Pollution's Impact On Climate Change: What's The Link?

Air pollution is the leading environmental cause of illness and premature death worldwide, with fine air pollution particles or aerosols causing 6.4 million deaths every year. Air pollution is also the main cause of climate change. Human activities such as burning fossil fuels and deforestation lead to increased carbon dioxide in the atmosphere, which traps heat through the greenhouse effect, impacting climate patterns and sea levels. While not all pollutants have the same effect, some cause warming, and others have a temporary cooling effect.

Greenhouse gases and the greenhouse effect

Greenhouse gases are gases in the Earth's atmosphere that trap the Sun's heat. This process is known as the greenhouse effect, and it is what makes Earth a comfortable place to live. The greenhouse effect works like a greenhouse, which stays warm inside even during the winter. Sunlight enters the greenhouse and warms the plants and air inside, and at night, the greenhouse stays warm because the glass walls trap the Sun's heat.

The greenhouse effect on Earth works similarly. Gases in the atmosphere, such as carbon dioxide, trap heat in a similar way to the glass roof of a greenhouse. These gases are called greenhouse gases, and they keep the Earth warm and cozy at an average of 58 degrees Fahrenheit (14 degrees Celsius).

Human activities, such as burning fossil fuels like coal and oil, have been increasing the amount of carbon dioxide and other greenhouse gases in our atmosphere. This has led to an increase in the greenhouse effect, causing the Earth to warm up.

The main greenhouse gases responsible for the greenhouse effect include carbon dioxide, methane, nitrous oxide, and water vapor. Carbon dioxide enters the atmosphere through burning fossil fuels (coal, natural gas, and oil), solid waste, trees, and other biological materials, as well as through certain chemical reactions like cement production. Methane is emitted during the production and transport of coal, natural gas, and oil, as well as from livestock, other agricultural practices, land use, and the decay of organic waste. Nitrous oxide is emitted during agricultural, industrial, and land use activities, as well as from the combustion of fossil fuels and solid waste. Fluorinated gases, such as hydrofluorocarbons and perfluorocarbons, are synthetic greenhouse gases emitted from a variety of household, commercial, and industrial applications.

Black carbon and other particulate matter

Black carbon, commonly known as soot, is a component of fine particulate air pollution (PM2.5). It is formed by the incomplete combustion of wood and fossil fuels, which also produces carbon dioxide (CO2), carbon monoxide, and volatile organic compounds. Black carbon has a warming impact on the climate, with a warming effect up to 1,500 times stronger than CO2 per unit of mass. This is because black carbon is very effective at absorbing light and converting it to heat. When suspended in the atmosphere, black carbon warms the air and surrounding surfaces, altering weather patterns and ecosystem cycles. It also influences cloud formation and impacts regional weather and rainfall patterns.

Black carbon's warming effect is particularly pronounced when it settles on snow and ice, accelerating their melting. This effect is estimated to have contributed to 0.04°C of warming since 1750. The Arctic and glaciated regions, such as the Himalayas, are especially vulnerable to this impact. Black carbon deposited on ice and snow reduces surface albedo (the ability to reflect sunlight) and heats the surface.

The average atmospheric lifetime of black carbon particles is just 4-12 days, but it has significant direct and indirect impacts. About 5.8 million tonnes of black carbon were emitted in 2019, with household energy accounting for nearly half of global emissions. In Asia and Africa, residential solid fuels contribute 60-80% of emissions, while in Europe and North America, diesel engines are the primary source, contributing about 70% of emissions.

Black carbon emissions are declining due to improved practices in brick manufacturing, reduced open burning in the agriculture sector, improved fuel and vehicle standards, cleaner household energy, and a global push for clean air. However, more can be done to accelerate their reduction. Targeted strategies to reduce black carbon emissions can provide relatively quick climate and health benefits. For example, implementing integrated waste management systems and adopting cleaner cooking technologies can significantly reduce emissions.

In addition to black carbon, other particulate matter (PM) can also impact climate change. Particulate matter can have either warming or cooling effects on the climate. For example, particulate sulfates have a cooling effect on the Earth's atmosphere. The impact of climate change on particulate matter is less certain, but research is underway to address these uncertainties.

The impact of air pollution on human health

Air pollution poses a major threat to human health and the climate. It is the presence of one or more contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke or vapour, in quantities and durations that can be harmful to human health. The main pathway of exposure is through the respiratory tract, but some pollutants can also enter the bloodstream. This can lead to inflammation, oxidative stress, immunosuppression, and mutagenicity in cells throughout the body, impacting the lungs, heart, and brain, among other organs.

Air pollution is a risk factor for all-cause mortality as well as specific diseases. The specific diseases most strongly linked to exposure to air pollution include stroke, ischaemic heart disease, chronic obstructive pulmonary disease, lung cancer, pneumonia, and cataract (household air pollution only). There is also evidence linking air pollution exposure with an increased risk of adverse pregnancy outcomes, other cancers, diabetes, cognitive impairment, and neurological diseases.

Fine particulate matter (PM2.5) is the air pollutant driving the most significant health problems and premature mortality. In 2021, 97% of the urban population was exposed to concentrations of fine particulate matter above the health-based guideline level set by the World Health Organization. The World Health Organization (WHO) has also provided evidence of links between exposure to air pollution and type 2 diabetes, obesity, systemic inflammation, Alzheimer's disease, and dementia.

Children and adolescents are particularly vulnerable to air pollution because their bodies, organs, and immune systems are still developing. Children who are exposed to air pollution are more likely to develop health issues during childhood and later in life. They are also less able to protect themselves or influence air quality policies. Older people, pregnant women, and those with pre-existing health conditions are also more susceptible to the health impacts of air pollution.

People in low-income communities and minority populations are disproportionately exposed to air pollution and are more vulnerable to adverse health impacts. This is due to factors such as living near busy roads or industrial areas, working or exercising outdoors, and lacking access to healthcare.

The economic costs of air pollution

Air pollution has a significant impact on the economy, with far-reaching costs. According to a report by Greenpeace Southeast Asia and the Centre for Research on Energy and Clean Air, the burning of fossil fuels, such as gas, coal, and oil, has led to a global economic cost of $2.9 trillion, equivalent to 3.3% of the world's GDP. This figure is staggering and highlights the immense burden that air pollution places on societies and economies worldwide.

The healthcare costs associated with air pollution further contribute to the economic burden. The treatment of respiratory and cardiovascular diseases, as well as other health issues caused by air pollution, places a significant strain on healthcare systems and increases public health expenditures. In 2018, sick leave and preterm births resulting from air pollution cost the world $100 billion and $90 billion, respectively. These costs not only affect individuals but also their guardians or caregivers, who may need to take time off work, further reducing labour force participation rates.

Air pollution also impacts the economy through its effects on agriculture and food security. Ground-level ozone (O3) pollution is a particular concern, as it can reduce crop yields and impact the quality of crops. According to the World Bank and the Institute for Health and Metrics, global welfare losses from PM2.5 and O3 exposure totalled $5.11 trillion in 2013. By 2030, O3 is expected to reduce stable crop yields by 26%, threatening global food security and nutrition.

Addressing air pollution is not just an environmental and health imperative but also an economic one. Implementing policies and technologies to reduce air pollution can have significant economic benefits. For example, achieving the Paris Agreement targets for mitigating climate change is estimated to cost $22 trillion, but the resulting health benefits could lead to savings of $54 trillion, according to UN Environment's sixth Global Environment Outlook.

How pollution affects ecosystems

Pollutants in the air can be toxic to plants and trees, and pollutants in rainfall can damage habitats by depositing acids or excess nutrients. Water bodies such as rivers and lakes are also susceptible to the effects of air pollution.

Ammonia and nitrogen deposition, for example, reduce plant species richness and diversity, favouring species that are tolerant of excess nutrients. This leads to changes in plant and animal communities within habitats and can also alter their ecosystem function.

Air pollution can also cause eutrophication, where excess nutrients are introduced to water bodies, driving algal blooms and reducing oxygen availability. This process can be harmful to both terrestrial and aquatic ecosystems, degrading environments and reducing biodiversity.

Ozone is another pollutant that damages tree leaves and negatively affects protected natural areas. Ozone enters plant leaves and reduces photosynthesis, slowing a plant's growth and increasing its vulnerability to pests and diseases. At the ecosystem level, high levels of ground-level ozone can drive the loss of species diversity and lead to changes in ecosystem structure and habitat quality.

In addition, heavy metal compounds emitted as exhaust from fuel combustion can eventually accumulate in plants and animals, some of which are consumed by people.

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