in a group of former users.
“However, stopping the pill without a suitable alternative increases the risk of unplanned pregnancy. Make sure women are well supported, well informed and provided with alternative contraceptive methods if necessary.” It is important that it be done.”
References: “The Association between Oral Contraceptive Use and Depression in U.S. Women” by Julia Gawronska, Katherine Meese, Lee Smith, Chao Cao, Nan Wang, and Susan Walker, October 11, 2023. Affective Disorders Journal. DOI: 10.1016/j.jad.2023.10.041
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