GLOBAL WARMING – SCENARIO

-Dr. J. Kannan and A.R. Mohamed Haroon

Atmospheric green house gases trap the outgoing energy and enhance the heat-trapping capability of the earth causing global temperature increase. Problem arises because of increase in the concentration of green house gases, like carbon dioxide, water vapour, ozone, methane, nitrous oxides and chloro-fluoro carbons. The combustion of fossil fuels and other human activities are the primary reason for the increased concentration of carbon dioxide. Burning of solid wastes, oil, natural

gas, coal, wood and wood products release CO2 into atmosphere Globally, 5 billion metric tonnes of carbon is released every year into atmosphere that works out to approximately 1 metric ton / person. 

In the global warming scenario, industrial processes contribute to 49%. Next major source being the energy usage, the renewable energy production can reduce the global warming potential. It is also better to switch over from coal usage to natural gas. Even though, carbon dioxide is the major source gas for global warming, the hydro-fluoro carbon, nitrous oxide and methane potential are higher than the carbon dioxide. Industrial processes generating hydro fluoro carbons and sulphur hexafluoride should be stopped and sought for alternates. Global warming potential depends on the heat trapping

efficiency of different gases. For example, Nitrous oxide absorbs 270 times more heat per molecule than carbon dioxide. Nitrous oxide emitted from agricultural and industrial activities can be reduced by following scientific farming methods.

The present concentration of 446 ppm of carbon dioxide causes global warming all over the world. If the concentration exceeds 600 ppm, the survival of human beings may become a question. The gases emitted from countries like USA and European countries contribute to half of the green house gases. The impact of global warming includes increase in earth's temperature, melting of glaciers, increase in sea level, losses of coastal low lands, erosion of beaches leading to increased salinity in estuaries. This may cause the 50% loss of wetlands, loss of biodiversity and affects the marine living organisms.

Agriculture

In the agricultural sector, global warming can change the length of growing season of various crops. The yield of crops like corn, wheat and soybean may decrease eventhough the photosynthesis can be

increased by solar radiation. This is due to wagering of monsoon and unpredicted rainfall and droughts in the region. Heat stress and reduced precipitation, may also be reason for reduced yields. 

Increased temperature not only increases photosynthesis, but also the respiration. The cattle population suffers from mortality due to increased disease occurrence. Global warming also reduces the milk production. This may also lead to wide-spreading of insects and vectors disposing diseases.

Humans

Human beings may suffer from increase in malnutrition, damage to housing, loss of properties and increased human health risk. Reduction in water supplies, weather extremes like heat waves & droughts causes seawater warming leading to hurricanes and typhoons. Threats to human health include the spread of malaria, encephalitis, yellow fever and dengue fever.

Loss of biodiversity

Global warming leads to the death and extinction of tree frogs due to outbreak of fungal diseases.

Disappearance of habitats of Asian tiger may lead to reduction in number and even extinction. Changes in ocean temperature may affect the Australia's great barrier coral reef. Polar bear may become extinct due to loss of habitat. Sea turtles population may be reduced due to the reduction in male population. North Atlantic whale may face the problem of extinction. Agricultural scientists predict that 1oC increase may lead to reduction of paddy yield of 75 kg / ha. Prevention of global warming can be done by substitution of solar energy and wind energy instead of petrol, diesel and coal. In kitchen, it is better to use solar and electric cooker. Solid wastes may be converted as organic manure instead of burning. Afforestation and growing of more trees can help to control global warming. Soil erosion may be controlled by growing vettivers and shelter belts.

(Extracted from AgriGold India's SwarnaSedyam)