The natural process in which the earth traps the rays of the sun, warms itself to support life and radiates back the long wavelength rays is known as greenhouse effect. This maintains the temperature of the earth and insulates it from getting very cold. However, some harmful gases when present in the atmosphere reflect the longer wavelength rays or heat energy back to the earth. The heat energy which would have escaped into space when reflected to the ground, heats it even further. This process of trapping the harmful heat energy, sending it back to the earth and increase earth’s temperature is called greenhouse effect. The harmful gases that trigger this process are called greenhouse gases. The gradual increase in earth’s temperature over the years due to greenhouse effect is known as global warming.
Causes of Greenhouse effect
Greenhouse effect is caused by greenhouse gases that disturb the energy balance on earth. The main greenhouse gases are water vapour (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and fluorinated greenhouse gases (Centre for Sustainable Systems). CO2, CH4 and N2O are natural gases and are stable in balanced concentrations. However, the proportion of these gases in the atmosphere has been increasing considerably over the years due to industrialisation, improved transportation, deforestation and use of fertilizers. CO2 is the main gas contributing to the harmful greenhouse effect, followed by CH4. The concentration of atmospheric CO2 has increased by 25% since 1850 (Schneider 771). The artificially created fluorinated greenhouse gases are used in refrigeration and distribution of electricity. This gases are present in atmosphere is very less quantity but have a major impact on heating of the earth surface. Once formed, these gases have high longevity and stay in air for thousands of years.
These greenhouse gases act as a mirror for the long wavelength infrared rays that are sent back to earth causing global warming.
Environmental Issues of Global Warming and Greenhouse Effect
Global warming is, primarily, caused by greenhouse effect. The harmful environmental issues of global warming and greenhouse effect are climate change, melting of polar ice caps, spread of diseases and economic losses.
The warming of the planet due to the effect of greenhouse gases affects the prevailing weather conditions in three main ways. First, it generates heat waves that damage the flora and further heat up the surface of earth. The heat wave that hit Europe in 2003 was one of its kinds and killed about 27,000 people (Wang and Chameides 3). Second, the intensity of flood and draught has increased in the recent years. Over the past 100 years, the contribution of heavy rainfall to total precipitation has increased from 7% to 12 % (Osborn and Maraun). Third, the global increase in temperature is affecting the melting polar ice caps causing a lot of environmental issues. A study conducted by the Intergovernmental Panel on Climate Change in 1999 indicates that impact of greenhouse gases on climate would be 2.6 to 11 times as large in 2050 as it was in 1992 (McCarthy 1).
Shrinking Snowpack and Rise in Sea Level
The rising temperature due to global warming is shrinking the snow cover of the mountains. Over the past 50 years, snow cover has reduced by 16% in the Rocky Mountains and by more than 50% in many sites of Washington (Wang and Chameides 13). Glaciers have also diminished considerably during these years. In regions with water scarcity, these snowpack and glaciers play an important role in supplying water for crops, aquatic life and generation of hydroelectricity.
Spread of Diseases
Higher temperature is favourable for multiplication of numerous vector borne diseases. It speeds up maturation, lengthens the activity and expands the geographical range for disease transmitting vectors. Incubation period of a mosquito is 12 days at 30°C and reduces to 7 days at 32 to 35°C (Wang and Chameides 24). Hence, resurgence of epidemic diseases also increases with rising temperature. According to World Health Organisation, global warming could lead to a major increase in insect borne disease in Britain and has called for an urgent action by the government (British Broadcasting Corporation)
Economic loss is an indirect consequence of the climatic change. Shifting of fishes and birds to different location impacts the economy of a region. Similarly, the impact shrinking of snowpack is felt on snow sports as artificial snow making is expensive. The spread of diseases in humans, animals and plants also leads to economic losses. Crops and energy generation is impacted adversely by shrinking of glaciers and mountain snowpack, thereby affecting economic growth.
Greenhouse effect and global warming impact human beings in multiple ways. The adverse effects are becoming increasingly visible in daily life. The key environmental issues are climatic change, rise in sea water level, shrinking snowpack and spread of diseases. All these issues contribute significantly to economic losses to a country. However, with increasing realization in governments, steps are being taken to reduce greenhouse gas emissions. Global negotiation submits like Kyoto Protocol is one such attempt to tackle global warming.
British Broadcasting Corporation. “Sci/Tech Global Warming Disease Warming”. Bbc.co.uk, 18 Jun. 1999. Web 3 May 2012
Centre for Sustainable Systems. “Greenhouse Gases”. Umich.edu, 2011. Web 3 May 2012.
McCarthy, James E. “Aviation and Climate Change”. Fas.org, 27 Jan. 2010. Web 26 Apr 2012
Osborn, Tim and Maraun, Douglas. “Changing Intensity of Rainfall over Britain”. Uea.ac.uk, 2008. Web 3 May 2012.
Schneider, Stephen H. “The Greenhouse Effect: Science and Policy”. Science, 243: 771-81. Online
Wang, James and Chameides, Bill. “Global Warming’s Increasingly Visible Impacts”. Environmentaldefense.org, 2005. Web 3 May 2012.