Extremes in Atmospheric Processes and Phenomenon: Assessment, Impacts and Mitigation

Extremes in atmospheric phenomena and processes can strongly affect ambient air quality that has harmful impacts on human and climate health. High urbanization and industrialization are highly responsible for causing disturbances in different spheres of environment like atmosphere and its processes and phenomena. This will further impact human and climate health. Various episodic extreme events are reported in urban areas causing health impacts like respiratory disorders, cardiovascular diseases and damage to central nervous system that often lead to death. This chapter focuses on factors governing in atmosphere that resulted in air pollution, fundamental understanding about recent and historic air pollution episodes, emergencies and extremes and their impacts on living organisms. Moreover, possible mitigation strategies have also been discussed to reduce the occurrence of air pollution episodes and minimize the disturbance in atmospheric processes. It also summarizes the highlights of different chapters signifying various aspects of atmospheric processes, mechanisms, extremities, impacts and disaster risk mitigation strategies.

Haze, fogs, wind-blown dust, and tornadoes are well-known examples of atmospheric phenomena. These atmospheric occurrences are normally observed around the world; however, some phenomena may be frequently observed over specific regions than others. For example, the United States (the U.S.) has the most experience in tornado strikes than any nation worldwide. The U.S. receives approximately 1200 tornadoes per year while this phenomenon annually occurs over New Zealand with about 20 tornadoes (the National Severe Storms Laboratory (NSSL), Severe weather 101—Tornadoes, 2021). When the strengths and intensities of these phenomena are raised, they become more and more severe; eventually, they turn to be natural hazards that threaten properties, economy, environment, and lives. In May 2011, Joplin, a destructive tornado, hit the city of Joplin, Missouri, USA that caused 161 fatalities and more than 1000 injuries; about 553 business structures and 7500 residential structures were destroyed. Economic loss of the city of Joplin after the devastating Joplin tornado stroke was estimated to be $2.8 billion (Houston et al., PLoS Curr 7:ecurrents.dis.18ca227647291525ce3415bec1406aa5, 2015; the National Institute of Standards and Technology (NIST), Joplin Missouri Tornado 2011, 2021).

The aim of this chapter is to demonstrate important atmospheric phenomena, in particular, hydrometeor and lithometeor, and their mechanism, since these atmospheric phenomena play a significant role in human livelihoods and human well-being with both positive and negative effects. On the other hand, human activities such as urbanization, industrialization, and intensive agriculture may accelerate the formation of these natural events and strengthen their intensities that may ultimately result in an increase in more frequent and more severe natural hazards. Therefore, in this chapter, effects of human activities on the mechanism of atmospheric phenomena are addressed and discussed. In the last session, we focus on the impacts of hydrometeors and lithometeor on human society in order to emphasize human-environment interactions, to raise awareness of environmental protection to societies which atmospheric phenomena should be integrated into environmental management. After all, the chapter illustrates how the environmental mechanisms enhanced by human activities are having tremendous impact on the human society ourselves.

Unregulated humans’ activities have over-exploited the earth’s natural resources, disturbed its terrestrial and aquatic ecosystems, and released vast amounts of pollutants into the environment. Air pollution is typically the presence of one or more contaminants in the atmosphere and in such quantity that is injurious to animals, plants, humans, and all other man-made and natural resources. World Health Organization (WHO) estimates that every 9 out of 10 people are exposed to high levels of air pollutants. World over air pollution is responsible for the death of about seven million people annually. A large proportion of this affected population (about 91%) resides in the developing economies in the South-East Asia and Western Pacific regions. The low- to middle-income groups are the ones who are most affected by air pollutants. Scientific studies have reported that a marginal increase of 10 μg/m³ of ambient PM₁₀ levels in Asian cities could lead to a surge in the mortality rate by 0.6%, which is significantly higher than the trends estimated for Western cities. The atmospheric CO₂ concentrations have already crossed the 410 ppm mark, which has never been recorded in human history. Air pollution operates on variable time scales and at various levels, i.e., local, regional, and global; and also produce impacts such as greenhouse effect and global warming; stratospheric; ozone depletion; atmospheric deposition, and acid rain; suppression of rainfall; atmospheric visibility reduction, etc. The severity of the impacts also varies from one organism to another and from one ecosystem to another ecosystem. Impacts on biota health are generally measured in terms of their influence on the morphological, biochemical, and physiological status and the responses generated thereof. Plants exposed to air pollutants may exhibit (1) direct or visible effects, which are often linked with short-term exposures to high concentrations of air pollutants or (2) indirect or invisible from long-term exposure to pollutants. Several national and international regulatory frameworks have been established to control and manage air pollutants. Despite intergovernmental and local efforts, air pollution has continued to rise across the major urban centers of the world, especially in developing economies like India and China. Scientific understanding and timely policy interventions are crucial in combatting the problem of air pollution emissions from the developed and developing world and consequently reducing their impacts on the living and non-living world. In this chapter, we have attempted to deliberate upon the major atmospheric pollutants (sulfur dioxide, oxides of nitrogen, ground level ozone, suspended particulate matter, fluorides, and peroxyacyl nitrates), their impacts on the atmosphere (global warming, stratospheric ozone depletion, acid rain, etc.), and threats to the biota health.

South Asian monsoon (SAM) is an important segment of the tropical monsoon system that mainly lies in the range of the seasonal oscillations of the intertropical convergence zone (ITCZ). About 70% of total rainfall in South Asia occurs during monsoon months each year, between June and September. Even within season, rainfall pattern is highly variable. The South Asian developing countries are mainly agro-based economies and livelihood of rural population is mainly dependent on natural resources which revive through the monsoon. The South Asian monsoon has influence on global atmospheric circulation and its future behavioural patterns will have serious implications for the entire world. Monsoon seasonal rainfall has temporal and spatial variability. There is no significant trend in Monsoon rainfall over past 100 years over the entire South Asian region. Ocean–atmosphere coupling in terms of ENSO and IOD has significant correlation with performance of monsoon over Indian subcontinent. IOD and ENSO are playing complementary to each other and maintaining good monsoon during recent decades. Along with year-to-year variability there exists intra-seasonal variations which are more markedly noticeable nowadays. These are in the form of prolong dry days with no rain or little rain and prolong wet days with rather good to very heavy rain forming a cycle of active and break spells. Extremes occur during active and break spells of monsoon. The extreme rainfall events mainly occur during synoptic scale weather systems like lows and depressions. Extreme events like flood, drought and more landslides are high impacting events that need proper strategies to overcome the adversities. The present study focuses on monsoon extremes, intra-seasonal variations and modulation by remote forcing and their future trends in global warming scenario. The global ocean–atmosphere coupling and its linkage with South Asian monsoon is on chance and how it will be progressing in future.

This chapter presents a brief review on the contribution of fog in changing air quality, its extremities and risks to environment and society. Fog is one of the extreme environmental phenomena which cause significant societal and economic problems specially as a great devastation to road and air traffic. As the hazardous effect of fog events is very high, their formation, spatial extent and evolution are needed to be investigated in detail. The detailed characterization of the formation and evolutionary mechanisms of fog pollution is necessary. The purpose of this chapter is to provide a brief outline on fog formation, development, distribution, characterization as well as its extremities and impacts on environment and society. In this chapter, we have started our study with the description of fog, its types and distribution worldwide, specifically in northern India. The microphysical structure, chemical composition and interactions which determine the behaviour of fog is also explained. The physicochemical characterization is described in detail which is necessary to understand the fog formation and its impact on environment and society. The chapter also describes the different factors responsible for fog formation. The different meteorological conditions and role of aerosol were explained which were amenable for fog formation. In the last section, the fog as an extreme event is described. The causes and their extremities on different aspects of environment and society are also provided in detail.

Sand and dust storms (SDS) are very important atmospheric extreme events that occurred under the influence of turbulent winds with dust particles in any arid region. These are the lower atmospheric meteorological events and their environmental implications are being recognized in recent years due to their growing significance with the climate, human health, and socio-economy. The SDS involves a reduction of visibility to less than 1000 m. The identification of SDS events and their frequency is important to assess their role as climatological and geomorphological agents. The SDS events pose a challenge to the goals of sustainable development. Generally, SDS is a common atmospheric phenomenon in arid, semi-arid, and dry sub-humid areas, though it can travel thousands of kilometers across the countries and oceans, and depends on the wind speed and particle size distribution. Sometimes, SDS accumulate other pollutants on their way and transport them from one place. On the routes of transportation SDS also affects the regional biogeochemical cycle. SDS have a several beneficial and adverse impact on the environment. The primary impacts of SDS events include atmospheric radiation balance, regional precipitation, and hurricane activity. The SDS events are also responsible for elevated levels of fine particulates in the atmosphere that are associated with premature mortality and cardiovascular problems, respiratory problems, lung carcinoma, and severe respiratory tract infections. Such inhaled fine particle is not only composed of fine mineral particles but also contains a hazardous mixture of chemicals, spores, microorganisms, fungi, and harmful allergens. Apart from their adverse effects on human health, they also pose several economic impacts such as disturbance of infrastructures, transportation, and supply chain set-ups. SDS events are also responsible for the elimination of the top fertile layer of the soil resulting in the decrease in the mineral content in the soil that ultimately affects the plant health and productivity of the landmass. The United Nations General Assembly (UNGA) adopted resolutions entitled “Combatting sand and dust storms” in 2015 and mentioned that SDS signify a major obstruction to the sustainable development that affect developing nations and their peoples. The objective of the current paper is to understand the nature and phenomena of SDS processes, current and past trends of SDS impacts, as well as to understand the impact of SDS hazards on environment and human health as well as extremities and their correlation with climate change.

Extreme temperatures, either elevated or low, are known to cause adverse impacts on the natural and human environment. Increased hospital admissions and mortality rates during heat and cold waves demonstrate the severity of the problem concerning human health. Heat waves (HWs) are expected to become more severe in terms of frequency, intensity, and duration due to climate change, whereas cold events will become rarer and milder. Along with rapid urbanization and deterioration of air quality due to human activities, heat waves pose a major threat for people’s well-being and quality living conditions, affecting especially the urban population. Thus, appropriate counter-measures and mitigation strategies are necessary worldwide in order to combat these effects in timely intervention. The current chapter focuses primarily on heat waves addressing in detail their definition, generation, future projection, and synergy with the urban heat island (UHI) effect and air pollution in cities, as well as their harsh impacts on several sectors and the approaches for mitigating these effects. A part of this chapter is also devoted to cold waves, while a case study concerning the inter-play between extreme temperatures, thermal comfort, and air pollution during a significant HW episode that occurred in Greece is presented.

The provinces of Punjab, Haryana and western Uttar Pradesh in northwest Indo-Gangetic Plain (IGP) produce two-thirds of India’s food grains, and are widely known as the “breadbasket” of India. This “breadbasket” accounts for roughly a quarter of the total annual fire events observed over India, and hence is a regional hotspot for biomass burning. The enormous amount of aerosols and trace gases, emitted largely from extensive post-harvest crop residue burning in autumn (October–November) and spring (April–May), along with events of wildfires, and domestic consumption of biofuels, unfurls its influence along the length of the IGP under the prevailing meteorological conditions. The elevated levels of pollutants, primarily generated from intense post-monsoon biomass burning over northwest IGP, under the influence of unfavourable meteorological conditions, contribute significantly to the episodes of extreme pollution over the regions downwind of northwest IGP. The downwind region of intense biomass burning experiences high values of particulate matter, including black carbon, organic carbon, ozone, volatile organic compounds and other ozone precursors, resulting in an intense photochemistry and an adverse air quality. Furthermore, excessive smoke aerosols in the atmosphere exert a strong surface cooling, but an overall atmospheric warming, thereby changing the regional radiative balance.

What makes Air Pollution dangerous?—it causes untimely death of innocent people, oblivious of the threat, and what did they do?- they breathed! Yes, that’s it. The victims are unsuspecting and at exposure of an inopportune risk. Annually, nearly 1.67 million Indians were killed due to air pollution, while so many more were endangered with some disease, allergies, health troubles, etc., due to the toxic air they breathed. Even though it is a silent killer, it is no more invisible. A noxious smog is seen hanging in the air every winter, dooming the once bright sunlit winter days, with its gloomy grayish-brown tint. Suspended particles in air scatter the sunlight away from the surface and what might appear as winter fog is actually the fatal smog, an intense blow to our fundamental right to breathe in a clean air. The critically impacted states include those in North India, such as Haryana, Punjab, Uttar Pradesh, and Delhi. The present chapter gives an overview of the challenges behind the increasing trend of smog events across Northern India. It seeks to deliver an understanding of the question of why the northern part of our country is becoming the pollution center of the world and intends to link the plausible causes and impacts for the rising extreme events of smog.

Volcanoes are an extreme expression of the mostly invisible movements of the fragments of the earth’s crust connecting the interior of the earth to its exterior. Since eons, they have had a major impact on the exterior surface of the earth and its gaseous envelope modulating the earth’s surface and its atmosphere. Depending on the type, intensity, and location of an eruption, the impacts can be both short term and long term, mild to extreme. The intensity of a volcanic eruption represents its explosivity in terms of volume of material ejected, ejection height, and distance the volcanic cloud travels away from its origin, which can span a wide range of scales. The requirement of a logarithmic scale to classify an eruption itself indicates how extreme one volcano can be compared to another. Volcanic emissions encompass all the three states of matter with tephra in solid form, lava in liquid form, and several acidic gases. The volume of ejected material for a very large eruption can amount to several cubic miles as in case of Krakatau (1883). Strong eruption can be related to silica-rich magma leading to large viscosity enabling trapping of gases until pressure builds up high enough to cause explosive eruption. The atmospheric impacts of volcanic eruptions range from small particles and ash playing havoc with aviation to ozone-depleting gases to global cooling as a result of emitted sulfur gases. The most explosive volcanoes can easily reach over 20 km and can lead to several feet of ash even 150 km away from the eruption site. Relationships between volcanic events and ENSO are an active field of research. Severe volcanic eruptions like Mt. Pinatubo have had an impact in all the five major spheres of the earth including the lithosphere, hydrosphere, atmosphere, biosphere, and the anthroposphere. The potential severe consequences of volcanic eruptions demand greater awareness and investigation of these extreme events with extreme consequences.

Bursting of firecrackers turns out to be a vital part of festivals and celebrations. The amount of air and noise pollutions caused by such celebrations has been increasing significantly for the past few years till the COVID episode. Particulate matter and toxic gases emitted as part of fire bursting pose a serious threat to human health. A variety of festivals and celebrations taking place in different parts of India pollute the rural and urban areas. Vishu is a regional New Year festival being celebrated with coordinated fireworks all over the south Indian state of Kerala. Intense fireworks usually start on the eve of Vishu from 18:00 to 22:00 h (IST) and on the day of Vishu from 04:00 to 07:00 h in two spells, which create smoke and dust in the atmosphere that leads to deterioration of air quality. Here, we describe the variations of surface ozone (O₃) and other trace pollutants for pre-, post- and Vishu days for two successive years (2020 and 2021) at Kannur town. No significant variations in air pollutants were observed on the Vishu days in 2020 due to countrywide lockdown to curb the transmission of COVID in India. But higher levels of trace pollutants were found during the intense fireworks during the two spells in the night of Vishu eve and early morning of Vishu day in 2021. Surface O₃ was found to be increased by 51% during the evening spell of fireworks on the eve of Vishu day and 61% on early morning spell on the Vishu day. A sharp increase in NO, NO₂, CO, SO₂, BTEX and NH₃, PM₁₀ and PM_2.5 concentration was observed during the evening spell of fireworks on the eve of Vishu day and early morning spell on the Vishu day when compared to the respective time in the pre-Vishu days. Metal concentrations associated with particulate matter were found to be higher during Vishu days than pre- and post-Vishu days. The average concentrations of metals are shown in the order S > Al > Cl > Ca > K > Zn > Na > Mg > Pb > Cu  > Ba > Cr > Fe > Ni > Sr > Mn. This shows that air pollution due to trace gases and particulate matter increases exponentially on fireworks days, unlike normal days. Such short duration activities carried out for visual and auditory pleasure have far-reaching effects. Therefore, it is evident that fireworks associated with celebrations and festivals are an event that can influence air quality to a large extent. In a densely populated area like Kerala, it is necessary to assess the consequences of such celebrations using fireworks and come up with a protocol for its use. Further, this work throws light on the absence of air pollution during the festival ban in 2020 in connection with a severe lockdown to curb COVID-19 transmission.

The occurrences of pollution episodes have brought out the strong linkages of pollution with health subsequently catalysing numerous regulations worldwide. Pollution episodes have been driven by a variety of mechanisms such as accidental large emission, trapping of pollution by stagnant meteorology and intense photochemistry involving strong anthropogenic emissions. Few regions of the world, e.g. the Indo-Gangetic Plain (IGP) and Northern China Plain (NCP), experience recurring pollution episodes with enhanced levels of fine particulate matter (PM_2.5), ozone (O₃) and other pollutants. Reductions in industrial and vehicular emissions should be planned by taking unfavourable meteorology also into account, besides control measures on burning of the crop residues and forest biomass to reduce the severity of pollution episodes. The development of greenbelts in residential and commercial areas and green roofing over buildings could reduce dust and other pollutants. Air quality monitoring over dense networks and high-resolution modelling with assimilation of observations would be of paramount importance for more accurate forecasts and better preparedness to minimize potential impacts.

Under most future emission projection scenarios, global temperature rise is imminent. Rising temperature is closely interlinked with balance in energy and water budget. As per the Clausius–Clapeyron equation, atmospheric moisture rises as 7% per °C rise. This means that both temperature and precipitation extremes such as heatwaves, floods and droughts will be more frequent and intense. Multiple atmospheric extremes events such as heatwaves with low moisture availability could have severe compounding impacts, e.g. increased risk of forest fires, droughts and dust storms. Moreover, global population is increasingly becoming more urban. Most future urban population growth is projected to be in the densely populated cities in Asia and Africa. Temperature and precipitation extremes are often exacerbated due to the presence of dense urban areas and are presented as urban heat islands, CO₂ domes, urban flooding, smog, etc. Cities, in general, show more vulnerability towards atmospheric extremes.

In order to mitigate such disasters, it is crucial to identify vulnerable hotspots and demographic groups most likely to be affected. The chapter outlines various disaster mitigation and adaptation strategies. Importance of science and decision support systems, data availability and sharing, early warning systems, timely information dissemination and post-disaster management are highlighted.

Over the past few years, air pollution has become a growing problem with an increasing number of acute incidents of air pollution in many cities across the world. As a direct consequence, air quality is contributing extreme risk to public health, accounting for about one in every nine deaths per year. Sudden and extreme air pollution episodes are creating disaster like situations causing an immediate public health emergency. Every year, as per the World Health Organization (WHO), about seven million people die tragically from air pollution-induced diseases around the world. Approximately four million such deaths occur in the Asia-Pacific region only. Now, it is not possible to perceive air pollution as an isolated environmental problem. It is high time that sudden air pollution management should be implemented into state and city planning processes. There is an urgent need for a concerted approach consisting of the generation and compilation of well-structured and exhaustive databases with geospatial locations on air pollution. There is also the requirement of effective representation and well-timely dissemination of air quality information, use of accurate and complex inferences to make significant implementation in air quality-related policy decisions.

Air pollution is a phenomenon harmful to the ecological system and the standard conditions of human existence. In the face of increasingly serious environmental pollution problems, various studies have been conducted on improving air quality better management of air pollution. Air pollution and higher rate of burning of fossil fuels consequently result into adverse weather patterns and atmospheric extremes like sand and dust storms (SDS) and wildfires. This chapter reviews some air pollution control technologies and their cost-effectiveness. We also provide an overview of atmospheric extreme events.

Air Pollution, across the globe is worsening despite efforts. It is an international concern due to its transboundary nature and its impacts on regional and global scale. Pollutants that are emitted to the atmosphere become an active participant in atmospheric reactions thereby altering the atmospheric processes. These alterations facilitate threatening air pollution episodes, what we call as “Air Pollution Extremes”. These extremes harmfully effect human health and the environment. There are mooted proposals from the researchers to consider the air pollution extremes as disasters. Disaster management institutes and agencies are to be given with responsibilities on this regard. Air pollution extremes namely, fog, smog, and dust storms have been responsible for multiple deaths per event and serious environmental havoc. World Health Organization (WHO) regards air pollution as a prime factor for human mortality and is to be blamed for seven million deaths in the world every year; therefore, control measures are imminent. Though countries already have in place the legislations and regulating authorities for the control and mitigation of air pollution, many Asian countries like India are still struggling. In this chapter, a two-way “green approach” has been discussed—lowering the source strength, i.e., keeping a check on emissions right at the source and mitigating the pollution that has already been released to the atmosphere. Adopting “green concepts” in economic development and better city planning, and strategically built green covers could be a promising alternative to avert extreme air pollution.

Air pollution is a public health concern worldwide. In India, deteriorating air quality is a grave issue causing nearly 1.1 million deaths in 2015 alone (Health Effects Institute, Burden of disease attributable to major air pollution sources in India, 2018). Globally, a significant proportion of human population is breathing poor air. While some megacities experience only episodic increases in air pollution, several Asian cities suffer from the problem chronically. Increases in ambient concentrations of criteria air pollutants above the prescribed air quality standards lead to a deterioration in air quality on different temporal scales. Direct emissions from natural and anthropogenic sources inject primary pollutants and their chemical transformations in the troposphere lead to the formation of secondary air pollutants. The life span of air pollutants can last from hours to decades depending on their chemical characteristics and concentrations at emissions. The need to control and manage the emissions of air pollutants and their ambient concentrations has been addressed through several international and national policy mechanisms that have paved a way for devising control strategies based on scientific solutions. However, these policy actions have not always provided a win-win solution owing to the complex nature of the problem involving multiple sectors and stakeholders. Learning from successful examples of coordinated implementation and timely achievement of objectives (as in the case of Montreal Protocol), it is imperative to build institutions that mature in their approach as the science on the issue develops. This is particularly applicable in the case of air pollution extremes where it is crucial to look for technological innovation while ensuring coordination between multiple agencies. This chapter reviews all the existing international and national policies that outline measures to curtail and abate ambient air pollution in chronic and episodic events as well as targeting abatement from natural and anthropogenic sources. The first half of the chapter covers  international policies that have been implemented to address the transboundary pollution with global implications. In the second part, policies adopted in India in response to abatement of deteriorating air quality at the state and national level are reviewed.

Management of atmospheric processes-related extremities is a challenging task for all kinds of regulatory authorities. It is a need of an hour to devise a methodology for which collaborative and participatory approach is important, so that micro limits of such extremities can be defined and identified. Unidirectional carrying capacity-based approach has been used by many researchers however multi-disciplinary, multidirectional approach is required where accountability should be in the core. Formulation of policies and its effective implementation with limited empowered work force is near to impossible; hence, bottom-up approach where decentralised and self-governance model is the only hope. The active and passive involvement of stakeholders is part of effective decision-making process, government agencies need people’s participation to manage public programs, its implementation and also for the mass awareness. The chapter talk through different approaches with national and international examples to understand effectiveness of participatory model. Participation of different stakeholders in decision-making process and managing the extremities is not straightforward process, hence role of training for state and non-state actors in this respect is important, for better governance and management. 

Further to this, role of participatory approach as potential solution to atmospheric extremities and its evolution has also been discussed. Chapter deliberates on different steps of participatory approach and postulates of effective management and response networks for the atmospheric processes-related extremities (APE).