Review•

Disappearing sperms and changing climate: correlating decreasing semen quality and population dynamics within the Sustainable Development Goals framework

Abstract

Background Recent studies have reported a significant decline in human semen quality worldwide, raising concerns about climate change and its extensive effects on human health and biodiversity.

Methods This article investigates the correlation between deteriorating semen quality and changing climate conditions, within the context of the United Nations Sustainable Development Goals (SDGs). It aims to explore the linkage between decreasing semen quality and climate change, and to understand its implications for population dynamics, reproductive health and sustainability.

Results Integrating findings within the SDGs framework, the study emphasises SDG 3 (good health and well-being), SDG 13 (climate action) and SDG 15 (life on land). A multidisciplinary approach, incorporating data from environmental science, epidemiology and demography, is used to statistically analyse global and regional trends in semen quality against climate variability indicators, such as temperature fluctuations and pollution levels. Preliminary findings indicate a strong correlation between adverse climate conditions and reduced semen quality, suggesting potential impacts on fertility rates and population health. The research highlights the importance of climate action (SDG 13) in protecting human reproductive health and ensuring population stability (SDG 3), while emphasising the interconnectedness of ecosystem health and human well-being (SDG 15).

Conclusion The article calls for integrated policy responses addressing climate change and reproductive health as interconnected challenges, advocating for enhanced cross-sectoral collaboration to achieve the SDGs through comprehensive strategies encompassing environmental protection, reproductive healthcare and population management for a sustainable future.

Background

The global decline in semen quality has become a critical concern in recent years, attracting significant attention from both the scientific community and the public.1 2 This alarming trend poses immediate threats to human reproductive health and fertility rates and raises profound questions about its broader implications for population dynamics, sustainable development and the future of human societies.3 In the context of the Sustainable Development Goals (SDGs) adopted by the United Nations4 in 2015, understanding the intricate connections between declining semen quality, changing climate conditions and sustainable development becomes imperative.

The discussion of this review relies on increasing evidence that adverse environmental and lifestyle factors,5 aggravated by climate change,6 7 are contributing to the decline in semen quality. Pollutants, endocrine-disrupting chemicals, rising temperatures and lifestyle changes are among the numerous factors implicated in this global health issue.8–10 These factors directly impact semen quality and reflect broader environmental challenges that intersect with several of the SDGs, including good health and well-being (SDG 3), clean water and sanitation (SDG 6) and climate action (SDG 13) and human well-being (SDG 15).4

Moreover, the implications of declining semen quality extend beyond individual health concerns to influence population dynamics, including fertility rates and age structures. This decline has potential knock-on effects on education, gender equality, economic growth and workforce sustainability.7 As such, this review posits that addressing the challenge of declining semen quality is a matter of reproductive health and a crucial component of the global agenda for sustainable development. In synthesising the latest research, this article aims to provide a comprehensive overview of the current understanding of the relationship between declining semen quality, climate change and sustainable development. It highlights the importance of interdisciplinary approaches in addressing this issue, calling for concerted efforts among scientists, policymakers and global health professionals to mitigate this emerging threat within the framework of the SDGs.

The impact of climate change on semen quality

Studies on climatic factors affecting semen quality

The impact of climate factors on semen quality has become a critical area of research, especially as environmental changes are increasingly linked to human health issues, including fertility (figure 1).6 11 Several climate-related factors, such as heat stress, air pollution, radiation pollution, heavy rainfall, floods and drought, have been implicated in affecting semen quality, which in turn can impact male fertility.12 13

Figure 1
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Schematic representation of the interconnections between climate change factors, declining semen quality and relevant Sustainable Development Goals (SDGs). (A) Environmental factors such as heat stress, air pollution, nutritional impacts, radiation pollution and extreme weather events contribute to decreased semen quality, resulting in lower sperm viability and motility. (B) These changes lead to lower fertility rates, which impact population dynamics. (C) Addressing these interconnected challenges is essential for achieving SDGs related to health and well-being (SDG 3), clean water and sanitation (SDG 6), climate action (SDG 13) and life on land (SDG 15).

Heat stress has been identified as a significant factor affecting semen quality.14 Studies have demonstrated that high temperature can lead to decreased sperm concentration and motility, both in human and animal models.14–16 For instance, a study on bulls showed that there are variations in semen quality due to seasonal changes, indicating the presence of heat-sensitive and heat-tolerant individuals. This suggests that high temperatures can impair semen quality by affecting sperm production and functionality, leading to reduced fertility rates.17

Air pollution is another environmental factor that negatively impacts semen quality.18 Pollutants such as dioxins, which are highly persistent in the environment and can accumulate in human and animal bodies, have been shown to cause serious reproductive, developmental and cancer problems.19 These pollutants act as endocrine disruptors and have been associated with reduced sperm concentration and motility in exposed individuals.20 21 This effect is believed to be due to the ability of pollutants to cause DNA damage and disrupt the hormonal balance necessary for healthy sperm production and function.20 Radiation pollution, stemming from both natural and artificial sources, can also detrimentally affect semen quality.22 Studies specifically linking radiation pollution to semen quality in humans are limited. However, the consensus in scientific literature indicates that high levels of radiation exposure can cause DNA damage in sperm, reducing their viability and motility.23 24

Extreme weather events such as heavy rainfall, floods and droughts, associated with climate change, can indirectly affect semen quality by impacting the overall health, nutrition and living conditions of individuals.6 For instance, these conditions can lead to increased stress, changes in diet and exposure to contaminated water, all of which can impact semen quality.25 26

Heat stress

The scientific investigation into the impact of heat stress on semen quality reveals a multifaceted interaction between environmental temperatures and male fertility, both in humans and livestock.15 17 The process of spermatogenesis is highly sensitive to variations in temperature, with elevated testicular temperatures resulting in impaired spermatogenesis.27 28 This understanding is crucial in light of global warming, which poses a significant threat to both animal welfare and fertility, with direct implications for the economic sustainability of agricultural industry.

In humans, several factors have been investigated for their potential impact on scrotal temperature and semen quality. These include prolonged sitting, the type of underwear worn, professional exposure to high temperatures and sauna visits.29 While the link between some factors, such as the type of underwear, and semen quality is not definitively proven, evidence suggests that professional drivers, particularly those operating heavy machinery, experience impaired fertility parameters.30 Moreover, fever has been associated with deteriorated semen quality, underscoring the negative impact of elevated body temperatures on male reproductive health.31

In the context of livestock, the repercussions of heat stress are complex and involve multiple pathways leading to a decrease in the fertilising capacity of spermatozoa.17 Key issues include an increase in reactive oxygen species, which leads to lipid peroxidation and motility impairment.32 Heat stress affects DNA integrity during cell division in spermatogenesis and makes postmeiotic DNA restoration impossible, adversely affecting embryonic development.29 31 Moreover, mitochondria lose membrane potential under stress, reducing energy production.28 Despite cellular defence mechanisms against heat stress, intense heat shocks can lead to cell death. Heat shock proteins, which help in eliminating protein clusters, play a crucial role in maintaining protein stability under heat stress.17

Given these findings, there is an urgent need for strategies to mitigate the effects of global warming on semen quality. For humans, lifestyle adjustments, such as reducing heat exposure and adopting practices that promote scrotal cooling, could improve semen quality. In livestock, the development of breeding strategies that increase resilience to heat stress, alongside management practices that reduce heat load of animals, will be vital in preserving fertility and ensuring the sustainability of agricultural operations.

Exposure to pollutants and chemicals

The impact of exposure to pollutants and chemicals on semen quality is a subject of growing concern within the scientific community, as it has been linked to decreasing semen quality, a proxy for male fertility and overall health.26 Research has shown that environmental and occupational exposure to pollutants can affect sperm quality parameters such as count, volume, concentration, motility, vitality and DNA integrity.20 21

A systematic review and meta-analysis included 22 studies to assess the impact of tobacco smoke, environmental and occupational pollution on sperm quality.33 The findings revealed significant alterations in at least one of the semen quality outcomes studied, in association with exposure to various pollutants. This evidence suggests that pollutants have a notable effect on male reproductive health, further highlighting the need for a deeper understanding of the relationship between pollutants and human, animal and planetary health.33

Moreover, a comprehensive study involving 78 952 samples from 33 234 study subjects from 2014 to 2020 examined the relationship between gaseous air pollution exposure and semen quality.34 The study used high-resolution grid pollution datasets to estimate personal exposures to carbon monoxide, sulfur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3) during the entire stage of semen formation and three crucial stages. The analysis found that sperm count and concentration were inversely related to exposure to SO2, NO2 and O3. Additionally, significant declines in progressive and total motility were observed with SO2 exposure. These results suggest that gaseous air pollutants negatively impact sperm quality, emphasising the importance of considering critical periods of sperm development when implementing protective measures.34 The existing body of evidence clearly demonstrates the harmful effects of environmental pollutants and chemicals on semen quality. These findings highlight the importance of protective measures and further research to understand the mechanisms through which pollutants impact reproductive health and to develop strategies to mitigate these effects.

Nutritional impacts due to climate change

The nexus between climate change, nutrition and semen quality presents a complex interplay of environmental, nutritional and physiological factors that contribute to male fertility.25 Research increasingly indicates that various environmental contaminants, such as dioxins and plastic-related chemicals like bisphenols, significantly impact semen quality and overall male reproductive health.19 Dioxins, produced through industrial and natural processes, are known for their ability to be absorbed by fat tissue and stored in the body for long periods, leading to reproductive, developmental and cancer problems.19 21 These contaminants act as endocrine disruptors and have been associated with reduced sperm concentration and motility in humans. Similarly, bisphenol A, a major component of plastics, has been linked to sperm DNA damage, mitochondrial dysfunction and a decrease in sperm count and motility, highlighting the endocrine-disrupting properties of such chemicals.35

The broader context of climate change exacerbates these concerns through its impact on global food systems, diet quality and nutritional security. The loss of biodiversity, including the diversity of crops and livestock species, directly correlates with food security and the nutritional quality of diets.36 The existing body of evidence clearly demonstrates the harmful effects of environmental pollutants and chemicals on semen quality. These findings highlight the importance of protective measures and further research to understand the mechanisms through which pollutants impact reproductive health and to develop strategies to mitigate these effects.37 Sustainable agricultural practices and diversified diets are recommended to mitigate these impacts and ensure food and nutritional security.

Moreover, climate change-related shifts towards plant-based diets, as recommended by the EAT-Lancet Commission, could offer both health benefits and environmental sustainability.38 However, ensuring these diets are nutritionally adequate is essential to prevent potential negative impacts on semen quality and reproductive health.25 The introduction of climate-smart food systems and agricultural innovations, such as the development of provitamin A-enriched maize resistant to aflatoxin contamination, exemplifies efforts to enhance nutrition while addressing climate change impacts.39 These innovations are crucial for reducing the effects of climate change on vulnerable communities and ensuring the nutritional quality of food systems remains high.

In conclusion, addressing the nutritional impacts of climate change on semen quality requires a multifaceted approach. This includes mitigating exposure to environmental contaminants, preserving biodiversity and food security, ensuring the nutritional adequacy of diets amid changing climate conditions and adopting sustainable agricultural practices. Such measures are critical for maintaining male reproductive health and for ensuring the overall well-being and sustainability of global populations in the face of climate change.

Case studies and geographical variations

The quality of human semen has been an area of increasing concern, with numerous studies indicating a global decline over the last few decades.1 40 This phenomenon has been attributed to a variety of factors, including environmental, lifestyle and possibly genetic influences.5 20 33 However, one of the intriguing aspects of this decline is its geographical variation, suggesting that local environmental and lifestyle factors may play significant roles.41 42

Early evidence of geographical differences in semen quality emerged from studies conducted in the late 20th century, which noted marked contrasts in mean sperm counts among men in different regions of the USA and between countries.40 43 For instance, a study from 1992 by Carlsen et al highlighted significant variations in mean sperm concentration values according to geographical origin, with notable differences between maximum and minimum mean values reported in Finland and India, respectively.40 This was further supported by a 1996 retrospective study in France that provided evidence of geographical contrasts in semen quality within a single country, indicating that these variations are not limited to broad continental or national differences and can be observed regionally.44 Further research has elaborated on these initial findings. For instance, a study involving young men from four European cities found differences in semen parameters, with Danish men having the lowest sperm concentrations and total counts, while Finnish men had the highest.45 This study, along with others, used standardised methodologies for semen analysis, emphasising the need for uniformity in data collection to accurately assess geographical variations.45

The decline in semen quality is also associated with an increase in male reproductive disorders such as cryptorchidism, hypospadias and testicular cancer, suggesting a possible common cause related to environmental and lifestyle factors.46 47 The testicular dysgenesis syndrome hypothesis proposes that disturbances in testicular development during a critical fetal development window may lead to these conditions.48 The geographic variation in the incidence of these conditions further supports the role of environmental factors.

In China, a longitudinal study among sperm donor candidates over 11 years highlighted significant decreases in sperm concentration, total sperm count and motility after adjusting for age, body mass index and days of sexual abstinence.49 This suggests that declines in semen quality are occurring globally but with regional differences possibly influenced by local environmental or lifestyle factors.49

The studies collectively underscore the complexity of factors affecting semen quality and the importance of considering geographical variation.42 50 It highlights the need for standardised methods in semen analysis to reliably compare data across studies and understand the impact of local environmental and lifestyle factors. The significant geographical variations in semen quality and their link to male reproductive disorders highlight the urgent need for effective public health strategies at both global and regional levels to address this issue. In conclusion, the geographical variation in semen quality underscores the influence of local environmental, lifestyle and possibly genetic factors. This variation, along with the global decline in semen quality, calls for further research to understand the underlying causes and develop effective interventions.

Semen quality and population dynamics

The role of semen quality in fertility rates

The role of semen quality in total fertility rates (TFR) is a topic of significant interest within the scientific community, as alterations in semen quality can have profound impacts on pregnancy outcomes and overall fertility rates.51 Recent studies have highlighted a concerning trend: a global decline in semen quality over the past few decades.1 40 Research findings from various geographical regions indicate a consistent decrease in sperm counts and a deterioration in other semen quality parameters. This decline has been observed in countries like China, New Zealand and across Europe, suggesting that the phenomenon is widespread rather than isolated to specific areas.1 52–54 The implications of these findings are substantial, as lower semen quality directly correlates with reduced fertility rates, impacting the ability of couples to conceive naturally.

Moreover, the decline in semen quality is not uniformly observed across all populations. For instance, while some studies in Sweden and Australia have reported stable semen quality over time, the predominant trend globally points towards deterioration.55 This variability underscores the complexity of factors influencing semen quality and fertility rates, including environmental, lifestyle and possibly genetic components.

The ongoing decline in semen quality necessitates a closer examination of its implications on TFR.6 7 It highlights the need for comprehensive strategies to address the underlying causes of this trend and to support couples facing fertility challenges. As research continues to unravel the complexities of this issue, the findings underscore the importance of semen quality as a crucial factor in reproductive health and the broader demographic changes in fertility rates globally. These observations are crucial for understanding the dynamics of human fertility and for developing strategies to mitigate the impact of declining semen quality on population growth and the health of future generations.

Implications of declining semen quality for global population trends

The implications of declining semen quality for global population trends are multifaceted and complex, intersecting various domains of public health, demography and socio-economic development. Studies have consistently shown a decline in semen quality, measured by parameters such as sperm concentration and total sperm count, across different regions and populations globally.1 43 44 A comprehensive meta-analysis has indicated a significant decline in sperm count between 1973 and 2018, with an overall decrease of 51.6% among unselected men from all continents and an accelerated decline post-2000.56 This decline in semen quality is not uniform across all geographical areas or study populations, suggesting the influence of both environmental and genetic factors, as well as potential biases in study methodologies.

Despite some studies reporting stable or even slightly increased semen quality in specific localities or time periods, the broader consensus points towards a general decline. This trend raises concerns about male reproductive health and its implications for fertility rates globally. The decline in semen quality, if sustained, could contribute to decreasing fertility rates, affecting population growth and demographics, especially in regions already experiencing low birth rates.57

The declining semen quality could have significant socio-economic and health implications.58 On a societal level, decreased fertility rates may lead to ageing populations, with a higher dependency ratio and increased pressure on healthcare and social security systems. On an individual level, couples facing infertility may experience psychological stress and may need to rely more on assisted reproductive technologies, which are often costly and not accessible to all.58

Given the potential for continued decline in semen quality and its implications for fertility and population trends, there is an urgent need for comprehensive research into the causes of this trend and strategies to mitigate its impact. These effort encompass more than just examining the environmental and lifestyle factors that may contribute to declining semen quality. These also involve improving public health strategies to support reproductive health and fertility. Additionally, enhancing and making fertility treatments more accessible, while raising awareness about male reproductive health, are crucial in addressing the global challenges associated with declining semen quality.

Integrating semen quality into Sustainable Development Goals

Analysis of relevant SDGs

The analysis of the SDGs, particularly SDGs 3 (good health and well-being), 6 (clean water and sanitation), 13 (climate action) and 15 (life on land) in relation to climate change-induced decreasing semen quality and population dynamics, requires a multidisciplinary approach that intersects environmental, health and social sciences (table 1).4 7 While specific literature directly linking climate change, semen quality and the mentioned SDGs is sparse, the broader impacts of climate change on human health, water resources, biodiversity, and climate action offer insights into potential indirect effects on population dynamics and reproductive health.6 12 13

Table 1
•
Impact of climate change on semen quality: causes, effects and SDG implications

Climate change and reproductive health

Climate change poses a significant threat to human well-being and the environment, with direct and indirect impacts on reproductive health.12 For example, increased temperatures and pollution are associated with adverse outcomes in semen quality, potentially affecting fertility rates. SDG 3 aims to ensure healthy lives and promote well-being for all, where reproductive health is a crucial component.59 The stress on healthcare systems due to climate change and the rising need for access to quality reproductive healthcare highlight the intersection of climate change, semen quality and population dynamics.

Water scarcity and sanitation challenges

SDG 6 focuses on ensuring availability and sustainable management of water and sanitation for all.60 Climate change exacerbates water scarcity and sanitation challenges, indirectly affecting human health, including reproductive health.61 Pollution and waterborne diseases can impact overall health status, potentially influencing semen quality and fertility rates.62

Climate action and mitigation

SDG 13 calls for urgent actions to combat climate change and its impacts.63 Addressing climate change through mitigation and adaptation strategies can reduce the environmental stressors that may impact semen quality and fertility rates. Strategies focusing on reducing greenhouse gas emissions, enhancing renewable energy use and promoting sustainable practices contribute to mitigating the indirect effects of climate change on reproductive health.

Biodiversity, ecosystem services and human health

SDG 15 emphasises the importance of life on land, advocating for the protection, restoration and promotion of sustainable use of terrestrial ecosystems.64 The degradation of natural habitats and biodiversity due to climate change affects ecosystem services, including those that support human health and well-being.65 A healthy ecosystem is essential for maintaining the natural balance and ensuring food security and clean water, indirectly supporting reproductive health and population dynamics.

The interlinkages between population dynamics and the SDGs highlight the importance of addressing population growth and reproductive health in the context of sustainable development. Investments in education, gender equality and family planning can slow population growth and contribute to achieving the SDGs. Educating women and girls, in particular, has been shown to influence family size and delay childbirth, empowering women to make informed decisions about their reproductive health.66

In conclusion, the relevance of SDGs 3, 6, 13 and 15 to climate change-induced decreasing semen quality and population dynamics underscores the interconnectedness of environmental, health and social issues. Addressing climate change through a comprehensive and integrated approach that includes promoting reproductive health, ensuring water and sanitation, taking climate action and protecting biodiversity is crucial for sustainable development and the well-being of current and future generations.

Strategies for incorporating reproductive health indicators into climate action plans

Incorporating reproductive health indicators into climate action plans within the framework of SDGs necessitates a nuanced approach that considers the multifaceted interplay between climate change and reproductive health (figure 1).59 SDG 13 underscores the urgency of taking action to combat climate change and its impacts, highlighting the profound connection between climate action and health outcomes.63 The European Environment Agency notes that climate change has led to an increase in extreme weather events, rising sea levels and shifts in infectious disease patterns, all of which have significant implications for reproductive health.67 These changes are expected to continue and intensify, affecting migration, conflict over resources and ultimately, the social determinants of health, including reproductive health.

The integration of reproductive health indicators into climate action strategies can benefit from a comprehensive sustainable development pathway that addresses multiple SDGs simultaneously. A study highlighted in Nature Climate Change outlines an ambitious scenario (SDP-1.5C) that integrates a broad spectrum of interventions aimed at sustainable development and ambitious climate change mitigation.68 These interventions range from poverty alleviation funded by carbon pricing revenues to shifts towards sustainable nutrition and energy access. The SDP-1.5C scenario covers 56 SDG indicators across all 17 goals, offering a holistic approach to sustainable development that includes health and well-being (SDG 3), climate action (SDG 13) and beyond.68

The approach emphasises the need for integrated strategies that address both reducing greenhouse gas emissions and social determinants of health, including reproductive health.69 The linkage between climate action and health outcomes suggests that effective climate policies can also lead to improvements in reproductive health by reducing the health impacts of climate change, promoting sustainable lifestyles and improving access to health services. For instance, policies aimed at reducing emissions can simultaneously reduce air pollution, thereby lowering the incidence of respiratory and cardiovascular diseases, which can affect pregnancy outcomes.

Furthermore, climate adaptation measures that strengthen health systems can improve resilience to climate-related health challenges, ensuring that reproductive health services remain accessible even as climate impacts intensify.70 This includes ensuring that health facilities are resilient to extreme weather events, integrating climate considerations into health planning and surveillance systems and promoting education and awareness around the health impacts of climate change.

Adopting these integrated strategies demands coordinated efforts across various sectors. This includes health and environmental policymakers and stakeholders in education, finance and urban planning. Effective implementation of these comprehensive strategies requires collaboration among governments, international organisations, civil society and the private sector.71 Additionally, policies and interventions must be tailored to local contexts, addressing the specific vulnerabilities and needs of various communities, especially those at high risk of adverse reproductive health outcomes due to climate change. Integrating reproductive health indicators into climate action plans within the SDG framework requires a holistic approach. This approach should acknowledge the interdependence of climate action, health outcomes and sustainable development.7 By addressing these areas in an integrated manner, it is possible to make significant progress towards achieving both climate resilience and improved reproductive health outcomes, contributing to the overarching aim of the SDGs to ensure well-being for all at all ages.

Role of education, healthcare and policy in addressing reproductive health and climate change

The interplay between education, healthcare and policy plays a pivotal role in addressing the dual challenges of reproductive health and climate change, particularly in relation to declining male fertility and TFR.6 This complex nexus demands a multifaceted approach to ensure a sustainable future.

Education is fundamental in understanding and addressing the impacts of climate change on reproductive health.72 It provides individuals with the knowledge necessary to make informed decisions regarding their health and the environment. A study examining fertility in relation to factors like education revealed the importance of considering regional differences to understand the impact of education on TFR.73 This research underscores the necessity of targeted educational programmes that cater to the specific needs and contexts of different regions, emphasising the role of female education in influencing fertility rates.73

Climate change exacerbates existing health inequalities, impacting reproductive health through various pathways.74 Hazardous environmental conditions, poverty and social inequities contribute to adverse sexual health outcomes, including increased vulnerabilities to HIV and other sexually transmitted infections.75 For instance, climate-induced extreme weather events can disrupt healthcare access, increase migration and sexual exploitation and elevate risks associated with infectious diseases, all of which can have detrimental effects on reproductive health.76 Climate change also affects reproductive health by increasing the prevalence of air pollution, wildfires, heat stress and vectorborne diseases, posing risks to male and female fertility, fetal development and obstetric outcomes.77

Environmental changes driven by climate change impact food security and nutrition, directly affecting reproductive health.39 Malnutrition, arising from climate change-induced alterations in food production and distribution, can lead to low birth weight and increased morbidity and mortality. The anticipated increase in foodborne diseases, along with changes in nutritional quality due to rising CO2 levels, further exacerbates these health risks, underscoring the need for integrated approaches to address the impacts of climate change on food security and reproductive health.78

In conclusion, addressing the challenges of reproductive health and climate change necessitates a coordinated approach that integrates education, healthcare and policy. By enhancing educational initiatives, improving access to healthcare and implementing robust policies to mitigate climate change and its impacts, we can safeguard reproductive health and ensure a sustainable future. Collaborative efforts across sectors are essential to address the complex interactions between environmental changes and reproductive health, with a particular focus on the intricate issues of declining male fertility rate and TFR.

Case studies and global initiatives: challenges and barriers

A comprehensive approach to integrating reproductive health with environmental policies is evidenced by the initiatives and measures taken by countries globally. The United Nations Population Fund conducted a survey, revealing significant progress in implementing the Programme of Action from the 1994 Cairo International Conference on Population and Development.79 This programme underscored the intricate links between population and development, emphasising the importance of reproductive rights and health, gender equality and women’s empowerment.79 A notable finding from this survey is that >90% of countries have incorporated family planning and safe motherhood into their primary healthcare systems. Additionally, measures to address adolescent reproductive health, including the integration of reproductive health education into school curricula, have been widely adopted.79 National AIDS commissions and programmes have also been established to combat the impact of the pandemic. This integration demonstrates a pragmatic approach by countries to focus on national priorities while aligning with global efforts to achieve Millennium Development Goals, including poverty reduction.80 However, while the integration of reproductive health and environmental policies shows promise, the challenges outlined, such as financial constraints and the need for continued international support, highlight the complexity of these issues. It is crucial that ongoing and future initiatives address immediate health needs and consider long-term environmental sustainability to ensure comprehensive and effective solutions.

Future directions

Research needs for a deeper understanding of the connections

The interplay between climate change, semen quality and population dynamics presents a complex web of interactions that is crucial for the achievement of SDGs. While the direct research focusing on the connections among climate change-induced decrease in semen quality and population dynamics is scant, insights can be drawn from broader studies on population dynamics and climate change. A key gap in the current body of knowledge is the systematic integration of population dynamics into climate change science. This integration is crucial for developing effective mitigation and adaptation strategies that are sensitive to the nuances of population growth, migration, urbanisation, ageing and household composition. For instance, strategies such as contraction and convergence highlight the importance of considering population as a major factor in achieving equitable per capita emission targets globally.

Research needs include detailed investigations into how climate change affects reproductive health and fertility patterns across different populations. Furthermore, understanding the socioeconomic, environmental and health-related factors that contribute to semen quality can provide insights into potential intervention points for both climate action and population management. There is an urgent need for interdisciplinary research that bridges the gap between environmental sciences, reproductive health and demographic studies to explore these connections comprehensively.

Policy recommendations for integrating semen quality considerations into climate action and sustainability

Policy recommendations should focus on integrating semen quality considerations into broader climate action and sustainability frameworks. This integration can occur through: (a) increased investment in reproductive health services, including family planning and education on reproductive health rights. These services directly contribute to the mitigation of climate change impacts by stabilising global populations and reducing poverty and gender disparities, thereby indirectly supporting semen quality through improved health outcomes and environmental sustainability; (b) promoting research and policies that address the environmental determinants of reproductive health, including semen quality, to create a more nuanced understanding of the impacts of climate change on human fertility; (c) encouraging multisectoral approaches that connect climate policy, health policy and population dynamics to ensure that actions in one area support and reinforce goals in the others.

Innovations in healthcare and environmental protection

Innovations in healthcare and environmental protection are increasingly focusing on sustainable practices that address both human health and the health of the planet. Technologies and initiatives that monitor and mitigate environmental pollutants can directly benefit semen quality and broader reproductive health outcomes. Additionally, advances in telemedicine and digital health platforms offer new ways to provide reproductive health services and education, particularly in underserved or hard-to-reach populations.

Environmental innovations, such as cleaner energy sources, sustainable agriculture and green urban planning, contribute to mitigating climate change and reduce exposure to environmental toxins that can affect semen quality and overall health. Collaborative efforts between environmental scientists, healthcare providers and policymakers can foster the development of integrated solutions that promote both environmental sustainability and human health.

In summary, addressing the complex relationship between climate change, semen quality and population dynamics requires a multifaceted approach that spans research, policy and innovation. Integrating semen quality considerations into climate action supports the achievement of SDGs and promotes a holistic view of sustainability that includes human reproductive health and well-being.

Conclusion

This review sheds light on the alarming trend of declining semen quality and its potential implications on global population dynamics, under the broader challenges posed by climate change. The key findings underscore the intricate links between environmental factors, human health and fertility rates, suggesting that the degradation of semen quality could have far-reaching effects on population sustainability and the achievement of SDGs. This complex interplay underscores the critical need for interdisciplinary approaches that bridge the gaps between environmental science, reproductive health and policy-making. Such integrated strategies are essential for developing comprehensive solutions that address both the causes and consequences of declining semen quality within the context of global environmental changes. To effectively address these interconnected challenges, integrated policy responses and cross-sectoral collaboration are imperative. Policymakers must work closely with experts in environmental science, public health and reproductive medicine to formulate strategies that mitigate the adverse effects of climate change on reproductive health. Collaborative efforts across sectors can enhance the effectiveness of interventions, ensuring that policies are scientifically sound and socially and economically feasible. This holistic approach will enable the development of robust frameworks that protect both human health and the environment.

The article serves as a call to action for policymakers, researchers and the global community to prioritise this underexplored issue. It advocates for enhanced research funding, the implementation of policies aimed at mitigating environmental risks to reproductive health and the promotion of sustainable practices that safeguard the planet for future generations. Ultimately, it emphasises that addressing the decline in semen quality is not just a matter of reproductive health but is integral to the global pursuit of sustainability and human well-being.

  • PS and SD are joint first authors.

  • Contributors: PS and SD participated in the conception and design of the study, literature search and data extraction. They also contributed to writing, revising and finalising the article. Both the authors have read and agreed to the published version of the manuscript. They accept full responsibility for the finished work and/or the conduct of the study, had access to the data and controlled the decision to publish.

  • Funding: The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests: None declared.

  • Patient and public involvement: Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

Ethics statements

Patient consent for publication:
Ethics approval:

Not applicable.

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  • Received: 19 June 2024
  • Accepted: 21 July 2024
  • First published: 31 July 2024

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