For years, scientists across the world have gathered evidence showing declines in sperm quality. Now, new research compiling the results of those studies has found that sperm count has dropped dramatically around the world, and the rate of decline is accelerating.
In a new analysis, researchers at Mount Sinai Medical Center, the University of Copenhagen, and the Hebrew University of Jerusalem, among others, found that sperm count globally dropped by more than half between 1973 and 2018, and that the decline is accelerating: Since 1972, sperm count has dropped by about 1% each year. Since 2000, the annual decrease has been, on average, more than 2.6%.
The findings raise concerns that an increasing number of people will need assistance to reproduce, as well as concerns about the overall health of human society, since low sperm count is linked to higher rates of some diseases. And while scientists are still trying to tease out the reasons for the drop, chemical exposures, especially to pesticides, are a likely factor — and climate change may even play a role. Researchers are calling for urgent action to bolster more research into sperm count, determine the causes of the decline, and prevent further deterioration of male reproductive health.
“We have clear evidence that there is a crisis in male reproduction,” Hagai Levine, lead author on the study and an epidemiologist at the Hebrew University of Jerusalem, told EHN.
An “alarming” decline
The study builds on the team’s previous research, which showed a decline in sperm count in North America, Europe, Australia, and parts of Asia of 28.5% between 1973 and 2011. Adding data from 38 studies to the new analysis has made the case for sperm decline stronger, Shanna Swan, an author on the paper and a leading reproductive epidemiologist at Mount Sinai, told EHN. “It’s really alarming,” said Swan, who is also an adjunct scientist with Environmental Health Sciences, which publishes EHN.org.
The research found that the average global sperm count in 2018 was 49 million per milliliter of semen. When a man’s sperm count drops below about 45 million per milliliter, his ability to cause a pregnancy starts dropping dramatically, said Swan. She said the results could mean that in the coming decades, large swaths of the global population of men could be subfertile or infertile, or could require assisted reproduction techniques, like in vitro fertilization (IVF), hormone treatment, or a technique called intracytoplasmic sperm injection (ICSI), in which sperm are directly injected into an egg.
In addition to the drop in average sperm count, Levine said it was surprising that the rate of decline was accelerating, rather than slowing down. “Is there a tipping point, that once you cross, you get an even worse situation?” he said. “That’s something to really pay attention to.”
Overall, said Levine, the results indicate that “something is very wrong with our global modern environment.”
Sperm count is not only a reproductive concern, but an indicator for other health problems in men, and is used as a predictor for male longevity. Men with poor sperm count tend to have higher rates of cardiovascular disease, certain cancers and even death, Michael Eisenberg, a professor of urology at Stanford University who was not involved in the research, told EHN. “This decline in sperm count could also suggest other health concerns,” he said.
A 2016 study authored by Eisenberg found that diabetes and other diseases were associated with lower reproductive health. However, said Eisenberg, the reason why overall health is linked to sperm quality is still unknown.
Eisenberg said the new study on sperm count decline is a “powerful addition” to previous evidence that sperm count across the globe has declined.
Reasons for the trend
Though the reasons for the drop were not discussed in the paper, scientists have known for decades that certain environmental factors, like exposures to pesticides (such as atrazine, alachlor, and diazinon) and other endocrine-disrupting chemicals, like phthalates, and polychlorinated biphenyls (PCBs), can have impacts on reproductive health. Nearly 20 years ago, for example, Swan and other researchers published an analysis of research into links between pesticide exposure and sperm quality, and found that 79% of studies indicated a decrease in sperm quality among those exposed to the chemicals. Diet, activity level, and stress may also play a role.
Swan and Levine said exposures to chemicals in the environment and other factors likely all play a substantial role in the sperm count trend. And, the risk factors are related; for example, obesity is a risk factor for lower quality sperm, but certain endocrine-disrupting chemicals — which interfere with how hormones work — are thought to contribute to obesity, as well. Diet is hard to decouple from chemical exposures, too, since pesticide residues linger on much of the food we eat.
Additionally, both Swan and Levine said climate change could be a factor, both due to climate-related stress and actual fluctuations in temperature, since heat waves are linked to decreases in sperm quality.
Prenatal exposure may be a contributor, too. Chemical exposures during the male “programming window,” when reproductive traits are formed in utero, have an outsized effect on sperm quality later in life, said Swan. For example, she said, when a man smokes — a known endocrine-disrupting activity — he lowers his sperm count by about 20%. When a male is born to a woman who smokes, his sperm count is reduced by about 50%. Those effects may last for generations before subsequent children and grandchildren return to normal sperm counts.
Protecting reproductive health
Levine is optimistic that scientists and policymakers can reverse the trend if they can determine the causes. Swan pointed to the sharp drop in cigarette smoking in the past 50 years as evidence that widespread lifestyle changes are possible, and said that any large-scale adoption of healthier habits, like better diets and more physical activity, can help improve reproductive health.
Making individual lifestyle changes like choosing organic, pesticide-free produce and staying away from certain plastics and chemical products can help lower a person’s exposure to endocrine-disrupting chemicals, too. However, doing so can be difficult, especially for disadvantaged populations with less access to fresh foods, higher environmental exposures, and fewer means to purchase safer, non-toxic household goods.
To truly tackle the problem, though, much more research is needed, said Swan. One thing she’d like to see would be better tracking of sperm count, similar to how the U.S. Centers for Disease Control and Prevention tracks obesity. Levine also said better surveillance tools will be crucial to understanding the problem more deeply.
Once humankind “defines a problem and puts our resources and mind into it, we find solutions that we could not have thought about when we started,” said Levine. “It's always theoretically reversible.”
Exposure to environmental stressors related to climate change - such as extreme weather and high temperatures - is associated with a higher risk of cardiovascular disease, according to a review of 492 studies published in JAMA Cardiology.
In short:
An increased risk of cardiovascular disease was specifically linked to extreme temperatures, ground-level air pollution, hurricanes, cyclones, and dust storms.
In some cases, experiencing a combination of stressors (such as pollution and high temperatures) amplified the risk.
Older adults, individuals from minority groups, and those in low income communities were disproportionately affected by these stressors.
Key quote:
“Urgent action is needed to reduce greenhouse gas emissions and lower climate change–associated cardiovascular risk in vulnerable populations.”
Why this matters:
As climate change continues to alter global weather patterns, the environmental consequences examined in this article are becoming more common and more intense. With international climate agreements like COP28 failing to definitively address fossil fuels and other drivers of global warming, the authors emphasize the need to recognizethe human health impacts of climate change as a way to push for concrete action.
CAMERON PARISH, La. — Late into the night, John Allaire watches the facility next to his home shoot 300-foot flares from stacks.
He lives within eyesight of southwest Louisiana’s salty shores, where, for decades, he’s witnessed nearly 200 feet of land between it and his property line disappear into the sea. Two-thirds of the land was rebuilt to aid the oil and gas industry’s LNG expansion. LNG — shorthand for liquified natural gas – is natural gas that's cooled to liquid form for easier storage or transport; it equates to 1/600th the volume of natural gas in a gaseous state. It’s used to generate electricity, or fuel stove tops and home heaters, and in industrial processes like manufacturing fertilizer.
In the U.S., at least 30 new LNG terminal facilities have been constructed or proposed since 2016, according to the
Oil and Gas Watch project. Louisiana and Texas’ Gulf Coast, where five facilities are already operating, will host roughly two-thirds of the new LNG terminals – meaning at least 22 Gulf Coast LNG facilities are currently under construction, were recently approved to break ground or are under further regulatory review.
Although the U.S. didn’t ship LNG until 2016, when a freight tanker left, a few miles from where Cameron Parish’s LNG plants are today, last year the country became the global leader in LNG production and export volume, leapfrogging exporters like Qatar and Australia. The
EIA’s most recent annual outlook estimated that between the current year and 2050, U.S. LNG exports will increase by 152%.
Allaire, 68, watches how saltwater collects where rainwater once fed the area’s diminishing coastal wetlands. “We still come down here with the kids and set out the fishing rods. It's not as nice as it used to be,” he told
Environmental Health News (EHN).
That intimacy with nature drew Allaire to the area when he purchased 311 acres in 1998. An environmental engineer and 30-year oil and gas industry veteran, he helped lead environmental assessments and manage clean-ups, and although retired, he still works part-time as an environmental consultant with major petroleum companies. With a lifetime of oil and gas industry expertise, he’s watched the industry's footprint spread across Louisiana and the Gulf of Mexico’s fragile shores and beyond. Now that the footprints are at the edge of his backyard, Allaire is among a cohort of organizers, residents and fisher-folk in the region mobilizing to stop LNG facility construction. For him, the industry’s expansion usurps the right-or-wrong ethics he carried across his consulting career. For anglers, oil and gas infrastructure has destroyed fishing grounds and prevented smaller vessels from accessing the seafood-rich waters of the Calcasieu River.
From the view of Allaire’s white pickup truck as he drives across his property to the ocean’s shore, he points to where a new LNG facility will replace marshlands. Commonwealth LNG intends to clear the land of trees and then backfill the remaining low-lying field.
“You see what’s happening with the environment,” Allaire said. “When the facts change, I got to change my mind about what we’re doing.”
Community bands together
John Allaire, left, purchased 311 acres in Cameron Parish in 1998, and has watched the oil and gas industry's footprint spread to his property.
Credit: John Allaire
During an Earth Day rally in April, community members gathered in the urban center of Lake Charles to demand local oil and gas industries help deliver a safer, healthier future for all. In between live acts by artists performing south Louisiana’s quintessential zydeco musical style, speakers like James Hiatt, a Calcasieu Parish native with ties to Cameron Parish and a Healthy Gulf organizer, and RISE St. James organizer Sharon Lavigne, who’s fighting against LNG development in rural Plaquemines Parish near the city of New Orleans, asked the nearly 100 in attendance to imagine a day in which the skyline isn’t dotted by oil and gas infrastructure.
Not long ago, it was hard to imagine an Earth Day rally in southwest Louisiana at all. For decades, the area has been decorated with fossil fuel infrastructure. Sunsets on some days are highlighted by the chemicals in the air; at night, thousands of facilities’ lights dot the dark sky.
“It takes a lot of balls for people to start speaking up,” Shreyas Vasudevan, a campaign researcher with the Louisiana Bucket Brigade, told EHN in the days after the rally. In a region with its history and economy intertwined with oil and gas production, “you can get a lot of social criticism – or ostracization, as well – even threats to your life.”
Many are involved in local, regional and national advocacy groups, including the Louisiana Bucket Brigade, Healthy Gulf, the Sierra Club, the Natural Resources Defense Council, the Turtle Island Restoration Network, the Center for Biological Diversity and the National Audubon Society.
“You see what’s happening with the environment,” Allaire said. “When the facts change, I got to change my mind about what we’re doing.” - John Allaire, environmental engineer and 30-year oil and gas industry veteran
But environmental organizers are fighting a multi-billion-dollar industry with federal and state winds at its back. And LNG’s federal support is coupled with existing state initiatives.
Under outgoing Louisiana Gov. John Bel Edwards — a term-limited Democrat — the state pledged a goal of reaching net-zero greenhouse emissions by 2050. Natural gas, which the LNG industry markets as a cleaner-burning alternative, is cited as one of the state’s solutions. Louisiana is the only state that produces a majority of its carbon emissions through fossil fuels refining industries, like LNG, rather than energy production or transportation. Governor Edwards’ office did not return EHN’s request for comment.
This accommodating attitude towards oil and gas industries has resulted in a workforce that’s trained to work in LNG refining facilities across much of the rural Gulf region, said Steven Miles, a lawyer at Baker Botts LLP and a fellow at the Baker Institute’s Center on Energy Studies. Simultaneously, anti-industrialization pushback is lacking. It’s good news for industries like LNG.
“The bad news,” Miles added. “[LNG facilities] are all being jammed in the same areas.”
One rallying cry for opponents is local health. The Environmental Integrity Project found that LNG export terminals emit chemicals like carbon monoxide –potentially deadly– and sulfur dioxide, of which the American Lung Association says long-term exposure can lead to heart disease, cancer, and damage to internal or female reproductive organs.
An analysis of emissions monitoring reports by the advocacy group the Louisiana Bucket Brigade found that Venture Global’s existing Calcasieu Pass facility had more than 2,000 permit violations.That includes exceeding the permit’s authorized air emissions limit to release nitrogen oxides, carbon monoxide, particulate matter and volatile organic compounds 286 out of its first 343 days of operation.
The Marvel Crane, the first liquid natural gas carrier to transport natural gas from the Southwest Louisiana LNG facility, transits a channel in Hackberry, Louisiana, May 28, 2019.
“This is just one facility,” at a time when three more facilities have been proposed in the region and state, Vasudevan said. Venture Global’s operational LNG facility — also known as Calcasieu Pass — “is much smaller than the other facility they’ve proposed.”
In an area that experienced 18 feet of storm surge during Hurricane Laura in 2020 — and just weeks later, struck by Hurricane Delta — Venture Global is planning to build a second export terminal Known as “CP2,” it’s the largest of the roughly two dozen proposed Gulf LNG export terminals, and a key focal point for the region’s local organizing effort.
Residents “don’t really want LNG as much as they want Cameron [Parish] from 1990 back,” Hiatt told EHN of locals’ nostalgia for a community before storms like Rita in 2005 brought up to 15 feet of storm surge, only for Laura to repeat the damage in 2020. Throughout that time, the parish’s population dipped from roughly 10,000 to 5,000. “But the wolf knocking at the door is LNG. Folks in Cameron think that's going to bring back community, bring back the schools, bring back this time before we had all these storms — when Cameron was pretty prosperous.”
“Clearly,” for the oil and gas industry, “the idea is to transform what was once the center of commercial fishing in Louisiana to gas exports,” Cindy Robertson, an environmental activist in southwest Louisiana, told EHN.
Helping fishers’ impacted by LNG is about “actual survival of this unique culture,” Cooke said.
In a measure of organizers’ success, she pointed to a recent permit hearing for Venture Global’s CP2 proposal. Regionally, it’s the only project that’s received an environmental permit, but not its export permit, which remains under federal review. At the meeting, some spoke on the company’s behalf. As an organizer, it was a moment of clarity, Cooke explained. Venture Global officials “had obviously done a lot of coaching and organizing and getting people together in Cameron to speak out on their behalf,” Cooke said. “So, in a way, that was bad. But in another way, it shows that we really had an impact.”
“It also shows that we have a lot to do,” Cooke added.
Environmental organizers like Alyssa Portaro describe a sense of fortitude among activists — she and her husband to the region’s nearby town of Vinton near the Texas-Louisiana border. Since the families’ relocation to their farm, Portaro has worked with Cameron Parish fisher-folk.
“I’ve not witnessed ‘community’ anywhere like there is in Louisiana,” Portaro told EHN. But a New Jersey native, she understands the toll environmental pollution has on low-income communities. “This environment, it’s so at risk — and it’s currently getting sacrificed to big industries.”
“People don’t know what we’d do without oil and gas. It comes at a big price,” she added.
Southwest Louisiana’s Cameron Parish is one of the state’s most rural localities. Marine economies were the area’s economic drivers until natural disasters and LNG facilities began pushing locals out, commercial fishers claim.
Credit: Xander Peters for Environmental Health News
Residents “don’t really want LNG as much as they want Cameron [Parish] from 1990 back,” James Hiatt , a Healthy Gulf organizer, told EHN. "But the wolf knocking at the door is LNG."
Credit: Xander Peters for Environmental Health News
For the most part, Cameron Parish’s life and economy has historically taken place at sea. As new LNG facilities are operational or in planning locally, locals claim the community they once knew is nearly unrecognizable.
Credit: Xander Peters for Environmental Health News
A disappearing parish
The stakes are seemingly higher for a region like southwest Louisiana, which is the epicenter of climate change impacts.
In nearly a century, the state has lost roughly 2,000 square miles of land to coastal erosion. In part driving the state’s erosion crisis is the compounding impacts of Mississippi River infrastructure and oil and gas industry activity, such as dredging canals for shipping purposes, according to a March study published in the journal Nature Sustainability. Louisiana’s Coastal Protection and Restoration Authority said Cameron Parish could lose more land than other coastal parishes over the next 50 years. A recent Climate Central report says the parish will be underwater within that time frame.
On top of erosion and sea level rise impacts, in August, 2023, marshland across southwest Louisiana’s Cameron Parish burned. The fires were among at least 600 across the Bayou State this year. Statewide, roughly 60,000 acres burned — a more than six-fold increase of the state’s average acres burned per year in the past decade alone.
But while the blaze avoided coastal Louisiana communities like Cameron Parish, the fires represented a warning coming from a growing chorus of locals across the region — one that’s echoes by the local commercial fishing population, who claimed to have experienced unusually low yields during the same time, according to a statement from a local environmental group. At the site of the Cameron Parish fires are locations for two proposed LNG expansion projects.
"The idea is to transform what was once the center of commercial fishing in Louisiana to gas exports.” - Cindy Robertson, an environmental activist in southwest Louisiana
It was an unusual occurrence for an area that’s more often itself underwater this time of year due to a storm surge from powerful storms. For LNG expansion’s local opposition, it was a red flag.
As the Louisiana Bucket Brigade has noted prior, the confluence of climate change’s raising of sea levels and the construction of LNG export terminals — some are proposed at the size of nearly 700 football fields — are wiping away the marshland folks like Allaire watched wither. Among their fears is that the future facilities won’t be able to withstand the power of another storm like Laura and its storm surge, which wiped away entire communities in 2020.
Amidst these regional climate impacts, LNG infrastructure has shown potential to exacerbate the accumulation of greenhouse gasses that cause global warming. For the most part, LNG is made up of methane — a greenhouse gas that’s more than 80 times more potent than carbon dioxide in the atmosphere. Among the 22 current LNG facility proposals, the advocacy group Sierra Club described a combined climate pollution output that would roughly equal to that of about 440 coal plants.
The climate impacts prompt some of the LNG industry’s uncertainty going forward. It isn’t clear if Asian countries, key importers of U.S. LNG, will “embrace these energy transition issues,” said David Dismuke, an energy consultant and the former executive director of Louisiana State University’s Center for Energy Studies. Likewise, European nations remain skeptical of embracing LNG as a future staple fuel source.
“They really don't want to have to pull the trigger,” Dismukes added, referring to Europe’s hesitation to commit more resources to exporting LNG from the American market. “They don't want to go down that road.”
While there will be a tapering down of natural gas supply, Miles explained, “we’re going to need natural gas for a long time,” as larger battery storage for renewables is still unavailable.
“I'm not one of these futurists that can tell you where we're going to be, but I just don't see everything being extreme,” Dismukes said. “I don't see what we've already built getting stranded and going away, either.”
For now, LNG seems here to stay. From 2012 to 2022,U.S. natural gas demand — the sum of both domestic consumption and gross exports — rose by a whopping 43%, reported the U.S. Energy Information Administration, or EIA. Meanwhile, in oil and gas hotbeds like Louisiana and Texas, natural gas demand grew by 116%.
Throughout 25 years, Allaire has witnessed southwest Louisiana’s land slowly fade, in part driven by the same industrial spread regionally. Near where the front door of his travel trailer sits underneath the aluminum awning, he points to a chenier ridge located near the end of the property. It’s disappearing, he said.
“See the sand washing over, in here?” Allaire says, as he points towards the stretches of his property. “This pond used to go down for a half mile. This is all that's left of it on this side.”
The University of Chicago has launched a Climate Systems Engineering initiative, aiming to explore solar geoengineering, despite the controversial nature and potential risks of the field.
The new initiative will focus on solar geoengineering and other Earth system modifications to combat climate change.
Solar geoengineering involves reflecting sunlight to cool the Earth, but it poses significant ethical, environmental, and geopolitical risks.
Critics fear it could lead to reduced efforts in carbon reduction and create unpredictable climate impacts.
Key quote:
“We’re going to wish we had effective carbon dioxide removal technologies operating at scale, or we’re going to wish we knew how to modulate temperatures with various forms of geoengineering to prevent human suffering.”
— Michael Greenstone, director of the Energy Policy Institute at Chicago (EPIC)
A new study reveals that the majority of the world's largest marine protected areas (MPAs) fail to implement effective conservation measures, allowing destructive activities to persist.
Only one-third of the world's largest MPAs have high or full protection, covering just 2.6% of the global ocean.
Many MPAs are "paper parks," existing in name only without any real conservation measures in place.
Some MPAs permit activities like mining and industrial fishing, undermining their conservation goals.
Key quote:
“There are 18,000 MPAs, but a hundred of them make up 90 percent of the area. These are the big needle movers.”
— Beth Pike, director of the Marine Protection Atlas
Why this matters:
Effective marine protection is vital to meeting international conservation targets and preserving marine biodiversity. The failure to implement meaningful protections jeopardizes global efforts to mitigate the impacts of climate change and human exploitation on our oceans. Read more: Can marine protected areas reduce marine disease?
George Woodwell, who founded the Woods Hole Research Center in 1985, was instrumental in shaping U.S. policies on toxic substances and climate change.
His research highlighted the dangers of synthetic pollutants and the impact of rising carbon dioxide levels, making him a key figure in early climate change awareness.
Woodwell's work led to significant environmental actions, including the federal ban on DDT and the establishment of the Environmental Defense Fund.
Key quote:
"I said the same things then that I say today. The climatic disruption has the potential of changing the earth as much as a nuclear war will."
— George Woodwell, ecologist
Why this matters:
George Woodwell's pioneering research and activism laid the groundwork for modern environmentalism and climate policy, spearheading the ongoing need to address climate change to protect public health and the environment. Read the announcement from the Woodwell Climate Research Center.
The world’s fossil fuel use increased by 1.5% in 2023, reaching 505 exajoules.
Developing countries, especially India, are driving this rise, with fossil fuels making up 89% of India's energy use.
Renewable energy sources like wind and solar also saw growth, but not enough to offset overall energy demand.
Key quote:
"In a year where we have seen the contribution of renewables reaching a new record high, ever increasing global energy demand means the share coming from fossil fuels has remained virtually unchanged at just over 80% for yet another year."
— Simon Virley, UK head of energy and natural resources at KPMG
Why this matters:
Rising fossil fuel use worsens climate change, increasing global CO2 emissions. Despite advancements in renewable energy, the slow transition away from fossil fuels endangers environmental and public health.
Pilgrims faced temperatures up to 117°F, causing many to collapse and some to die.
Families struggled to locate missing loved ones at a medical complex in Mecca.
Saudi Arabia has invested heavily in safety, but climate change may increase future risks.
Key quote:
“. . . saw a lot of people collapsing to the ground unconscious.”
— Khalid Bashir Bazaz, Indian pilgrim
Why this matters:
The scorching temperatures, made worse by the ongoing global climate crisis, have transformed the spiritual undertaking into a life-threatening ordeal. With millions of faithful traveling to Mecca each year, the risks associated with extreme weather events are becoming increasingly clear.
“Of all the levels of radium in produced water or brine around the world that I’ve looked at, I have encountered none that are consistently as high as what comes out of the Marcellus Shale.”
