Air Pollution And Climate Change

 

Air pollution is connected to climate change in various ways. First is that some of the causes of air pollution are also major causes of climate change. Climate change is caused by greenhouse gas emissions of which fossil fuels is the biggest source. Mining and extraction of fossil fuels as well as refining and the use of coal, petroleum and natural gas produces air borne pollutants such as carbon monoxide, sulphur dioxide, both nitrous oxide and nitrogen dioxide as well dioxins, furans and particulate matter.

In addition to this, the use of fossil fuels produce the greenhouse gases carbon dioxide, methane and nitrous oxide which all are greenhouse gases and warm climate.

Image source - Annenberg Learner

The second connection is that there are substances which are both climate forcers and pollutants. A climate forcer is anything whose presence affects climate in one way or the other. That is, they “force” climate. These substances include particulate matter particularly black carbon, and the gases methane, ozone and hydrofluorocarbons.

Black carbon, methane, ozone and hydrofluorocarbons (HFCs) are collectively referred to as short-lived climate pollutants or SLCPs. They affect both climate and air quality. Let’s start with black carbon. This is basically particulate matter of diameter less than 2.5 micrometers, and it is solid carbon particles in the air. These are produced from partial (not thorough) combustion of fossil fuels. Some sources include vehicle and ship exhaust systems, power plants and industries. They are also made from the burning of vegetation, green or otherwise. Black carbon is the reason why soot is black. It gives smoke its dark or grey color.

Black carbon is produced in huge quantities from wildfires, and open burning of fields in agriculture. It is also a byproduct when wood fuel is used in households to provide energy or make food. Black carbon remains in the atmosphere for about 7 to 14 days before it is removed and settles on the surface. Black carbon has a strong global warming potential, because dark substances absorb more heat. However, its effect is mainly localized to its point source, and that’s one of the reasons it is not regulated under climate change agreements.

When the particles of black carbon settle on ice, it darkens the surface doing two things that affect climate. One is that by covering the surface it reduces reflectivity of light (albedo) by ice. That is, sunlight cannot be reflected back to space. Additionally, since it is dark, it leads to more heat being absorbed than would happen normally. This induces melting of ice in glaciers and in the sea and so contributes to sea level rise.  All this adds to global warming and hence climate change.

Black carbon is a pollutant that affects the pulmonary tract causing or worsening bronchitis, asthma or other respiratory health problems. It also irritates the eyes and affects the heart.

Methane is a greenhouse gas produced from mining and burning of coal, oil and natural gas. It is 25 times stronger over a period of a hundred years than carbon dioxide in terms of warming. It stays in the atmosphere for about 8 years. Methane is also produced from landfills, open dumpsites, flooded rice paddies, compost heaps, the gut system of cows and livestock in general.

Aside from being a greenhouse gas, methane is a direct contributor to the formation of ground-level ozone alongside carbon monoxide and other gases. By itself however, methane does not affect human health but does so through ozone. About half of all ground-level ozone is influenced by methane.

So cutbacks in methane cause cutbacks in ozone.

Ground-level ozone is also known as tropospheric ozone. The troposphere is the lowest layer of the atmosphere within which life also exists. It is a component of smog, and a particular feature of urban areas. Ozone is a greenhouse gas on its own, and also a pollutant. It does not naturally occur at the Earth’s surface but is present due to manmade reasons. According to the weather conditions, it remains in the air from hours to days/weeks.

It is formed from the action of volatile organic compounds and nitrogen oxides in the presence of sunlight. Both VOCs and NOx are pollutants released from transport sources and use of fossil fuels. Therefore on hotter days, more ozone is formed especially in urban areas where there is plenty of the above named necessary components. Climate change leads to an increase in the number of hotter days than the recorded usual.

Ozone is a part of vehicle exhaust and factory emissions. So it is present in more quantities in industrial areas.

It wreaks havoc on the respiratory tract when breathed in. It also destroys crops and green vegetation and thus negatively impacts agriculture by leading to damage to crops, impacting food security and causing financial losses. It negatively impacts the natural world.

Hydrofluorocarbons are greenhouse gases with a global warming potential (GWP) thousands of times bigger than carbon dioxide over a measured time frame. These particular group of fluorinated gases are manmade and used in the cooling industry, as solvents, foam blowing substances and in aerosols.  

They however stay in the air for a shorter time compared to carbon dioxide.

Other ways in which climate change affects air pollution is that warmer weather and increased levels of carbon dioxide promote growth of mold and pollen, both of which cause respiratory systems and are dangerous to human health.

Accordingly, climate change leads to increased precipitation. It leads to high humidity in combination with higher temperatures which lead to dampness. With intense rainfall and storms in a short space of time, wetter conditions spur on the growth of mold, some of which causes allergies and is quite hazardous to human health like black mold. Mold in general causes pneumonia, coughing, asthma, skin and eye irritation, headaches etc. The spores of mold are carried through the air, and so can easily spread. Black mold on surfaces and houses lowers the immunity of people and is poisonous.

An extended pollen season is one of the effects of climate change in the natural world.

In other ways, climate change increases incidence of wildfires which in turn release more particulate matter into the atmosphere. Particulate matter is air pollution affects public health and in fact people are advised to cover their noses when they breathe, take a bath and launder their clothes later on.

Poor air quality is responsible for about 7 million deaths yearly, and action on methane and black carbon can save 2.4 million lives from early deaths by the end of this decade.

Choosing green energy over fossil fuels and use of clean fuels and effective cooking stoves would greatly reduce this number.

SLCPs are responsible for about 45% of warming and tight regulation could result to a 0.6 degree of avoided warming by 2050.

Short-lived climate pollutants stay in the air for a short period, as compared to carbon dioxide which dwells there for centuries. But all the four SLCPs are stronger than carbon in terms of holding heat, which means that for whatever period of time they are in the air, they warm it at a grander scale than carbon dioxide.

In effect, these four substances are stronger than CO2 in the short term, while carbon dioxide is more significant in the long term. So, cutting down on amounts of SLCPs emitted would immediately act on climate and reduce warming in a quick and effective manner.

This is the reason why SLCPs are also labeled as near term climate forcers by the IPCC. That is, they force climate in the near future, while carbon dioxide does so on a century scale.

By all means the world needs to choose a low carbon development pathway, which means cutting carbon emissions. But action on black carbon, hydrofluorocarbons, ozone and methane is faster, less costly and easier to implement. So, the two should go hand in hand.

Now, climate change increases desertification. Due to extended periods of higher temperature and scarce rainfall, the soil on the Earth’s surface becomes loose and dry. It becomes prone to wind erosion and also intense sandstorms.

These storms carrying dust are a form of air pollution, a danger to human health and trigger a host of respiratory problems.

Clearly, acting on climate change straightaway improves air quality, and enforcing protective action on air quality also is climate mitigation.

The two are interconnected and global standards of air quality need to be adopted throughout the world. The world shares a single atmosphere, and wind and heat in the air is capable of mixing the air thoroughly, meaning that air pollution in a single place while mostly affecting the origin or point source will also have an effect elsewhere.