Extreme weather events

A growing number of studies are contributing towards an understanding of human influences on climate change and extreme weather events (Zhai et al. Reference Zhai, Zhou and Chen2018). Berry et al. (Reference Berry, Bowen and Kjellstrom2010) characterise these climate change-related weather events as acute, sub-acute and chronic. Examples of acute events include extreme weather events or natural disasters such as flooding, storms and hurricanes. Sub-acute events include drought and climate change-related epidemics. Chronic events include desertification, changes in ambient air temperature and rising sea levels. The effects of natural disasters on mental health include increases in a range of mental health problems. Flooding, an event we are likely to experience in Ireland, comes with risks of chronic mental distress and Post Traumatic Stress Disorder (PTSD) (Jermacane et al. Reference Jermacane, Waite, Beck, Bone, Amlôt, Reacher, Kovats, Armstrong, Leonardi, Rubin and Oliver2018; Munro et al. Reference Munro, Kovats, Rubin, Waite, Bone, Armstrong, Beck, Amlôt, Leonardi and Oliver2017; Reacher et al. Reference Reacher, McKenzie, Lane, Nichols, Kedge, Iversen, Hepple, Walter, Laxton and Simpson2004).

Severe storms also increase population-level mental health risks. After Hurricane Katrina, 16% of survivors sought treatment for mental health problems in the 8 months following the hurricane and this represented just one in three of the individuals whom reported significantly elevated psychological symptoms in that same period (Wang et al. Reference Wang, Gruber, Powers, Schoenbaum, Speier, Wells and Kessler2007). Almost one in four Hurricane Katrina survivors who were undergoing mental health treatment prior to the hurricane reduced or discontinued their treatment because of the disruption they experienced (Wang et al. Reference Wang, Gruber, Powers, Schoenbaum, Speier, Wells and Kessler2007).

Effects of heat

Extreme heat and drought are known consequences of climate change (Dai, Reference Dai2013; Di Lorenzo et al. Reference Di Lorenzo, Cobb, Furtado, Schneider, Anderson, Bracco, Alexander and Vimont2010). Potential impacts may have already been seen in suicide rates in middle-aged males in rural areas of Australia that have experienced unprecedented periods of drought since the millennium (Hanigan et al. Reference Hanigan, Butler, Kokic and Hutchinson2012). More broadly, extreme temperatures tend to have dose–response effects associated with a variety of population-level indicators of mental health including emergency presentations, mortality associated with neuropsychiatric disorders and mental health admissions (Page et al. Reference Page, Hajat and Kovats2007; Wang et al. Reference Wang, Lavigne, Ouellette-Kuntz and Chen2014; Page et al. Reference Page, Hajat, Kovats and Howard2012). These effects are replicated across different social contexts and continents (Shiloh et al. Reference Shiloh, Shapira, Potchter, Hermesh, Popper and Weizman2005; Sung et al. Reference Sung, Chen, Lin, Lung and Su2011; Wang et al. Reference Wang, Zhang, Xie, Zhao, Zhang, Zhang, Cheng, Bai and Su2018; Wang et al. Reference Wang, Lavigne, Ouellette-Kuntz and Chen2014). There is limited understanding of the factors influencing why air temperatures are associated with increased mortality, admissions and emergency presentations of individuals living with severe mental illness. Comorbid physical illness, awareness of self-care, social isolation and inadequate housing are potential factors that could explain this relationship. There is a need for mental health professionals, particularly in heatwave prone countries to include this aspect of patient care in their risk assessments.

Inequalities and migration

Climate change will disproportionately affect those experiencing disadvantage whom are likely to have higher pre-existing prevalence of mental disorder. The disproportionate effects of climate change will also occur on a variety of scales, both between and within countries. Climate change will mean fewer resources in already vulnerable areas experiencing biocapacity strain, such as the Sahel region of Africa, and this is likely to lead to further armed conflict. We may expect estimated population transfers of at least 200 million people from regions with high climate change susceptibility and low climate change adaptability, such as African and South Asian river deltas (Myers, Reference Myers2005). These future climate change-related migrants will have high levels of vulnerability, facing many cultural, economic and linguistic barriers (Bhugra, Reference Bhugra2004). In Ireland, asylum seekers have 5–6 fold higher risks of mental health disorders such as depression and PTSD, compared to the general population (McMahon et al. Reference McMahon, MacFarlane, Avalos, Cantillon and Murphy2007; Toar et al. Reference Toar, OʼBrien and Fahey2009). Migrant status and specifically cultural distance have also been associated with increased risks of psychotic disorders (Selten et al. Reference Selten, Van Der Ven and Termorshuizen2020). Despite known health risks associated with migration, few countries in the developed world have developed migrant reception procedures and services that promote optimal health and well-being. This is an area of pressing need where mental health professionals need to advocate further.

Natural and built environments

Unhealthy, air-polluted urban environments are increasingly being shown to have a negative impact on mental health (Braithwaite et al. Reference Braithwaite, Zhang, Kirkbride, Osborn and Hayes2019; Newbury et al. Reference Newbury, Arseneault, Beevers, Kitwiroon, Roberts, Pariante, Kelly and Fisher2019). Potential mechanisms for this association such as effects of air pollution on brain inflammation and oxidative stress have been investigated in both human cohort studies and experimental animal models (Hajipour et al. Reference Hajipour, Farbood, Gharib-Naseri, Goudarzi, Rashno, Maleki, Bakhtiari, Nesari, Khoshnam, Dianat and Sarkaki2020; Peters et al. Reference Peters, Ee, Peters, Booth, Mudwa and Anstey2019). Access to green spaces has been repeatedly associated with better mental and physical health and reduced all-cause mortality (Callaghan et al. Reference Callaghan, McCombe, Harrold, McMeel, Mills, Moore-Cherry and Cullen2021; Rojas-Rueda et al. Reference Rojas-Rueda, Nieuwenhuijsen, Gascon, Perez-Leon and Mudu2019). Investments in creating safe and effective modes of active travel and mass transit and promoting increased physical exercise will help to reduce carbon emissions, particulate matter and toxin exposure and improve mental health. Active travel is an evidence-based health imperative and the medical community needs to be more effective in advancing it.

Pandemics and biodiversity

In discussing the climate crisis, we must remember that we are facing a dual crisis in the environment. We are not just faced with the threat of a warming atmosphere but also that of biodiversity loss. As humans encroach further and further into remote places of the natural world, we face increasing risks of more spill-over events from more phylogenetically distant, and therefore more potentially virulent and transmissible micro-organisms (Johnson et al. Reference Johnson, Hitchens, Pandit, Rushmore, Evans, Young and Doyle2020). Indeed climate change is suspected to play a role in increasing bat diversity in the Chinese province of Yunnan that has been associated with the emergence of both SARS COVID 1 and 2 (Beyer et al. Reference Beyer, Manica and Mora2021). We have recently experienced the mental health impacts of the COVID-19 pandemic (Moreno et al. Reference Moreno, Wykes, Galderisi, Nordentoft, Crossley, Jones, Cannon, Correll, Byrne, Carr and Chen2020). These effects have been substantial and are likely to persist for many years to come. Preventing the next pandemic by increasing early warning response systems through public health infrastructure investment is an urgent and absolute priority.

Building capacity

Mental health and public health professionals are experienced in understanding science, communicating it effectively and enabling behaviour change. Therefore, they are uniquely valuable to the climate crisis. Our role should be twofold: Reducing the impact of our activities on the environment and providing trusted, hopeful leadership to prepare for the effects of climate change on the population’s mental health. The carbon footprint of healthcare accounts for 4.4% of worldwide emissions. Ireland is a major emitter and there is much we must do to reduce the impact in our domestic health sector (Karliner et al. Reference Karliner, Slotterback, Boyd, Ashby and Steele2019). To prepare and strengthen the healthcare system to serve the population, the focus of care must shift from an individual, illness-based model to a whole community, health-based approach including prevention and fostering of social capital, community resilience and personal empowerment (Maughan et al. Reference Maughan, Berry and Davison2014). Our medical and psychiatric training and curricula must also be climate proofed (Maughan et al. Reference Maughan, Berry and Davison2014). COVID-19 has witnessed the world looking to healthcare professionals for leadership; our clinicians must be equipped to manage this effectively. Framing the climate crisis as a health crisis is both true and necessary, with the added benefit of increasing public engagement which is crucial in building momentum to avert catastrophic climate breakdown (Myers et al. Reference Myers, Nisbet, Maibach and Leiserowitz2012).

Climate grief to climate action

Capturing the intersection of environmental change and mental health, Albrecht et al. (Reference Albrecht, Sartore, Connor, Higginbotham, Freeman, Kelly, Stain, Tonna and Pollard2007) described ‘Solastalgia’ (synonymous with eco-anxiety, ecological grief, climate grief and climate anxiety). This phenomenon is defined as personal distress associated with environmental change and destruction. Albrecht et al. (Reference Albrecht, Sartore, Connor, Higginbotham, Freeman, Kelly, Stain, Tonna and Pollard2007) first described this phenomenon in the drought-stricken Hunter Valley region in Australia. MacSuibhne (Reference MacSuibhne2009) argued that ‘Solastalgia’ is not yet a mental illness as it is not part of the diagnostic armamentarium of psychiatrists. Nevertheless, concepts such as climate grief have captured the public imagination through the activism of young people and, it is likely to be a term we will increasingly encounter. Climate anxiety in young people can be viewed as a response to an impending major crisis in which those most affected by threat have the least agency to enforce change. Beyond recognising the threat, health professionals should promote acceptance of the seriousness of climate change and endorse value-based actions to help everyone in society live more sustainable lives (Wu et al. Reference Wu, Snell and Samji2020). The existence of organisations such as Irish Doctors for the Environment (www.ide.ie) and leadership from the World Health Organisation are hopeful signs that the medical profession is mobilising to address the climate crisis (WHO, 2017). There is little time to waste in promoting action. Every degree of warming counts.