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The Impact of Aerosols on the Environment

The Impact of Aerosols on the Environment. By Bertha Munuku Texas Tech University. Thesis Statement.

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The Impact of Aerosols on the Environment

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  1. The Impact of Aerosols on the Environment By Bertha Munuku Texas Tech University

  2. Thesis Statement Current research shows that aerosols in the atmosphere have the following main effects: reflection of radiation from the sun, interaction with clouds (causing them to change shape and structure), as well as cooling effects.

  3. Terminology • Aerosols: solid or liquid particles suspended in the atmospherethat can be natural or man-made (anthropogenic). • Radiative forcing/climate forcing: the difference of radiant energy (sunlight) received by the Earth and energy radiated back to space. • Aerosol optical depth (AOD): the thickness or transparency of the aerosols. • Aerosol lifetime: the amount of time that an aerosol particle resides in the atmosphere. • Convective clouds: clouds which are formed on top of rising air columns.

  4. Impact on Radiation • Research shows that aerosols contribute to the amount of radiative forcing experienced in the upper atmosphere. • Variation in the optical depth and lifetimes of aerosols have effects on the way the sun’s radiation is reflected back into space (Mahowald et al. 47, 49). • Many researchers have discovered that the composition of the aerosols also plays a key role in the amount of radiation that is reflected by the said aerosols(Fischer-Bruns et al. 514-515; Andreaeet al. 1187). • Research shows that the intensity of the radiative effects of aerosols is also determined by location and time of year with significant changes found at low latitudes in winter (Chang-Keunet al. 864; Roeckneret al. 553).

  5. Impact on Clouds • Current research reveals that aerosols affect clouds through chemical interactions with the water vapor droplets. • Aerosol particles act as the condensation nuclei in cloud formation, with water vapor and ice crystals forming around them. This reduces cumulus clouds driven by strong convection while increasing non-precipitating clear-sky cumuli (Mahowald et al. 52; Chang-Keun et al. 871). • Satellite data analysis shows that, for convective clouds, increase in aerosol loading is associated with taller invigorated clouds, larger cloud fraction and more extensive ice portions (Mahowald et al. 53; Koren et al. 5001). • Research revealed that increased cloud lifetimes is the impact of any kind of aerosol, not just sulfate aerosols (Koren et al. 5001; Chang-Keun et al. 871).

  6. Cooling Effects • According to studies conducted in the field, the impact of aerosols on clouds and radiative forcing all culminate to produce a cooling effect on the environment. • Aerosols have played an important role in the alteration of shortwave radiative forcing which results in a complex mechanism involving surface cooling and modified atmospheric circulation (Mahowald et al. 49; Paethand Feitcher 52). • Changing the condensation nuclei of clouds, aerosols produce smaller water droplets which collectively make the clouds more reflective (Koren et al. 5008; Andreaeet al. 1187). • On the other hand, Mickley et al. found that surface temperatures are set to increase in the long run upon the removal of these aerosols (545).

  7. Conclusion • Aerosols have an effect on radiation and clouds, which thus results in the cooling of the environment to varying degrees. • There are still several uncertainties in the field thus there is room for more research. • It would be useful to carry out more studies with more replicates in order to produce a more accurate result with a smaller margin of error. • Perhaps in the future, if not present today, there will be multi-layered models which can be able to put all factors into consideration when assessing the impacts of aerosols.

  8. Works Cited • Andreae, Meinrat O., Chris D. Jones, and Peter M. Cox. "Strong Present-Day Aerosol Cooling Implies a Hot Future." Nature 435.7046 (2005): 1187-1190. Academic Search Complete. Web. 18 Jun. 2014. • Chang-Keun Song, et al. “Direct and Semi-Direct Radiative Effects of Anthropogenic Aerosols in The Western United States: Seasonal and Geographical Variations According to Regional Climate Characteristics.” Climatic Change 111.3/4 (2012): 859-877. Academic Search Complete. Web. 18 Jun. 2014.  • Fischer-Bruns, Irene, Dorothea Banse, and Johann Feichter. "Future Impact of Anthropogenic Sulfate Aerosol on North Atlantic Climate." Climate Dynamics 32.4 (2009): 511-524. Academic Search Complete. Web. 18 Jun. 2014. • Koren, I., et al. “Aerosol-induced Changes of Convective Cloud Anvils Produce Strong Climate Warming.” Atmospheric Chemistry and Physics 10.10 (2010): 5001-5010. Academic Search Complete. Web. 18 Jun. 2014. • Mahowald, Natalie, et al. “Aerosol Impacts On Climate And Biogeochemistry.” Annual Review of Environment & Resources 36. (2011): 45-74. Academic Search Complete. Web. 18 Jun. 2014. • Mickley, L.J., et al. “Regional Warming From Aerosol Removal Over the United States: Results from a Transient 2010–2050 Climate Simulation.” Atmospheric Environment 46. (2012): 545-553. Academic Search Complete. Web. 18 Jun. 2014. • Paeth, Heiko, and Johann Feichter. “Greenhouse-Gas Versus Aerosol Forcing and African Climate Response.” Climate Dynamics 26.1 (2006): 35-54. Academic Search Complete. Web. 18 Jun. 2014. • Roeckner E., et al. "Impact Of Carbonaceous Aerosol Emissions on Regional Climate Change." Climate Dynamics 27.6 (2006): 553-571. Academic Search Complete. Web. 18 Jun. 2014.

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