Climate Change & Air Pollution

By Katie Fawcett
August 2020

When we hear the words ‘climate change’ the images that come to mind are rising seas, flooding and burning forests. The consequences of these events will be devastating for people all over the world, causing displacement, famine and water shortages. As we continue our research on climate change, increasingly worrying side effects are being identified, with severe effects on people and ecosystems. This article explores some of the lesser known interactions of a changing climate on air pollution.

According to the WHO, air pollution causes seven million deaths globally each year. The worst pollutants include nitrogen dioxide, particulate matter, ammonia, sulphur dioxide and volatile organic compounds. These pollutants cause health problems including stroke, heart disease, lung cancer and respiratory infections. Over 80% of people in cities across the world live in areas of poor air quality with the highest pollution levels in developing countries. The main sources of outdoor air pollution derive from road traffic, household combustion and industry. Indoor air pollution sources include cleaning products, wood, coal and gas burning stoves (a particular concern in developing countries) and building materials. Air pollution also simultaneously harms some plant and animal species, whilst allowing others to thrive, directly impacting the food chain. As the climate changes, the concentration, dispersion and impacts of air pollutants are also predicted to change.

Diagram showing the main indoor and outdoor sources of air pollution taken from Defra’s 2019 Clean Air Strategy.

Diagram showing the main indoor and outdoor sources of air pollution taken from Defra’s 2019 Clean Air Strategy.

Climate change is defined by the IPCC as “a change in the state of the climate which can be identified by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer”. Since approximately 1750, anthropogenic greenhouse gas emissions have increased, leading to an increase in average global temperatures. It is predicted that climate change will alter rainfall patterns and increase average global temperatures causing ice sheet melting and sea level rise. There is also expected to be an increase in the frequency of extreme weather events, such as droughts, floods and heatwaves.

Global temperature predictions under a very stringent emissions reduction scenario (RCP 2.6) and a scenario where emissions continue to rise (RCP 8.5) taken from the Intergovernmental Panel on Climate Changes AR5 report on the physical science basis…

Global temperature predictions under a very stringent emissions reduction scenario (RCP 2.6) and a scenario where emissions continue to rise (RCP 8.5) taken from the Intergovernmental Panel on Climate Changes AR5 report on the physical science basis of climate change. A dark red colour indicates the areas predicted to have the largest temperature increases.

Climate change will impact air quality across the world. As the worst impacts of climate change will be experienced in developing countries, this is where its combined impact with air quality will be the most severe. Droughts will exacerbate dust production, which is harmful to our health and there will be less rain to remove dust from the air and wash it away. When the wind blows this dust will be resuspended in the air. An increase in dust will also require more water use to suppress it on construction sites, which in turn will reduce water availability - already under stress due to climate change and population increase. Changing wind patterns and increased frequency and intensity of storms will change how pollutants disperse, however increased wind speeds could reduce pollution concentration in open areas. Warmer temperatures will increase ozone concentrations due to chemical interactions of compounds in the atmosphere with sunlight. Increased droughts and reduced rainfall will mean farms must increase fertiliser use, increasing the emission of ammonia. With predicted increases in temperature and heatwaves, more people will need to use air conditioning. If the energy used to power this is from a non-renewable source then more air pollutants will be released. Conversely, as winters will be warmer there will be less use of heating, reducing energy demands. According to the US Environmental Protection Agency, emissions of particles can have either warming or cooling effects on the climate, depending on the chemical composition.

Many of the policies aimed at reducing climate change will also reduce air pollution as the burning of fossil fuels is the main source of air pollution, as well as greenhouse gases. This includes promoting renewable energy sources, installing insulation and encouraging electric car and public transport use. It should be noted that some technologies which have been promoted as being beneficial for the environment may in fact be worse for air quality, such as biomass combustion and diesel engines. Both of these measures emit high concentrations of particulate matter. The fight against air pollution and climate change must be integrated to ensure the solution for one problem doesn’t worsen impacts of the other.

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