Uncovering the Link between Aerosols and Global Warming
Aerosols are very small particles dispersed in our atmosphere that work in opposition to greenhouse gases. While greenhouse gases trap solar energy and contribute to warming our planet, aerosols typically have more of a competing, cooling effect. In fact, some estimates even suggest that since the 1950s, these aerosol particles have likely counteracted about a third of greenhouse gas-driven global warming.
Natural aerosols, such as sea salt, dust particles, and organic compounds from plants make up about 90% of the aerosols in our atmosphere and constitute an important part of our planet's atmosphere. The other 10% occur from human activities, namely industrial pollution and the burning of tropical forests.
Although often regarded as air pollution for their damaging effects on human health and agricultural productivity, these aerosols collectively play a crucial role in counteracting global warming. Sulfate aerosols, in particular, are considered by many scientists as the most significant aerosols as they absorb no solar radiation, but rather reflect it back into space. In addition to increasing our planet’s albedo, aerosols can also influence the climate via clouds. As a matter of fact, there would be no rain without aerosols to act as the nuclei or “cloud seeds” on which water vapour can condense.
Recently, the interaction between aerosol particles and our climate has gained increasing attention from the science community (and rightfully so), wherein some research has found that geographic location markedly influences the cooling potential of a given aerosol emission.
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Certain models have demonstrated that the cooling potential of aerosol emissions from Western Europe is fourteen times that of those from India. Meanwhile, more and more developed countries are beginning to prioritise the benefit of cleaner air from mitigating aerosols, namely by switching to renewable sources of energy such as solar energy. This means that aerosol emissions from regions with greater cooling potential are actually on the decline.
At the same time, emissions from Asia are picking up, suggesting that as newer, lesser developed economies become the main emitters, the rate at which aerosols offset global warming might actually decline quite rapidly in the future.
Such findings indicate that the prospect of regulatory intervention and geoengineering to stabilise the global climate may actually be necessary. Some of the more popular proposals put forward include direct air capture (DAC) to remove carbon dioxide from the air, and releasing reflective aerosols into the stratosphere. Bearing in mind that each technique has its pros and cons, in-depth research into each strategy and how we could best deploy it has become more crucial now than ever.