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| CORPORATE |  What is Global Warming? Records show that the earth's average surface air temperature has increased by between 0.3-0.6°C over the last century. Scientists of the Intergovernmental Panel on Climate Change (IPCC) now agree that human activities are having a noticeable impact on global climate and anticipate a further increase of 2°C or more by the year 2010. A number of factors affect global climate, such as the earth's orbit around the sun and volcanic and solar activity. The Greenhouse Effect is a natural phenomenon, without which the earth's surface temperature would be about -15°C and life could not be sustained. It works via certain gases in the atmosphere, which create a barrier to the infrared radiation of the sun's rays reflecting from the surface of the earth, the most important one being water vapour (or clouds). It is the addition of manmade global warming gases to the atmosphere that is believed to be causing an increase in average atmospheric temperatures. A decision to reverse this effect was taken at the United Nations Framework Convention on Climate Change (UNFCCC) in Rio de Janeiro in 1992, when international action was agreed to identify and control the release of man-made greenhouse gases. Even so global GHG emissions due to human activities have grown since pre-industrial times, with an increase of 70% between 1970 and 2004. What makes a gas a greenhouse gas? It is the ability of the gas to absorb infrared radiation that gives it its greenhouse properties. The strength of the effect of a particular greenhouse gas depends on three factors; the quantity of gas emitted in the atmosphere; its atmospheric lifetime; and the infrared reflecting properties of the molecule. The most abundant manmade greenhouse gas is carbon dioxide. Others include water vapour, methane, nitrous oxide, fluorocarbons and tropospheric ozone. Some manmade pollutants, primarily nitrous oxide and volatile organic compounds (such as hydrocarbons) have an indirect greenhouse effect as they react and generate ozone in the lower atmosphere, causing smog. Carbon dioxide, methane and nitrous oxide Atmospheric concentrations of carbon dioxide are about 35% higher than levels of 200 years ago. The global atmospheric concentration of CO2 increased from a pre-industrial value of about 280ppm to 379ppm in 2005. Human activities result Carbon dioxide (CO2) is the most important anthropogenic GHG (ie resulting from human activity). Its annual emissions have grown between 1970 and 2004 by about 80%, from 21 to 38 gigatonnes (Gt), and represented 77% of total anthropogenic GHG emissions in 2004. The largest growth in GHG emissions between 1970 and 2004 has come from energy supply, transport and industry, while residential and commercial buildings, forestry (including deforestation) and agriculture sectors have been growing at a lower rate. The problem is compounded as carbon dioxide has a long atmospheric lifetime. Around 25% of carbon dioxide emitted this year will still be in the atmosphere contributing to global warming in 500 years time. The two other main greenhouse gases in terms of emissions in 2004 are methane at 14.9% and nitrous oxide at 7.9%. HFCs The UNFCCC includes HFCs in the basket of "other gases" that contribute to global warming. However, the consideration of the relatively high GWPs of fluorocarbons must be set against the relatively small volumes emitted, the energy efficient quality of their applications and their role in replacing CFCs (which themselves have a much greater global warming impact than HFCs) and their use in important applications that benefit society. The F-Gases including HFCs contributed 1.1% to total GHG emissions in 2004 in terms of CO2 equivalents. While the use of HFCs is projected to grow, the development of fluorochemicals with substantially lower Global Warming Potential will considerably reduce the projected growth in HFC use and emissions if adopted globally. Legislation already in place will ensure a more efficient use of all fluorocarbons.  |