Analysis of Articles about Climate Change - Literature review Example

Climate change Can we imagine an Earth where there are no green mountains, no deep blue seas and no living creatures? No. But a disaster of such magnitude and dimension is looming over Earth. Humans have identified this threat, defined it and given it a name, global warming. This dangerous proposition is based on the truth that even a 5 % increase in the surface temperature on Earth can wipe out life from this beautiful planet. And the temperature is increasing as never before. It was in 1990s that the world began to hear serious warnings on global warming and climate change. The summary for policy makers prepared as part of the first assessment report by Inter-governmental Panel on Climate Change was the first ever in depth study on this topic (Houghton, Jenkins and Ephirams, 1990). This report explored climate change and stumbled upon revolutionary revelations. This study announced in very clear terms that there is a natural green house gas effect. This was the first research report which suggested that the atmospheric emissions caused by human activities are heightening the atmospheric concentrations of the greenhouse gases, namely, CO2, methane, CFCs and nitrous oxide (Houghton, Jenkins and Ephirams, 1990). This increased concentration, suggested the study (Houghton, Jenkins and Ephirams, 1990), will augment the greenhouse effect. Finally this phenomenon will end up in an extra warming up of the Earths surface, warned the authors (Houghton, Jenkins and Ephirams, 1990). This was for the first time that humanity was realizing that CO2 was the major gas responsible for about half the creation of greenhouse effect. The report also called for a conscious reduction of such gas emissions by controlling human activities that caused them. The report was very precise in terms of the prediction about temperature enhancement. The projection of the available data into the future years led the authors (Houghton, Jenkins and Ephirams, 1990) of this study to predict that global mean temperature will increase by 0.3 oC per decade during the 21st century. The shocking part of this prediction was that this kind of a temperature increase had never happened within the time span of past 10,000 years (Houghton, Jenkins and Ephirams, 1990). But this report also cautioned about the possibilities of errors in its assessments in relation with the timing, scale and regional variations of climate change and attributed such errors to the incomplete understanding of sources and sinks of green house gases, namely, the clouds, oceans and polar ice sheets (Houghton, Jenkins and Ephirams, 1990). An average rate of global mean sea level rise of about 6 cm per decade over the next century was also predicted (Houghton, Jenkins and Ephirams, 1990). This was assumed to be the result of thermal expansion of the oceans and the melting of land ice (Houghton, Jenkins and Ephirams, 1990). This report pointed its fingers towards humans for polluting the atmosphere with green house gas emissions and thus destroying the Earth. But this report also showed us a path of redemption. It (Houghton, Jenkins and Ephirams, 1990) suggested that if humans reduce the green house gas emissions, climate change could be averted. Soon after this report came out, Dansgaard et al. (1993, 218) made another study, Evidence for general instability of past climate from a 250-KYR ice-core record. This research paper (Dansgaard et al., 1993, 218-220) approached the issue of climate change from a tangential angle and their conclusions indicate that global warming was not a human-made phenomenon. The authors (Dansgaard et al., 1993, 218-220) of this research study questioned the traditional geological notion of a stable Holocene and stated that the stable climate that we experience now might be an exception rather than rule. They (Dansgaard et al., 1993, 218-220) reached upon this conclusion by preparing a detailed stable-isotope record for the entire Greenland Ice-core project summit ice core, ranging over the past 250 kyr BP (thousands of years before present), based on a calculated time scale. They (Dansgaard et al., 1993, 218-220) also challenged the prior belief that climate changes is a phenomenon related to glacial periods and asserted that the last interglacial period might also had seen drastic changes in climate. Their (Dansgaard et al., 1993, 218-220) conclusions also included the theory that the last interglacial had lasted longer than presumed by earlier studies. And this is assumed to be because of the climate instability during the early period of the last interglacial which might have delayed the melting of Saalean ice sheets in America and Euresia. We are now supposed to be again in an interglacial period and these findings, if proven without doubt, are crucial regarding the options before humanity to survive in the face of global warming and climate change. If interglacial periods are prone to climate changes, and as explained by Dansgaard et al (1993), if these changes can happen even within the short span of a decade, it is high time that we stay prepared for the worse. And the saddest thing would be that we could do nothing to prevent global warming, which according this study, could only be viewed as a natural phenomenon rather than a human-made issue. As far as science is concerned, the ratio of 18O to 16O in ice and deep sea beds depends on the temperatures that these geographical structures have endured through centuries. So this ratio is one of the best ways to trace the history of climate change. During glaicals, the oceans were much colder resulting in higher evaporation of 16O. Hence 18O, which was heavier, maintained a higher concentration in the sea during that period. During warmer periods, on the contrary, land had more concentrations of 18O than the sea. Some amoeboid organisms of that era formed their shells by combining oxygen dissolved in water with carbon and calcium and their fossils found in the sea beds thus present us with a blue print of the 18O to 16O ratio . This blue print serves as a precise record of global climate change through the Quaternary. The 18O to 16O ratio is called the oxygen isotope record and is represented by the symbol, δ in the study of Dansgaard et al (1993). In this study, the timescale calculations are based on the assumption that stratigraphy has remained more or less undisturbed. The authors (Dansgaard et al., 1993, 218-220) also have crosschecked thus assumption for errors which might have been caused by foldings close to hilly bedrocks and boudinage effect (Dansgaard et al., 1993, 218-220). The stable isotope record thus prepared shows a stable climate during the past 10kyr (Dansgaard et al., 1993, 218-220). But for the rest of the time period, the records show highly fluctuating and even abrupt δ variations (Dansgaard et al., 1993, 218-220). The numbering of glacial interstadials found in previous studies, 14C datings and a series of Europian pollen horizons prepared earlier are also found to match with these findings (Dansgaard et al., 1993, 218-220). The authors also draw attention to the fact that these calculations are supported by Milankovitch cycles as well (Dansgaard et al., 1993, 218-220). The interglacial 5e (the last one before the present one), according to this study, might have seen periods as cold as 5a and 5c which were actually glacial periods (Dansgaard et al., 1993, 218-220). Thus this study (Dansgaard et al., 1993, 218-220) contradicts the findings of the first IPCC report (Houghton, Jenkins and Ephirams, 1990). It removes the element of predictability from the whole scenario of global climate change. But still, it warns us of a possible climate change as Houghton, Jenkins and Ephirams (1990) did, but for different reasons. A limiting factor of this study is that it overlooks the impact of green house gas emissions artificially created by humans and do not try to see whether there is a link between this and the warming patterns in the present interglacial in which there is a lot of aggressive human intervention. Of course, such an enquiry does not come under the scope of this study but people with vested profit motives could make use of these findings to go ahead with their polluting industries, unhindered. The discussions that make rounds in the world regarding global warming has seen a series of similar attempts. Another study conducted by McCormick, Thomason, and Trepte (1995) provides a platform to resolve these controversies in a better light. This study (McCormick, Thomason, and Trepte, 1995) delineates the atmospheric impact of Mt. Pinatubo eruption in 1991 which caused unprecedented and long-lasting climate changes. This study report begins with the observation that “human activity is perturbing the chemical composition and radiative balance of the Earth’s atmosphere” (McCormick, Thomason, and Trepte, 1995, 399). Moving on to the natural phenomenon of Mt. Pinatubo eruption, this study (McCormick, Thomason, and Trepte, 1995) states that the attempt made in it “to model the dispersion of the aerosol and the radiative and the chemical impact of the (volcano) eruption are ‘acid tests’ of our understanding of atmospheric processes”. The cloud of water vapour, sulphur dioxide and aerosol from the volcano Mt. Pinatubo was found to circle the globe in around 22 days (McCormick, Thomason, and Trepte, 1995). The sulphur dioxide gradually converted itself into sulphuric acid and water aerosols (McCormick, Thomason, and Trepte, 1995). This fast movement of volcanic material across the equator within a few days was new information for the scientific community. Soon it was made clear that this was caused not by planetary-scale transport patterns but simply by local heating (McCormick, Thomason, and Trepte, 1995). The absorption of infra red rays by newly formed aerosols was the cause of this local heating (McCormick, Thomason, and Trepte, 1995). This kept warm the lower tropical stratosphere for the rest of the year and eventually, these aerosols were transported into the troposphere thereby impacting the cloud optical properties and changing Earth’s radiative processes (McCormick, Thomason, and Trepte, 1995). Earth’s sunlight reflectivity is enhanced in this process and so there is a cooling effect on Earth. But all the same, there is also a green house warming effect caused by the aerosols absorbing infra red rays. The former was found to be more prominent than the latter which made 1992 the coolest year in three decades (McCormick, Thomason, and Trepte, 1995). Thus this cooling phenomenon proved true, the green house warming effect created by industrial gas emissions, through providing a reverse example (McCormick, Thomason, and Trepte, 1995). The revelation by this study that there was no considerably higher concentration of chlorine in the stratosphere as a result of the volcanic eruption substantiates the fact that chlorine, which depletes the stratospheric ozone is rather a product of anthropogenic chlorofluorocarbons emitted by industries (McCormick, Thomason, and Trepte, 1995). The importance of heterogenous reactions in ozone loss was also underlined by this report (McCormick, Thomason, and Trepte, 1995). This study draws a correlation between natural atmospheric phenomena and human-made atmospheric phenomena and provides a model to assess the gravity of latter for the future based on the former. Thus this study warns us that though we cannot avert natural warming processes in nature, we can at least try to lessen its intensity by understanding such processes better and by reducing the atmospheric pollution created by us. References Dansgaard, W. et al. 1993 Evidence for general instability of past climate from a 250-KYR ice-core record. Nature, 364, 218-222. Houghton, J.T., Jenkins, G.J. and Ephiraums, J.J. 1990 Climate change: the intergovernmental panel on climate change scientific assessment – policy makers’ summary. McCormick, P.M., Thomason, L.W. and Trepte, C.R. 1995. Atmospheric effects of the Mt. Pinatubo Eruption. Nature 373, 399-404 Read More