Category: Academic Reportage

Source: The Conversation – USA (3) – By Jonathan Levy, Professor and Chair, Department of Environmental Health, Boston University

The Trump administration took a major step in its efforts to unravel America’s climate policies on Feb. 12, 2026, when it moved to rescind the 2009 endangerment finding – a formal determination that six greenhouse gases that drive climate change, including carbon dioxide and methane from burning fossil fuels, endanger public health and welfare.

But the administration’s arguments in dismissing the health risks of climate change are not only factually wrong, they’re deeply dangerous to Americans’ health and safety.

As physicians, epidemiologists and environmental health scientists, we’ve seen growing evidence of the connections between climate change and harm to people’s health. Here’s a look at the health risks everyone face from climate change.

Extreme heat

Greenhouse gases from vehicles, power plants and other sources accumulate in the atmosphere, trapping heat and holding it close to Earth’s surface like a blanket. Too much of it causes global temperatures to rise, leaving more people exposed to dangerous heat more often.

Most people who get minor heat illnesses will recover, but more extreme exposure, especially without enough hydration and a way to cool off, can be fatal. People who work outside, are elderly or have underlying illnesses such as heart, lung or kidney diseases are often at the greatest risk.

Heat deaths have been rising globally, up 23% from the 1990s to the 2010s, when the average year saw more than half a million heat-related deaths. Here in the U.S., the 2021 Pacific Northwest heat dome killed hundreds of people.

Climate scientists predict that with advancing climate change, many areas of the world, including U.S. cities such as Miami, Houston, Phoenix and Las Vegas, will confront many more days each year hot enough to threaten human survival.

Extreme weather

Warmer air holds more moisture, so climate change brings increasing rainfall and storm intensity and worsening flooding, as many U.S. communities have experienced in recent years. Warmer ocean water also fuels more powerful hurricanes.

Increased flooding carries health risks, including drownings, injuries and water contamination from human pathogens and toxic chemicals. People cleaning out flooded homes also face risks from mold exposure, injuries and mental distress.

Climate change also worsens droughts, disrupting food supplies and causing respiratory illness from dust. Rising temperatures and aridity dry out forests and grasslands, making them a setup for wildfires.

Air pollution

Wildfires, along with other climate effects, are worsening air quality around the country.

Wildfire smoke is a toxic soup of microscopic particles (known as fine particulate matter, or PM2.5) that can penetrate deep in the lungs and hazardous compounds such as lead, formaldehyde and dioxins generated when homes, cars and other materials burn at high temperatures. Smoke plumes can travel thousands of miles downwind and trigger heart attacks and elevate lung cancer risks, among other harms.

Meanwhile, warmer conditions favor the formation of ground-level ozone, a heart and lung irritant. Burning of fossil fuels also generates dangerous air pollutants that cause a long list of health problems, including heart attacks, strokes, asthma flare-ups and lung cancer.

Infectious diseases

Because they are cold-blooded organisms, insects are directly influenced by temperature. So with rising temperatures, mosquito biting rates rise as well. Warming also accelerates the development of disease agents that mosquitoes transmit.

Mosquito-borne dengue fever has turned up in Florida, Texas, Hawaii, Arizona and California. New York state just saw its first locally acquired case of chikungunya virus, also transmitted by mosquitoes.

And it’s not just insect-borne infections. Warmer temperatures increase diarrhea and foodborne illness from Vibrio cholerae and other bacteria and heavy rainfall increases sewage-contaminated stormwater overflows into lakes and streams. At the other water extreme, drought in the desert Southwest increases the risk of coccidioidomycosis, a fungal infection known as valley fever.

Other impacts

Climate change threatens health in numerous other ways. Longer pollen seasons increase allergen exposures. Lower crop yields reduce access to nutritious foods.

Mental health also suffers, with anxiety, depression and post-traumatic stress following disasters, and increased rates of violent crime and suicide tied to high-temperature days.

Young children, older adults, pregnant women and people with preexisting medical conditions are among the highest-risk groups. Lower-income people also face greater risk because of higher rates of chronic disease, higher exposures to climate hazards and fewer resources for protection, medical care and recovery from disasters.

Policy-based evidence-making

The evidence linking climate change with health has grown considerably since 2009. Today, it is incontrovertible.

Studies show that heat, air pollution, disease spread and food insecurity linked to climate change are worsening and costing millions of lives around the world each year. This evidence also aligns with Americans’ lived experiences. Anybody who has fallen ill during a heat wave, struggled while breathing wildfire smoke or been injured cleaning up from a hurricane knows that climate change can threaten human health.

Yet the Trump administration is willfully ignoring this evidence in proclaiming that climate change does not endanger health.

Its move to rescind the 2009 endangerment finding, which underpins many climate regulations, fits with a broader set of policy measures, including cutting support for renewable energy and subsidizing fossil fuel industries that endanger public health. In addition to rescinding the endangerment finding, the Trump administration also moved to roll back emissions limits on vehicles – the leading source of U.S. carbon emissions and a major contributor to air pollutants such as PM2.5 and ozone.

It’s not just about endangerment

The evidence is clear: Climate change endangers human health. But there’s a flip side to the story.

When governments work to reduce the causes of climate change, they help tackle some of the world’s biggest health challenges. Cleaner vehicles and cleaner electricity mean cleaner air – and less heart and lung disease. More walking and cycling on safe sidewalks and bike paths mean more physical activity and lower chronic disease risks. The list goes on. By confronting climate change, we promote good health.

To really make America healthy, in our view, the nation should acknowledge the facts behind the endangerment finding and double down on our transition from fossil fuels to a healthy, clean energy future.

This article includes material from a story originally published Nov. 12, 2025.

Jonathan Levy receives funding from the National Institutes of Health, the Federal Aviation Administration, the City of Boston, the Masschusetts Office of the Attorney General, and the Mosaic Foundation.

Howard Frumkin has no financial conflicts of interest to report. He is a member of advisory boards (or equivalent committees) for the Planetary Health Alliance; the Harvard Center for Climate, Health, and the Global Environment; the Medical Society Consortium on Climate Change and Health; the Global Consortium on Climate and Health Education; the Yale Center on Climate Change and Health; and EcoAmerica’s Climate for Health program, and chairs the National Academy of Medicine Committee on the Roadmap for Transformative Action to Achieve Health for All at Net-Zero Emissions—all voluntary unpaid positions.

Jonathan Patz receives funding from the National Institutes of Health. He is affiliated with the Medical Society Consortium for Climate and Health, and its affiliate Healthy Climate Wisconsin.

Vijay Limaye is affiliated with the Natural Resources Defense Council.

– ref. Trump’s EPA decides climate change doesn’t endanger public health – the evidence says otherwise – https://theconversation.com/trumps-epa-decides-climate-change-doesnt-endanger-public-health-the-evidence-says-otherwise-275619

Source: The Conversation – USA (3) – By Christopher Lieu, Professor of Medical Oncology, University of Colorado Anschutz Medical Campus

An increasing number of people are dying of colorectal cancer at a young age, including those as young as 20. Actor James Van Der Beek, who was diagnosed with colorectal cancer in 2023, died at age 48 on Feb. 11, 2026, bringing the disease back into the limelight.

The Conversation U.S. asked gastrointestinal oncologist Christopher Lieu and cancer researcher Andrea Dwyer to explain what’s known about early-onset colon cancer and what young people can do to protect themselves.

Why are more young people getting colorectal cancer?

Researchers have identified a number of factors associated with increasing numbers of young people developing colorectal cancer, but there is no one clear answer that explains this trend.

Lifestyle factors like ultra-processed foods and alcohol, as well as lack of exercise, have been linked to early-onset colorectal cancer. However, these are correlations that aren’t proven to be the cause of colorectal cancer in young adults.

Many researchers are focusing on the gut microbiome, which is an ecosystem of microorganisms in your gut that helps your body digest food and carry out other important functions. When the microbes in the gut are out of balance – a condition called dysbiosis – this causes a disruption that allows for inflammation and negative health effects, including increased cancer risk.

What increases your risk of developing colorectal cancer?

Beyond genetics, several lifestyle factors can increase your risk of developing colorectal cancer.

For example, someone’s diet plays a role in cancer risk. Eating a lot of red meat and processed foods and not enough dietary fiber can increase your risk of colorectal cancer. Alcohol also causes cancer – even having less than one drink a day can increase your cancer risk.

Smoking, obesity and lack of exercise are other factors that increase cancer risk.

What’s the survival rate for young people with colon cancer?

There is a lot of debate among researchers on whether there are differences in survival rates between those with early-onset colorectal cancer survival and those who develop the disease after age 50.

Finding cancer at an early stage can lead to five-year survival rates as high as 80% to 90%. When cancer is detected at an advanced stage where it has spread to other parts of the body, survival rates are closer to 10% to 15%.

One study found that young patients with metastatic colon cancer had a slightly lower survival rate compared with those age 50 or older.

What are early symptoms of colorectal cancer?

The most common signs and symptoms for early-onset colorectal cancer are blood in the stool, abdominal pain and a change in bowel habits, or any combination of these conditions. Unexplained anemia, or low red blood cell levels, is another potential symptom. These are warning signs that people should not ignore.

Having these symptoms does not necessarily mean you have colorectal cancer, but they are worth discussing with a physician. In some cases, your doctor may request a colonoscopy for further evaluation.

How does colon cancer screening work?

The first step is to have a conversation with your health care team about which test is right for you. Understanding what your risk category is helps guide screening, prevention and lifestyle changes to reduce your likelihood of colorectal cancer.

People with an average risk for colorectal cancer typically have no personal or significant family history of colorectal cancer, hereditary cancer, precancerous polyps or inflammatory bowel disease. They have several options for screening, including stool tests that check for blood and abnormal cells, as well as imaging scans to visualize the colon and rectum. Screening is recommended to begin at age 45 and should continue at regular intervals until age 75.

People with a high risk of colon cancer typically have a personal or family history of colorectal cancer, hereditary cancer or inflammatory bowel disease. They may also have several lifestyle risk factors. Colonoscopy is the only recommended screening test for those with high risk, and earlier and more frequent screening may be necessary.

How can you reduce your risk of colon cancer?

Communication and action are key. Talk to your health care team about your personal risk based on your age, family history and any signs and symptoms to ensure you’re matched with the screening exam and test best for you.

Take charge of your health. There are lifestyle factors you can control to reduce your personal risk of colorectal cancer. These include regular physical activity; a diet high in fruit, vegetables and fiber, and low in processed meats; and maintaining a healthy weight. Moderating or eliminating alcohol and tobacco use can also reduce your colorectal cancer risk.

Share information with loved ones and your health care team. Knowing your personal and family history of polyps or colorectal cancer and communicating it with your doctor can help ensure you get the right test at the right time. Sharing your personal history could save the lives of your children, siblings and parents.

The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

– ref. Colorectal cancer is increasing among young people, James Van Der Beek’s death reminds – cancer experts explain ways to decrease your risk – https://theconversation.com/colorectal-cancer-is-increasing-among-young-people-james-van-der-beeks-death-reminds-cancer-experts-explain-ways-to-decrease-your-risk-275886

Source: The Conversation – USA – By Jamey Jacob, Regents Professor of Aerospace Engineering and Executive Director, Oklahoma Aerospace Institute for Research and Education, Oklahoma State University

When the Federal Aviation Administration closed the airport in El Paso, Texas, and the airspace around it on Feb. 10, 2026, the cause was, ironically, the nearby use of a technology that could be key to keeping airports and airspace open and safe.

According to news reports, Customs and Border Protection officials used a Department of Defense anti-drone laser weapon to target what they identified as a drone crossing the border from Mexico. The FAA closed the El Paso airport and airspace out of concern that the weapon inadvertently posed a threat to air traffic in the area.

The targeted drone turned out to be a party balloon, though U.S. officials claim that drug cartels based in Mexico have flown drones at the U.S.-Mexico border. The episode highlights the need for counter-drone technologies, the state-of-the-art systems used by the U.S. military, and the challenges to safely and effectively countering drones, which are also known as uncrewed aircraft systems.

I am an aerospace engineer and director of the Counter-UAS Center of Excellence at Oklahoma State University, where we develop and evaluate technologies to detect, identify and counter drone threats. The military laser weapon CBP that personnel used near El Paso is an example of one of three categories of counter-drone technologies: directed energy weapons. The other two are radio frequency jamming and kinetic, or physical, weapons like missiles and nets.

The emerging threat

Starting in 2015, the ISIS terrorist group modified commercial off-the-shelf drones to drop grenades and mortars on U.S. troops in Iraq and Syria, who had little way to combat the threat. This started the trend of modifying consumer drones for military purposes that continues to this day on the Russian-Ukrainian front lines.

While military bases ostensibly have some protective capabilities, critical U.S. infrastructure such as airports and power plants have few methods to track, let alone defend against, drones. For example, in 2018, traffic at London Gatwick International Airport in the U.K. was shut down for three days because of an unidentified drone in the airport’s airspace. Hundreds of flights were canceled, affecting over 100,000 passengers.

Sites such as civilian and military airports, power plants and stadiums are vulnerable to drone flights, both from malicious and negligent operators. Drone flight over open stadiums such as those hosting upcoming FIFA World Cup soccer matches are banned by the FAA. But the ban wouldn’t prevent an errant civilian drone or a drone used in a terrorist attack from entering a stadium and potentially causing serious harm to spectators.

On June 1, 2025, Ukrainian forces deployed more than 100 “kamikaze” drones deep in Russian territory in an attack labeled Operation Spiderweb that damaged a significant portion of Russia’s bomber fleet. There is little stopping something like this from happening in the U.S.

To address this threat, companies are evaluating numerous ways to track, identify and, most importantly, defeat drones and protect critical U.S. infrastructure. At present, however, there is no one-size-fits-all solution.

Counter-drone technologies

Radio frequency waves that both track and jam drones have become widely used in the Russia-Ukraine war. Like all remote control devices, drones use radio frequencies to control flight and monitor video coming from the drone camera. Detectors can track these radio frequency signals to determine a drone’s location.

Devices that emit radio frequency signals can be used to block, or jam, communications between drones and their operators or send false, or spoofed, signals. Jamming or spoofing a drone typically causes it to enter into a “return to home” mode and leave the defended area. Radio frequency systems are helpful in situations where a low-impact response is required, because they prevent drones from completing their intended mission without causing physical damage to them.

However, this doesn’t necessarily work if a drone is operating in a “run silent” mode by not transmitting information back to a remote operator. Similarly, jamming GPS can cause a drone to lose its ability to navigate using the satellite system, but this also blocks GPS signals for other users. Drones can also navigate without GPS, with less accurate techniques such as following terrain with cameras or the dead reckoning approach commonly used by pilots.

Directed energy systems, on the other hand, use high-energy lasers or microwave beams to disable drones. These systems work by directing a concentrated beam of energy toward an incoming drone. A laser or microwave can heat components rapidly until the drone becomes inoperative. A laser can also disable a drone’s camera, disabling its surveillance capability. Additionally, because these systems use energy beams, they can engage multiple drones at once.

However, fast-moving drones may be difficult for the weapons to target, and the cost of such systems makes them prohibitively expensive for widespread use.

Kinetic systems involve physically intercepting drones to neutralize them. This category includes everything from net-carrying interceptor drones to traditional projectile weapons, such as firearms and missiles. Kinetic systems physically disable or capture drones, making them particularly useful in scenarios where it is necessary to quickly remove drones from sensitive areas or when the drone presents an immediate threat.

However, because a damaged aircraft can crash in unpredictable locations, these systems may be more effective in battlefields where falling debris is less likely to cause unwanted damage on the ground.

Swiss cheese safety

Together, these three types of counter-drone technologies – radio frequency, directed energy and kinetic – provide a comprehensive tool kit for addressing the diverse threats posed by unauthorized drones. However, there is no single ideal solution to counter these threats.

To maximize safety, the Swiss cheese model is often the best approach. In this analogy, each defensive strategy is a slice of the familiar holey cheese. While some threats may pass through a hole in one layer, the next layer can capture what passes through. This way, a drone making it through the weaknesses in one system can be defeated by the next slice of cheese.

Jamey Jacob receives funding from the Depts. of Defense and Homeland Security to evaluate Counter-UAS capabilities and UAS threats. He is affiliated with AUVSI, the Association of Unmanned Vehicle Systems International (AUVSI).

– ref. Counter-drone technologies are evolving – but there’s no surefire way to defend against drone attacks – https://theconversation.com/counter-drone-technologies-are-evolving-but-theres-no-surefire-way-to-defend-against-drone-attacks-229595

Source: The Conversation – USA (2) – By Gary W. Yohe, Professor of Economics and Environmental Studies, Wesleyan University

In 2009 the U.S. Environmental Protection Agency formally declared that greenhouse gas emissions, including from vehicles and industry, endanger public health and welfare. The decision, known as the endangerment finding, was based on years of evidence, and it has underpinned EPA actions on climate change ever since.

The Trump administration is now tearing up that finding as it tries to roll back climate regulations on everything from vehicles to industries.

“This is as big as it gets,” EPA Administrator Lee Zeldin said in announcing with President Donald Trump on Feb. 12, 2026, that the administration had “terminated” the endangerment finding. Zeldin argued that the finding had “no basis in law.” Trump, smiling next to him, talked about the benefits of fossil fuels and said the finding that greenhouse gas emissions endanger public health and welfare “had no basis in fact. None whatsoever.”

There’s no question that the EPA’s decision will be challenged in court. The legal question over the EPA’s authority to regulate greenhouse gases will be debated, just as it was in 2009. The administration’s claim that the finding was scientifically wrong, however, has no basis in fact.

The world just experienced its three hottest years on record, evidence of worsening climate change is stronger now than ever before, and people across the U.S. are increasingly experiencing the harm firsthand.

Several legal issues have already surfaced that could get in the EPA’s way. They include evidence from emails submitted in a court case that suggest political appointees sought to direct the scientific review that the administration has used to defend its plan, at the exclusion of respected scientific sources. On Jan. 30 a federal judge ruled that the Department of Energy violated the law when it handpicked five researchers to write the climate science review. The ruling doesn’t necessarily stop the EPA, but it raises questions.

To understand what happens now, it helps to look back at history for some context.

The Supreme Court started it

The endangerment finding stemmed from a 2007 U.S. Supreme Court ruling in Massachusetts v. EPA.

The court found that various greenhouse gases, including carbon dioxide, were “pollutants covered by the Clean Air Act,” and it gave the EPA an explicit set of instructions.

The court wrote that the “EPA must determine whether or not emissions from new motor vehicles cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare.”

But the Supreme Court did not order the EPA to regulate greenhouse gas emissions. Only if the EPA found that emissions were harmful would the agency be required, by law, “to establish national ambient air quality standards for certain common and widespread pollutants based on the latest science” – meaning greenhouse gases.

The EPA was required to follow formal procedures – including reviewing the scientific research, assessing the risks and taking public comment – and then determine whether the observed and projected harms were sufficient to justify publishing an “endangerment finding.”

That process took two years. EPA Administrator Lisa Jackson announced on Dec. 7, 2009, that the then-current and projected concentrations of six key greenhouse gases in the atmosphere – carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride – threatened the public health and welfare of current and future generations.

Challenges to the finding erupted immediately.

Jackson denied 10 petitions received in 2009-2010 that called on the administration to reconsider the finding.

On June 26, 2012, the U.S. Court of Appeals for the D.C. Circuit upheld the endangerment finding and regulations that the EPA had issued under the Clean Air Act for passenger vehicles and permitting procedures for stationary sources, such as power plants.

This latest challenge is different.

It came directly from the Trump administration without going through normal channels. It was, though, entirely consistent with both the conservative Heritage Foundation’s Project 2025 plan for the Trump administration and President Donald Trump’s dismissive perspective on climate risk.

Trump’s burden of proof

To legally reverse the 2009 finding, the agency was required to go through the same evaluation process as before. According to conditions outlined in the Clean Air Act, the reversal of the 2009 finding must be justified by a thorough and complete review of the current science and not just be political posturing.

That’s a tough task.

Energy Secretary Chris Wright has talked publicly about how he handpicked the five researchers who wrote the scientific research review. A judge has now found that the effort violated the 1972 Federal Advisory Committee Act, which requires that agency-chosen panels providing policy advice to the government conduct their work in public.

All five members of the committee had been outspoken critics of mainstream climate science. Their report, released in summer 2025, was widely criticized for inaccuracies in what they referenced and its failure to represent the current science.

Scientific research available today clearly shows that greenhouse gas emissions harm public health and welfare. Importantly, evidence collected since 2009 is even stronger now than it was when the first endangerment finding was written, approved and implemented.

For example, a 2025 review by the National Academies of Sciences, Engineering and Medicine determined that the evidence supporting the endangerment finding is even stronger today than it was in 2009. A 2019 peer-reviewed assessment of the evidence related to greenhouse gas emissions’ role in climate change came to the same conclusion.

The Sixth Assessment of the Intergovernmental Panel on Climate Change, a report produced by hundreds of scientists from around the world, found in 2023 that “adverse impacts of human-caused climate change will continue to intensify.”

In other words, greenhouse gas emissions were causing harm in 2009, and the harm is worse now and will be even worse in the future without steps to reduce emissions.

In public comments on the Department of Energy’s problematic 2025 review, a group of climate experts from around the world reached the same conclusion, adding that the Department of Energy’s Climate Working Group review “fails to adequately represent this reality.”

What happens now that the EPA has dropped the endangerment finding

As an economist who has studied the effects of climate change for over 40 years, I am concerned that the EPA’s rescinding the endangerment finding will lead to faster efforts to roll back U.S. climate regulations meant to slow climate change.

It will also give the administration cover for further actions that would defund more science programs, stop the collection of valuable data, freeze hiring and discourage a generation of emerging science talent.

Cases typically take years to wind through the courts, but both the Environmental Defense Fund and the Union of Concerned Scientists expect to file lawsuits quickly once the rescission is published in the Federal Register.

Unless a judge issues an injunction, I expect to see an accelerating retreat from U.S. efforts to reduce climate change. For example, consider the removal in early February of the climate science chapter from a new “Reference Manual on Scientific Evidence” that advises judges. Republican state attorneys general had complained to the Federal Judicial Center of the National Academies of Science, Engineering, and Medicine that the manual “treated human influence on climate as fact.” But it is fact. That is not just my opinion. The National Academies itself said so in 2020 and again in 2025.

I see no scenario in which a legal challenge doesn’t end up before the Supreme Court. I would hope that both the enormous amount of scientific evidence and the words in the preamble of the U.S. Constitution would have some significant sway in the court’s considerations. It starts, “We the People of the United States, in Order to form a more perfect Union,” and includes in its list of principles, “promote the general Welfare.

This article, originally published Feb. 2, 2026, has been updated with EPA rescinding the endangerment finding.

Gary W. Yohe does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. EPA rescinds 2009 endangerment finding, clearing way for Trump to shred more US climate rules – but serious court challenges await – https://theconversation.com/epa-rescinds-2009-endangerment-finding-clearing-way-for-trump-to-shred-more-us-climate-rules-but-serious-court-challenges-await-274194

Source: The Conversation – USA (3) – By Jonathan Levy, Professor and Chair, Department of Environmental Health, Boston University

The Trump administration took a major step in its efforts to unravel America’s climate policies on Feb. 12, 2026. It moved to rescind the 2009 endangerment finding, a formal determination that greenhouse gas emissions, such as carbon dioxide and methane from burning fossil fuels, endanger public health and welfare. But the administration’s arguments in dismissing the health risks of climate change are not only factually wrong, they’re deeply dangerous to Americans’ health and safety.

As physicians, epidemiologists and environmental health scientists, we’ve seen growing evidence of the connections between climate change and harm to people’s health.

Here’s a look at the health risks everyone face from climate change.

Extreme heat

Greenhouse gases from vehicles, power plants and other sources accumulate in the atmosphere, trapping heat and holding it close to Earth’s surface like a blanket. Too much of it causes global temperatures to rise, leaving more people exposed to dangerous heat more often.

Most people who get minor heat illnesses will recover, but more extreme exposure, especially without enough hydration and a way to cool off, can be fatal. People who work outside, are elderly or have underlying illnesses such as heart, lung or kidney diseases are often at the greatest risk.

Heat deaths have been rising globally, up 23% from the 1990s to the 2010s, when the average year saw more than half a million heat-related deaths. Here in the U.S., the 2021 Pacific Northwest heat dome killed hundreds of people.

Climate scientists predict that with advancing climate change, many areas of the world, including U.S. cities such as Miami, Houston, Phoenix and Las Vegas, will confront many more days each year hot enough to threaten human survival.

Extreme weather

Warmer air holds more moisture, so climate change brings increasing rainfall and storm intensity and worsening flooding, as many U.S. communities have experienced in recent years. Warmer ocean water also fuels more powerful hurricanes.

Increased flooding carries health risks, including drownings, injuries and water contamination from human pathogens and toxic chemicals. People cleaning out flooded homes also face risks from mold exposure, injuries and mental distress.

Climate change also worsens droughts, disrupting food supplies and causing respiratory illness from dust. Rising temperatures and aridity dry out forests and grasslands, making them a setup for wildfires.

Air pollution

Wildfires, along with other climate effects, are worsening air quality around the country.

Wildfire smoke is a toxic soup of microscopic particles (known as fine particulate matter, or PM2.5) that can penetrate deep in the lungs and hazardous compounds such as lead, formaldehyde and dioxins generated when homes, cars and other materials burn at high temperatures. Smoke plumes can travel thousands of miles downwind and trigger heart attacks and elevate lung cancer risks, among other harms.

Meanwhile, warmer conditions favor the formation of ground-level ozone, a heart and lung irritant. Burning of fossil fuels also generates dangerous air pollutants that cause a long list of health problems, including heart attacks, strokes, asthma flare-ups and lung cancer.

Infectious diseases

Because they are cold-blooded organisms, insects are directly influenced by temperature. So with rising temperatures, mosquito biting rates rise as well. Warming also accelerates the development of disease agents that mosquitoes transmit.

Mosquito-borne dengue fever has turned up in Florida, Texas, Hawaii, Arizona and California. New York state just saw its first locally acquired case of chikungunya virus, also transmitted by mosquitoes.

And it’s not just insect-borne infections. Warmer temperatures increase diarrhea and foodborne illness from Vibrio cholerae and other bacteria and heavy rainfall increases sewage-contaminated stormwater overflows into lakes and streams. At the other water extreme, drought in the desert Southwest increases the risk of coccidioidomycosis, a fungal infection known as valley fever.

Other impacts

Climate change threatens health in numerous other ways. Longer pollen seasons increase allergen exposures. Lower crop yields reduce access to nutritious foods.

Mental health also suffers, with anxiety, depression and post-traumatic stress following disasters, and increased rates of violent crime and suicide tied to high-temperature days.

Young children, older adults, pregnant women and people with preexisting medical conditions are among the highest-risk groups. Lower-income people also face greater risk because of higher rates of chronic disease, higher exposures to climate hazards and fewer resources for protection, medical care and recovery from disasters.

Policy-based evidence-making

The evidence linking climate change with health has grown considerably since 2009. Today, it is incontrovertible.

Studies show that heat, air pollution, disease spread and food insecurity linked to climate change are worsening and costing millions of lives around the world each year. This evidence also aligns with Americans’ lived experiences. Anybody who has fallen ill during a heat wave, struggled while breathing wildfire smoke or been injured cleaning up from a hurricane knows that climate change can threaten human health.

Yet the Trump administration is willfully ignoring this evidence in proclaiming that climate change does not endanger health.

Its move to rescind the 2009 endangerment finding, which underpins many climate regulations, fits with a broader set of policy measures, including cutting support for renewable energy and subsidizing fossil fuel industries that endanger public health. In addition to rescinding the endangerment finding, the Trump administration also moved to roll back emissions limits on vehicles – the leading source of U.S. carbon emissions and a major contributor to air pollutants such as PM2.5 and ozone.

It’s not just about endangerment

The evidence is clear: Climate change endangers human health. But there’s a flip side to the story.

When countries work to reduce the causes of climate change, they help tackle some of the world’s biggest health challenges. Cleaner vehicles and cleaner electricity mean cleaner air – and less heart and lung disease. More walking and cycling on safe sidewalks and bike paths mean more physical activity and lower chronic disease risks. The list goes on. By confronting climate change, we promote good health.

To really make America healthy, in our view, the nation should acknowledge the facts behind the endangerment finding and double down on our transition from fossil fuels to a healthy, clean energy future.

This article includes material from a story originally published Nov. 12, 2025.

Jonathan Levy receives funding from the National Institutes of Health, the Federal Aviation Administration, the City of Boston, the Masschusetts Office of the Attorney General, and the Mosaic Foundation.

Howard Frumkin has no financial conflicts of interest to report. He is a member of advisory boards (or equivalent committees) for the Planetary Health Alliance; the Harvard Center for Climate, Health, and the Global Environment; the Medical Society Consortium on Climate Change and Health; the Global Consortium on Climate and Health Education; the Yale Center on Climate Change and Health; and EcoAmerica’s Climate for Health program, and chairs the National Academy of Medicine Committee on the Roadmap for Transformative Action to Achieve Health for All at Net-Zero Emissions—all voluntary unpaid positions.

Jonathan Patz receives funding from the National Institutes of Health. He is affiliated with the Medical Society Consortium for Climate and Health, and its affiliate Healthy Climate Wisconsin.

Vijay Limaye is affiliated with the Natural Resources Defense Council.

– ref. Trump says climate change doesn’t endanger public health – evidence shows it does, from extreme heat to mosquito-borne illnesses – https://theconversation.com/trump-says-climate-change-doesnt-endanger-public-health-evidence-shows-it-does-from-extreme-heat-to-mosquito-borne-illnesses-275619