Slide 1:GLOBAL WARMING A THREAT TO THE WORLD PRESENTED BY N.V.RAVI SHEKHAR LECTURER DEPARTMENT OF CHEMISTRY DISHA INSTITUTE OF MANAGEMENT & TECHNOLOGY RAIPUR (C.G)


Slide 2:INTRODUCTION GLOBAL WARMING HAS BECOME A MAJOR SCIENTIFIC AND POLITICAL ISSUE OVER LAST DECADE. THE GLOBAL TEMPERATURE HAS INCREASED BY ONLY 4OC OVER THE LAST 18,000 YEARS. OWING TO RAPID INDUSTRALIZATION AND URBANIZATION TEMPERATURE HAS INCREASED BY ABOUT 1-1.5OC.THE RATE OF GLOBAL WARMING FOR THE PAST CENTURY WAS GREATER THAN ANY PERIOD SINCE 1880.THE EXPECTED INCREASE IN AVERAGE GLOBAL TEMPERATURE BY 3OC TO 4OC OVER A CENTURY MAY SEEM SMALL, BUT SCIENTISTS SAY THAT IT IS SUFFICIENT TO MELT POLAR ICE CAPS AND INCREASE THE SEA LEVEL BY A METRE. SCIENTIST ARE CONCERNED ABOUT THE WARMING TREND AND CONCERNED TO BE EMERGING WITH EVERY PASSING YEAR.


WHAT IS GLOBAL WARMING ? :WHAT IS GLOBAL WARMING ? Global Warming is the increase in the average temperature (by3-4OC over a Century) of earth’s surface air and oceans due to green house gases. (GREEN HOUSE EFFECT)


WHAT IS GREEN HOUSE EFFECT ? :WHAT IS GREEN HOUSE EFFECT ? The term green house effect was first coined by J-Fourier in 1827 and was first investigated quantitatively by Svante Arhenius. The green house effect is a warming effect produced by the presence of carbondioxide, CFC’s, methane, nitrous oxides and water vapour in the lower atmosphere. The effect is also called as Atmospheric effect or Global warming or carbondioxide problem.


CAUSES OF GLOBALWARMING :CAUSES OF GLOBALWARMING Carbondioxide (CO2) Methane (CH4) Chlorflurocarbons (CFC’s) Nitrogen Oxide (N2O)


Slide 6:CO2-50% CH4-19% CFC-17% O3-8% N2O-4% H2O-2% PERCENTAGE COMPOSITION OF GREEN HOUSE GASES


Slide 7:CO2 CO2 CO2 CO2 Factory V V OCEAN CO2?HCO3 CO3- WORKING OF GREEN HOUSE EFFECT V V


Slide 8:WORKING OF GREEN HOUSE Carbondioxide absorbs infrared radiations or reflects it back to the earth.CO2 works as glass and allows the solar radiations in it and holding back the longer wavelength radiation, which attempts to return. The result is warmer temperature in the green house than outside. The overall process is natural and an essential system for maintaining the earth’s temperature. Without carbondioxide in the atmosphere the earth’s surface would cool very rapidly at night, much more rapidly than at present. On the other hand, increasing or reducing the amount of carbondioxide in the atmosphere could increase or slow down the speed at which the green house effect occurs.


Slide 9:Thus green house is a phenomenon which is based on the principle of infrared absorption of gases. Higher the concentration of CO2 greater will be the absorption of heat radiation and also increasing global temperature. Thus green house may be defined as “The progressive warming up of the earth surface due to blanketing effect of man made CO2 in the atmosphere” or we can say it is “The phenomenon due to which the earth retains heat”.


MECHANISM OF GREEN HOUSE EFFECT :MECHANISM OF GREEN HOUSE EFFECT SOLAR RADIATION EARTH SURFACE INFRARED REMITTED FROM EARTH & ABSORBED BY CO2


Slide 11:Red colour indicates global warming


Slide 15:PICTURE OF A HOUSE IN VISIBLE RAYS INFRARED RAYS


MAJOR SOURCES OF GREEN HOUSE EFFECT :MAJOR SOURCES OF GREEN HOUSE EFFECT Factories, power stations those use fossil fuels (Coal, Oil etc). Automobiles, railways, aircraft etc use immense quantity of petrol, diesel etc. Burning of fire woods and deforestation. Halogenated gases (CFC’s) are also released while using as Coolants and propellants. Large scale forest fire also contributes to the release of CO2


IMPACT OF GREEN HOUSE EFFECT ON GLOBAL CLIMATE :IMPACT OF GREEN HOUSE EFFECT ON GLOBAL CLIMATE With rise in temperature, oceans warm and sea level would rise flooding low lying regions. In temperate regions (i) Winter- shorter & warmer. (ii) Summer-long and hotter. Increase in industralization & decrease in forests will create a layer of impenetrable gases.


Contd… :Contd… Ecosystem (Plants and Animals) will be affected. Plants will be less rich in nitrogen resulting high susceptible to pests.


CONSEQUENCES OF GREEN HOUSE EFFECT :CONSEQUENCES OF GREEN HOUSE EFFECT With increase in CO2, temperature of earth rises causing more evaporation of surface water leading to further temperature increase.


Contd… :Contd… Increase in CO2 causes more oceans warmer hence more cyclones and hurricanes and early snow melt in mountains will cause floods in monsoons.


Slide 21:Contd… Rise in temperature will result in receding of glaciers and melting of polar ice caps, hence increase in sea level.


Slide 22:A PICTURE OF A POLAR BEAR


Slide 23:Contd… At higher altitude CO2 undergo photochemical reactions producing CO which is drastically dangerous.


Contd… :Contd… With increase in temperature world food production will be affected hence it is necessary to maintain at least one third forest area of total land on earth.


CONTROL & REMEDIAL MEASURES OF GREEN HOUSE EFFECT :CONTROL & REMEDIAL MEASURES OF GREEN HOUSE EFFECT Reducing the consumption of fossil fuel by depending on Non-conventional energy sources. Greenery and reforestation is only the immediate solution for reducing CO2 concentration. Biogas is the another alternative source of conventional energy for domestic use.


Slide 26:Contd… Buy energy efficient appliances with the “Energy star” label. Learn to adapt and accept the changing climate. International co-operation for attempting to reduce green house gases.


Slide 27:The developed countries should give sufficient aid to under developed countries to generate solar energy on commercial level. Contd…


Slide 28:THANK YOU