Climate Change

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1. Introduction
Scientific evidence of the world’s changing climate is unequivocal. The expected impacts of the changing climate are likely to adversely affect the well being of all countries and particularly the poorest countries, some of which are in Africa. The changing climate has been manifested in the form of: increased severity and frequency of droughts; floods and storms; water stress, coastal erosion, and higher incidence of vector borne diseases among others. The resulting declines in agricultural productivity and food security, widespread incidence of water-related diseases, particularly in tropical areas have had a telling effect on economic development. The poorest countries and communities are likely to suffer the earliest and hardest because of their geographical location, low incomes, and low institutional capacity, as well as their greater reliance on climate-sensitive sectors. Addressing climate change is, therefore, central to achieving sustainable development and poverty reduction in the continent. Climate change is a long-term shift in the climate of a specific location, region or planet. The shift is measured by changes in features associated with average weather, such as temperature, wind patterns and precipitation. Climate change can manifest itself in a number of ways, for example changes in regional and global temperatures, changing rainfall patterns, expansion and contraction of ice sheets, and sea-level variations. These regional and global climate changes are responses to external and internal forcing mechanisms. Climate change occurs when the climate of a specific area or planet is altered between two different periods of time. This usually occurs when something changes the total amount of the sun's energy absorbed by the earth's atmosphere and surface. It also happens when something changes the amount of heat energy from the earth's surface and atmosphere that escapes to space over an extended period of time. Such changes can involve both changes in average weather conditions and changes in how much the weather varies around these averages. The changes can be caused by natural processes like volcanic eruptions, variations in the sun's intensity, or very slow changes in ocean circulation or land surfaces which occur on time scales of decades, centuries or longer. Humans also cause climates to change by releasing greenhouse gases and aerosols into the atmosphere, by changing land surfaces, and by depleting the stratospheric ozone layer. . Research by various scientists has shown that the temperature of the Earth is controlled by the balance between the input from energy of the sun and the loss of this back into space and that certain atmospheric gas are critical to this temperature balance and are known as greenhouse gases. (Greenhouse gases are the gases in an atmosphere that absorb and emit radiation within the thermal infrared range). The energy received from the sun is in the form of short-wave radiation, i.e. in the visible spectrum and ultraviolet radiation. On average, about one-third of this solar radiation that hits the Earth is reflected back to space. Of the remainder, some is absorbed by the atmosphere, but most is absorbed by the land and oceans. The Earth’s surface becomes warm and as a result emits long-wave ‘infrared’ radiation. The greenhouse gases trap and re-emit some of this long-wave radiation, and warm the atmosphere. Naturally occurring greenhouse gases include water vapor, carbon dioxide, ozone, methane, and nitrous oxide, and together they create a natural greenhouse or blanket effect, warming the Earth by 35°C. Despite the greenhouse gases often being depicted in diagrams as one layer, this is only to demonstrate their ‘blanket effect’, as they are in fact mixed throughout the atmosphere. The Earth’s atmosphere is composed of 78% nitrogen, 21% oxygen, and 1% other gases. It is these other gases that we are interested in, as they include the greenhouse gases....
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