Global Warming.docx

BRW Group Members Sadia Qureshi (62695) Hina Qureshi (62694) Uroosa Farooq (62634) Areej Naz (62502)

GLOBAL WARMING AND ITS CAUSES INTRODUCTION The continuous rise in temperature of the planet is really upsetting. The root cause for this is global warming. Global warming begins when sunlight reaches the Earth. The clouds, atmospheric particles, reflective ground surfaces and surface of oceans then sends back about 30 % of sunlight back into the space, whilst the remaining is absorbed by oceans, air and land. This consequently heats up the surface of the planet and atmosphere, making life feasible. As the Earth warms up, this solar energy is radiated by thermal radiation and infrared rays, propagating directly out to space thereby cooling the Earth. However, some of the outgoing radiation is re-absorbed by carbon dioxide, water vapours, ozone, methane and other gases in the atmosphere and is radiated back to the surface of Earth. These gases are commonly known as greenhouse gases due to their heat-trapping capacity. It must be noted that this re-absorption process is actually good as the Earth’s average surface temperature would be very cold if there was no existence of greenhouse gases. The dilemma began when the concentration of greenhouse gases in the atmosphere was artificially increased by humankind at an alarming rate since the past two centuries. As of 2004, over 8 billion tons of carbon dioxide was pumped thermal radiation is further hindered by increased levels of greenhouse gases resulting in a phenomenon known as human enhanced global warming effect. Recent observations regarding global warming have substantiated the theory that it is indeed a human enhanced greenhouse effect that is causing the planet to heat up. The planet has experienced the largest increase in surface temperature over the last 100 years. Between augmented between 0.6 to 0.9 degrees Celsius, however the last 50 years saw the rate of temperature increase nearly doubling. Sea levels have shown a rise of about 0.17 meters during the 20th century. The extent of Arctic sea ice has steadily reduced by 2.7 % per decade since 1978. Millions of pounds of methane gas are generated in landfills and agricultural decomposition of biomass and animal manure. Nitrous oxide is released into the atmosphere by various nitrogen-based fertilizers including urea and diammonium phosphate and other soil management utilizations. Once released, these greenhouse gases stay in the atmosphere for decades or even longer. According to Intergovernmental Panel on Climate Change (IPCC), carbon dioxide and methane levels have increased by 35 % and 148 % since the industrial revolution of 1750. HISTORY Back in the 1890s, however, the concept of warming the planet was remote an d even welcomed. As Arrehenius wrote, “By the influence of the increasing percentage of carbonic acid [CO2] in the atmosphere, we may hope to enjoy ages with more equable and better climates, especially as regards the colder regions of the earth.” By the 1930s, at least one scientist would start to claim that carbon emissions might already be having a warming effect. British engineer Guy Stewart Callendar noted that the

United States and North Atlantic region had warmed significantly on the heels of the Industrial Revolution. Callendar’s calculations suggested that a doubling of CO2 in Earth’s atmosphere could warm Earth by 2 degrees C (3.6 degrees F). He would continue to argue into the 1960s that a greenhouse-effect warming of the planet was underway.While Callendar’s claims were largely met with skepticism, he managed to draw attention to the possibility of global warming. That attention played a part in garnering some of the first government-funded projects to more closely monitor climate and CO2 levels. Global Warming Gets Real The early 1980s would mark a sharp increase in global temperatures. Many experts point to 1988 as a critical turning point when watershed events placed global warming in the spotlight.The summer of 1988 was the hottest on record (although many since then have been hotter). 1988 also saw widespread drought and wildfires within the United States.Scientists sounding the alarm about climate change began to see media and the public paying closer attention. NASA scientist James Hansen delivered testimony and presented models to congress in June of 1988, saying he was “99 percent sure” that global warming was upon us .

LITERATURE REVIEW Global Warming One of the most prominently discussed topics in the world nowadays is “Global Warming.” Global warming is the ominous phenomenon of heating up of Earth’s atmosphere by greenhouse gases (GHG) such as water vapour, carbon dioxide (CO2), sulphur oxide (SO2), nitrous oxide (NO2), and chlorofluorocarbon (CFCs) etc (Liu, 1994). In the normal levels, these gases maintain the atmospheric temperature and are the important reasons that life sustains on Earth. Regrettably, anthropogenic activities have made atmospheric emission levels of GHG surpassing beyond the safety levels of 350 ppm (Hensen, 2008) and continues to increase the Earth’s temperature at the range of 1.55.8°C (IPCC, 2007). Currently, China, USA, Russia, India, and Japan, respectively, are the five major contributors of global warming. Global warming leads to devastating consequences and forces the Humans to face inevitable changes such as sea level increase up to 16 m, drastic changes in rainfalls etc. (Rohling, 2007).