Green House Effect is a process by which radiant heat from the sun is captured by gases in the atmosphere that increase the temperature of the earth ultimately. The gases that capture heat are called CH4 20% CO2 60% Green House Gases which include carbon dioxide CFC 14% (CO2), methane (CH4), Nitrous Oxide (N2O) and a variety of manufactured chemicals like chlorofluorocarbon (CFC). Increase in greenhouse gases lead to irreversible changes in major ecosystems and climate patterns. For example, coral ecosystem is affected by increase in temperature, especially coral bleaching observed in Gulf of Mannar, Tamil Nadu.
Human activities lead to produce the green house effect by
• Burning fossil fuels, which releases CO2 and CH4
• Way of Agriculture and animal husbandry practices
• Electrical gadgets like refrigerator and air conditioners release chloro fluoro carbons
• The fertilizers used in Agriculture which release N2O
• The emissions from automobiles. T he increase in mean global temperature (highest in 4000 years) due to increased concentration of green house gases is called global warming. One of the reasons for this is over population which creates growing need for food, fibre and fuel and considered to be the major cause of global warming.
Effects of Global Warming
• Rise in global temperature which causes sea levels to rise as polar ice caps and glaciers begin to melt causing submergence of many coastal cities in many parts of the world.
• There will be a drastic change in weather patterns bringing more floods or droughts in some areas.
• Biological diversity may get modified, some species ranges get redefined. Tropics and sub-tropics may face the problem of decreased food production.
Sources of Green House Gases Emission (Natural and Anthropogenic)
CO2 (Carbon dioxide)
• Coal based power plants, by the burning of fossil fuels for electricity generation.
• Combustion of fuels in the engines of automobiles, commercial vehicles and air planes contribute the most of global warming.
• Agricultural practices like stubble burning result in emission of CO2.
• Natural from organic matter, volcanoes, warm oceans and sediments.
Methane is 20 times as effective as CO2 at trapping heat in the atomosphere. Its sources are attributed paddy cultivation, cattle rearing, bacteria in water bodies, fossil fuel production, ocean, non-wetland soils and forest / wild fires.
N2O (Nitrous oxide)
It is naturally produced in Oceans from biological sources of soil and water due to microbial actions and rainforests. Man-made sources include nylon and nitric acid production, use of fertilizers in agriculture, manures cars with catalytic converter and burning of organic matter.
Global Warming Effects on Plants
• Low agricultural productivity in tropics
• Frequent heat waves (Weeds, pests, fungi need warmer temperature)
• Increase of vectors and epidemics
• Strong storms and intense flood damage
• Water crisis and decreased irrigation
• Change in flowering seasons and pollinators
• Change in Species distributional ranges
• Species extinction