The linkages between air pollution and climate change

While introducing the causes of air pollution in the previous two entries, the word ‘greenhouse’ surfaced several times. Greenhouse gases and the greenhouse effect are elements tied closely to the intense contemporary debate on climate change, which forms the basis for this entry.

The greenhouse effect is an important natural process in which atmospheric greenhouse gases trap heat that would otherwise escape to space. Without the greenhouse effect, Earth’s average surface temperature is predicted to be some 33°C lower (NASA, n.d.), making many parts of the globe inhabitable. However, the unchecked emission of greenhouse gases traps and reflects more heat back to the surface. Over time, the resultant ‘enhanced’ greenhouse effect disrupts Earth’s surface energy balance and inevitably leads to global warming.

Figure 1. Differences between the natural greenhouse effect (Normal CO2) and enhanced greenhouse effect (Rampant CO2)

In a similar vein, the suspension of aerosols and particulate matter in the atmosphere also has long-term effects on climate. While certain aerosols like black carbon are good at absorbing heat, all other aerosols work the other way by instead reflecting incoming solar radiation from the sun to cool the atmosphere and planet (NASA, 2009) . If you are like me and live in a tropical country like Singapore, you might be tempted to start releasing aerosols to seek respite from the sweltering heat – but wait, that’s not all there is to aerosols. Research has revealed that aerosols exert significant influence on precipitation patterns. The abundance of aerosols acting as condensation nuclei extend the lifespan of storm clouds, bringing about more destructive storms and floods (ScienceDaily, 2016). On the other hand, the cooling effect produced by aerosols can also undermine wind circulation, suppress rainfall, and cause droughts in some parts of the world (Fadnavis et al., 2019). Perhaps releasing those aerosols is not that great of an idea afterall…

Accelerating climate change in turn aggravates air pollution to establish a mutually synergistic relationship. According to UCAR (n.d.), warmer temperatures stimulate chemical processes that create unhealthy levels of surface ozone. Higher temperatures also create hot and stagnant air that undergoes limited mixing, thereby reducing the dispersal of local air pollutants. Furthermore, Halofsky et al. (2020) highlight that climate change will likely raise the frequency of “large and severe” wildfires, which are major contributors of atmospheric nitrous oxide and particulate matter. Finally, let’s not forget human comfort – prolonged global warming is expected to be followed by a worldwide increase in air conditioning usage. Keeping up with air conditioning demand would unfortunately require more fossil fuels to be burnt, thereby worsening air pollution through the emission of greenhouse gases and refrigerants used in air conditioners (The Economist, 2021).

Figure 2. Projections of global air conditioning use from 2010 to beyond 2050 (The Economist, 2021)

Indeed, humans have set up a vicious cycle between air pollution and climate change. This never-ending, mutually reinforcing relationship is further supported by the fact that what goes into the air stays in the air. While it is certainly imperative for green solutions to be developed for the mitigation of global warming, it is further crucial for greater awareness and individual action geared towards managing and curbing the onslaught of climate change induced by air pollution before it is all too late.

Until the next entry, breathe safe and be safe!

 

References

The Economist. (2021). Demand for air conditioning is set to surge by 2050. The Economist. Retrieved February 5, 2023, from https://www.economist.com/graphic-detail/2021/08/10/demand-for-air-conditioning-is-set-to-surge-by-2050

Fadnavis, S., Sabin, T. P., Roy, C., Rowlinson, M., Rap, A., Vernier, J.-P., & Soris, C. E. (2019). Aerosols and droughts: Is there a connection? India Water Portal. Retrieved February 5, 2023, from https://www.indiawaterportal.org/articles/aerosols-and-droughts-there-connection

Halofsky, J. E., Peterson, D. L., & Harvey, B. J. (2020). Changing wildfire, changing forests: The effects of climate change on fire regimes and vegetation in the Pacific Northwest, USA. Fire Ecology, 16(1), 1–26. https://doi.org/10.1186/s42408-019-0062-8