· Global warming refers to a gradual rise of atmospheric temperature and consequent changes in the radiation balance mainly due to human action leading to climatic change at different levels – local, regional and global.
· As per recent estimates, it has been found that the surface air temperature over the past 100 years has increased by about 0.50C to 0.70C. This is due to green house effect.
Working of a Green House :
· In cold countries, a green house is meant for plants, where total heat, especially during winter season, is not sufficient to support plant growth.
· The transparent walls and roof of the green house are such that these allow the visible sunlight to enter but prevent the longwave radiations to go out.
· Thus, the sunlight is absorbed by the soil and structure of the green house.
· It is then re-emitted as heat which can not pass through the glass.
· The amount of energy in the green house thus increases until its temperature is high enough for the slight leakage of heat through the glass to take away as much energy as gets in as sunlight.
· Subsequently walls and roof re-emit absorbed radiation into the house.
· Thus, during the day time, infra-red radiation pass into the green house and warm the atmosphere and the ground on which the green house stands.
· Coating of glass with a non-heat radiation film transparent to sunlight further maximizes heating effect of the radiation.
· Therefore, if our earth has become a green house, then there are certain gases which act like the glass panels of a green house allowing the sun’s rays to pass through but preventing the heat from escaping into the outer space and there by warming the atmosphere.
· This is happening due to deforestation and industrialization.
· These gases are
1. carbon dioxide (CO2),
2. methane (CH4)
3. nitrous oxides (NOx) and
4. chlorofluorocarbon (CFC) and hence known as green house gases.
· Out of these four gases,
1. carbon dioxide contributes about 55%,
2. chlorofluorocarbon contributes about 24%,
3. methane (about 15%) and
· Do you know the sources of these gases?. Burning of fossil fuels and fire woods, large fleet of automobiles and number of factories emit carbon dioxides.
· Growing paddies, livestock, waste dumps and coal mining are the major source of methane.
· The use of aerosols as coolants in refrigerators and air conditioning devices release chlorofluorocarbons into the atmosphere Nitrous oxide is mainly emitted from chemical industries, and due to deforestation and certain agricultural practices.
· Construction of green houses in temperate region helps the plant protection and ecological balances whereas concentration of green house gases on the earth’s atmosphere upsets the earth’s biological system.
Consequences of green house effect :
· It is estimated that if the present rate of increase in CO2 level continues, it will result in rise of atmospheric temperature by 20C to 30C by end of 21st century.
· This will result in receding many glaciers; melting of icecaps in the polar regions and disappearance of deposits of ice on the other parts of world in large scale.
· According to an estimate, if all the ice on the earth would melt, about 60M of water would be added to surface of all oceans and low lying coastal areas.
· A rise in sea-level of only 50-100 cm caused by global warming would flood low lying areas of the world such as Bangladesh, West Bengal as well as densely populated coastal cities from Shanghai to San-Fancisco.
· Because of increased concentration of CO2 and due to much warmer tropical oceans, there may occur more cyclones and hurricanes.
· Early snow melt in mountains will cause more floods during monsoon.
· According to United Nations Environment Programme (UNEP), within about three decades, rising levels of seas will be able to and flood coastal cities like Bombay, Boston, Chittgang and Manila.
· A slight increase in global temperature can adversely affect the world food production.
· Thus the wheat production zones in the northern latitudes will be shifted to north of temperate latitudes.
· The biological productivity of the ocean would also decrease due to warming of the surface layer, which in turn reduces the transport of nutrients from deeper layers to the surface by vertical circulation.
Control and Remedial Measures of Green House Effect :
· CO2 concentration can be reduced by drastic cut in the consumption of fossil fuels in the highly developed and industrialized countries like USA and Japan and developing country like China and India.
· Scientific efforts should be made to develop alternative efficient fuels. Methane may be a substitute of petroleum.
· Development of hydro-electric better alternatives.
· There should be a restriction on the emission of dangerous CO2, CFCs, and as NO2 from the factories and automobiles.
· Limiting the driving days in megacities can be another option. Cities like singapore and mexico are following the practice.
· In tropical and sub-tropical countries, the solar energy may be developed as an alternative to the fossil fuels.
· Biogas plants should be used which is another source of conventional energy for domestic use.
· Enhancing afforestation will certainly reduce the CO2 level thereby decreasing the green house effect.
Emerging Trends in Environmental Management :
Kyoto Protocol :
· The Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) is an international treaty that sets binding obligations on industrialized countries to reduce emissions of greenhouse gases.
· The UNFCCC is an environmental treaty with the goal of preventing dangerous anthropogenic (i.e., human-induced) interference of the climate system.
· There are 192 parties to the convention: 191 states (including all the UN members except Andorra, Canada, South Sudan and the United States) and the European Union.
· The United States signed but did not ratify the Protocol and *Canada withdrew from it in 2011. The Protocol was adopted by Parties to the UNFCCC in 1997, and entered into force in 2005 .
· As part of the Kyoto Protocol, many developed countries have agreed to legally binding limitations/reductions in their emissions of greenhouse gases in two commitments periods.
· The first commitment period applies to emissions between 2008-2012, and the second commitment period applies to emissions between 2013-2020.
· The protocol was amended in 2012 to accommodate the second commitment period, but this amendment has (as of January 2013) not entered into legal force
Global Warming Potential (GWP) :
· GWP is the global warming impact that a GHG would have over a 10-year timeframe .
· By definition, CO2 is used as the reference benchmark .
Details of the Agreement :
· National emission targets specified in the Kyoto Protocol exclude international aviation and shipping.
· Kyoto Parties can use land use, land use change, and forestry (LULUCF) in meeting their targets.
· LULUCF activities are also called "sink" activities. Changes in sinks and land use can have an effect on the climate.
· Forest management, cropland management, grazing land management, and revegetation are all eligible LULUCF activities under the Protocol
Carbon Credits :
· “A carbon credit is a generic term for any tradable certificate or permit representing the right to emit one tone of carbon dioxide or the mass of another greenhouse gas with a carbon dioxide equivalent (CO2) to one ton of carbon dioxide.
· Carbon credits and carbon markets are a component of national and international attempts to mitigate the growth in concentrations of greenhouse gases.
· If a cement manufacturer reduces its CO2 emissions by one ton by adapting some changes into its process or by any other means; say just by planting some trees around its plant, it is awarded ―one carbon credit.
· This carbon credit can be sold to any industry, allowing it to emit one extra ton of CO2 than its allowable limit.
Clean Development Mechanism (CDM):
· The Clean Development Mechanism (CDM) is one of the flexibility mechanisms defined in the Kyoto Protocol (IPCC, 2007) that provides for emissions reduction projects which generate Certified Emission Reduction units which may be traded in emissions trading schemes.
National Clean Development Mechanism (CDM) Authority :
· Accordingly the Central Government constituted the National Clean Development Mechanism (CDM) Authority for the purpose of protecting and improving the quality of environment in terms of the Kyoto Protocol;
Ecological Footprint :
· The Ecological Footprint is a measure of human demand on the Earth's Ecosystems.
· It is a standardized measure of demand for natural capital that may be contrasted with the planet's ecological capacity to regenerate.
· It represents the amount of biologically productive land and sea area necessary to supply the resources a human population consumes, and to assimilate associated waste.
· Using this assessment, it is possible to estimate how much of the Earth (or how many planet Earths) it would take to support humanity if everybody followed a given lifestyle.
The Convention on Biological Diversity (CBD) :
- CBD, known informally as the Biodiversity Convention, is a multilateral treaty.
The Convention has three main goals:
· conservation of biological diversity (or biodiversity)
· sustainable use of its components; and
· fair and equitable sharing of benefits arising from genetic resources