Global environmental change (an account on global warming and ozone depletion its causes, its effects and measures taken to reduce this)
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Global environmental change (an account on global warming and ozone depletion its causes, its effects and measures taken to reduce this)



this is about global warming and ozone depletion its causes,effects and remedies

this is about global warming and ozone depletion its causes,effects and remedies



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    Global environmental change (an account on global warming and ozone depletion its causes, its effects and measures taken to reduce this) Global environmental change (an account on global warming and ozone depletion its causes, its effects and measures taken to reduce this) Presentation Transcript

    • In 21st century this may be a major global problem. Major issues of global environmental changes are GLOBAL WARMING and OZONE DEPLETION in stratosphere.
    • One of the major environmental issues haunting people is Global warming. Everyone agrees that our planet is getting warmer.  Global Warming is one of the most dangerous situations, that the earth has to suffer in the upcoming years  It's very important to consider this problem, because it is the problem of human existence.
    • • Global warming is a phrase that is used to describe the increase in the earth s temperature.
    • Temperature increase ?
    • Why do you think the Earth’s natural warming process is named the greenhouse effect?
    • The natural process in which greenhouse gases trap heat from the Sun’s rays in the atmosphere is termed the greenhouse effect. It warms the atmosphere and sustains life on the Earth.
    • • The amount of greenhouse gases in the atmosphere has increased dramatically over the last two centuries because of industrialisation and other human activities. • Due to the rapid increase in the amount of greenhouse gases, more heat is trapped in the atmosphere, causing the phenomenon known as the enhanced greenhouse effect.
    • GREEN HOUSE GASES Greenhouse gases are those that can absorb and emit infrared radiation . The primary greenhouse gases in the Earth's atmosphere are • • • • • • Water vapor Carbon dioxide Methane Nitrous oxide Ozone. Chlorofluorocarbons ( CFC)
    • contribution of percentage of greenhouse gases to global warming 6% 14% CO2 CH4 CFCs 20% 60% N2O
    • Causes of global warming Sources of carbon dioxide: Burning fossil fuels in cars, factories and power plants Increase in greenhouse gas emissions due to human activities Sources of CFCs: Aerosol cans, airconditioners, refrigerators, pl astic forms Sources of nitrous oxides: Vehicle exhaust pipes, fertilisers, liv estock wastes Sources of methane: Landfills, rice paddies, guts of cattle
    • IMPACTS OF ENHANCED GREEN HOUSE EFFECT Global temperature increases Rise in sea level Effects on human Health And Agriculture
    • • Ice melting and rise in sea level • As the seas expand and ice in the Polar regions melts due to rising temperatures, sea levels around the world will increase. • Low-lying coastal wetlands and islands, coral reefs and parts of the world’s coastal cities will be subjected to flooding.
    • Changes in weather conditions • Prolonged droughts in dry regions • Frequent heat waves • Severe flooding in wet regions Severe flooding Severe drought
    • Impact on people • Rising temperatures in the Tropics allow mosquitoes to thrive, causing the spread of diseases like dengue fever, malaria and yellow fever • Heat waves cause people to die of dehydration or heat stroke.
    • • In the last 150 years, global temperatures have been rising and the amount of carbon dioxide in the atmosphere has reached phenomenal levels. • The ozone layer over the Polar regions has depleted to alarmingly low levels since the 1950s. Studies conducted by NASA have shown that ozone depletion over the Antarctic and Arctic regions will be at its worst between 2010 and 2019 1979 2005
    • OZONE DEPLETION • Ozone layer, a region of the atmosphere from 19 to 48km above the earth’s surface. • Ozone is formed by the action of sunlight on oxygen. • Concentration at ground level are dangerous to breath and can damage lungs
    • • However, because the ozone layer of the atmosphere protects life on earth from the full force of the sun’s cancer causing ultra violet radiation, it is critically important. • In 1985, scientists discovered that the ozone layer was so severely depleted to the extent that a gapping ‘hole’ had appeared in the ozone layer over the Antarctica. This gradual destruction of the ozone layer is known as ozone depletion.
    • • CFCs have been Cause of ozone identified as the main depletion cause of damage to the ozone layer. • CFCs are mainly found in aerosol cans, refrigerators, airconditioners and plastic foams. • Once CFCs are released into the air, the chlorine in them reacts and destroys the ozone particles in the ozone
    • •Although the ozone layer can replace itself over time as ozone is continually produced in the atmosphere, the rate of ozone depletion far exceeds that of its replacement. •With the depletion of the ozone layer, huge amounts of UV rays can reach the Earth’s surface. •This has severe consequences on animals, plants, and people UV rays reaching the Earth’s surface due to ozone depletion
    • Consequences of ozone depletion
    • Impact on animals and plants •The increase in UV radiation damages plant tissues and may destroy crops, causing a decline in food supply. •Excessive UV radiation kills plankton, which is the food for many marine animals. As a result, the survival of the marine animals dependent on plankton will be threatened. •Fish supply could decrease and some marine species may face extinction.
    • Impact on people •People may develop more severe sunburns, eye cataracts (clouding of the eye’s lens which reduces vision and if left untreated, may cause blindness), and skin cancers. •Excessive exposure to UV rays weakens the immune system, making people more vulnerable to illnesses and diseases.
    • Measures to Reduce the Impact of Ozone Depletion: International efforts Montreal Protocol (1987) • Signed by many countries around the world to reduce the emissions of CFCs • The ozone layer is estimated to recover to 1980s levels by 2050 and 1950 levels by 2100 if the world takes consistent preventive measures to ban the production and use of CFCs. • However, due to the persistent nature and huge amounts of CFCs in the atmosphere, ozone recovery will take a long time.
    • Measures to Reduce the Impact of Global Warming: International efforts Kyoto Protocol (1997) • Aims to reduce emissions of carbon dioxide, methane and nitrous oxide to about 5.2% below 1990 levels by 2012 • However, some developed countries did not sign the treaty because they argue it will adversely affect the profits of their industries and cause many people to lose their jobs.
    • Measures to Reduce the Impact of Global Warming: National efforts Using alternative sources of energy • Promoting the usage of vehicles that run on alternative fuel (e.g. hybrid cars) which consume less fuel and emit less pollutants • For example, Singapore introduced the Green Vehicle Rebate in 2001 to promote the use of ‘green’ cars. • From 01January 2006, buyers of hybrid cars are also entitled to tax incentives and rebates.
    • Measures to Reduce the Impact of Global Warming: National efforts Enforcing laws and regulations • Introduce and enforce laws that regulate the emission of greenhouse gases by vehicles, industries and power stations • Encourage industries to develop energy efficient technologies Look out for this green label on electrical appliances. Products with this label require less energy to produce which means less fossil fuels are burned during its production. Thus, less greenhouse gases are released into the atmosphere.
    • Measures to Reduce the Impact of Ozone Depletion: National efforts Reducing use of CFCs • Use of CFCs are banned in accordance to the Montreal Protocol • Ozone friendly substitutes are developed to replace CFCs in refrigerators, aerosol cans and air-conditioners. • For instance, since 1995, Singapore law requires all new cars to be fitted with CFC-free air-conditioning systems.
    • Measures to Reduce the Impact of Global Warming: Individual efforts Helping to reduce emissions of greenhouse gases • Taking public transport, choosing to cycle or walk to destinations whenever possible • Car pooling • Using energy efficient appliances
    • Measures to Reduce the Impact of Ozone Depletion: Individual efforts Helping to reduce ozone depletion • Avoid buying products which contain CFCs • Ensure proper disposal of products with CFCs, such as old air-conditioners, through a waste management company
    • Global Warming and Ozone Depletion: The Challenges Ahead • We have to take action now to reduce the catastrophic impacts of global warming and ozone depletion. • If every one puts in a little effort to change our lifestyles, it will go a long way to ensure that the Earth will be a pleasant place for our future generations.