Pollution's Impact: Climate Change And Our Future

Air pollution is the leading environmental cause of illness and premature death worldwide, causing 6.4 million deaths annually. It is also the main cause of climate change. Human activities such as burning fossil fuels and deforestation increase the levels of carbon dioxide and other greenhouse gases in the atmosphere, which trap heat and alter climate patterns and sea levels. While not all pollutants have the same effect, with some causing temporary cooling, the overall warming impact of greenhouse gases is significant. Addressing air pollution is crucial for tackling climate change and protecting human health, especially in low- and middle-income countries.

Greenhouse gases, such as carbon dioxide, trap heat in the atmosphere

Carbon dioxide (CO2) is a greenhouse gas that absorbs and re-emits infrared energy from the Sun. When sunlight reaches the Earth, the surface absorbs some of its energy and re-emits it as infrared waves, which we feel as heat. These infrared waves travel up into the atmosphere and will escape back into space if they are unimpeded. However, CO2 molecules absorb energy at a variety of wavelengths that overlap with those of infrared energy. As a result, when CO2 absorbs this infrared energy, it vibrates and re-emits the energy back in all directions, with about half returning to Earth as heat. This contributes to the greenhouse effect, trapping heat in the atmosphere and raising the planet's average temperature.

The greenhouse effect is essential for maintaining Earth's climate and making life possible. Without it, the Earth's average temperature would be below freezing. However, an excess of greenhouse gases can lead to global warming and climate change. Human activities, such as burning fossil fuels, deforestation, and industrial processes, have significantly increased the concentration of CO2 and other greenhouse gases in the atmosphere. This has enhanced the greenhouse effect, resulting in a net increase in the Earth's temperature.

The increase in greenhouse gases is primarily driven by vehicle exhaust, emissions from factories and power plants, agriculture, and other sources. CO2 has a long atmospheric lifetime, remaining in the atmosphere for hundreds of years. As a result, the added CO2 accumulates much faster than it can be naturally removed, leading to a net increase in the atmosphere. This has significant implications for global warming and climate change.

In addition to CO2, other greenhouse gases such as methane and water vapour also contribute to the greenhouse effect. Methane, another potent greenhouse gas, has a shorter atmospheric lifetime of about 12 years. Water vapour, the most common greenhouse gas, also absorbs and re-emits infrared radiation, contributing to the warming of the planet. However, the amount of water vapour in the atmosphere is influenced by temperature, with warmer air holding more water. As carbon dioxide and other greenhouse gases heat up the planet, more water evaporates into the atmosphere, creating a positive feedback loop that further enhances the greenhouse effect.

Black carbon, a particulate pollutant, contributes to warming the Earth

Black carbon is a particulate pollutant that contributes significantly to the warming of the Earth. It is a component of fine particulate air pollution (PM2.5) and is formed by the incomplete combustion of wood and fossil fuels, a process that also releases carbon dioxide (CO2), carbon monoxide, and volatile organic compounds. Black carbon is very effective at absorbing light, which contributes to its warming effect on the planet.

Black carbon's ability to absorb sunlight and heat the atmosphere makes it a key driver of global warming. It reduces the planet's albedo, or reflectivity, particularly when deposited on snow and ice. This reduction in albedo leads to increased surface temperatures, accelerating the melting of snow and ice. The warming effect of black carbon is estimated to be up to 1,500 times stronger than that of CO2 per unit of mass.

The average atmospheric lifetime of black carbon particles is relatively short, ranging from 4 to 12 days. However, during this time, it has significant direct and indirect impacts on the climate, snow and ice, agriculture, and human health. Black carbon influences cloud formation and impacts regional weather and rainfall patterns. It plays a crucial role in altering weather patterns and ecosystem cycles, particularly in regions where it is highly concentrated.

The sources of black carbon emissions vary across regions. Residential solid fuels, such as wood-burning stoves and open fires, contribute significantly to emissions in Asia and Africa. In contrast, diesel engines, including those used in transportation and industrial processes, are the primary source of black carbon emissions in Europe and North America.

Reducing black carbon emissions is crucial for mitigating global warming in the near term. Due to its short atmospheric lifetime, lowering black carbon concentrations can provide relatively rapid climate and health benefits. Implementing clean energy solutions, improving fuel and vehicle standards, and adopting cleaner household energy sources are effective strategies to reduce black carbon emissions. Additionally, open burning in the agricultural sector can be replaced by no-burn waste management techniques, and brick manufacturing processes can be modified to reduce black carbon emissions significantly.

Wildfires, caused by climate change, release pollutants and harm human health

Climate change is a key factor in increasing the risk and extent of wildfires. Research shows that changes in climate create warmer and drier conditions, with higher temperatures and lower soil moisture, all of which contribute to the spread of wildfires. In addition, climate change has led to longer fire seasons, with drought and low humidity extending the length of fire seasons at a faster rate than initially predicted by climate models. The combination of these factors increases the frequency, size, and severity of wildfires.

Wildfires release hazardous air pollutants, including smoke, black carbon, nitrogen oxides, hydrocarbons, and particulate matter, which can affect both the environment and human health. These pollutants can cause respiratory problems and other health issues for people living nearby, especially vulnerable groups such as children, the elderly, pregnant people, and those with pre-existing health conditions. Wildfire smoke can irritate the eyes and throat and damage the lungs, particularly in vulnerable individuals. It can also worsen existing respiratory conditions such as asthma and allergies, triggering asthma attacks. The tiny airborne particles in smoke and soot are especially dangerous as they can penetrate the lungs and bloodstream, worsening bronchitis and potentially leading to heart attacks.

Furthermore, wildfires can release toxic pollutants when human-made structures containing synthetic materials are burned. These toxic pollutants can contaminate water systems and pose additional risks to human health. For example, wildfires that burn in residential areas can melt plastic water pipes, causing contamination of water systems with known carcinogens.

The impact of wildfires on air quality can be significant and far-reaching. In 2023, smoke from wildfires in Canada's boreal forest travelled thousands of miles to the East Coast of the United States, affecting air quality in multiple regions. Wildfires can also have economic impacts, with firefighting costs, infrastructure damage, and healthcare expenses contributing to the financial burden.

To reduce the risks associated with wildfires, communities, builders, and homeowners can implement fire-resistant design features and materials in buildings, increase space between structures and nearby vegetation, and develop recovery plans to minimize habitat damage and erosion. Additionally, addressing climate change by reducing greenhouse gas emissions and improving forest management practices can help mitigate the frequency and severity of wildfires.

Ozone in the troposphere is a greenhouse gas and a health hazard

Tropospheric ozone is a powerful greenhouse gas that absorbs radiation and traps heat in the Earth's atmosphere, contributing to climate change. It alters evaporation rates, cloud formation, precipitation levels, and atmospheric circulation, leading to increased warming. The impact of tropospheric ozone is more pronounced in the regions where its precursor pollutants are emitted, disproportionately affecting the Northern Hemisphere.

Ozone in the troposphere is also a significant health hazard. Breathing ground-level ozone can result in a range of adverse health effects, particularly for individuals with respiratory issues. It can trigger asthma, worsen bronchitis and emphysema, and permanently damage lung tissue. Long-term exposure to ozone air pollution is linked to approximately one million premature deaths annually due to respiratory diseases.

Ozone pollution is especially harmful to children, the elderly, and people with pre-existing lung or cardiovascular diseases. During periods of high ozone pollution, people with respiratory problems are advised to take extra precautions or stay indoors. Additionally, ozone can irritate the eyes, causing chest pain, coughing, nausea, headaches, and chest congestion.

To address the issue of tropospheric ozone, strategies focus on reducing methane emissions and cutting levels of atmospheric pollution from vehicles, power plants, and other sources. Taking action to reduce methane emissions can lead to rapid reductions in tropospheric ozone pollution and mitigate its health and environmental impacts.

Short-lived climate pollutants, such as methane, are more potent warmers than carbon dioxide

Short-lived climate pollutants (SLCPs) are greenhouse gases and other climate pollutants that have shorter atmospheric lifetimes compared to carbon dioxide. SLCPs include methane, black carbon, tropospheric ozone, and hydrofluorocarbons (HFCs). Per molecule in the atmosphere, these pollutants have a stronger warming effect than carbon dioxide, making them more potent warmers.

Methane, a powerful SLCP, is a greenhouse gas that is 84 times more potent than carbon dioxide in its first 20 years in the atmosphere. It is produced by bacteria in the stomachs of ruminant livestock, natural gas and petroleum systems, waste disposal in landfills, and natural sources like wetlands. Methane is also a precursor to tropospheric ozone, another potent SLCP. Tropospheric ozone is not directly emitted but is formed through chemical reactions involving methane, carbon monoxide, nitrogen oxides, and volatile organic compounds.

Black carbon, another significant SLCP, is produced through the incomplete combustion of biomass and fossil fuels. Its major anthropogenic sources include biomass and fossil fuel burning for heat, cooking, and transportation. Black carbon absorbs sunlight, contributing to the warming of the atmosphere, and it accelerates the melting of snow and ice.

HFCs, the final key SLCP, are used in air conditioning, refrigeration, foam blowing, aerosol propellants, and solvents. While they have a shorter atmospheric lifetime than carbon dioxide, their warming impact is projected to grow without controls on their production.

Despite their short atmospheric lifetimes, SLCPs have a potent impact on near-term global warming. Reducing SLCP emissions can rapidly bend the global warming curve and help limit temperature rise to 1.5°C, as targeted by the Paris Agreement. Additionally, many SLCPs are air pollutants that negatively impact human and plant health. Therefore, reducing SLCP emissions not only slows global warming but also improves public health and food security.

Frequently asked questions