Mitigation Strategies and Solutions Essay Example | Topics and Well Written Essays - 1750 words

Mitigation Strategies and Solutions - Essay Example Kemp (2004) estimates that the earth’s surface temperature have increased by 0.3Â °c-0.6Â °c since 1900. The years 1995-2006 ranked amongst eleven of the twelve warmest years on record since climatic records began in 1850. The IPCC also estimates that by 2020, the earth’s temperatures will have risen by a further 0.2Â °c. Natural Causes/Contributions of Global Warming Earth’s Orbital Variation The Milankovitch Theory of climate change predicts that the Earth’s orbit around the sun is not a perfect circle but an ellipse, which makes the earth closer to the sun at certain periods. This currently occurs in January, making northern hemisphere winters slightly milder than previous winters. With greater eccentricity the length of the Earth’s seasons varies, which can lead to the build up of ice sheets when there are cooler summers. Sun Spot Activity The sun is now believed to be its most active for 300 years (Kemp, 2004). In the past 120 years, 0.5Â ° c rise in global temperatures occurred before 1940, which is earlier than the biggest rise in greenhouse gas (GHG) emissions released by humans. Further evidence comes from tree ring data in which 17 out of 19 of the warmest spells in the past 10,000 years coincided with peaks in solar activity (Goudie, 2000). Ocean Circulation Changes The Earth’s oceans cover around 70% of the Earth’s surface and absorb twice the amount of sun’s radiation as the atmosphere of the land surface (Jackson and Jackson, 1996). With their huge heat capacity, and means to move vast quantities of heat across the planet, they have a major effect on the earth’s temperatures, e.g. during an El Nino cycle, the west coast of South America experiences higher temperatures with greater rainfall due to the transportation of warm waters from the South Pacific replacing the usual up-welling of nutrient rich cooler waters (Thomas and Goudie, 2000). The North Atlantic Jet and Gulf Stream also has a major affect on the earth’s surface temperatures in North Europe, which transports warm heat from the Caribbean up to high latitudinal regions making temperatures artificially high for their latitudinal position. Human Causes/Contributions of Global Warming Burning of Fossil Fuels The burning of fossil fuels such as coal, oil and gas releases anthropogenic emissions of GHG’s, such as carbon dioxide, methane, nitrous oxide and halocarbons. These gases absorb some of the infrared radiation emitted by the Earth which would otherwise escape back into space. This creates the enhanced greenhouse effect, in which increased CO? levels (280ppm from pre industrial levels to 379pmm by 2005) have warmed global temperatures by around 0.5Â °c over the past century (IPCC, 2007) Deforestation The world’s forests have decreased by around 38% over the past century (Jackson and Jackson, 1996). This has led to increased levels of CO? in the earth’s atmosphere because there are not enough trees to absorb the additional carbon rates caused by increased human activity. Increased agriculture and livestock such as cows release significant amounts of methane, which contribute towards global warming. Levels of methane have doubled since pre-industrial times to 1.765 ppmv (Kemp, 2004). CFC’s CFC’s and other halocarbons released from refrigerators, insulating foams, aerosol spray cans and industrial plants all destroy the stratospheric ozone, and are a significant cause of global warming due to their higher concentration levels of greenhouse gases (Goudie, 2000). Positive and Negative