If global warming continues, rising temperatures might cause ice-caps to melt in the Polar Regions and a change in weather patterns.
Heat energy in the form of long and short wave solar radiation enters the earth's atmosphere. This electromagnetic radiation or light energy is reflected back onto Earth or emitted into space.
Greenhouse gasses in the lower layers of the atmosphere more readily absorb longer wavelength radiation from the sun and black body radiation from the Earth. Subsequently some heat energy is unable to escape, therefore warming of the atmosphere occurs. Short wavelength radiation is less readily absorbed by greenhouse gasses and does leave our atmosphere. Life on Earth could not exist without the naturally occurring Greenhouse Effect because it keeps the Earth's temperature at about 40C warmer than it would be without this process.
Since the industrial revolution human activities such as: increasingly specialized agriculture, land clearing and combustion of fossil fuels have acted to increase the amount of greenhouse gasses in the Earth's atmosphere. Currently, fossil fuels account for 80-85% of the carbon dioxide being added to the atmosphere. An increase in methane is sourced from the growing number of cattle being farmed across the globe, as cows release methane into the atmosphere. Other practices including coal mining and rice cultivation produce methane. Human activities have increased the concentration of methane 145% above what would be present naturally in the atmosphere. All these activities have increased the Earth's temperature, called Global Warming, which has resulted in changes meteorological patterns, influenced by the effect of Global Warming on our Polar Ice Caps.
The Ozone Layer is that part of the Earth's atmosphere that contains a relatively high concentration of ozone, namely a few parts per million by volume. Ozone or O3 is a naturally occurring atmospheric gas which blocks about 95% of Ultra Violet rays which can cause skin cancer and other DNA abnormalities, heat stroke and dehydration and so very important to humans.
Prior to 1978 chlorofluorocarbons were used in all refrigerators, air conditioners, solvents, fire extinguishers and aerosol propellants. This was a concern to scientists because the ozone layer can be depleted by "free radical catalysts", including the greenhouse gas nitric oxide but also by chlorine and bromide from the many man-made greenhouse gases like chlorofluorocarbons.
Ozone depletion from the interaction of UV radiation with chloride and bromide molecules of CFCs cause a significant thinning in the ozone layer known as the ozone hole, this most commonly occurs over certain areas, namely over the Arctic and Antarctic poles. These are called Ozone holes. Here, each free radical is able to start a chain reaction which breaks down 10,000 ozone molecules. Measures we have taken to reduce its size include recycling, installing solar energy for devices such as pool water heating, planting more trees, designing more energy efficient appliances and white goods, using different kinds of propellent and cooling gases such as HFCs.
The ozone level, over the northern hemisphere has dropped by 4% per decade since the introduction of CFC like compounds. In 2002 most CFC use was phased out for more environmentally friendly chemicals such as haloalkanes. Recently, taking into account seasonal changes, there has been a slight improvement in the ozone holes around the world as a result of the phasing out of CFCs. Also, in 1987 allying countries signed a treaty called the Montreal Protocol designed to enforce international cooperation in phasing out production of many substances believed to be responsible for ozone depletion.