It is a scientific consensus that climate change is a significant threat to global mental health and well-being 1. Subacute or long-term climate-related events, such as heat waves and higher temperatures have been found to be associated with increased mental health issues and even suicide rates 2. For example, a large sampled study examining the relationship of historical meteorological data and information of two million US residents found that shifting of monthly temperatures between 25 °C and 30 °C or above increased the probability of mental health difficulties by 0.5% points, and 1°C of 5-year warming associated with a 2% point increase in the prevalence of mental health issues 3. Measuring and monitoring the impacts of climate change on mental health requires a long-term and pragmatic approach by incorporating multiple data sources. Unfortunately, most studies to date investigating the impact of climate change on mental well-being have been conducted with cross-sectional surveys which may suffer from recall biases or failed to evaluate the underlying mechanisms 4. In addition, they have focused solely on clinical mental health outcomes such as hospital attendance or admission, and suicide. Little is known about the real-time emotional impacts such as negative moods, and the more subtle impact on mental well-being caused by climate change. There is also insufficient understanding of how climate change-induced emotional well-being influences downstream pro-environmental behaviours. To answer those inquiries and address these gaps, the current research aims to link social media data and meteorological data to provide a more comprehensive understanding of the impact of climate change on public emotional well-being, the potential mechanisms through cognitive responses, and their impact on pro-environmental tendencies.
The impact of climate changes on people’s emotional well-being
There has been extensive evidence that long-term climate change-related events were associated with adverse mental health outcomes including various mental disorders, hospitalizations due to mental health, and even suicide 4,5. Both more chronic meteorological changes and acute extreme weather pose significant threats to individuals’ psychological well-being. Concerning the impacts of long-term meteorological changes, a systematic review suggested most meteorological factors such as temperature increase, aridity, and heat waves were associated with mental health outcomes, including hospital admissions for mental health reasons, exacerbation of mental health conditions, sleeping difficulty, fatigue and suicide 6. Another systematic review of ambient temperature and mental health revealed that an increased 1°C of daily temperature was associated with a 1.7% increased incidence of suicide 4. It has been consistently reported that acute extreme weather events, such as flooding and drought, were associated with diverse mental health issues, including post-traumatic stress disorder, anxiety, and depression 7. While numerous studies have examined the links between weather indicators and mental health outcomes, many of them primarily concentrated on post-trauma scenarios utilizing cross-sectional surveys. It is important to note that such surveys may be susceptible to recall biases, impeding participants' ability to accurately recall their exposure, especially for those who have suffered from mental health problems 3,8,9. In addition, current studies on the impact of climate change on mental health outcomes barely measured its underlying mechanism 4. Except for clinical outcomes, various non-clinical outcomes such as mood, positive and negative affect, and overall well-being were also employed to assess the impact of climate change on mental health 4. Relatedly, climate anxiety, also termed as eco-anxiety for some, has been commonly used to describe the psychological distress resulting from worries or other negative emotional responses related to perceiving the adverse ramifications of climate change and powerlessness in taking climate action 10. While those measures may not directly indicate the clinical profile of individuals, they allow for a broader understanding of the effects of climate change on mental health in wider populations. This broader generalizability can be beneficial for the early detection of individuals who are at risk.
Although climate change affects all populations. The impacts can be disproportionally higher for people living in some regions and in specific seasons 11. For instance, evidence showed that hot temperatures in summer had a larger impact on individuals’ expressed sentiment 12, negative mood 13, and suicide 14 than in other seasons. Specific vulnerable groups, including children, the elderly, and communities that rely on the natural environment for sustenance and livelihood, as well as populations living in areas most susceptible to specific climate change events, are at increased risk for adverse mental health outcomes 15. Countries and regions with widespread poverty, and ineffective governments are also at a disadvantage situation in mitigating the impact of extreme weather events due to the low resilience with poorly equipped to prepare for and prevent environmental threats 16. This evidence suggests that the impact of the changing climate on mental health is also moderated by regional vulnerability and resilience 11. The framework for assessing vulnerability in human-environment systems proposed three core components - exposure, sensitivity, and resilience 17,18. Exposure captures the frequency and magnitude of hazard exposure. Sensitivity measures the degree of available biophysical and social resources in modifying the hazard impact while resilience refers to adaptive capacity to recover or evolve from climate-related events. In a recent study conducted in China, researchers examined regional health vulnerability to extreme heat by constructing a composite index of vulnerability based on those three dimensions: exposure (such as PM 2.5 and frequency of heat waves), sensitivity (including factors like elderly dependency and poverty population ratio), and resilience (considering factors like economy and green coverage) 19. The results indicated that the vulnerability index was positively associated with the proportion of deaths on hot days in summer (r = 0.518). However, Zhang et al.’s study (2021) focused on the associations and patterns at the aggregate level and the outcome of suicide. Little is known about how regional vulnerabilities can moderate the emotional impact of climate change at the individual level.
Climate change on emotional well-being: cognitive responses as potential mediators
While climate change-related events can directly affect individuals’ mental well-being 5, literature has documented several important mechanisms that could explain how climate change can indirectly impair human mental health. First, the physiological mechanism argues that exposure to heat waves may induce biological changes in neural mechanisms that may further affect and exacerbate symptoms in individuals with mental health conditions 20. Second, cognitive perspectives found that sleep deprivation caused by environmental changes can affect human cognitive capacity and contribute to mental health problems 21. Third, the environmental and social process states that climate change-related events can erode social and community well-being by reducing economic and agricultural outputs, ultimately leading to mental health problems 22. However, there remains limited knowledge regarding how cognitive responses such as individuals thinking styles, affiliative strategies, and personal somatosensory experiences interact with climate change-related events and mental well-being. Investigating these cognitive strategies can offer important insights for mitigating the impacts of climate change on mental well-being.
Thinking style
In accordance with the Stimulus-Organism-Response framework, meteorological changes in the environment can induce cognitive and emotional responses in human being and ultimately impact human health directly or indirectly 23. According to Daniel Kahneman, the cognitive responses to a stimulus or information involves two styles: intuitive thinking (System 1) and analytical thinking (System 2) 24. Intuitive thinking is a process that is usually fast, automatic, and sometimes unconscious process, while analytical thinking is a process that is more logical and deliberative. People are usually predisposed to a specific cognitive style, the more intuitive or analytic one, 25, but in more stressful contexts, the more analytic style can be suppressed while the more intuitive style can be activated 26. Individuals who adopt an analytical thinking style tend to perceive more control in a specific situation compared with those who mainly adopt the intuitive thinking style 27,28. Consequently, individuals relying on analytical thinking are more likely to experience positive emotions, as they perceive greater control 27 and self-efficacy 29, and are more likely to engage in future pro-environmental behaviours (PEBs) 30. Conversely, intuitive thinking is associated with greater skepticism towards climate change 31. The potential reason could be that analytical (vs. holistic) thinkers perceive a greater sense of connection with the environment, have more positive attitudes towards environmentalism, and hence pro-environmental intentions 32. However, there is also a stream of studies that found cognitive sophistication may magnify politically biased processing 33. Nevertheless, these studies didn’t examine thinking styles as a potential mediator of the impacts of the changing climates on emotional well-being.
Social connectedness and affiliations
Based on the Social Safety theory, social connectedness and affiliations (perceived being connected and affiliated with others) serve as an important factor that buffers the emotional impacts of major environmental hazards 34. Extensive research has demonstrated that individuals with high affiliative motives are more likely to experience positive emotions and exhibit better mental health outcomes compared to those with self-focused motives 35,36. Additionally, research in social psychology suggested a reciprocating relationship between affiliative motives and positive emotions 37. Engaging in affiliate motives and altruistic acts could alleviate and help prevent mental health difficulties, leading to better emotional outcomes 38. In turn, those positive emotions encourage individuals to help others who are in need and form an ongoing cooperative relationship 39. When faced with a novel or threatening event such as climate change, individuals were likely to experience an increased desire to affiliate with others who shared similar experiences to mitigate the same threat 40. A recent review on drivers for climate action has revealed that social groups and the individual attachment to these groups can be influential on individual climate actions 41. Relatedly, environmental groups have commonly employed more affiliative language such as emphasizing collective identity and efficacy to engage people in collective action 42. However, there is limited knowledge regarding the triangle relationship between affiliate motives, climate change-related events, and public emotional well-being.
Somatosensory experiences
The existing literature elucidates the mechanism linking somatosensory, brain, and affect systems revealing the pathway of how somatosensory systems mediate the impact of climate change on mental health 21,43. The process begins with the body’s sensory system receiving the signals from climate change-related stimuli and subsequently transmitting those signals to the brain systems that control affective function. The somatosensory system is responsible for the conscious perception of various bodily somatic sensations, including touch, pressure, pain, temperature, body position, movement, and vibration 44. Previous research on the association between different body sensations and emotions demonstrated that somatosensory experiences could trigger conscious emotional responses and different bodily sensations are associated with different emotions 45. Given the connection between somatosensory experiences and emotional responses, it is reasonable to speculate that individuals may perceive and interpret different bodily signals when exposed to increased temperatures and extreme weather events, potentially leading to the activation of negative emotional states. However, empirical testing is required to confirm this hypothesis.
Will poorer emotional well-being due to climate change hinder pro-environmental behaviours?
The cognitive and emotional impacts of climate change can go beyond and influence people’s behaviours. Research indicates that negative emotions triggered by climate change can have a bi-directional impact on pro-environmental behaviours 46. On the one hand, coping mechanisms suggest that negative emotions triggered by climate change-related events can motivate individuals to take action to mitigate the negative impacts of climate change 47. For example, a cross-sectional study involving 32 countries found that climate anxiety positively correlates with pro-environmental behaviours and environmental activism 48. On the other hand, some argue that chronic negative mental health problems may lead to eco-paralysis, a state in which individuals passively respond to climatic and ecological challenges, feeling hopeless and powerless 49. A recent study also reported an association between higher climate anxiety and fewer pro-environmental behaviours, highlighting that climate anxiety led to lower efficacy and dampened individuals’ ability to take climate actions 50. Despite some evidence, existing studies have yet to examine whether the more real-time negative impact of climate change on emotional well-being would harm their pro-environmental intentions and tendencies.
Using social media data to monitor public emotional well-being and psychological responses to climate change
Numerous studies have demonstrated social media’s potential to understand the public’s perception and emotional responses to climate change-related events 51-53. Through the use of natural language processing and network analysis, researchers have been able to study public reactions and sentiments to climate policy actions on social media platforms such as X (formally known as Twitter) 54. While the sentiment and emotional expressions on social media may not indicate the clinical profiles, previous studies have demonstrated that linguistic expressions including content features (e.g., words and context), style features (e.g., punctuations and emoji), and word categories (e.g., discrete emotion dictionaries) have shown strong predicting power for various mental well-being outcomes including depression and suicide 55,56. Sentiment and emotional distress identified from those digital content can be used for early detection of individuals who are in need and provide in-time interventions 57. Among those psycholinguistic methods, Linguistic Inquiry and Word Count (LIWC) dictionary has demonstrated great potential and validity in capturing social media users’ emotional and cognitive responses to science communication agendas such as climate change 42,58 and COVID-19 pandemic 59,60.
While social media data has been widely utilized to comprehend public reactions to climate change, only a limited number of studies have employed a combination of social media data and offline meteorological data to monitor the influence of offline temperature changes and extreme weather events on the public's emotional responses to climate change 61,62. This approach may provide a more comprehensive picture of real-time interactions between climate change and the public’s affective responses in a large-scale population. A recent study leveraged social media data and offline meteorological data to investigate how temperatures can impact the expressed sentiment on Weibo revealed that maximum temperatures above 35°C led to an 89% reduction in sentiment 12. Compared with the study conducted by Wang et al. (2020), our study holds three important separations. First, we aim to uncover potential cognitive mechanisms that elucidate the impact of climate change on mental well-being. Second, our conceptualization and definition of the changing climate events (detailed in study measures) expands upon this study that solely relied on daily mean and maximum temperatures. We argue that extreme weather indicators should be constructed with regional meteorological characteristics and the regions’ historical records. Using a one-size-fits-all criterion (e.g., 35°C) to model the extreme weather may be biased and problematic by overweighting the regions with hotter temperatures 63. Third, we explored regional differences in climate impact with systematic regional vulnerability factors (detailed in measures), which can shed light on future climate mitigations and policies.
Building on the knowledge gaps discussed above, this study aimed to investigate the real-time impact of acute extreme meteorological events, including extreme daily temperatures and precipitations, and more long-term meteorological changes, including deviations in daily temperatures and precipitations, on the public’s emotional well-being and cognitive responses, using one popular online social media platform - Weibo data and offline regional meteorological and vulnerability data. Weibo was chosen because it is one of the most popular social media platforms in China. In September 2023, the monthly active users reached 605 million, and the average daily active users were 260 million 64. In addition, Weibo has been widely used to investigate climate change discourses 65 and impacts 12,51. Guided by the climate response-related theories as our theoretical foundation, we propose and test one novel mechanism between meteorological indicators and emotional responses through three cognitive pathways (Figure 1). Specifically, we anticipate that:
H1. Extreme meteorological events and meteorological changes are associated with public emotional well-being displayed in climate-change discourse. Specifically, extreme hot days and increased temperatures are associated with more negative emotional well-being.
H2. The association of H1 is not universal across the whole country or four seasons. People who live in regions with higher vulnerability and in seasons with hotter days (e.g., summer) are more prone to be influenced.
H3. The association of H1 is mediated by individuals' intuitive-analytical thinking style, social affiliations, and somatosensory experiences. Specifically, extreme hot days and hotter temperature changes trigger intuitive-leaning thinking style, less affiliative attitude, and a higher level of somatosensory experience would be associated with more negative emotional well-being.
H4. Extreme hot days have a negative impact on people’s pro-environmental tendencies. This effect is channeled through their emotional well-being where extreme hot days lead to poorer emotional well-being and hence a lower willingness to be pro-environmental.