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Carbon Dioxide Levels Have Passed a New Milestone

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Carbon Dioxide Levels Have Passed a New Milestone

Source: National Oceanic and Atmospheric Administration’s Global Monitoring Laboratory

The chart shows monthly numbers of carbon dioxide molecules per million molecules of dry air. Because of seasonal differences, levels are higher in May than in August.

Carbon dioxide acts like Earth’s thermostat: The more of it in the air, the more the planet warms.

In 2023, global levels of the greenhouse gas rose to 419 parts per million, around 50 percent more than before the Industrial Revolution. That means there are roughly 50 percent more carbon dioxide molecules in the air than there were in 1750.

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As carbon dioxide builds up in the atmosphere, it traps heat and warms the planet.

More carbon dioxide, warmer temperatures

Source: NOAA (carbon dioxide); NASA (temperature)

The chart shows the change in global surface temperature relative to 1951–1980, versus global carbon dioxide levels. The dotted line shows the trend line.

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Every additional amount of carbon dioxide in the atmosphere contributes to more warming, which is why climate scientists stress the need to get to zero emissions.

Currently, carbon dioxide levels are rising at near-record rates.

According to data released by the National Oceanic and Atmospheric Administration’s Global Monitoring Laboratory earlier this month, last year had the fourth-highest annual rise in global carbon dioxide levels.

Annual change in carbon dioxide levels

Source: NOAA’s Global Monitoring Laboratory

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The chart shows the increase in global carbon dioxide levels over the course of each year. In 2023, they grew by around 2.8 parts per million.

The long-term rise in carbon dioxide levels is caused by burning fossil fuels, as well as other human activities such as deforestation and concrete production.

But there is also a lot of variation from year to year, which you can see in the chart above.

How much carbon dioxide levels rise in a given year depends on two factors: the amount of fossil fuels burned globally, and the share of these emissions that are absorbed by the land and the ocean.

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Consider the first factor: While it’s true that clean energy production is rising globally, so is the demand for energy.

Fossil fuels have made up the difference. This is why global fossil fuel emissions are still at record-high values (with a brief dip during the pandemic). And they stayed high in 2023, according to a projection by the Global Carbon Budget.

Not all of these emissions end up in the air. The ocean and land absorb roughly half of the carbon dioxide that humans emit, while the rest stays in the air, said Glen Peters, a senior researcher at the CICERO Center for International Climate Research.

Where do carbon dioxide emissions go?

Source: Global Carbon Budget

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The chart shows the net amounts of carbon dioxide emissions absorbed by the atmosphere, land and ocean. The emissions are produced by burning fossil fuels, deforestation and other human activities. Data does not include 2023.

That one-half figure is an approximation. It varies from year to year depending on weather conditions and other environmental factors, resulting in the jagged lines you see in the chart above. For example, in a warm and dry year with many wildfires, the land may absorb less carbon dioxide than usual.

As the Earth warms further, climate scientists expect the land and the ocean to absorb a smaller share of carbon dioxide emissions, causing a larger share to end up in the air, said Doug McNeall, who studies these effects at Britain’s Met Office.

Xin Lan, the lead scientist responsible for NOAA’s global carbon dioxide measurements, referred to the natural absorption as a “carbon discount.”

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“We pay attention to it because we don’t know at which point that this discount is gone,” she said.

In addition to carbon dioxide, the levels of other potent greenhouse gases like methane and nitrous oxide are also on the rise, which further contribute to warming.

An exceptional year

2023 was unusually hot, both on land and in the ocean. (The oceans absorb over 90 percent of the excess heat caused by global warming.) It was the hottest year in over 170 years of record keeping, even exceeding scientists’ predictions.

One contributing factor to 2023’s extreme heat was El Niño, a climate pattern that tends to raise global temperatures. During El Niño, warm ocean currents in the Pacific Ocean cause warmer and drier weather in the tropics. This can lead to droughts that slow the growth of trees and increase the risk of wildfires.

When this happens, the land tends to absorb less carbon dioxide, and more of it ends up in the air. Several climate scientists said this may be why last year’s rise in carbon dioxide levels was substantially higher than in the years preceding it.

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Getting to zero

The current high emissions levels make the climate goal of limiting global warming to 1.5 degrees Celsius increasingly difficult to reach.

To limit warming to this threshold, experts say countries need to slam the brakes on global emissions and bring them down to near-zero in about a decade. And some are even considering more extreme technological solutions to help bridge the gap.

Even if global emissions were brought down to half of their current value, we would still continue to add carbon dioxide to the air, causing further warming.

“You need to bring them essentially down to zero in order to stop warming,” Mr. McNeall said.

How much more warming will occur depends on how long it takes for this to happen.

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On one hand, clean energy investments are booming, and renewable energy production is rising globally. But energy demand is also projected to rise, coal power plants are still being built, and some sectors of the economy — like construction and manufacturing — are harder to decarbonize, making the task ahead a steep challenge.

Even if the world exceeds the 1.5-degree threshold, “every fraction of a degree matters,” Mr. McNeall said.

“The closer that you can get to that threshold, the better.”

About the data

NOAA’s annual global carbon dioxide measurements are an average of thousands of measurements made near sea level at about 30 locations around the world. To account for local differences in humidity, measurements are made using dry air.

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Opinion: Most older Americans who need hearing aids don't use them. Here's how to change that

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Opinion: Most older Americans who need hearing aids don't use them. Here's how to change that

Having depended on hearing aids for nearly three decades, I’m astounded by the lack of Medicare coverage for devices that can solve a problem afflicting tens of millions of older Americans.

Nearly two-thirds of Americans over age 70 have some degree of hearing loss, and over half of those 75 and older experience impairment serious enough to be considered disabling. But most don’t wear hearing aids.

Because the legislation that created Medicare nearly 60 years ago specifically excluded hearing aids, those who rely on the program’s traditional coverage must pay for them out of pocket. That expense is among the chief barriers to wider use of the devices.

Age-related hearing loss impedes basic communication and the relationships that depend on it. Expanded access to hearing aids could therefore do no less than enable more older Americans to establish and maintain the social connections that are essential to a meaningful life.

Hearing loss is like an invisible, muffling curtain that falls in front of anyone speaking. Asking people to repeat themselves can yield irritated and hurtful responses. And it’s hopeless to ask a soft-spoken person to speak up. Sometimes it’s easier just to nod and smile.

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Many older people I know choose to avoid social gatherings altogether because they can’t hear well. Without hearing aids, I’d stay home too.

Hearing loss can harm one’s health in other ways. For example, I’ve written about the need for a comprehensive approach to reducing cancer risk at older ages, including preventive services such as colorectal cancer screening. But these services rely on conversations between patients and their healthcare providers. An older patient’s ability to hear and understand such conversations shouldn’t be taken for granted or ignored.

The Food and Drug Administration did improve access to hearing aids by making some of them available without a prescription in 2022, but the over-the-counter devices are inadequate for serious hearing loss like mine. My private health insurance, meanwhile, started covering hearing aids a few years ago, providing up to $2,500 for them every five years. One hearing aid alone can cost that much or more, however.

Despite its limitations, my private coverage for hearing aids is better than nothing, which is what traditional Medicare provides.

Hearing loss is more common among lower-income people and those without advanced education. The toll from noisy workplaces compounds age-related hearing loss for some. One analysis found that most Americans with a serious hearing disability can’t afford the typical price of hearing aids.

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Many of the older adults who can’t come up with these significant out-of-pocket expenses spent their working years in low-wage jobs that our country depends on. Denying them treatment for their hearing loss is a lousy way to treat people who gave years of service to our society.

Although some older adults with hearing loss won’t benefit from hearing aids, Medicare coverage for the devices might encourage more beneficiaries to get their hearing tested so they can get the treatment that’s right for them. And while Medicare coverage alone won’t address the stigma some people associate with hearing aids, the availability of newer, more comfortable and less obvious technology might win over some refuseniks.

Legislation reintroduced with bipartisan support last year would finally correct this glaring gap in Medicare coverage by removing the hearing aid exclusion from the law. There’s no reason to delay action on this any longer. Are our representatives listening?

Mary C. White is an adjunct professor of environmental health at Emory University’s Rollins School of Public Health, a Public Voices fellow at AcademyHealth in partnership with the OpEd Project and a former federal epidemiologist.

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Second human case of bird flu detected in Michigan dairy worker

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Second human case of bird flu detected in Michigan dairy worker

A second human case of bird flu in a diary worker has been confirmed in Michigan, state and federal health officials announced Wednesday.

The symptoms were mild, consisting of conjunctivitis. The Texas dairy worker who contracted the virus in March also came down with pink eye.

At a press call on Wednesday, Nirav Shah, principal deputy director of the U.S. Centers for Disease Control and Prevention, said the finding was “not unexpected” and that it was a scenario “that we had been preparing for.”

He said that since the discovery of H5N1 in dairy cattle, state and federal health officials have been closely monitoring farmworkers and slaughterhouse workers and urging farmers and farmworker organizations to “be alert, not alarmed.”

Federal officials say they still believe the human health risk of bird flu is low; however, it underscores the need for people who are interacting with infected or potentially infected farm animals or birds to take precautions, including avoiding dead animals and wearing personal protective equipment (PPE) if there’s a need to be in close contact.

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Though a nasal swab from the person in Michigan tested negative for influenza, an eye swab from the patient was shipped to the CDC and tested positive for influenza A(H5N1) virus.

This is the third case of H5N1 reported in the United States. A poultry worker in Colorado was identified in 2022.

Although the symptoms in the three farmworkers in the U.S. have been mild, people elsewhere in the world have suffered more severe illness, including death. According to the World Health Organization, between Jan. 1, 2003, and March 28, 2024, there have been 888 cases of human infection from 23 countries; 463 were fatal.

In preparation for a more widespread outbreak, the CDC updated its guidance for PPE in dairies and issued a nationwide order for healthcare providers to be on the lookout for novel influenza.

On Tuesday, the CDC asked clinical laboratories and health departments to increase the number of influenza samples being analyzed “to maximize the likelihood of catching a case of H5N1 in the community,” Shah said.

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The US Department of Agriculture is also expanding its surveillance and support by providing $1500 to non-infected farms to beef up biosecurity, and $100 to producers who want to buy inline samplers to test their milk. The agency will also provide $2000 per farm to cover veterinary fees for testing, as well as shipping costs to send those tests to laboratories for analysis.

There have been no cases of H5N1 detected in California’s dairy herds.

Officials said ongoing analysis of the nation’s dairy supply suggests it is safe to consume, Despite the risk to human health being low, an official with the Administration for Strategic Preparedness and Response said it will make Tamiflu available upon request “to jurisdictions that do not have their own stockpile and are responding to pre-symptomatic persons with exposure to confirmed or suspected infected birds, cattle or other animal exposures.”

Dawn O’Connell, assistant secretary of the preparedness agency, said it started the “fill and finish” process for approximately 4.8 million doses of vaccine “that is well matched to the currently circulating strain of H5N1 through the national pre-pandemic influenza vaccine stockpile program.”

She said the decision to get started on H5N1 vaccines was not a response to any heightened concern, but since it takes several months to fill and finish vaccine doses, the agency “thought it made sense given what we were seeing.”

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Gas stoves may contribute to early deaths and childhood asthma, new Stanford study finds

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Gas stoves may contribute to early deaths and childhood asthma, new Stanford study finds

Lung-irritating pollution created by cooking with gas stoves may be contributing to tens of thousands of premature deaths and cases of childhood asthma in the United States, according to a new study published in the journal Science Advances.

For decades, scientists have known the flames from a gas stovetop produce nitrogen dioxide, a pungent gas that can inflame a person’s lungs when inhaled. But for the first time, a team of researchers from Stanford University and Oakland-based research institute PSE Healthy Energy published a nationwide estimate of the long-term health consequences associated with cooking with natural gas and propane stoves.

Researchers concluded that exposure to nitrogen dioxide emissions alone may contribute to nearly 19,000 premature deaths in the United States each year. It has also resulted in as many as 200,000 current cases of pediatric asthma compared with cooking with electric stoves, which do not produce nitrogen dioxide.

Aggressive and impactful reporting on climate change, the environment, health and science.

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Stanford researcher Yannai Kashtan noted higher levels of pollution were correlated with the amount of gas that was burned. But pollution also accumulated at higher levels inside smaller homes.

“If you live in a smaller house, you’re exposed to more pollution, and that can lead to income and racial disparities in exposure,” Kashtan said. “In general, folks living in neighborhoods with higher levels of outdoor pollution also tend to have higher indoor pollution. So this environmental injustice extends indoors as well.”

The American Gas Assn., a trade organization representing more than 200 local energy companies nationwide, dismissed the findings as “misleading and unsupported.”

“Despite the impressive names on this study, the data presented here clearly does not support any linkages between gas stoves and childhood asthma or adult mortality,” the association’s president and CEO, Karen Harbert said in a statement earlier this month.

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The study is the latest examining the serious health effects associated with breathing fumes from gas stoves, which release planet-warming carbon emissions and a variety of air pollutants. In recent years, the popular household appliance has become a political hot-button issue as policymakers and regulators have weighed environmental impacts against consumer choice.

Many large cities in California, including Los Angeles, have moved toward phasing out gas stoves in newly constructed residences. Earlier this month, the California Assembly advanced a bill to the Senate that would require gas stoves to come with warning labels detailing the pollution and health effects that can arise from cooking with gas.

Gas stoves emit a variety of pollutants, including asphyxiating carbon monoxide, cancer-causing formaldehyde and benzene. The flame also creates nitrogen dioxide, a precursor to smog and a pollutant that can cause difficulty breathing.

Environmental groups say consumers should be notified about these pollutants and the potential harm they can cause.

“Gas stoves create pollution in our homes, increasing the risk of childhood asthma and other respiratory problems for our families,” said Jenn Engstrom, state director for California Public Interest Research Group. “However, this risk has largely been hidden from the public. Consumers deserve the truth when it comes to the danger of cooking with gas. Warning labels will give consumers what they need to make informed decisions when they purchase appliances for their homes.”

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Kashtan and other researchers had previously discovered cooking with gas stoves presented a similar cancer risk as inhaling second-hand cigarette smoke. They also found some gas stoves leaked contaminants even when the burners were off.

The effects are especially devastating to children, whose smaller and still-developing lungs need to take more breaths than adults, Kashtan said. Older adults, especially those with cardiovascular or respiratory illness, are also more vulnerable to pollution from gas stoves.

To alleviate indoor air pollution, experts recommend using ventilation hoods and opening windows while cooking,

Starting in 2008, California required new and redeveloped homes to have ventilation that could prevent pollution from building up indoors. But during their research, measuring emissions in more than 100 households across the country, Yannai said they found many kitchens didn’t have ventilation hoods at all.

Although the health effects of breathing these pollutants are clear, researchers still wonder to what degree these conditions could be reversible. As communities take steps to mitigate their exposure or transition away, he said we could soon see the results.

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“It’s never too late to stop breathing in pollution,” he said.

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