CHAPTER 10: GLOBAL WARMING AND OZONE DEPLETION

ENHANCED GREENHOUSE EFFECT: CAUSES

-co2 -nitrous oxide -CFCs -methane

Temperature at or near the Earth's surface is determined by:

-Amount of sunlight the Earth receives -Amount of sunlight the Earth reflects -Retention of heat by the atmosphere -Evaporation and condensation of water vapour

OZONE LAYER DEPLETION: causes

-CFCs main cause -chlorine contained in CFCs are destroying ozone molecules → rate of ozone depletion increase -ozone layer depleting faster than it can recover

GREENHOUSE EFFECT:

-Earth is surrounded by a layer of gases - atmosphere. -Sun's rays pass through the atmosphere and are reflected by the Earth's surface. -Gases in the atmosphere trap some of the heat - warming the Earth's surface and the lower atmosphere. -Gases such as water vapour, carbon dioxide, methane, nitrus oxide and CFCs are known as greenhouse gases (GHG).

OZONE LAYER DEPLETION: measures to reduce impacts - individual

-Helping to reduce emissions of GHG. → Taking public transport. → Using appliances that are more energy-efficient. -Helping to reduce ozone depletion. → Avoid buying products that contain CFCs.

OZONE LAYER DEPLETION: definition

the gradual destruction of the ozone layer caused mainly by the release of chlorofluorocarbons (CFCs) into the atmosphere

OZONE LAYER DEPLETION: measures to reduce impacts - international 2

-Kyoto Protocol in 1997, required developed countries to reduce emissions of greenhouse gases by an average of 5.2% by 2012. -In 2005, 141 countries engaging in human activities that contribute to 55% of the emissions of greenhouse gases have acceded to the treaty. -Unfortunately not all developed nations are responding to the urgency of the issue as they are concerned that the profits of their industries would be affected. -In April 2006, Singapore acceded to the treaty.

OZONE LAYER DEPLETION: measures to reduce impacts - international 1

-Montreal Protocol in 1987, signed by 24 nations - reduction of global emissions of CFCs to 50% of 1986 emissions. -Since the protocol was signed, it has become apparent that ozone depletion is a much more serious problem. -Even with the stipulation met, ozone depletion will result in 5% to 20% more ultraviolet radiation reaching the Earth in the next 40 years. -Not all chemicals that cause ozone layer depletion are covered by the protocol. -Unfortunately not all industrial nations are responding to the urgency of the issue due to the economic gap between wealthy and poorer nations. E.g. China and India chose not to participate in the protocol.

EFFECTS OF GLOBAL WARMING

-Temperatures increased more at the Poles than at the Equator. -changes in weather conditions -impacts on plants and animals -impact on people -rising sea level

OZONE LAYER DEPLETION: measures to reduce impacts - national

-Using alternative sources of energy. -Promote the usage of vehicles that run on alternative fuel e.g. hybrid vehicles that run on petrol and electric batteries. -Enforcing laws and regulations. -Reducing use of CFCs → illegal to import products containing CFCs into Singapore

OZONE LAYER DEPLETION: effects

-impact on plants and animals → damage to earth's food chains both on land & in oceans -impacts on humans → human health effects

GREENHOUSE EFFECT: definition

Greenhouse effect is a natural process that helps to make the Earth a warm and comfortable place to live in.

GLOBAL WARMING: definition

Natural or human induced increase in the average global temperature of the atmosphere near the Earth's surface.

ENHANCED GREENHOUSE EFFECT: definition

an accelerated greenhouse effect caused by rapid increase in the amount of greenhouse gases in the atmosphere, trapping more heat from the sun in the lower atmosphere