Introduction

The effects of anthropogenically induced climate change are becoming increasingly apparent across ecosystems and human systems worldwide. Future projections predict that global warming will exceed 1.5 °C during the twenty-first century, which will have profound implications for human health and well-being (Magnan et al. 2021, Intergovernmental Panel on Climate Change 2023). Climate change is already impacting human health, including illnesses and deaths from extreme weather events, notably heatwaves, storms, and floods, as well as food insecurity from the disruption of food systems, increased outbreaks of food- and water-borne infectious diseases, vector-borne diseases, and mental health issues (Baxter et al. 2022; Ortiz-Bobea et al. 2021). Vulnerable groups, such as women, children, ethnic minorities, low-income communities, migrants or displaced people, elderly populations, and those with underlying health conditions, will be disproportionately affected by climate change (Romanello et al. 2022). The World Health Organization (WHO) has identified climate change as the greatest health threat facing humanity (WHO 2021). Awareness of the health risks posed by climate change has been growing among health professionals (Day 2023; Ebi et al. 2021). Recent surveys among physicians worldwide found that the majority were aware of the health threats of climate change and were willing to participate more actively in climate-related initiatives; however, many noted that a lack of time and knowledge prevented them from doing so (André et al. 2022, den Boer et al. 2021, Kotcher et al. 2021).

In recent decades, Japan has experienced more frequent extreme weather events, in particular intensifying heatwaves, flooding, and landslides (Wang et al. 2019). According to Japan's Climate Change Impact Assessment Report for 2020, heat-related deaths, heat stroke, and vector-borne diseases were reported as a national high priority (Ministry of the Environment 2020). The Central Disaster Prevention Council within the Cabinet Office reported that the number of deaths from heat stroke was 5.5 times higher than the number of deaths from natural disasters, with the majority of those affected aged 65 years and older, the highest proportion of the country’s population (Central Disaster Prevention Council 2021). Facing this new reality, there is a growing need to develop solutions to mitigate various health, social, and economic problems related to climate change and to think about how to modify daily activities to minimize damage to the environment.

The number of studies worldwide to assess physicians’ views of climate change and health has been growing; however, few studies have examined physicians’ knowledge, attitudes, and practices regarding climate change and its impact on human health in Japan. Therefore, this study aimed to assess the knowledge, attitudes, and practices (KAP) of physicians in Japan toward climate change and health, their delivery of climate-specific advice to patients, and their advocacy for climate change policy. KAP studies gather data among a specific community on what is known, believed, and practiced concerning a particular topic. Understanding the levels of knowledge, attitudes, and practices of the physicians can enable a more efficient process of identifying specific gaps and aid in developing solutions suited to meet their needs (Jacobsen 2016).

Methods

Study design and participants

This cross-sectional study included licensed physicians actively engaged in clinical practice in Japan. The physicians were recruited from 7240 registered members of PLAMED Inc. (PLAMED) who fit the inclusion criteria.

Data collection

Data were collected anonymously from November 21 through November 27, 2023, using a self-administered questionnaire through PLAMED’s web-based platform. The 32-item questionnaire was designed based on the KAP theory and existing questionnaires (André et al. 2022, Kotcher et al. 2021, Völker and Hunchangsith 2018) and was piloted among six physicians in Japan before data collection. Eligible physicians who completed the questionnaire were given 100 PLAMED points (1 point = 1 JPY). The distribution of physicians was adjusted to reflect the real-world distribution where physicians work (35% in clinics, 65% in hospitals) based on Ministry of Health, Labour, and Welfare (MHLW) data (MHLW 2020).

Variables of interest

Four main areas of interest were assessed in this study: knowledge of climate change, awareness of climate change and its impact on human health, delivery of climate-specific advice to patients, and advocacy on sustainable healthcare and climate change policy.

Knowledge of climate change

Four questions were asked to measure the physicians' general knowledge of climate change, such as the cause of climate change and the healthcare sector's contribution to greenhouse gas emissions.

Awareness of climate change and its impact on human health

The physicians’ perception of climate change's current and future adverse impacts on people's health in Japan was assessed with questions about how they think climate change will affect health issues such as heat-related illnesses, respiratory illnesses, vector-borne diseases, and mental illnesses.

Delivery of climate-specific advice to patients

To assess the physicians’ behavior concerning delivering climate-specific advice to patients, questions such as if they provide information to their patients on the links between climate change and their health, advise patients on health co-benefits (sustainable lifestyle changes that patients can make in their own lives which simultaneously benefit their health and that of the environment), or take routine environmental history checks were asked.

Advocacy on sustainable healthcare and climate change policy

To understand the practice and willingness of physicians to advocate for sustainable healthcare practices in their facility and for climate change policy, questions were asked about their participation in advocacy.

Demographic characteristics

General demographic data of the physicians were collected, including age, gender, type of facility where they practice, medical field of practice, and where they graduated from medical school. Questions on participation in any medical school courses or continuing professional education related to climate change and health and/or membership in professional associations that engage in climate change and health advocacy were also asked.

Data analysis

Descriptive statistics were used to illustrate the physicians’ demographic characteristics for the analysis. Multivariable logistic regression was employed to examine the association of prior climate change education and training, knowledge, and awareness with physicians' practice in providing climate-specific advice to patients and advocating for climate change policy. The variance inflation factor (VIF) was calculated to check the multicollinearity of the independent variables used in the regression model. All VIF values were below 5, suggesting that there is not enough correlation to warrant corrective measures, and thus they remained in the model for analysis. All analyses were performed using Stata/SE 18 (StataCorp, College Station, TX, USA).

Results

Sociodemographic characteristics of the physicians

A total of 1100 physicians (952 men, 133 women, 14 non-binary, and one non-disclosed) were included in the analysis. Table 1 shows the sociodemographic characteristics of the physicians, with a mean age of 51.2 years (SD11.9). Most of the physicians have been in practice for 20 years or more (64.9%), with the most represented medical field being physicians practicing in internal medicine (16.1%), followed by gastroenterology (8.0%) and psychiatry (8.0%).

Table 1 Sociodemographic characteristics of the physicians
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Knowledge of climate change

Most physicians are aware that climate change is happening (87.9%); however, they do not have sufficient knowledge of it. Table 2 shows the responses of the physicians towards climate change knowledge. Four knowledge questions were asked in the questionnaire, and only 2% of the physicians were able to answer all correctly, followed by 13.6% who answered three or more questions correctly. The physicians were also asked if they were familiar with the term “planetary health,” and only 18.2% responded “yes,” suggesting the term is not widely recognized.

Table 2 Physicians’ knowledge of climate change
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Awareness of climate change and its impact on health

The impact of climate change on health is recognized by most physicians; 78.1% perceive that climate change is currently impacting people’s health in Japan, with 51.4% recognizing this impact among their patients. The physicians were asked their opinion on climate change’s current adverse health impacts and their predictions over the next 10 years (Fig. 1). The physicians perceived the most adversely affected health impacts from climate change as physical harm and injury from extreme weather events, heat-related illness, and vector-borne diseases.

Fig. 1
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Health issues that are currently adversely affected by climate change compared with the predicted impact on health in 10 years time

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Delivery of climate-specific advice to patients

Many physicians recognize the responsibility that physicians have to educate their patients on the impact climate change has on their health. More than half (56.7%) agreed that physicians should advise their patients on the links climate change has on their health. Moreover, 59.7% of physicians agreed that physicians can contribute to helping their patients change their behaviors to engage in a more sustainable lifestyle. Conversely, when asked, “Do you advise your patients on the links between climate change and health?” less than half of the physicians (32.6%) responded that they do. As for advising patients on health co-benefits, similarly, less than half (33.2%) responded that they do. Furthermore, concerning taking a routine environmental history check of patients they perceive may have potential exposure to environment-related health risks, 36.9% responded that they do.

Barriers to engagement in delivering climate-specific advice to patients

There is a significant gap between the physicians’ willingness and what happens in practice, even though physicians recognize how climate change affects health and agree it is their responsibility to counsel patients on the links climate change has on their health. When asked about some of the factors that reduce their action to engage in delivering climate-specific health advice and advocacy, the physicians responded with the main factors as lack of information/resources (54.4%), lack of knowledge (52.7%), and lack of time (51.7%), followed by lack of support from their facility (26.8%) (Fig. 2).

Fig. 2
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Barriers to engaging in delivering climate-specific advice to patients and climate-related advocacy

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Moreover, only 20.1% of physicians responded that they had seen educational materials about climate change and health in their facility. The physicians were also asked about their opportunities to obtain education on climate change and health through courses in medical school or continuing professional education. Only 6.5% of physicians responded “yes” to having participated in a course on climate change and health in medical school, and 11.6% responded “yes” to having participated in any continuing professional education, indicating there is limited access to education on climate change and health for physicians.

Advocacy on sustainable healthcare and climate change policy

Physicians possess several qualities that make them essential catalysts for change within their facilities. While 57.5% of the physicians agreed that physicians have a responsibility to advocate within their facility for implementing mitigation measures for more sustainable healthcare, 40.2% responded that they had done so. Nevertheless, 68.8% responded that they would willingly choose more environmentally sustainable medical products and equipment. However, when asked if their facility currently supports sustainable healthcare practices, only 37.5% responded that their facility did. As for participating in national advocacy for climate change, 73.9% responded that they would personally consider participating in advocacy campaigns led by health professionals to support more robust climate change policy. However, 96.6% of physicians responded that they were unaware of any climate change-related initiatives or advocacy within their medical associations.

Association between having prior education or training, knowledge, and awareness with physicians’ delivery of climate-specific advice to patients and advocating for more climate change policy

The multivariable logistic regression model showed that having prior climate change education or training, knowledge, and awareness is associated with physicians’ delivery of climate-specific advice to patients (Table 3) and advocating for climate change policy (Table 4). Additionally, physicians working in a clinic are significantly associated with delivering climate-specific advice to patients compared to physicians working in a hospital.

Table 3 Factors associated with physicians' delivery of climate-specific advice to patients (n = 1100)
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Table 4 Factors associated with physicians' engagement in climate change advocacy (n = 1100)
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Discussion

Physicians worldwide are becoming increasingly aware of the impact climate change has on the health of humans. Consistent with previous studies in other countries, physicians who participated in this study have a strong awareness that climate change is happening and an understanding of the adverse impact that climate change has on human health (André et al. 2022, den Boer et al. 2021, Kotcher et al. 2021). The physicians also understand that physicians have a responsibility to advise their patients on the links between climate change and health; however, only some physicians put this into practice. Some of the reported barriers are lack of information/resources, lack of knowledge, lack of time, and lack of support from their facility. The physicians also reported limited opportunities to obtain education on climate change and health.

This study has four main findings. First, it highlighted that physicians have insufficient knowledge about climate change. Second, there is limited access to education on climate change and health. Third, healthcare facilities do not support enough sustainable healthcare practices. Fourth, physicians are willing to advocate for climate change policy.

Physicians have insufficient knowledge about climate change

More than half of the physicians agreed that physicians have a responsibility to advise their patients on the health impacts of climate change and that physicians can play a role in changing the behavior of their patients to engage in more environmentally sustainable lifestyle choices. However, in practice, most physicians responded that they hardly advise their patients on the links between climate change and health or on health co-benefits. When assessing the physicians' knowledge, less than half of the physicians were able to answer any of the four questions correctly. Furthermore, the majority of the physicians were unfamiliar with the term ‘planetary health.’ The data suggests that physicians have insufficient knowledge of climate change. Previous studies conducted among physicians in other countries had similar findings, that a lack of knowledge impeded physicians from engaging in more climate-related initiatives (André et al. 2022, den Boer et al. 2021, Kotcher et al. 2021).

This could be one of the reasons that although physicians recognize the need to advise patients on the links between climate change and their health, they may feel averse to doing so due to insufficient knowledge. A study conducted in Thailand on the drivers of physicians’ engagement in addressing eco-health problems showed that physicians’ knowledge of the links between the ecosystem and health is significantly associated with whether or not physicians advise their patients on how to reduce environmental health risks and increase exposure to more positive environmental factors (Völker and Hunchangsith 2018).

There is limited access to education on climate change and health

When asked about factors that reduced their action to deliver climate-specific health advice and advocacy, some of the main barriers included a lack of information/resources and a lack of knowledge. Furthermore, the majority of the physicians reported not having taken any courses in medical school or any continuing professional education on climate change and health. Moreover, more than half reported rarely seeing educational materials about climate change and health in their facility.

As adverse health impacts of climate change are expected to become more severe over the coming years, physicians must understand their important role in educating the public and their patients in mitigating and adapting to climate change and recognizing its impact on their health. Therefore, physicians must be sufficiently knowledgeable to assume greater responsibility for patients and public education to serve in that role. A German study on climate-specific health literacy and medical advice showed that patients who were informed by physicians about the links between climate change and health had a higher awareness of climate-related health risks and were more willing to engage in more environmentally sustainable lifestyle choices (Reismann et al. 2021).

The Japan Ministry of Education, Culture, Sports, Science, and Technology (MEXT) published the 2022 revisions in the Medical Education Model Core Curriculum, adding compulsory topics such as “climate change and medical care” for medical students; however, planetary health is not included (MEXT 2022). The concept of planetary health has given rise to a growing field of research focusing on the interdependencies between human health and the state of Earth’s complex natural systems and how this impacts the health and well-being of humans and our planet (Whitmee et al. 2015; Veidis et al. 2019). While climate change is a critical environmental crisis threatening the health of current and future generations, an understanding of the intricate relationship between anthropogenically induced degradation of the planet’s natural systems and the interconnectedness with human health is also essential. The integration of planetary health in the education and training of future physicians is fundamental for developing the competencies required to help address the accelerating impacts of the shifting ecosystems on human health.

A multinational study found that planetary health education was incorporated into only 15% of medical students' curricula and that the interest in learning more about planetary health among medical students is exceptionally high (Omrani et al. 2020). Therefore, it is recommended that “climate change and medical care” be taught through a planetary health approach. The ideas and concepts of what planetary health education could look like have already been outlined in several educational frameworks (Guzmán et al. 2021; Shaw et al. 2021; Stone et al. 2018). Evaluation from an elective course on planetary health delivered to medical students at the University of Oslo showed that the course provided students with enhanced knowledge and skills not offered in the current medical curriculum. In addition, some of the students expressed a greater interest in learning more about how to estimate the carbon footprint of health care, sustainable quality improvement, and health service adaptation to climate change (Aasheim et al. 2023).

Moreover, this study shows that prior education or training, knowledge, and awareness of climate change are significantly associated with physicians’ practice in delivering climate-specific advice to their patients. Therefore, the increased knowledge of future physicians could lead to a more active role in educating their patients about the health risks of climate change and health co-benefits, which could help mitigate the worsening climate crisis. Continuing professional education courses could bridge the knowledge gap of physicians currently in clinical practice.

Healthcare facilities lack environmentally sustainable healthcare practices

While more than half of the physicians feel they should advocate within their facilities to promote mitigation measures for more sustainable healthcare practices, less than half actively engage in any advocacy. The healthcare sector contributes around 4.4% to the total global greenhouse gas emissions worldwide, and if healthcare were a country, it would be the fifth-largest emitter on the planet (Pichler et al. 2019).

According to a policy paper by Health Care Without Harm, the climate footprint of Japan’s healthcare sector as a percentage of national emissions is 6.4%, placing the nation among the top major emitters by healthcare sector (Health Care Without Harm 2023). Thus, it is critical to reduce carbon emissions from the healthcare sector and focus on creating more sustainable healthcare systems. The WHO defines a ‘sustainable healthcare system’ as a system that improves, maintains, or restores health while minimizing negative impacts on the environment and leveraging opportunities to restore and improve it to the benefit of the health and well-being of current and future generations (WHO 2023).

Therefore, integrating sustainability into healthcare practice should be a priority in the healthcare sector. However, more than half of the physicians in this study responded that the facilities where they work do not support sustainable healthcare practices. Fortunately, in recent years, greening the healthcare sector has been a growing trend, and there are many promising examples in countries like England to provide guidance for developing and adopting more sustainable healthcare practices, such as the National Health Service (NHS) of England's 2020 strategy "Delivering a Net Zero National Health Service" (NHS England 2024).

Physicians could be at the forefront of shaping targeted strategies within the healthcare system, mitigating the consequences of climate change in the future by reducing greenhouse gas emissions in the facilities where they work. Increasing numbers of health professionals are aware of the need for more sustainable healthcare systems, with many moving toward engaging in climate change advocacy (Luong et al. 2021). There is already a great deal of potential, as many of the physicians in this study expressed a desire to choose more environmentally sustainable medical products and equipment.

Physicians are willing to engage in advocating for climate-specific policy changes

Despite the physicians’ high level of interest in engaging in advocacy on climate-specific issues led by health professionals, among the physicians in this study only 3.4% responded that they were aware of any climate-related initiatives or advocacy opportunities within the professional associations they are a part of. Professional associations are membership-based organizations that provide physicians with a network of peers and offer professional development, research, community health education, etc. These societies can also provide physicians with the resources and opportunities to advocate for creating more sustainable practices within healthcare systems and to engage with policymakers to strengthen their commitments to more robust climate change policy.

A multinational study that examined the factors that influence health professionals’ willingness to engage in climate advocacy showed that affective issue involvement has a strong positive association with the perception that climate advocacy is the responsibility of health professionals, which in turn has a strong positive association with willingness to advocate (Lee et al. 2021). The climate crisis must be aggressively and quickly addressed at all societal levels to mitigate its effects. Physicians from a qualitative study on motivations for advocacy work responded that most of their support for advocacy work has always come from professional associations; therefore, providing accessible opportunities through professional organizations may increase advocacy participation (Warwick et al. 2022).

Addressing climate change requires interventions both to the healthcare system and to the factors driving the demand. Thus, mitigation to reduce the source of greenhouse gases and adaptation to adjust natural and human systems is essential (Winkler et al. 2015). Globally, the health community has a vital part to play in accelerating progress to address climate change, and physicians are well-positioned to understand and communicate the implications of climate change and the necessity of taking action to protect the health of humans and the environment. Moreover, physicians can use their influence and scientific knowledge to facilitate climate-specific health education to the public through their patients, which will be good for both patient health and mitigating climate change. Additionally, physicians can advocate for more systems-level policy changes to promote sustainable healthcare practices within their facilities.

Strengths and limitations

This is the first national-level study to explore the knowledge, attitudes, and practices relating to climate change and health among physicians in Japan. The cross-sectional study design represents the views of only a sample of physicians in Japan; nevertheless, several important findings emerged, yielding tentative conclusions. Despite such limitations, the findings from the study are useful to improve the knowledge of current and future physicians on climate change and health. Moreover, this study may encourage more advocacy for climate change policy among physicians.

Conclusion

Physicians can apply their expertise and influence to combat climate change at various levels. Still, they will need to be better equipped with the education, materials, and support to do so. Having more training and support within medical schools, medical facilities, and professional associations, physicians can better identify patients at high risk of acquiring health issues due to climate change and provide climate-specific advice and health co-benefits of climate action. They can make more significant efforts to reduce their carbon footprints and raise awareness of the environmental impact within their facilities. Furthermore, they can serve as community role models to promote sustainable lifestyles and advocate for more robust climate change policy to improve population health. Future research could look at longitudinal studies of sustainable behavior change in patients in Japan who have been given climate-specific advice by their physicians. Physicians counsel patients daily and have gained society's recognition and trust, giving them a significant amount of personal and political influence; as such, physicians should become more aware of their essential role in being change agents to achieve a sustainable future.