UNIT–III: Global climatic issues and mitigation strategies

Greenhouse effect –global warming – acid rain – ozone layer depletion – International efforts-key initiatives of Montreal protocol, Rio declaration, Kyoto protocol, Johannesburg summit.

Acid Rain

• Acid rain is a broad term that includes any form of precipitation with acidic components, such as sulfuric or nitric acid that fall to the ground from the atmosphere in wet or dry forms.  This can include rain, snow, fog, hail or even dust that is acidic. 

Effects of Acid Rain

• Acid rain has been shown to have adverse impacts on forests, freshwaters, and soils, killing insect and aquatic life-forms, causing paint to peel, corrosion of steel structures such as bridges, and weathering of stone buildings and statues as well as having impacts on human health.

Ozone and Environment

Ozone

• O₃
• a gas composed of three atoms of oxygen
• bluish gas that is harmful to breathe
• Nearly 90% of the Earth's ozone is in the stratosphere and is referred to as the ozone layer
• Ozone absorbs a band of ultraviolet radiation called UVB

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Ozone-Depleting Substance(s) (ODS): �

• CFCs,
• HCFCs,
• halons,
• methyl bromide,
• carbon tetrachloride, and
• methyl chloroform.

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Various sources

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Effects of OLD

• -- Skin Cancer (melanoma and nonmelanoma)�-- Premature aging of the skin and other skin problems�-- Cataracts and other eye damage�-- Immune system suppression

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The Antarctic Ozone Hole�

• The ozone hole is defined as the area having less than 220 dobson units (DU) of ozone in the overhead column (i.e., between the ground and space).

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EGEE 102 - Pisupati

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Source: http://jwocky.gsfc.nasa.gov/multi/recent_ozone91200.gif

What can we do?

• Make sure that technicians working on your car air conditioner, home air conditioner, or refrigerator are certified by an EPA approved program to recover the refrigerant (this is required by law).
• Have your car and home air conditioner units and refrigerator checked for leaks. When possible, repair leaky air conditioning units before refilling them.

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What can we do?

• Contact local authorities to properly dispose of refrigeration or air conditioning equipment.
• Protect yourself against sunburn. Minimize sun exposure during midday hours (10 am to 4 pm). Wear sunglasses, a hat with a wide brim, and protective clothing with a tight weave. Use a broad spectrum sunscreen with a sun protection factor (SPF) of at least 15 and 30 is better.

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Ground level Ozone Formation

• Secondary Pollutant
• VOCs+ NO_x 🡪 Ozone
• In presence of sunlight
• Ozone + NO_X + HCs 🡪 Smog (haze)

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Photochemical Smog

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Smog Sources

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Source: http://www.epa.gov/oar/oaqps/regusmog/smog.html

Sources of Volatile Organic Carbons

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Sources of NO_x

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What can We do?

• Keep your automobile well tuned and maintained.
• Carpool, use mass transit, walk, bicycle, and/or reduce driving, especially on hot summer days.
• Be careful not to spill gasoline when filling up your car or gasoline-powered lawn and garden equipment. During the summer, fill your gas tank during the cooler evening hours.

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What can we do?

• Make sure your car's tires are properly inflated and your wheels are aligned.
• Participate in your local utility's energy conservation programs.
• Seal containers of household cleaners, workshop chemicals and solvents, and garden chemicals to prevent VOC from evaporating into the air. Dispose of them properly.

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