What Damage Is Being Done By Aerosols Environmental Sciences Essay
Industrial pollutants, and in particular, aerosols, are greatly disrupting our environment and our atmosphere. We often hear the terms 'global warming' and 'climate change' but we do not take time to look for the cause of these phenomena. This essay will look at how industrial aerosols are inadvertently affecting our weather and climate. We will look at the reasons why these pollutants are affecting weather the way that they are, as well as look at the potential outcome of these aerosols on the weather and climates of the future.
Inadvertent weather modification is the change in weather, and climate, due unintentional human actions. This stems from the industrial sector, and not the deforestation of the earth's forests as this would then be advertent as this is an intentional modification of the natural environment. Another form of advertent weather medication is called cloud seeding which ultimately increases the amount of water and water vapour in a cloud, causing precipitation. However, our concern is in regards to unintentional actions which are causing far more worrying results.
Aided by the loss of forests, which is causing a decrease in the oxygen levels in the atmosphere, industrial aerosols are causing temperatures to rise. Atmospheric inversions are the probable reason for this effect due to the fact that they cause these pollutants to be dispersed variably, thus, under favourable conditions, creating an insulating layer of industrial aerosols.
Surface inversions occur on calm, clear days, often in the evening through the night. These inversions should not have to great an effect on the weather as they are not effective during the day time when insolation can occur. Insulation from the sun is needed for the weather modifications to occur. This modification best occurs during day time and when an elevated inversion occurs, allowing the pollutants to disperse upwards into the atmosphere creating a greenhouse layer (Tyson and Preston-Whyte, 1989). Radiation is able to get through this layer and heat the surface, however, the radiation reflected by the surface albedo is trapped below this greenhouse layer creating a warming effect of the surrounding atmosphere. These major greenhouse causing aerosols are carbon dioxide, methane and sulphur dioxide (Tyson and Preston-Whyte, 1989). They are commonly released through industrial processes, agriculture and vehicles.
Arguments for the change of the climates of certain areas have been around since before the new millennium, with publications, such as those by Mitchell and Johns (1997), suggesting that by as early as 2030 we can expect a significant weakening of the monsoon cycle and a complete change of climate for South-East Asia. These effects are suggested to be caused by carbon dioxide aerosols. Models were produced by Mitchell and Johns (1997) which showed that the ocean-atmosphere interactions will be disrupted due to these aerosols, hence the change and weakening to the monsoon cycle and the ultimate climate change to South-East Asia, and also Europe. This is due to the fact that these regions rely heavily on the hydrological cycle in the oceans, which is already being disrupted, and possibly reversed, due to carbon dioxide in the atmosphere. Mitchell and Johns (1997) also suggested, through their modelling, that this has been an increasing and ongoing action since industrialisation, therefore showing that these aerosols from industries having become an increasing problem in inadvertent weather modification.
The Intergovernmental Panel on Climate Change (IPCC) has done numerous surveys, models and projections on climate change. In 2007 they had a refined table showing the possible impacts of climate change because of severe and significant changes in weather and climate events. The most likely change to occur, rated 'virtually certain' is that most land areas are going to experience a warming up of the seasons, meaning a warmer winters and more hot days and nights in summer. Other less certain, but possible effects of drastic climate change are; more frequent heat-waves, droughts, heavy precipitation events, larger tropical cyclones and a higher stable sea-level (IPCC, 2007). Although we cannot pin these activities on industrial aerosols and the ever increasing industrialisation, it is obvious that these events and changes are going to occur due a significant global warming, which will increase temperatures, evaporation and ice cap melts. These three changes will each have their own impact on the people and the environment; higher temperatures will cause droughts, while the rain we will get will come from infrequent heavy episodes. Land masses will decrease in size due to higher sea levels. One might argue that these events would occur whether humans had anything to do with it or not, but we must wonder if our increased release of aerosols, particularly carbon dioxide (Mitchell and Johns, 1997) is having an effect on the time we expect it to take for these events to start occurring as part of our climate, as opposed to their occurrence as anomalies from time to time. Also included in the table by the IPCC (2007) are examples of projected impacts by these changes on the different major sectors of the world. Of these, the projections for the agricultural sector are very negative, as all the above mentioned events will cause poorer crops, and smaller yields in general meaning that the world is likely to experience devastating food shortages in regards to the staple crop foods.
The issue of greenhouse gases has been known for quite some time, and with the study and subsequent knowledge of greenhouse gases came an understanding of other pollutants. Sulphates, which, like carbon dioxide, are released during combustion, have been found to increase the earth's albedo due to their light reflective properties, thus decreasing temperature. These particles are able to offset the heating of the earth's atmosphere by greenhouse gases so as to slow down the rapidity of the global warming (Charleson, Schwartz, Hales, Cess, Coakley, Hansen and Hofmann, 1992). Charleson et al. (1992), as well as Mitchell and Johns (1997) both suggest the introduction of sulphates into the atmosphere as a way of counter-acting the effects by the industrial aerosols. If their thoughts were correct, this simple solution would have profound effects on the rate of global warming and climate change. This would then reduce the changes to weather and climate and prevent the projections by the IPCC (2007, as above) from becoming reality. However, we would be risking lots by increasing the amounts of sulphates in the atmosphere, as this is the main component of acid rain. Acid rain is renowned for its destructive properties and various reports by broadcasters such as the BBC and CNN have shown how acid rain is destroying the national monuments of Italy. Camuffo (1991) suggests that this phenomenon has been occurring in various degrees for decades, and possibly even centuries, and yet only now has it become an issue. It is something to wonder, what is more valuable, human existence or our history, and can we find a way to continue growing as a civilisation, while impacting the environment less drastically? Is it possible for capitalists in the big cities to become conservationists in small towns?
This rather rapid rate of climate change due to our inadvertent releasing of industrial aerosols is referred to as "climate forcing" (Charleson et al, 1992, page 424). However, the above mentioned sulphates are being released more commonly by volcanoes. The recent eruption in Iceland would probably have released a rather significant quantity of sulphates such as sulphur dioxide into the atmosphere. These events create a slight cooling in the atmosphere due to the increased surface albedo. With the increased number of eruptions in the past decade, we have, although localised to the area of effect, seen a slight drop in the rate of change (Charleson et al, 1997), and it is possible that nature is fighting back. One might argue that the earth is responding to the increased amounts of industrial aerosols, and the ever increasing change in climate. However, this would be inconclusive and impossible to prove. It is more likely that we, through our naivety, are changing the climate, though be it inadvertently.
The future ahead, particularly according to the many models, tables and predictions, does not look bright. We do, however, have a warning and it is possible that we may be able to prepare not only ourselves, but possibly parts of our environment for the changes that are likely to come. The bible talks of the 'end times' by fire, and science is showing that we can expect vast and large temperature increases, but there is still time to stop, and if it is impossible to stop, then our goal, like that of the IPCC, should be to divert the potential catastrophe and hopefully prevent it. There are no certainties, and science has been wrong before, but if it is to believed, we are running out of time, and soon, possibly even in our lifetime, we can expect to see one of the most catastrophic climate shifts in the history of the earth.
Camuffo, D., 1991, Acid Rain and deterioration of monuments: How old is the phenomenon? Atmospheric Environment. Part B. Urban Atmosphere. 26 (2), 241 - 247.
Charleson, R. J., Schwartz, S. E., Hales, J. M., Cess, R. D., Coakley Jr., J. A., Hansen, J. E., and Hofmann, D. J., 1992, Climate Forcing by Anthropogenic Aerosols, Science, New Series. 255 (5043), 423 - 430.
IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: Impacts, Adaptations and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. M. L. Parry, O. F. Canziani, J. P. Palutikof, P. J. van der Linden, and C. E. Hansen, Eds., Cambridge University Press, Cambridge, UK, 7 - 22.
Mitchell, J. F. B., and Johns, T. C., 1997, On Modification of Global Warming by Sulfate Aerosols, Journal of Climate. 10 (2), 245 - 267.
Tyson, P. D., and Preston-Whyte, R. A., 1988, The Atmosphere and Weather of Southern Africa. Oxford University Press, Cape Town.
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