See collections

Last revised:

Climate change and male fertility

According to the Centers for Disease Control and Prevention (CDC), climate change influences human health in a myriad of ways — from increased respiratory and cardiovascular disease to decreased mental health. There’s also emerging evidence climate change can negatively impact reproduction, sperm health, and male fertility. Let’s explore the research on climate change and male fertility, other environmental effects on male fertility, and steps you can take to stay healthy.

Key takeaways

  • Climate change impacts people’s health, including male fertility and sperm quality.
  • Animal and human studies indicate hot weather negatively affects sperm production and sperm quality.
  • Besides climate change, exposure to other environmental factors, like air pollution and endocrine disruptors, also contributes to male-factor infertility.
  • You can take steps toward sperm quality improvement and freeze your sperm to preserve your fertility as the climate continues to change.

What is climate change?

Climate change describes long-term shifts in temperatures and weather patterns in particular regions. These shifts may be caused naturally, through variations in the solar cycle, or they can be a result of human activities, namely the burning of fossil fuels like coal, oil, and gas. These fossil fuels produce greenhouse gas emissions that trap the sun’s heat and drive up temperatures.

Since the 1880s, Earth’s temperature has risen by at least 0.14°F on average every decade. And, in fact, the rate of global warming over the past 40 years has been more than twice that, with a 0.32°F increase per decade since 1981. This increase has resulted in temperature extremes in different areas at different times of the year, decreased snow cover and sea ice, heavier rainfall, and an altered habitat for plants and animals. It also threatens our overall health.

Climate change and male fertility

One aspect of our health under threat is fertility, especially when it comes to sperm health and sperm quality. Several animal studies suggest sperm quality is especially vulnerable to the effects of climate change. This likely has implications for human sperm as well.

Animal studies on climate change and sperm production

A 2021 study indicated rising temperatures may impair sperm production, reducing the human and animal populations.

The research looked at the common fruit fly, comparing species in tropical and mid-latitude habitats versus other widespread locations. Experts have found the tropical and mid-latitude species were more at risk of extinction because of the rising temperatures in these areas.

Why? While some experts originally believed the threat of extinction was related to the organisms’ upper critical thermal limits (the maximum body temperature that can be tolerated before they stop moving and die), researchers in the 2021 study found male fertility thermal limits were an even better indicator of their vulnerability.

Male fertility thermal limits tend to be far lower than critical thermal limits. In other words, while a fruit fly might fall into a heat coma and die at a particular temperature, its ability to reproduce is already impaired at a lower temperature — preventing future generations of fruit flies from being born and rendering the species extinct through infertility.

The researchers also found little evidence of adaptive responses to warming in any fruit fly species. That means the common fruit fly, at least, doesn’t seem able to evolve as quickly as our planet is warming. This suggests a dire conclusion: species are living closer to their upper male fertility thermal limits, and evolution isn’t able to keep up to rescue these populations from the possibility of extinction.

Another study looked at the red flour beetle. This research also found rising temperatures negatively affected sperm function, sperm quality, and reproductive success, with male sperm count declining by 75%. The ejaculated sperm often struggled to migrate into the female tract, and were more likely to die before successful fertilization.

This study concluded that heat waves consistently halved male reproductive fitness in the red flour beetles — and the problems didn’t stop when the temperature returned to normal. Researchers also discovered that offspring produced by males who had lived through heat waves had shorter life spans and impaired reproductive capabilities.

Human research into the effect of climate change on male fertility

Climate change may negatively affect human sperm quality and male fertility, too. While more studies are needed, research from 2020 indicated climate change may impact male fertility directly, through increased heat that may disrupt reproductive hormones and sperm quality, or indirectly, through allowing for the rise of new infectious organisms or impacting food quality and therefore overall health and male fertility.

Comparisons of semen analyses collected in the summer and winter have also indicated that hot weather affects sperm production and sperm quality. A 1988 study of men in New Orleans found semen specimens collected during the summer had “significantly lower sperm concentration, total sperm per ejaculate, percent motile sperm, and motile sperm concentration than samples provided at other times of year,” especially for men whose jobs were not air-conditioned.

The same research team followed up with a small study of men in San Antonio in 1990. Again, they found summer spelled “significant reductions” in sperm concentration (32%), total sperm count (24%), and sperm motility (28%). They also found the impact of heat was most detrimental for sperm quality in men who already had lower semen parameters.

While this didn’t specifically look at how rising global temperatures could impact male fertility — and there’s not a direct line from warmer climates to male-factor infertility — it’s clear warmer weather and heat waves have a significant negative effect on sperm health and sperm quality for humans as well as animals.

Environmental effects on male fertility

Climate change isn’t the only environmental threat to male fertility. Researchers have noted a connection between air quality and male fertility and discovered endocrine disruptors (chemicals found in plastics and pesticides, among other sources) can also interfere with the hormonal and reproductive systems of both sexes.

Pollution, air quality, and male fertility

Researchers have long suspected that environmental factors, like air quality, contribute to male-factor infertility. A 2000 study from the Czech Republic found elevated air pollution resulted in both a decrease in sperm quality, including crucial parameters such as sperm motility (sperm movement) and a degradation of sperm morphology (sperm shape). A more recent 2021 study of over 10,000 couples in China also indicated that air quality was strongly tied to male fertility. Couples in the upper quartile of pollution exposure had nearly twice the risk of experiencing infertility compared to couples in the lowest quartile.

A 2020 meta analysis that reviewed 11 studies with over 4,500 participants also suggested increased levels of air pollution were linked to sperm quality, specifically lower semen volume, sperm concentration, sperm motility, and sperm morphology. There is also evidence that exposure to air pollutants may contribute to a higher chance of premature birth, low birth weight, and miscarriage.

Endocrine disruptors and male fertility

Endocrine disruptors are chemicals that interfere with the function of hormones in the endocrine system. Endocrine-disrupting chemicals (EDCs) can be found in everyday products like canned food, water bottles and other plastic food containers, fertilizers, pesticides, cosmetics, and toys.

Research indicates that persistent and long-term exposure to these chemicals may have negative effects on human reproductive health by interfering with the production and action of the sex hormones. Studies suggest exposure to EDCs like bisphenol A (BPA), which is found in plastics, and perfluoroalkyl and polyfluoroalkyl substances (PFAS), which are found in paper coatings and nonstick pans, may be linked to lower testosterone levels, decreased sperm quality, abnormal sperm morphology, and reduced sperm count, viability, and motility. There is also evidence that exposure to EDCs may increase prostate cancer progression.

What can you do to safeguard your fertility?

Even if you recycle, drive an electric car, and take other actions to minimize your carbon footprint, you cannot solve the climate crisis alone. However, there are steps you can take to safeguard your fertility no matter what. Here are some ideas:

  • Support legislation that addresses climate change. The increasing temperature of our planet has real detrimental effects on our health and male fertility.
  • Stay cool. Do everything you can to reduce the impact of warmer temperatures on your sperm. Wear loose-fitting underwear, avoid sedentary positions, minimize hot tub or bath use, and keep laptops and cell phones away from the scrotum, which can add heat and radiation to the area.
  • Use products free from BPA and DEHP. These two common endocrine disruptors can negatively impact male fertility.
  • Refrain from smoking. It can worsen your air quality and take a toll on the reproductive system, including sperm quality.
  • Improve your sperm quality with supplements designed to help increase your fertility.
  • Test your sperm quality with an at-home semen analysis kit to find out how healthy your sperm is right now.
  • Consider freezing your sperm to preserve your fertility for years to come.

Test your fertility from the comfort of your own home

You can keep track of your reproductive health by testing your fertility with a semen analysis. Legacy makes it easy and convenient to test your sperm quality with an at-home semen analysis kit. You can find out key parameters including semen volume and sperm count, concentration, motility, and morphology. Once you understand your current sperm health, you can take the right steps toward sperm quality improvement and increased fertility.

Preserve your fertility with sperm freezing

Sperm health declines with time, both with age and from exposure to the environment and other factors. Sperm freezing is an effective way to preserve your fertility in its current state, allowing you to draw on healthier sperm once you’re ready to build your family. Even if climate change negatively affects your fertility, Legacy’s affordable plans and secure storage can help you protect your sperm for years into the future.

Explore more collections