When we contemplate the whole globe as one great dewdrop, striped and dotted with continents and islands, flying through space with other stars all singing and shining together as one, the whole universe appears as an infinite storm of beauty. — John Muir

is a major stressor in contemporary life. There is not a single day that we don’t read about the hazards of climate change, learn about a horrible disaster plausible connected with climate change. For those of us who accept the science, we often feel outrage at people — especially those in power — who not only refute climate change, but roll-back efforts intended to address the hazards facing our planet and species. In addition to outrage, , sorrow, helplessness, , disgust, eroding , and the like... nothing good for emotional wellness.

What kind of animal are we to continue down this path, faced with what we now know? We know that the is powerful. Crowds of people will walk by someone dying on the sidewalk, and do nothing. We tell ourselves that someone else will do something, absolving ourselves from having to act, a deadly human characteristic called "diffusion of responsibility" which comes out in groups. The more the merrier, one might darkly quip.

We also fail to act because we go along with the herd. If no one else is addressing the issue, perhaps most importantly our leaders, why should I risk separating myself from the group? Being exiled is, evolutionarily speaking, tantamount to a death sentence more often than not. That's part of why rejection feels so bad, why social exclusion lights up pain centers in the brain. Social is a powerful and lethal force, as much as it shapes society in positive ways as well.

How do weather factors affect our health?

Numerous studies have provided evidence that climate change is associated with poor mental and emotional well-being. Many of these studies have been smaller scale or focused on specific populations. That is, until now.

Researchers from MIT, Harvard, UCSD, the Laureate Institute for Brain Research, and the Edith Nourse Rogers Memorial Veterans Hospital (2018) published the results of a large-scale study providing empirical evidence of the mental health risks threatened by climate change. Working from a broad framework for mental health, they recognize that “[s]ocial, economic and physical systems are critical determinants of psychological well-being.” They note that mental health disorders exact a high price, with close to 50 percent of Americans experiencing some mental health issue in their lifetime, affecting , general health and quality of life. The WHO has identified mental health issues such as depressive and disorders as tantamount to an epidemic, a public and global health crisis which will take a massive toll on all of human society if left unchecked.

The authors note that while many studies have shown the negative impact of specific events, including increased and posttraumatic disorder after hurricanes and floods, increased rates during heat waves and drought, and increased hospitalization when the temperature rises, well-designed studies of the large-scale effects of climate change on population mental health have been harder to conduct.

New research on mental health and climate change.

To look at the question of the effects of climate change on population mental health, researchers tapped a database of 2 million US residents between the years of 2002 and 2012, using data from the Center for Disease Control and Prevention’s Behavior Risk Factor Surveillance System. People answered the question, “Now thinking about your mental health, which includes stress, depression, and problems with emotions, for how many days during the past 30 days was your mental health not good?” This one question was chosen by the CDC because it has been shown to be a simple, reliable indicator of mental health with statistical validity comparable to other accepted measures.

They took this data and related it to meteorological information using research methodologies from “climate econometrics” to look at relationships between facets of climate change and mental health, over time. The focused in on three high-impact types of stressor: short-run weather exposure, warming over a span of years, and the near-term effects of natural disaster.

They posed several questions:

Do recent meteorological stressors affect mental health?

Are more vulnerable groups affected more severely by meteorological stressors?

Does longer-term warming adversely affect mental health over a span of years?

Does direct impact from tropical storms worsen mental health?

How climate change affects mental illness rates for 2 million people.

They found that all three climate change experiences — the immediate effects of weather, warming over several years, and tropical storm exposure — significantly worsened mental health. They found that shifts in average monthly temperatures from 25 to 30 degrees centigrade to over 30 degrees worsened mental health in a dose-dependent manner. For each degree of average temperature increase, mental health worsened by a 2 percent increase in the rate of reported mental health issues. They found that in acute cyclone disaster zones, using Hurricane Katrina data, rates of mental health difficulties were 4 percent higher than in unaffected areas. For short-term weather changes, both increased heat and increased rain worsened mental health in a dose-dependent relationship.

Based on the short-term effects of warmer and more rainy months alone, extending their findings to the whole US population translates into nearly 2 million extra people with mental health difficulties in any given month when the weather is worse. We all know how tough it can be to struggle through a heat-wave, or a period of prolonged bad weather — these numbers tell the story of our personal experiences writ large.

The chilling implications for spiraling mental illness with unchecked climate change.

These are disturbing findings, and would, for any rational creatures, be a wake-up call. The number of people expected to have significantly worsening mental health, when extended to the population of the US, let alone the world, means millions and millions more people with increased suffering, physical health problems, and impairment in function. Our current mental health systems are already grossly inadequate to meet the current demand for care, as rates of depression, anxiety disorders, and other illnesses continue to rise, and healthcare costs along with them. And these numbers are for a relatively well-resourced, first-world country. Climate change may have more profound effects in regions already under great strain, close to the tipping point.

The broad-brush strokes of this study show that on the population level, climate change has a major negative impact on our well-being, and future work will be more granular, looking at specific mental health and related issues. Areas of interest include the effects on mental health from different meteorological stressors for different groups, including psychiatric illness, , and impact on substance use. In addition to clinical outcomes, distress which does not reach diagnostic significance nevertheless can have major negative effects on individual well-being, family, and culture which we have yet to envision.

The future is uncertain.

Moreover, if we don’t get ahead of the mental health impact of climate change and do something about it, we are likely to get caught off guard and have difficulty responding effectively, compounding the problem further. As with many other anxiety-provoking issues for which there is no clear, good solution, we tend to use denial and avoidance to manage our emotional states, at our own peril.

This research, in some ways, represents a turning point in understanding the effects of climate change on mental health. We need to better understand the causal relationships among weather-related factors and mental health outcomes. Underlying factors could include, authors note, changes in inflammation as a direct effect of climate, or could be due to factors such changes in level of exercise or eating habits.

Other factors not included in this study, harder to measure at this time, may also be important — such as a rise in sea-level. The study authors note that worry about climate change may itself be a primary factor. There's no question, that at least subjectively the day-in-day-out barrage of terrifying news causes massive amounts of anxiety, whether you are someone who numbs out, worries actively, and/or is trying to do something about climate change. This is truly the stuff of , as anyone afflicted with apocalyptic nightmares can tell you.

Ongoing research can start to look at these factors so we can understand what is happening when climate change impairs emotional well-being and identify areas of intervention to make us more resilient. If climate change continues to escalate as scientists predict, and the United Nations stridently warns, and we fail to heed these warnings, we open ourselves up to unfathomable, preventable horrors which will affect everyone. Understanding why people refute climate change will help to develop ways to educate and persuade.