Basics of Energy and Environment : Climate Change Notes

In recent times due to domestic and industrial coal burning, the concentration of radiative gages like CO₂, CH₄, N₂O and CFCs are increased in the lower atmosphere. As they can absorb long-wave infrared, these are known as greenhouse gases.

The increased amounts of greenhouse gages in the atmosphere are affecting the global climate and this phenomenon is recognized as Global Climate Change.

The sequence of greenhouse gases according to their harmful effect are:

CO₂ > CH₄ > N₂O > CFCs

Difference Between Climate and Weather:

Climate:

It is an outcome of the interaction of temperature, humidity, etc. of a particular place for a long period of time which should not be < 35 years.

Weather:

The weather or place is an outcome of the interaction of temperature, humidity, etc. for a shorter period of time.

The difference between weather and climate is a measure of time.

Weather is what conditions of the atmosphere are a short period of time, and climate is how the atmosphere behaves over a relatively long period of time.

In most places, weather can change from minute-to-minute, hour-to-hour, day-to-day, and season-to-season whereas climate is the average of weather over time and space.

Greenhous Gases

The word ‘Greenhous Gases’ was coined by Joseph Fourier.

The concept of greenhouse gases is derived from the glasshouses which were constructed in the polar region to ensure growth and development of greenery in the form of vegetable crops.

These glasshouses in polar areas are transparent to incoming solar radiations and opaque to outgoing long wave radiations, that is why, they trap heat energy which is used in the growth of vegetables and crops. Since greenhouse gases also work in the same way i.e., they are also transparent to incoming solar radiation and opaque to outgoing long wave terrestrial radiation, hence they raise the temperature of the atmosphere and responsible for global warming.

1.  Types of Greenhous Gases:

There are basically two types of greenhouse gases

Controlled: CO₂, CH₄, Nitrous Oxide(NO₂), CFC, HFC SF₆

Uncontrolled: Water vapor (H₂O) Ozone

The excessive increase in concentrations of these greenhouse gases in the atmosphere would retain more and more of the infrared radiation, resulting in an enhanced greenhouse effect.

2. Effects of Greenhous gases:

The increasing abundance of greenhouse in the atmosphere has the following possible effects:

1. CO₂ fertilization
2. Global warming
3. Depletion of Ozone layer in the stratosphere

GLOBAL WARMING

The term ‘Global Warming’ was given by Wally Brockert.

Global warming is a phenomenon which refers increase in a average temperature of atmosphere of the earth over long period of time.

Before pre-industrial revolution, average atmospheric temperature of earth was 15°C. Currently is 16.6°C. In last 100 years the increment is 0.76°-0.80°C.

Effects on Weather and Climate

The global mean temperature has increased by approximately 0.6°C in the 20^th Century. The average temperature of the earth may increase by 1.4 to 5.8°C by the year 2100 from the 1990 level.

The warming of the atmosphere will considerably increase its moisture carrying capacity. While the troposphere warms up, the stratosphere will cool down.

This would cause widespread changes in precipitation patterns due to the changing pattern of air-mass movement. Precipitation is expected to increase at higher latitudes in both summer and winter because temperature changes are expected to be most marked in the region of middle and higher latitude.

Approaches to Deal with Global Warming

Reducing the emulsion of greenhouse gases by limiting the use of fossil fuels.

Increasing vegetation cover.

Minimizing the use of N₂ fertilizer in agriculture for reducing N₂O emission.

Developing substitutes CFCs.

OZONE LAYER

The ozone layer was discovered in 1913 by French Physicists Charles Fabry and Henl Bulssion. Its properties were explored in detail by the British meteorologist G.M.B. Dobson who developed a simple spectrometer known as Dobson Meter, that is used in the measurement of the thickness of ozonosphere.

Dobson Unit (DU)

A Dobson Unit measure the total amount O₃ in an overhead column of the atmosphere.

DU are measured by how thick layer of ozone would be, if it is compressed into 1 layer at 0°C and with a pressure of 1 atmosphere above it.

1 DU = 0.01 mm

i.e. 1 mm = 100 DU

The average amount of ozone in the stratosphere across the globe is about 300 D.U. (i.e. thickness is only 3 mm)

Ozon Depletion

In 1974 Mario Molina and Sherwood Rowland California University U.S.A. theorised that UV rays from the sun would break-up chlorofluorocarbon in the stratosphere and what frees chlorine atoms which finally cause destruction of ozonosphere.

Absorption of UV radiation by ozone layer increases exponentially with its thickness. Therefore, maximum amount of UV-radiation passing through the atmosphere reaches the surface in the tropic region (i.e. near the equator).

The concentrations of O₃ in the stratosphere changes with seasons, the concentration being highest during the February-April (Spring season) period and lowest during July-October period.

The Ozone hole was first discovered in 1974 over Antarctica. It was also confirmed over Arctic in 1990.

The traditional measure of stratospheric ozone assume that if thickness of ozone is about 300 DU-350 DU then it is in normal condition. But if it decreases lower than 200 DU, then it is known as ozone hole

Such ozone loss now occurs every spring time above Antarctica and to a lesser extent above the Arctic region where special meteorological condition and very low air temperature causes the formation of ozone hole (Due to less temperature, oxygen in poles is less reactive and poles receive less UV rays).

Effect of Ozone Holes

• Decreasing the abundance of phytoplankton which effect the food stock fishes and absorption of CO₂.
• Decreasing the diversity of aquatic organisms which result into extinction of several fishes and amphibians

• Damage plant DNA molecules due to which plants are more susceptible to pathogens and pest attack.

• Reduction in photosynthetic capacity in the plants, which results in slower growth and smaller leaves.

• It also causes mutation mammals and destroys membranes.

• It is responsible for skin cancer.

• Cataracts and eye disorder.

• It effect immune system adversely

List of Ozone Depleting Elements

CFCs

Halons             

CCI₄

Methyl Chloroform     

Methyl Bromide

Substitutes of Ozone Depleting Elements

HFC(Hydrofluorocarbon)       

PFC(Perfluorocarbon)

NF₃(Nitrogen Trifluoride)       

SF6(Sulphur Hexafluoride)

Policies and Program to phase-out Ozone Depletion

1. Co-ordinating Committee Ozone layer was established UN Environment Program (UNEP) in 1970s.
2. Vienna Convention for protection of Ozone layer was held in 1985.
3. Montreal Protocol was laid down in 1987 and it was re-defined in London in 1990, in which, time limit was suggested for developed and developing countries to phase out ODS.

Developed countries had to phase out ODS by 2000 and developing countries by 2010.

India, being developing country, enacted Ozone Depletion Substances Act 2003 to phase out all ODS except for medicinal purpose.

CONVENTIONS ON CLIMATE CHANGE

There have been many conventions held on climate change. Some of them are.

• United Nations Framework on Climate Change (UNFCCC)

• Rio Summit (Earth Summit-I)

• Evolution of the concept of Conference of Parties (COP)

• Kyoto Protocol

• Durban Summit

NATIONAL ACTION PLAN ON CLIMATE CHANGE

National Action Plan on Climate Change was announced in 2008. It is coordinated by the Ministry of Environment, Forest, and Climate Change and executed by nodal ministries. The plan includes:

1. National Solar Mission: it aims at creating 20,000 MW solar electricity capacity in the country by 2020.
2. National Mission for Enhanced Energy Efficiency: its objective is to create new institutional mechanisms to enable the development and strengthening of energy efficiency markets.
3. National Water Mission: Its objective is to promote the integrated management of water resources and increase water use efficiency.
4. National Mission for Sustaining the Himalayan Ecosystem: Its objective is to establish an observational and monitoring network for the Himalayan ecosystem in order to access the climate impacts on the Himalayan glaciers.
5. National Mission for Sustainable Agriculture: This mission focuses on enhancing agricultural productivity and resilience, so as to reduce agricultural vulnerability to climatic conditions.
6. National Mission of Strategic Knowledge for Climate Change: The objective of this mission is to identify challenges arising from climate change and to promote developmental knowledge on the issue. Also to diffuse the knowledge in response to these challenges in the fields of health, demography, migration, and livelihood of coastal communities.
7. National Mission on Sustainable Habitat: This mission promotes the introduction of sustainable transport, energy-efficient buildings, and sustainable waste management in cities.
8. National Mission to Green India: This mission seeks to afforest an additional TO million hectares of forest lands, wastelands, and community lands.

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