Introduction and background

Human-induced climate change (CC) and the degradation of ecosystems that all species on earth depend on for life has accelerated at greater-than-predicted rates over the past decades. The effects of these changes have been widespread: increasingly frequent disruptions in weather and climate patterns; severe weather events; habitat loss and destruction; declines in biodiversity (ie, the variability among all living organisms within and between species.); food insecurity; increases in emerging infectious diseases; and adverse clinical and other health outcomes in people, animals, and the environment.¹ Studies by researchers from multiple disciplines and sectors have documented the drivers of CC that are interconnected with the degradation of terrestrial, marine, and aquatic ecosystems, biodiversity loss, and human and animal life, health, livelihoods, and well-being.^1–3 Tragically, some parts of the world have already experienced limits to how much they can adapt to their changing environment.¹

Veterinary medicine has provided leadership in the comparatively recent field of One Health, which aims to identify and implement effective, sustainable solutions to complex and interrelated human, animal, and environmental health problems.⁴ Given the rapid and escalating adverse environmental conditions and health impacts to humans, animals, and environmental health stemming from CC, there is an urgent need for all veterinarians to recognize and understand the drivers behind and health impacts of these changes, and the actions they and the veterinary profession at large must take to provide optimal care to their patients under changing environmental conditions. These actions can help society mitigate and adapt to these changes in concert with efforts by other health and environmental disciplines and sectors.^5–7

Over past decades, veterinarians have served as principal and co-investigators on important environmental research^2,4–8; provided leadership on environmental health in senior organizational positions at state levels; and participated as experts on national and international committees addressing CC and environmental health.^3,4 More recently, a few schools of veterinary medicine have sponsored symposia⁹ and developed websites¹⁰ that have focused on the causes and adverse health effects of CC. Some veterinary professional organizations have developed or signed onto either a position (eg, World Veterinary Association, 2022¹¹) or developed policies (eg, Australian¹² and British¹³ Veterinary Associations) on veterinary contributions to confronting CC. Several scientific groups and health professions have recognized the urgency and immense scale of the challenges to health posed by CC and have already identified actions and initiatives they are committed to taking to reduce and curb its causes (mitigation) or to help society reduce its impacts (adaptation) on health and well-being.^5,6,14–17

Nonetheless, even with these contributions and a brief AVMA policy on CC,¹⁸ the range of contributions that veterinary medicine has to offer in addressing the health consequences of CC perhaps may not have been effectively communicated to others, with the unfortunate consequence that veterinary expertise and perspectives have often been absent in interprofessional and multisectoral discussions and initiatives related to CC.^5–7

Adverse health impacts from CC are already affecting individual patients, animal populations and clients of veterinary practitioners, and the communities where they live.^7,19 It is critical, therefore, that in addition to other causes of illness and injury in which they are trained, veterinarians also have the knowledge and expertise to detect, diagnose, and treat adverse clinical conditions caused by CC.^2,7 Greater knowledge about the drivers of CC would empower veterinarians to educate their clients and communities about its escalating health and production consequences and accompanying declines in biodiversity that are adversely affecting the health, welfare, and well-being of companion animals, food-producing animals, wildlife, and human health.^{1,3,5,7,19–21} Moreover, veterinarians are respected and trusted by their clients and communities as reliable sources of scientific information on animal, human, and environmental health because of their training in animal health and welfare, public health, the comparative medical aspects of multiple species, and biomedical research.^4,22

Here, we focus explicitly on the challenges to the health of animals, humans, and the environment posed by CC and the ongoing degradation of ecosystems. We begin with a brief summary of the basic drivers and health implications of CC that are connected to veterinary medicine. Then, building on observations and recommendations by others,^{2,4–8,19–21} we propose a set of recommendations for veterinarians and the veterinary profession to act upon with urgency to mitigate and adapt to CC at local, state, national and global levels. In addition, we call for 1) greater recognition of the foundational consequences of CC to the health of humans, animals, and the environment; 2) greater national and global engagement by the veterinary medical profession to address the serious One-Health challenges and consequences posed by accelerating CC; 3) integrating environmental health more fully into veterinary medical education and research, including CC drivers, ecosystem degradation, and health consequences; and 4) the US veterinary medical profession to build and expand upon the current AVMA policy¹⁸ to develop a more comprehensive policy position aimed at mitigating and adapting to CC as well as a strategic plan for how to enact this policy. We hope that our view will inspire further discussion and urgent consideration of the range of contributions that the veterinary profession can make to mitigate and adapt to CC in collaboration with its One-Health partners.

Brief overview of drivers of climate change and ecosystem degradation

For decades, the world has depended on fossil fuels to meet energy needs for societal development and to produce food and water to meet the nutritional needs of an exponentially growing human population expected to reach 9 to 10 billion people by 2050.^1,23 That dependence has unfortunately led to agricultural, water, and infrastructure policies that cause deleterious changes to our climate and the degradation of ecosystems that undergird life on earth.^1,3,23 Past and current global dependence on fossil fuels to meet these needs have precipitously increased greenhouse-gas (eg, carbon dioxide, methane, nitrous oxide) concentrations in earth’s razor-thin atmosphere. The result is that as of 2020, the earth’s average mean surface temperature has increased 1.1 °C. Experts estimate a greater than 50% likelihood that global warming will reach or exceed 1.5° C by 2030 at current emission rates. If warming should exceed 1.5 °C, the risks of irreversible damage to vulnerable ecosystems are projected to increase substantially. Because rates of temperature increase vary by region, some areas of the world have already surpassed the dangerous threshold of 1.5 °C.¹ In addition to threatening vulnerable ecosystems, this rise in average surface temperature and oceans warmed from the absorption of increased carbon dioxide concentrations has amplified the frequency of extreme weather events—hurricanes, tornadoes, atmospheric rivers, intense rainfall bombs, severe flooding, droughts, and wildfires. These are all serious threats to human, animal, and environmental health that could outpace the ability of society to adapt.¹

Agricultural policies to increase land available for growing human food and animal feed crops have also led to large-scale deforestation and depleted soils from monoculture crops and polluted rivers, lakes, estuaries, and oceans from the runoff of chemical fertilizers and pesticides.^1,23 Rivers have been dammed to produce hydro power, water reservoirs for irrigating and transporting crops to port, for recreational uses, and for supplying urban centers with drinking water. However, the dams also have caused elevated river temperatures and changes in river flows, altering and destroying river habitat that is critical for the reproduction and survival of many wildlife species.²⁴ In looking to enhance economic development, countries have often turned to extractive industries (eg, logging and mining for minerals, metals, oil and gas) that have led to additional deforestation and river pollution.²⁵ The chemical, metal, and plastic contaminants that these and other industries produce have contributed to the pollution of our air, water, and land.^25–27 In addition, pharmaceuticals and other waste from human and veterinary medical practices also contribute to environmental pollution from their inadequate environmental disposition.²⁸ Substantial environmental pollution and the degradation of forests, rivers, watersheds, and other ecosystems are accelerating the rapid extinction of many aquatic and terrestrial species and threatening biodiversity critical to human, animal, and environmental health.^1,3,29,30

Why climate change and ecosystem degradation are veterinary health issues

Traditional veterinary education has focused on protecting the health of food-producing animal populations to help meet the nutritional needs of the global human and animal populations. However, as the global human population has increased, and given the finite availability of grazing land and water, veterinarians must learn to balance their responsibilities for ensuring the health and welfare of food-producing livestock with preserving the health of broader ecosystems that are critical to supporting all forms of life.^3,23 Moreover, the global decrease in insects, birds, and many other animal pollinators impacted by CC is jeopardizing food production and security around the world.³¹ We submit, therefore, that given veterinary medicine’s role in protecting the health, welfare, and well-being of non-human species, the profession has an essential responsibility and role to play in protecting biodiversity. These connections are entwined with veterinary medicine’s newest responsibility of preventing and treating diseases of honey bees, our nation’s top managed commercial pollinator species.³²

Clinically, extreme heat and other severe weather events associated with CC are causing higher rates of heat-related and cardiovascular morbidity and mortality in humans^1,33 and animals^7,19 than would occur from other causes alone. Air pollution from wildfires and industrial emissions is a major risk factor for asthma, allergies, respiratory, and cardiovascular diseases in humans^34,35 and adversely impacts the health of animals.^36,37 Given the impacts of extreme heat and environmental pollution on human and animal health, and as some animals are more sensitive than people to these environmental changes, veterinarians have collaborated with human health partners on employing animals as sentinels for environmental stresses and pollution-related human illness.^2,8,38

With respect to infectious diseases, increased temperatures are expanding the range of arthropod vectors into higher elevations and northern climes, thereby impacting their ecology and behaviors and the risk of diseases, such as malaria, dengue, hantavirus, Rift Valley fever, Lyme disease, and others.^39,40 Elevated surface temperatures and severe weather are also adversely impacting water quality and pathogens, resulting in climate-sensitive disease outbreaks and morbidity and mortality from diarrheal disease, cholera, dengue, cryptosporidiosis, campylobacter, leptospirosis, and harmful algal blooms.⁴⁰

Climate change resulting in substantial sea level rise and environmental degradation is leading to civil conflict and the forced migration and relocation of coastal human populations and their animals, thereby threatening their physical and mental health, livelihoods, and cultural well-being.⁴¹ With regard to these and other climate-related emergencies, veterinarians have worked on emergency response teams with other health professions to provide rescue, recovery, and relief to people and animals exposed to extreme temperatures, floods, wildfires, drought, famine, and other unhealthy environmental conditions.^42,43 Veterinary responders have helped to ensure animal welfare under these conditions and assisted in translocating animal populations affected by these severe environmental conditions and the migration of human communities associated with rising sea levels.⁴⁴

The World Organization for Animal Health (WOAH) has addressed the connections between CC and multiple determinants of animal health, including the changing patterns of infectious diseases, and veterinary services.²¹ The UN Food and Agricultural Organization (FAO) has emphasized support for countries to mitigate and adapt to the effects of CC through research-based, practical programs focused primarily on agriculture to improve human health and well-being and to enhance societal development, with animal health as a contributing element.⁴⁵

Educating veterinarians to address climate change and ecosystem degradation

Current and future threats from CC to human, animal, and environmental health will continue far into the future. It is essential, therefore, that veterinarians be educated on the linkages among CC, environmental health, and the diagnosis, prevention, and treatment of climate-related animal, human, and environmental health impacts. This need is supported by the results of a recent survey that showed veterinarians and students recognize CC as a growing threat and have identified a need for more environmental education.²⁰ This education should be included in veterinary medical educational curricula²⁰ (as it has been recommended for the curricula of human medicine⁴⁶) and in continuing education courses and other educational programs.

More veterinary schools should consider sponsoring symposia and websites with resources on the causes and health consequences of CC and unhealthy ecosystems, as well as recommended actions to mitigate and respond to these threats. Topics would include addressing adverse animal clinical consequences and the public health impacts of CC, sustainable food systems, biodiversity loss, and other topics.^9,10 The USDA National Veterinary Accreditation Program already includes training modules for a subset of relevant areas, such as animal disease control, emergency response and honey bee medicine.⁴⁷ In 2022, the AVMA launched a First Responder Certificate Program⁴⁸ to train veterinarians to work with other first responder agencies (state and federal agencies and nonprofit organizations) to confront a range of disasters, including those associated with changes with CC, such as floods, hurricanes, and wildfires. Recently, the American College of Veterinary Preventive Medicine established a special interest group on sustainability for their diplomates. Topics for discussion will focus on the “role of veterinarians to protect ecosystem health and contribute to CC mitigation and environmental protection … including, but not limited to, advising on acceptable use of resources (feed, manure, and animal by-products) and the appropriate handling of medical waste.”⁴⁹

Proposed actions by veterinary medicine to mitigate and adapt to climate change in collaboration with One-Health partners

There is an important niche to fill and an urgent need for veterinary medicine to engage with health professionals, environmental scientists, and others to take action to mitigate and adapt to CC health threats.^{2,4,6,7,44,45} There is a clear opportunity and role for veterinarians to help educate their clients and communities on the causes and health implications of CC for animals, people, and the environment, as well as on feasible, effective actions to address these health challenges. In 2019, one professional veterinary group proposed an action agenda comprising seven recommendations modified from a 2011 National Research Council Report, “Advancing the Science of Climate Change,” for animal health and veterinary medical professionals. Among the recommendations were actions to promote animal health linked through CC to ecological and human health; investigate and communicate to decision-makers, communities, and other professions the implications of CC on animal health, conservation, sustainable food production systems, food security, public health, and community resilience; and incorporate CC into veterinary undergraduate and graduate curricula.⁶.

Building on this work and other previous studies and observations, we propose a broader range of recommended actions that are related to veterinary medicine and that are consistent with the AVMA veterinary oath: to protect animal health and welfare, prevent and relieve animal suffering, conserve animal resources, and promote public health.⁵⁰ These actions listed below, when acted upon individually or in partnership with other health professions, would help reduce the adverse health consequences from CC and environmental degradation

Recommendations for veterinarians to mitigate (M) causes of human-induced climate change and ecosystem degradation

M1. Veterinarians, based on their education, training, professional responsibilities, and as a trusted source of scientific information, should be knowledgeable about and able to communicate and discuss:

• The fact that CC is a global emergency.

• The basic evidence for CC, its threat to human, animal, and environmental health, and options for mitigation.

• Sustainable and regenerative agricultural systems and practices to produce healthy, food-producing animals (including bees and other pollinators), crops for human food and animal feed, and food safety and security to meet nutritional needs while minimizing greenhouse gas emissions and the degradation of ecosystems and wildlife habitat.

• Current causes and the accelerated rate of species extinction; the implications of biodiversity loss to human, animal, and environmental health; and policies and programs that conserve and promote healthy wildlife habitat and biodiversity.

• The impacts of CC on the transmission of emerging zoonotic infectious disease pathogens (including those that are vector-borne) in human and animal populations, their changing ecology, and effective disease prevention and control strategies.

M2. Veterinarians should support evidence-based policies for energy, agriculture, water, biodiversity conservation, and extractive industries that will: substantially and rapidly reduce and ultimately eliminate dependence on fossil fuels; reduce greenhouse gases to Net Zero (carbon neutrality); slow global and ocean warming; conserve terrestrial, marine, and other aquatic wildlife habitats; prevent the importation and spread of invasive species¹; and prevent or reduce pollution and contamination of our air and ecosystems with harmful pathogens, chemicals, metals, plastics, and other contaminants.

M3. Veterinarians must responsibly dispose of medical pharmaceuticals, supplies, and waste produced by clinical practices to reduce environmental pollution.

M4. Veterinarians must share their knowledge and expertise about animal health, zoonotic diseases, and animal welfare with decision-makers addressing CC.

M5. The veterinary profession should continue to proactively reach out to and engage with other health professions to conduct multidisciplinary research and identify important actions that veterinarians and the veterinary profession can take to mitigate CC in concert with actions by others.

Recommended actions to adapt (A) to climate change

A1. Veterinarians must have the knowledge and medical skills to prevent, diagnose, and effectively treat climate-related adverse health consequences. Examples would include: hyper/hypothermia from temperature extremes; cardiovascular and respiratory events; increased risks of exposure to zoonotic and vector-borne infectious diseases, especially in new geographic areas; morbidity and mortality from storms, floods, droughts, or famine; poisonings from pollution and harmful algal blooms; poor air quality from particulates in wildfire smoke and other industrial airborne emissions. Veterinarians can help clients and community members to be aware of and understand the substantial impact these adverse environmental conditions pose for human and animal health. Veterinarians can advise clients on potential husbandry modifications that could be made to prepare and protect their patients from further climate-related risks to animal health.

A2. Veterinary scientists should proactively reach out to and engage with human, agricultural, and environmental scientists to identify priorities for infectious disease prevention and control related to CC. Factors to consider would include human and animal infectious disease associated morbidity and mortality; livestock and other agricultural production losses; the economics of disease prevention, control, elimination, and eradication; the availability of feasible and effective interventions; and environmental impacts and costs, among others.

A3. Veterinarians must be knowledgeable about and proactively provide leadership in protecting and ensuring the welfare of animals living in conditions impacted and stressed by CC. They should be prepared to participate in the development of integrated management plans for the protection of coastal areas with special emphasis on the health and welfare of affected animals.

A4. As some animals are more sensitive than humans to changes in environmental conditions that pose risks to health, such as extreme temperatures and environmental pollution, veterinarians should be knowledgeable about the role and use of animals as sentinels of environmental stresses and human illness from CC to assure more timely diagnosis and treatment of animals and to provide advance notice of potential risks to exposure of environmental health threats to human populations.

A5. Veterinarians should be knowledgeable about and trained for participation in emergency preparedness and response teams with other health professions to respond to emergencies related to CC, such as impacts from severe weather events and or other disasters. This would include being:

• Prepared to assist people and animals exposed to extreme temperatures, floods, wildfires, droughts, famine, and other unhealthy environmental conditions.

• Knowledgeable about the 2006 Pets Evacuation and Transportation Standards Act, which requires communities to include plans for evacuation of pets as well as people in emergencies to qualify for US Federal Emergency and Management Administration funds (enacted following the widespread disaster of Hurricane Katrina in 2005 on the Gulf Coast when people refused to evacuate without their animals/pets).⁴³

• Prepared to assist in and or lead (as called upon) the safe, humane translocation of animal populations affected by severe environmental conditions and the migration of communities associated with rising sea levels.

• Knowledgeable about emergency communication protocols and channels to relay critical, timely information among human, animal, and environmental health professionals and sectors.

A6. Veterinarians with relevant post-graduate education should lead and participate in multidisciplinary biomedical and agricultural research to identify factors that enable some species to adapt more successfully to rapidly changing environmental conditions, which would advance agricultural and biomedical research in this critical area.

Discussion

In 2015, The Rockefeller Foundation and The Lancet journal introduced the new field of Planetary Health to address more emphatically the connections between human societal development (and the accompanying unsustainable increases in energy, water and food consumption) and ecosystem health, ultimately circling back to adverse impacts on human health and well-being.³ The report called for greater engagement by the health professions to address the existential threat of CC in the Anthropocene era.

Several health professions, research networks, and organizations have joined environmental and environmental-social scientists to identify actions their members can take to mitigate and adapt to CC. They have published recommendations and pledges to affirm commitments to acting on CC to protect personal, community, and planetary health and to restore the diversity of life on our planet.^3,5,12–17 The American Medical Association (AMA) is now considering how CC affects the health of their patients and members and identifying actions they can take to mitigate and adapt to the health challenges posed by CC.¹⁷ Highlighting the need for multidisciplinary engagement, another human health research group listed 13 actions to which a unified health profession should commit, including learning about CC, advocating for equity, protecting the natural systems that underpin a viable planet for future generations, sharing knowledge, and serving as trusted members of society, among others.¹⁴

The role of veterinarians in protecting and advancing animal and public health is well recognized. However, there is an urgent need to further develop the vital role that veterinary medicine can play in preventing and responding to CC, along with its One-Health partners.^5–7 Veterinary medicine has been a leader in the field of One Health to effectively confront the complex health challenges of today through multisectoral collaboration. Given the threats to animal, human, and environmental health from CC and ecosystem degradation, it is critical to add our voices to veterinary and other health and science colleagues calling for greater urgency and engagement to identify and commit to ways in which veterinary medicine can confront these continuing threats.

We have presented a broad range of actionable steps that veterinarians and the veterinary profession can take to confront CC. Some are drawn from activities in which veterinarians are already engaged (eg, disaster response teams) or are actively pursuing (eg, veterinary schools finding ways to incorporate CC education into their programs). Veterinary medical contributions could come from veterinarians who serve as private clinical practitioners⁷; local, state,⁴³ or federal government or non-governmental organization experts²; academic faculty^5,8, or knowledgeable sources of scientific information in their communities.^4,22

Our list is not meant to be final or comprehensive—nor are we suggesting that all recommendations be acted upon concurrently and immediately. The important point is that as veterinarians, we begin to recognize and embrace the existential threat that CC poses to the health and sustainability of animals, humans, and the environment, and that we begin to take immediate action to the best of our abilities and in collaboration with others. In the US, the veterinary profession could begin to build upon AVMA’s current “Climate Change and One Health” policy.¹⁸

Our hope is to catalyze a fuller discussion and inspire further thought on actions that veterinarians, veterinary staff, and veterinary medical organizations can take to confront this challenge. Finally, given the growing recognition that unhealthy, degraded ecosystems lead to unhealthy humans, animals, and plants,^1,3 we suggest that the One-Health paradigm more fully and visibly highlight the foundational connections between CC and the lives, health, and well-being of humans, animals, and plants at population and individual levels.

Nature is demanding that much greater attention be paid to protecting the health of all ecosystems that make life possible. Now is the time for action to confront this most urgent and critical threat to animal, human, and environmental health. We strongly recommend that the veterinary medical profession prioritize this challenge and act with great urgency.