Carbonaceous aerosols
Carbonaceous aerosols are fine particles composed primarily of carbon that are suspended in the atmosphere, primarily resulting from the incomplete combustion of fossil fuels. Commonly referred to as "soot," these aerosols have significant implications for both human health and the climate. They are linked to respiratory issues, allergies, and pollution-related mortality due to their ability to clog the air sacs in the lungs. In terms of climate impact, carbonaceous aerosols consist of two main components: organic carbon (OC), which scatters light, and black carbon (BC), which absorbs light. Their presence can influence the Earth's energy balance by reflecting sunlight back into space and altering cloud properties, either cooling or warming the atmosphere depending on various factors.
The interaction of these aerosols with trace gases and their varying effects based on particle size and composition contribute to the complexity of their role in global warming, with some estimates suggesting black carbon may account for 15 to 30 percent of the warming observed. Research into carbonaceous aerosols is challenging due to their transient nature and uneven distribution in the atmosphere. Additionally, these aerosols can impact the hydrologic cycle and plant health, potentially reducing rainfall and impairing photosynthesis. Understanding carbonaceous aerosols is crucial for addressing climate change and mitigating their health effects.
Carbonaceous aerosols
Definition
Aerosols are fine solid or liquid particles suspended in a gas. Carbonaceous aerosols are fine, solid carbon particles suspended in the atmosphere. They result from burning fossil fuels, which are not completely consumed in the combustion process. Sometimes, these aerosols are referred to as “soot.” They can affect the global climate, as well as cause problems for people who breathe the air: They are associated with allergies and respiratory diseases, as they interfere with breathing by clogging the air sacs in a person’s lungs. These aerosols are also a major cause of pollution-related mortality.
Significance for Climate Change
Carbonaceous aerosols are made up of two parts: organic carbon (OC), which scatters light, and black carbon (BC), which absorbs light. These particles can block radiation from the Sun and scatter light, so they can affect Earth’s climate in several ways. They can scatter and absorb radiation from the Sun. They can reflect light back into space, increasing Earth’s albedo directly, and they can also make clouds more reflective, increasing it indirectly. OC in particular is able to do this, the warming that cause. Carbonaceous aerosols, particularly BC, can also heat the atmosphere by absorbing sunlight.
Carbonaceous aerosols can block light from reaching the Earth’s surface. BC also does this, which can lead to cooling the Earth’s surface. They can affect the amounts of trace gases in the atmosphere, which may affect warming or cooling of the atmosphere depending on which type of gas is affected. They can combine with each other and other particles to interact in different ways that lead to unusual, and sometimes perplexing, effects on the global climate.
Thus, carbonaceous aerosols can affect both the warming and cooling of the Earth and its atmosphere. Scientists are still trying to understand the complexities of how these aerosols affect global climate change, though some estimate that black carbon particles may be responsible for 15 to 30 percent of global warming.
The effect that carbonaceous aerosols have on the environment can be influenced by the number of these particles contained in the total volume of air, the size of the particles, and the proportion of organic versus black carbon composing each particle. Studying aerosols can be difficult. Carbonaceous aerosols do not last long and do not mix in the same way in all areas across the Earth, which makes analyzing their effects difficult. The way these particles interact with water, particularly saltwater, and over areas covered with snow and ice is not well understood and is a subject of scientific inquiry. Previous major studies, such as the Asian-Pacific Regional Aerosol Characterization Experiment (ACE-Asia) in 2001 and the Indian Ocean Experiment (INDOEX) in 1991, relied on large teams of scientists using aircraft, balloons, ships, and surface stations to help analyze these effects.
Carbonaceous aerosols can affect the hydrologic cycle by cutting down the amount of sunlight that is able to reach the ocean, affecting how quickly seawater evaporates into the air. They may also affect how clouds are formed. Both these actions can reduce the amount and frequency of rainfall. Carbonaceous aerosols can also affect plants by coating their leaves and affecting their ability to photosynthesize or use light to break down chemical compounds, thus also contributing to global climate change.
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