Aerosols They are small particles that remain suspended in the Earth's atmosphere and can have a strong impact on both the climate change as in the air qualityThey can originate from natural sources such as volcanic eruptions or desert dust, as well as from human activities such as the burning of fossil fuels.
What are aerosols and why are they important?
When we talk about aerosols, many people think of household products in pressurized containers, but in climatology, aerosols cover a wide range of particles, from natural mineral dusts to compounds resulting from industrial activity. Aerosols of anthropogenic origin have a significant influence on the climate by their ability to reflect or absorb solar radiation and affect cloud formation.
These particles are of different sizes and characteristics. For example, sulphate sprays generated by the burning of fossil fuels or biomass tend to disperse solar radiation, causing a cooling effect. These particles act as small mirrors that deflect part of the sunlight that reaches the Earth. In contrast, aerosols such as black coal, also known as soot, absorb solar radiation, which causes local temperatures to rise.
Origin and types of aerosols
Aerosols have two main origins:
- Aerosols of natural origin: They come from natural processes such as volcanic eruptions, sandstorms or salt from the oceans carried by the winds. These aerosols are generally larger in size and have a relatively short life in the atmosphere.
- Anthropogenic aerosols: They are caused by human activity, such as the burning of fossil fuels. These aerosols include sulphates, nitrates and black carbon, among others. They are often smaller than natural aerosols, and because they remain in the atmosphere for longer, their impact is more prolonged and widespread.
In addition, it is common to find mixed aerosols that combine these two sources. For example, in urban areas, particles from industrial activity can mix with suspended natural dust particles.
Effect of aerosols on climate: A complex role
Aerosols play a key role in the planet's climate system due to their ability to affect the balance between the energy arriving from the Sun and the energy radiated back into space. There are two main ways in which aerosols influence this system:
- Direct effect: Some aerosols, such as sulphate aerosols, have the ability to reflect sunlight back into space, reducing the amount of radiation reaching the Earth's surface. This phenomenon causes a cooling effect about the weather.
- Indirect effect: Aerosols also influence cloud formation and evolution. They act as condensation nuclei for water vapor, allowing cloud droplets to form. The more aerosols there are in a region, the greater the number of droplets in the clouds, but these droplets will be smaller, which could increase cloud reflectivity and prolong their lifetime, generating additional cooling.
However, not all aerosols cool the planet. Aerosols such as black carbon, which is produced by the incomplete combustion of fossil fuels and biomass, absorb sunlight and heat the atmosphere. This causes the overall effect of aerosols on climate change is complex and, in some cases, even contradictory.
The impact of aerosols on cloud formation
A key aspect of aerosols is their influence on cloud formation, which in turn affects precipitation and local weather. Clouds formed in the presence of high levels of particulate matter can be brighter and more reflective, meaning less sunlight reaches the Earth's surface.
However, when there is an excess of aerosols in the atmosphere, the cloud formation process can be disturbed. Recent NASA studies have shown that smoke and dust aerosols They can absorb radiation, warming the surrounding air. This counteracts the upward flow of air and prevents clouds from fully developing, i.e. they do not allow water vapor to condense into droplets large enough to precipitate as rain. Excess aerosols can therefore reduce the frequency of rainfall, potentially altering local weather patterns.
Aerosols and climate change: masking global warming
One of the most important characteristics of aerosols in the context of climate change is that they act as a mechanism that masks part of global warming caused by greenhouse gases. According to studies by the Intergovernmental Panel on Climate Change (IPCC), aerosols have counteracted about one-third of the warming caused by the increase in carbon dioxide and methane since the Industrial Revolution.
However, this offset effect presents a dilemma. As countries implement policies to reduce aerosol emissions due to their harmful health effects, the cooling effect of aerosols is expected to diminish, which could accelerate global warmingThis phenomenon has already begun to be noticed in industrial areas of Asia and Europe, where improvements in air quality have led to an increase in regional temperatures.
The cost of public health and climate policies
Although aerosols have a cooling effect, they should not be considered a solution to climate change due to their serious effects on public healthAerosols, especially those from the burning of fossil fuels and biomass, are linked to respiratory and cardiovascular diseases and contribute to millions of deaths each year. According to the World Health Organization (WHO), air pollution is responsible for approximately 7 million premature deaths annually.
Climate policies in many countries are therefore seeking to balance improving air quality with the need to control global warming. New technologies, such as carbon capture, are being investigated to mitigate greenhouse gas emissions without increasing aerosol emissions.
Technological advances and informed decision-making will be key in the coming years to maintain the balance between mitigating climate change and improving public health.
There is no doubt that aerosols are a crucial component in climate science and that their influence on global warming – whether cooling or warming the planet – is undeniable. Future research will be essential to better understand their effects and how we can manage their impact on our planet.