a) Climate change
(i) Climate change refers to seasonal changes over a long period with respect to the growing accumulation of greenhouse gases in the atmosphere.
(ii) Industrial revolution has increased the concentration of carbon dioxide in the atmosphere by 40 %.
(iii) Several parts of the world have experienced warming of coastal waters, high temperatures, a marked change in rainfall patterns and an increased intensity and frequency of storms.
(iv) Sea levels and temperatures are expected to be rising.
b) Acid rain
(i) Acid rain is one of the results of air pollution.

(i) Electronic waste is the new by product of the Info Tech society.
(ii) It includes a growing range of electronic devices from household appliances, such as refrigerators, air conditioners, cell phones, computers.
(iii) e-waste can be defined as the result when consumer, business and household devices are sent for re-cycling (e.g., television, computers, audio-equipments, VCR, DVD, telephone, Fax, Xerox machines, wireless devices, video games).

Discharge of sewage and waste water:
(i) Sewage, garbage and liquid waste of households, agricultural runoff and effluents from factories are discharged into lakes and rivers.
(ii) These wastes contain harmful chemicals and toxins which make the water poisonous for aquatic animals and plants.
Dumping of solid wastes:
(i) The dumping of solid wastes and litters in water bodies cause huge problems.
Discharge of industrial wastes:
(i) Industrial waste contains asbestos, lead, mercury, grease oil and petrochemicals.
Oil Spill:
(i) Sea water gets polluted due to oil spilled from ships and tankers.
Acid Rain:
(i) When the acidic particles caused by air pollution mix with water vapour, it results in acid rain.
Global warming:
(i) The increase in water temperature affects aquatic plants and animals.
Eutrophication:
(i) The increased level of nutrients in water depletes oxygen in water and this negatively affects fish and other aquatic animal population.

Indoor Air Pollution:
(i) It refers to toxic contaminants that we encounter in our daily lives in our homes, schools and workplaces.
(ii) (e.g.) cooking and heating with solid fuels on open fires.
Outdoor Air Pollution:
(i) It refers to ambient air.
(ii) The common sources of outdoor air pollution are caused by combustion processes from motor vehicles, solid fuel burning and industry.

(i) The law of conservation of matter and energy, emphasizes that in any production system "what goes in must come out".
(ii) All resources extracted from the environment eventually become unwanted wastes and pollutants.
(iii) Production of output by firms from inputs results in discharge of solid, liquid and gaseous wastes.
(iv) Waste results from consumption activities by households.
(v) Thus material and energy drawn from environment are used for production and consumption and returned back to the environment as wastes.
(vi) \(\mathrm{R}=\mathrm{W}_{1}+\mathrm{W}_{2}\)
(vii) Input = Output