Climate change contributing to harmful substance use

The pace and extent of climate change means that weather-related disasters are constantly happening somewhere in the world. Last year, the U.S. experienced devastating wildfires; Europe suffered record-breaking heatwaves, killing more than 20,000 people; and Australia entered its fourth back-to-back La Niña, leaving thousands homeless from floods.

Such disasters spawn blanketing stress and take a toll on mental health and wellbeing. People try their best to cope and, sometimes, coping means seeking new or increased comfort and escape in alcohol, tobacco, nonmedical prescription drug use or other psychoactive substances.

The inability to cope with the effects of worsening weather-related disasters is just one of many roads connecting climate change to harmful substance use. In a study published in Perspectives on Psychological Science, we map out these main roads and backroads to show how climate change can increase the risk of harmful substance use and make people more vulnerable to relapse.

Substance-use disorders already have enormous costs for individuals and society. They disrupt education and employment; increase accidents and crime; undermine social relationships and family functioning; and contribute to more than 16 million deaths each year. And many more people use substances at harmful levels that do not meet criteria for formal disorders.

By driving and compounding multiple stressors, climate change is likely to increase the overall burden of substance misuse. We propose this happens in five main ways.

  1. Stress

The frequency and severity of extreme weather-related stressors can have direct and indirect impacts on health and wellbeing. Acute weather events can lead to damaged infrastructure, agricultural losses, school closures, homelessness and displacement, all significant sources of psychosocial distress that activate acute and chronic stress responses in the body.

Extensive evidence from human and animal studies shows that exposure to stress can increase harmful substance use and relapse vulnerability. This often occurs through multiple pathways, including the use of substances as a means of coping (“self-medication”), changes in behaviour that increase impulsivity and reward sensitivity, and altered social contexts that may increase exposure to substance use.

  1. More mental-health problems

Weather-related stressors have knock-on effects directly affecting people’s wellbeing. Studies show rates of mental problems also are likely to increase due to climate stressors. Mental disorders and substance use are strongly linked and often co-occur. Around half of people with a mental disorder also have a substance-use disorder.

Most people with a substance-use disorder report that their use problems began after the onset of mental-health problems, an observation that is supported by long-term follow-up studies. Furthermore, evidence from genetic studies shows that individuals with several mental disorders – such as depression, bipolar disorder and schizophrenia – face higher risks of tobacco smoking and use of other substances.

Taken together, the evidence suggests that increasing rates of mental disorders, driven in part by climate change, are likely to lead to an increase in rates of harmful substance use.

  1. Greater physical health burden

The effects of climate change on physical health are now extensively documented. This includes increases in injuries from extreme weather events, heat stress, infectious diseases (e.g., malaria), malnutrition, wildfire smoke exposure, dehydration and developmental stunting due to reduced food and water quality to name only a few.

Physical health problems can contribute to the burden of harmful substance use in several ways. For example, disabilities and other chronic health problems are linked with higher rates of harmful substance use, possibly due to “self-medication” as a means of coping.

Chronic health problems are linked with higher rates of harmful substance use as a means of coping.

The treatment of many health conditions involves exposure to substances with addictive potential – such as painkillers – that in turn can increase the likelihood of longer-term dependence. Physical health problems also increase the risk of developing a comorbid mental-health problem that may then increase long-term substance-use vulnerability.

  1. Changes to established behaviour patterns

Climate change can alter our lives dramatically through a single catastrophic event, like a storm or flood. But subtle changes in climate and day-to-day weather patterns can also affect behaviour and routines that are relevant to substance use.

For example, studies show that warmer than average temperatures can harm sleep, an important protective factor against harmful substance use, as well as increase injury risk, decrease learning and academic performance, alter physical activity, increase hostile language and violent conflict and depress emotional sentiment – even when historically unusual temperatures are no longer socially remarkable.

These behavioural changes can have direct and indirect effects on substance use. For instance, warm weather can directly increase people’s alcohol consumption and increase exposure to drug cues and craving indicators – such as the sight of drugs and alcohol and their contexts of use – that play a significant role in drug use and relapse outcomes.

  1. Negative psychological responses to the threat of climate change

Surveys from countries around the world show that climate change generates complex emotional responses including feelings of anxiety, worry, fear, guilt, anger, grief and helplessness.

There is some anecdotal evidence that people who are concerned about the ecological impacts of climate change may be more likely to engage in harmful substance use. This idea is supported by studies that show that certain negative emotional states – such as sadness – are linked with long-term addiction among smokers and play a role in substance-use relapse. Other negative emotional states driven by climate change could also increase harmful substance use as a means of coping although further work is needed to better understand these associations.

Protecting those at highest risk

Substance-use problems already cause considerable suffering worldwide. Marginalized and disadvantaged communities are usually affected even more.

Although most people who use substances won’t meet criteria for a substance-use disorder, their patterns of use can still cause significant harm to themselves, their families and their communities.

Most substance-use problems start early in life – the peak age of onset for any addictive disorder is 19.5 years – highlighting the need to protect and support young people as climate change advances. This is critical because, once substance-use disorder is established, only one in seven will receive treatment. Furthermore, relapse rates are high – around 50 per cent, comparable with other chronic diseases.

There is no single cause of substance-use problems. Genetic liability, personality, family and peer relationships, poverty and stress all play a role. This means that multidimensional prevention strategies are needed.

Climate change can no longer be stopped. Its effects can be slowed through rapid emissions reductions – but effective adaptation planning will also be essential, including substantial global health investments, especially in mental health.

Making these changes now will pay dividends in the future – for vulnerable individuals, for health-care budgets and for the health and wellbeing of future generations. Can we afford it, you ask? The real question is: Can we afford not to?

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Francis Vergunst


Francis Vergunst is Associate Professor in psychological and social difficulties at the department of Special Needs Education, University of Oslo.

Helen Berry


Helen Berry is honorary professor of psychiatric epidemiology at Macquarie University, Australia.

Kelton Minor


Kelton Minor is Postdoctoral Research Scientist at Columbia University’s Data Science Institute exploring human adaptation to planetary risks and climate hazards.

Nicholas Chadi


Nicholas Chadi is a paediatrician specialized in adolescent medicine at the Université de Montréal.

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