**9. Wildfires**

Rising global temperature affects public health in urban and rural communities across the world [185]. In recent years urban heat waves have become more severe, which has corresponded with an increase in heat-attributable deaths during times of extreme summer temperatures [186]. In rural communities, phenomena such as dust storms and crop failures, along with invasive insect infestations and invasions, have increasingly appeared [187–193]. To make things worse, CC also creates an environment more prone to wildfires, which are affecting rural communities with increased frequency, and are progressively more common near more densely populated areas [7, 14, 194]. Human consequences of all of the above factors, especially when acting synergistically, will be both profound and difficult to calculate [7, 14]. As average global temperatures continue to rise it is imperative to quantify the burden that the health systems will face due to more severe heatwaves and wildfires [195].

Heatwaves are often defined as 2 or more consecutive days with temperatures above the 95th percentile for the summer [196, 197]. Relative risk of mortality increases during heatwaves in urban centers, particularly among elderly patients and patients with pre-existing cardiorespiratory conditions [198, 199]. This was demonstrated during an August 2003 heatwave in Europe, when heatwaveattributable mortality reached 14,800, the risk of out-of-hospital cardiac arrests increased by 14%, and hospitalizations significantly increased among asthma patients [200, 201]. Patients with pre-existing cardiorespiratory conditions were most at-risk for heat-related mortality [200, 201]. It is important to consider cardiovascular and respiratory conditions because they are among the most common pre-existing conditions within a progressively aging general population [202–205]. The specific physiologic processes causing increased mortality in patients with existing cardiovascular conditions during heatwaves are still poorly understood. However, it can be postulated that longer and more severe heatwaves place more strain on the cardiovascular system to maintain physiologic body temperatures via thermoregulation. Additionally, high temperatures are associated with elevated heart rate, increased blood viscosity from dehydration, and higher blood cholesterol levels. These factors together with sub-optimal electrolyte balance and reduced cerebral perfusion place higher demands on the cardiovascular system, which could exacerbate symptoms in vulnerable patients [206, 207].

Respiratory conditions on the other hand could be worsened because of lengthening frost-free periods and increasing levels of dusts and other pollutants in the urban atmosphere [208, 209]. This can be further exacerbated by the simultaneous presence of wildfires (e.g., California or Colorado, Summer 2020) [7, 14, 210, 211]. Evidence suggests that as carbon dioxide levels increase, ragweed (which is ubiquitous in urban communities) flowers earlier and produces 30-90% more pollen [212, 213]. By association, allergic sensitivity may lead to exacerbations of respiratory illness like asthma, but the phenomenon may have other synergistic components that are also directly or indirectly tied to CC [214].

Traditionally, rural communities have offered a relative escape from the smog and heat trapping environment of the city [215]. However, rising global temperatures are diminishing the air quality of rural communities by creating a dry landscape that is prone to wildfires and dust storms [216–218]. More specifically, particulate matter smaller than 2.5 um (PM2.5), carbon monoxide, nitrogen oxide, ozone precursors, and other harmful substances are released from wildfires, with various other components present within the cloud of a typical dust storm [154, 219, 220]. Of note, PM2.5 exposure during wildfires has been associated with increases in emergency department and hospital visits related to respiratory illnesses [221], with asthma exacerbations and wheezing in patients 65 and older having the greatest morbidity impact [222]. Evidence of cardiovascular and noncardiopulmonary morbidity from particulate matter exposure is less consistent, with clear need for further research to better characterize any potential underlying associations [7].

### **10. Wind disasters**

The number and severity of wind disasters appears to be increasing over the past two decades [168, 223, 224]. This connection between CC and increasing number and intensity of major hurricanes and other similar weather events is not fully understood [225], but more recent evidence does support a more causative effect [226, 227]. The current 2020 hurricane season in the United States is among the worst on historical record [228]. Its logistical impact is further compounded by the co-presence of the Novel Coronavirus pandemic [228]. Similar to flood disasters (which may also occur simultaneously), wind disasters and their aftermath may also have significant impact on life within the affected regions [229]. The impact of wind disasters on humans goes far beyond direct physical damage and bodily injuries [230]. Forced human migrations and post-traumatic stress add a massive component of complexity to the overall post-disaster recovery process [231–233]. Moreover, there seems to be an association between post-traumatic stress following wind disasters and the emergence of cardiovascular and other comorbid disease manifestations (or exacerbations) [231, 234]. Such longer-term manifestation appear to be more pronounced among members of underrepresented minorities, further highlighting issues of social and health-care inequity [231, 235, 236].

### **11. Climate change: effects on mental health and societal crises**

Public health is influenced by a diverse collection of factors, many discussed in earlier sections of this chapter. One of the most under-appreciated factors is the effect of CC on mental health, both directly and indirectly, at both personal and societal levels [237, 238]. One of many subtle manifestations of societal distress is the proposed link between global warming, crop failures, and armed conflict [239, 240].

### *Impact of Climate Change on International Health Security: An Intersection of Complexity… DOI: http://dx.doi.org/10.5772/intechopen.96713*

As a result, we begin to see greater incidence of mass migrations and refugee crises [241, 242]. An associated surge in mental disorders and stress related diseases is inextricably tied to such occurrences [243, 244]. Given the intersectionality of stress related disorders and their effect on the mental health of populations, it is not surprising that many are being pushed to their coping limits when faced with food insecurity, environmental pollution, increasing frequency of natural disasters, crops failures, and economic and political instability [245]. Moreover, long-term effects of such new global status quo are equally difficult to predict [246].

Large scale human migrations due to natural disasters, conflict, famine, or political and economic instability, have been associated with mental health and stress related illnesses across the globe [247–249]. All population segments are affected, from rich to poor, from urban to rural, from young to old, without exception [250–252]. Exposures to potentially traumatic events, regardless of the exact nature of the event, are known to cause an increased risk for mental disorders including post-traumatic stress disorder (PTSD) [253–255]. Associated downstream consequences may include increased incidence of depression and increased suicide rates [256].

Significant proportion of the world's population does not have sufficient access to mental health support, including both high income regions (HIRs) and lowand-middle-income regions (LMIRs) [257–260]. Individuals from regions affected by CC (and secondary phenomena related to CC) may find themselves experiencing a myriad of stressors affecting mental health and resulting in various stress related diseases (including substance abuse) [245]. At the personal level, a number of different approaches can be used to effectively manage behavioral health symptoms, including cognitive behavioral therapies, medical-based treatments, as well as short- and long-term coping management therapies, with generally positive outcomes [261, 262]. At the societal level, public health education regarding mental health and wellness is of great importance [263–265]. Of course, governments and societies must continue to curb and address situations that contribute to ongoing stress and mental health related disorders. This focus in particular is critical to stabilizing populations affected most by CC and related crises [266].
